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  Subjects -> ENGINEERING (Total: 2358 journals)
    - CHEMICAL ENGINEERING (201 journals)
    - CIVIL ENGINEERING (192 journals)
    - ELECTRICAL ENGINEERING (107 journals)
    - ENGINEERING (1240 journals)
    - ENGINEERING MECHANICS AND MATERIALS (394 journals)
    - HYDRAULIC ENGINEERING (56 journals)
    - INDUSTRIAL ENGINEERING (72 journals)
    - MECHANICAL ENGINEERING (96 journals)

CIVIL ENGINEERING (192 journals)                     

Showing 1 - 194 of 194 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 20)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 37)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 31)
Agregat     Open Access   (Followers: 1)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 33)
Architectural Engineering     Open Access   (Followers: 5)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 2)
Archives of Civil Engineering     Open Access   (Followers: 12)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 4)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 6)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 9)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bioinspired Materials     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 14)
Building & Management     Open Access   (Followers: 1)
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 14)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 6)
Canadian Journal of Civil Engineering     Hybrid Journal   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 11)
Case Studies in Structural Engineering     Open Access   (Followers: 9)
Cement and Concrete Composites     Hybrid Journal   (Followers: 19)
Challenge Journal of Concrete Research Letters     Open Access   (Followers: 3)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 6)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 8)
Civil And Environmental Engineering Reports     Open Access   (Followers: 7)
Civil and Environmental Research     Open Access   (Followers: 17)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 21)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 11)
Civil Engineering Dimension     Open Access   (Followers: 10)
Civil Engineering Infrastructures Journal     Open Access   (Followers: 1)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 272)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 11)
Computers & Structures     Hybrid Journal   (Followers: 38)
Concrete Research Letters     Open Access   (Followers: 7)
Construction Economics and Building     Open Access   (Followers: 4)
Construction Engineering     Open Access   (Followers: 11)
Construction Management and Economics     Hybrid Journal   (Followers: 21)
Construction Science     Open Access   (Followers: 5)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 3)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal   (Followers: 1)
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 17)
Enfoque UTE     Open Access   (Followers: 4)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 7)
Engineering Structures     Hybrid Journal   (Followers: 13)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 10)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 9)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 17)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 6)
Geomaterials     Open Access   (Followers: 3)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotechnik     Hybrid Journal   (Followers: 3)
Géotechnique Letters     Hybrid Journal   (Followers: 7)
GISAP : Technical Sciences, Construction and Architecture     Open Access  
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indonesian Journal of Urban and Environmental Technology     Open Access  
Indoor and Built Environment     Hybrid Journal   (Followers: 2)
Infrastructure Asset Management     Hybrid Journal   (Followers: 2)
Infrastructures     Open Access  
Ingenio Magno     Open Access   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 29)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 3)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 17)
International Journal of Civil, Mechanical and Energy Science     Open Access   (Followers: 1)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 15)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 10)
International Journal of Geo-Engineering     Open Access   (Followers: 3)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 4)
International Journal of Masonry Research and Innovation     Hybrid Journal   (Followers: 1)
International Journal of Pavement Research and Technology     Open Access   (Followers: 6)
International Journal of Protective Structures     Hybrid Journal   (Followers: 6)
International Journal of Steel Structures     Hybrid Journal   (Followers: 2)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 8)
International Journal of Structural Integrity     Hybrid Journal   (Followers: 2)
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Built Environment     Open Access   (Followers: 5)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 8)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 7)
International Journal Sustainable Construction & Design     Open Access   (Followers: 1)
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 14)
Journal of Building Engineering     Hybrid Journal   (Followers: 1)
Journal of Building Materials and Structures     Open Access   (Followers: 2)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 14)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 9)
Journal of Civil Engineering Research     Open Access   (Followers: 7)
Journal of Civil Engineering, Science and Technology     Open Access   (Followers: 1)
Journal of Civil Society     Hybrid Journal   (Followers: 4)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites     Open Access   (Followers: 80)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 13)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 23)
Journal of Construction Engineering     Open Access   (Followers: 8)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 18)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 6)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 4)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 6)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 2)
Journal of Green Building     Full-text available via subscription   (Followers: 10)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 14)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 19)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 5)
Journal of Marine Science and Engineering     Open Access   (Followers: 1)
Journal of Materials and Engineering Structures     Open Access   (Followers: 5)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 7)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 9)
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 3)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 6)
Journal of Rehabilitation in Civil Engineering     Open Access   (Followers: 3)
Journal of Solid Waste Technology and Management     Full-text available via subscription   (Followers: 1)
Journal of Structural Engineering     Full-text available via subscription   (Followers: 36)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 6)
Journal of Sustainable Architecture and Civil Engineering     Open Access   (Followers: 3)
Journal of Sustainable Design and Applied Research in Innovative Engineering of the Built Environment     Open Access   (Followers: 1)
Journal of the Civil Engineering Forum     Open Access  
Journal of the South African Institution of Civil Engineering     Open Access   (Followers: 2)
Journal of Water and Environmental Nanotechnology     Open Access  
Jurnal Spektran     Open Access   (Followers: 1)
Jurnal Teknik Sipil dan Perencanaan     Open Access   (Followers: 1)
Konstruksia     Open Access  
KSCE Journal of Civil Engineering     Hybrid Journal   (Followers: 2)
Latin American Journal of Solids and Structures     Open Access   (Followers: 4)
Materiales de Construcción     Open Access   (Followers: 1)
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 4)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 15)
npj Materials Degradation     Open Access  
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 9)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 3)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Bridge Engineering     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 13)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 9)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 2)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 3)
Promet : Traffic &Transportation     Open Access  
Random Structures and Algorithms     Hybrid Journal   (Followers: 5)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 6)
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Road Materials and Pavement Design     Hybrid Journal   (Followers: 11)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 5)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Selected Scientific Papers - Journal of Civil Engineering     Open Access   (Followers: 3)
Slovak Journal of Civil Engineering     Open Access   (Followers: 2)
Soils and foundations     Full-text available via subscription   (Followers: 5)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 4)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 10)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 8)
Structural Engineering International     Full-text available via subscription   (Followers: 11)
Structural Mechanics of Engineering Constructions and Buildings     Open Access   (Followers: 1)
Structural Safety     Hybrid Journal   (Followers: 6)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 24)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 12)
Structures     Hybrid Journal   (Followers: 1)
Study of Civil Engineering and Architecture     Open Access   (Followers: 10)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access   (Followers: 1)
Teknik     Open Access  
The IES Journal Part A: Civil & Structural Engineering     Hybrid Journal   (Followers: 6)
The Structural Design of Tall and Special Buildings     Hybrid Journal   (Followers: 5)
Thin Films and Nanostructures     Full-text available via subscription   (Followers: 2)
Thin-Walled Structures     Hybrid Journal   (Followers: 4)
Transactions of the VŠB - Technical University of Ostrava. Construction Series     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Underground Space     Open Access  
Water Science & Technology     Partially Free   (Followers: 25)
Water Science and Technology : Water Supply     Partially Free   (Followers: 22)

           

Journal Cover Journal of Fluids and Structures
  [SJR: 1.282]   [H-I: 70]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0889-9746 - ISSN (Online) 1095-8622
   Published by Elsevier Homepage  [3175 journals]
  • Nonlinear modelling of tuned sloshing dampers with large internal
           obstructions: Damping and frequency effects
    • Authors: J.S. Love; T.C. Haskett
      Pages: 1 - 13
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): J.S. Love, T.C. Haskett
      Internal obstructions are commonly employed in tuned sloshing damper (TSD) tanks to increase the inherent damping of the sloshing liquid closer to its optimal value for the targeted excitation amplitude. However, these obstructions also produce added mass, which acts to decrease the natural sloshing frequency of the tank. Using potential flow theory, this study develops both a linearized equivalent mechanical model and a fourth-order nonlinear multimodal model that are capable of accommodating the fluid drag and added mass that are generated by the paddles. The linearized equivalent mechanical model represents the sloshing liquid as an equivalent spring–mass–dashpot system with amplitude-dependent damping. The fourth-order nonlinear multimodal model captures the nonlinear coupling that occurs among the first four sloshing modes. Shake table tests are then conducted on a scale model TSD tank equipped with vertical paddles of cruciform plan section. The sloshing forces predicted by the linearized and nonlinear models are in reasonable agreement with the experimental results. The nonlinear model is generally in good agreement with the experimental wave heights, whereas the linearized model often underestimates the peak wave heights considerably. A plot is created which shows the frequency shift produced by the paddles as a function of the width of the paddles. If the paddles’ widths are greater than approximately 5% of the tank width, the effect on the natural sloshing frequency is noticeable.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.012
      Issue No: Vol. 79 (2018)
       
  • Frequency lock-in in pitch–heave stall flutter
    • Authors: Dominique Poirel; Luba Goyaniuk; Azémi Benaissa
      Pages: 14 - 25
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): Dominique Poirel, Luba Goyaniuk, Azémi Benaissa
      Coupled pitch–heave oscillations of a rigid but elastically mounted NACA0012 wing are experimentally investigated in a range of airspeeds corresponding to transitional Reynolds numbers (6.5  ×  104–12.0  ×  104). The elastic axis is set at 35% and the frequency ratio ω ¯ = ω h ∕ ω θ , is varied from 0.68 to 1.43. The system exhibits self-sustained large amplitude symmetric oscillations attributed to stall flutter in pitch. Pitch oscillation amplitudes are in the order of 40°, whereas the heave amplitude varies from 6% to 60% of chord length. For the most part the heave DOF plays a subordinate role as it is driven by the pitch dynamics; the system oscillates at a frequency determined by the pitch DOF. However, for a range of frequency ratios close to one, a strong coupling occurs from the heave to the pitch associated with a significant increase in heave amplitude and a lock-in of the LCO frequency onto the heave dictated frequency. This lock-in parallels classical observations of the elastically mounted cylinder in cross-flow interacting with its own wake in the form of von Kármán vortex street.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.006
      Issue No: Vol. 79 (2018)
       
  • Laboratory measurements of the vortex-induced vibrations of an untensioned
           catenary riser with high curvature
    • Authors: J.R. Chaplin; R. King
      Pages: 26 - 38
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): J.R. Chaplin, R. King
      Measurements of the vortex-induced vibrations of an instrumented catenary model riser with high curvature and very low bending stiffness are presented and discussed. The riser had a diameter of 56 mm and a length of 5.36 m. It was tensioned only by its own weight and by drag and was tested in a recirculating water channel 2m deep at flow speeds up to 1.4 m/s in both directions, i.e. with the upstream anchorage on the floor of the tank and the downstream one at the surface (defined as positive current cases), and then vice versa (negative currents). In many cases much of the riser rested on the tank floor with the touch-down point determined by the flow-induced forces on it. Attention is focused mainly on the frequencies of cross-flow vibrations after careful analysis of the effects of gravitational contamination on acceleration measurements. Response spectra were found to have a higher bandwidth than those of tensioned risers perpendicular to the flow and often exhibited more than one distinct peak. Dimensionless peak frequencies (having been normalised with respect to the diameter and a characteristic velocity) were much lower than that associated with a Strouhal number in the region of 0.2. In positive currents (based on the normal incident velocity at the top of the riser, where it was near vertical) it was generally uniform over the length of the riser at about 0.11. In negative currents, away from the tank floor, the riser’s profile was a straight line whose inclination was such that the normal incident velocity was independent of the current speed when this exceeded about 0.5 m/s. In these conditions the dimensionless peak frequency (based on the uniform normal incident velocity) was about 0.13.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.008
      Issue No: Vol. 79 (2018)
       
  • Large-amplitude flow-induced vibration of cylindrical pendulums
    • Authors: Junyoung Kim; Minho Song; Daegyoum Kim
      Pages: 39 - 49
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): Junyoung Kim, Minho Song, Daegyoum Kim
      We experimentally investigated the self-excited vibration of a cylindrical pendulum in a uniform flow as a fundamental step in evaluating its feasibility for energy harvesting. In the pendulum configuration, a cylinder is fixed to rigid plates via a thin elastic sheet so that it can swing perpendicularly to the free stream and cause periodic deformation of the elastic sheet. The dynamics of the pendulum were examined by varying free-stream speed and several geometric parameters of the cylinder. In contrast to past studies of vortex-induced vibration, which mainly used reduced velocity to characterize the pendulum dynamics, our study introduced non-dimensional free-stream velocity, which is the relative magnitude of the restoring bending moment of the sheet to the hydrodynamic moment acting on the cylinder. We confirmed that all pendulums converted to an oscillatory mode at similar non-dimensional velocity and had almost identical amplitude and frequency responses at given non-dimensional velocity. The pendulum was able to oscillate with the amplitude much larger than its diameter in the limited range of the non-dimensional velocity. Mutual interactions between the two cylindrical pendulums closely arranged in tandem were also investigated, and the dependence of the amplitude response on center-to-center distance and the transition from vortex-induced vibration to wake galloping were observed.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.011
      Issue No: Vol. 79 (2018)
       
  • Simulating the hydrodynamic response of a floater–net system in
           current and waves
    • Authors: Hao Chen; Erik Damgaard Christensen
      Pages: 50 - 75
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): Hao Chen, Erik Damgaard Christensen
      We present a novel numerical model for simulating current and wave interaction with a floater–net system. The main contribution of the paper is the integration of the floater motion and the fluid–structure interaction analysis of the net structure in the same modelling framework via the computational fluid dynamic approach. The sinker and the mooring lines were not directly resolved, but their effects were partially modelled. The model couples a hydrodynamic solver, a rigid body motion solver, a mesh motion solver and a structural solver in a segregated manner. In the numerical model, the net structure was modelled as a set of dynamic porous zones. A lumped mass model was coupled with it to realize fluid–structure interaction analysis for the net structure. The floater was treated as a rigid body, which was resolved by the body-fitted computational mesh in the fluid domain. The motion equation for the floater was set up based on the principle of linear and angular momentum balance. Different motion integration schemes were implemented and tested in the numerical model. The numerical model was validated against three sets of available experimental data in the open literature. The first set of validation cases treated the floater motion in regular waves. The second set of validation cases focused on the fluid–structure interaction analysis of the net structure. The final one was related to the whole floater–net system in regular waves, and combined current and wave condition.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.010
      Issue No: Vol. 79 (2018)
       
  • A three-dimensional computational analysis of bridges subjected to
           monochromatic wave attack
    • Authors: Raphael Crowley; Corbin Robeck; Philip Dompe
      Pages: 76 - 93
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): Raphael Crowley, Corbin Robeck, Philip Dompe
      A modeled bridge subjected to monochromatic wave train attack was computationally modeled in three dimensions using commercially available software. A number of slightly different geometric variations were computed to learn more about the high-frequency forcing component and to further investigate venting as a mitigation procedure for low lying bridges vulnerable to wave attack. Results appeared to show that the high-frequency component is the result of a combination of reflective effects and trapped air. Additionally, the vertical quasi-static force also appears to be partially caused by trapped air. Transverse venting was investigated as a means to reduce high-frequency forces on the bridges, and these measures appear to be highly effective. Finally a two-dimensional comparison was conducted. Results appear to indicate that while two-dimensional modeling provides valuable insight into the physics associated with this problem, it may miss effects due to lateral air movement.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.02.001
      Issue No: Vol. 79 (2018)
       
  • Structural-acoustic interaction of a three-dimensional
           panel–cavity–duct system with non-uniform boundary restraints
    • Authors: Yang Liu; Jingtao Du
      Pages: 94 - 114
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): Yang Liu, Jingtao Du
      Plate drum-silencer has received a lot of research attention due to its excellent low frequency noise attenuation and flow-through characteristics. The majority of existing studies are limited to the classical or uniform elastic boundary conditions, while there is little effort devoted to the study of boundary restraint non-uniformity effect on the vibro-acoustic behavior of such silencing system. Motivated by the current limitation, the structural-acoustic coupling model of a three-dimensional panel–cavity–duct silencer is established, in which the elastic boundary restraint can be set as arbitrary distribution function. Energy principle is formulated to describe the vibro-acoustic dynamics of such 3-D panel–cavity–duct silencing system, with the admissible field functions constructed as the superposition of standard Fourier series and the auxiliary edge/interface smoothed terms. All the coupled system response information can be derived in conjunction with Rayleigh–Ritz procedure. Numerical examples are presented to validate the proposed model through the comparison with those from other approaches. The coupling effects of boundary restraining coefficient and plate bending stiffness on sound attenuation performance of such cavity–backed plate–duct silencer are then discussed and analyzed. The results show that the relationship of translational restraints at the duct entrance and exit, k x 0 and k x L x , can be obtained through property inverse proportional functions to achieve the optimal sound attenuation. There will be significant improvement in some special frequency band compared with the uniform restraints distribution, especially for the plate with lower bending stiffness The experimental study is also performed to verify the theoretical prediction from current model. In reality, the arbitrary non-uniform elastic edge restraints represent the most general class of boundary conditions, and can provide more optimal space for such drum silencer design.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.02.002
      Issue No: Vol. 79 (2018)
       
  • Numerical and experimental investigations on mooring loads of a marine
           fish farm in waves and current
    • Authors: Yugao Shen; Marilena Greco; Odd M. Faltinsen; Ivar Nygaard
      Pages: 115 - 136
      Abstract: Publication date: May 2018
      Source:Journal of Fluids and Structures, Volume 79
      Author(s): Yugao Shen, Marilena Greco, Odd M. Faltinsen, Ivar Nygaard
      A realistic aquaculture fish farm system in both regular and irregular waves is investigated by numerical simulations and model tests. The main purpose is to develop a reliable numerical tool and in this respect to investigate the survival conditions of the system. The structural and hydrodynamic modelings of the system are briefly introduced. Numerical sensitivity analysis is performed to investigate which physical parameters are dominant when modeling the system. The considered fish farm comprises a floating collar with two concentric tubes, a flexible net cage including a cylindrical part and a conical part with a center point weight at the bottom, and a sinker tube attached directly to the net. The system is moored with a complex mooring system with bridle lines, frame lines and anchor lines, supported by buoys. The mooring loads in the front two anchor lines and bridle lines are investigated in detail. Numerical results are first validated by the experimental data. Both numerical and experimental results show that one of the bridle lines experiences larger load than the rest of the mooring lines, which is surprising. Then a sensitivity analysis is carried out. The mooring loads are not sensitive to the majority of the parameters. The flow reduction factor in the rear part of the net is the most important parameter for the anchor loads. Modeling the floating collar as a rigid body has a small effect on the anchor loads but not for the bridle lines as it will alter the force distribution between bridles. The mooring loads are not sensitive to the wave load model for the floating collar in both regular and irregular seas and modeling the floating collar as elastic with zero frequency hydrodynamic coefficients is enough to give reliable results. Finally, the survival conditions of the fish farms with different set-ups is studied. Numerical results indicate that the dominant limitation to move the conventional fish farms to more exposed sea regions is the large volume reduction of the net cage. The existing mooring system can be applied in offshore regions as long as the bridle lines are properly designed. The maximum stress in the floating collar is moderate compared with the yield stress.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.02.004
      Issue No: Vol. 79 (2018)
       
  • Aerodynamic admittance of streamlined bridge decks
    • Authors: Shaopeng Li; Mingshui Li; Guy L. Larose
      Pages: 1 - 23
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Shaopeng Li, Mingshui Li, Guy L. Larose
      In this paper, the generalized one-wavenumber aerodynamic admittance (3D one-wavenumber AAF), two-wavenumber aerodynamic admittance (3D two-wavenumber AAF) and two-dimensional aerodynamic admittance with the second (spanwise) wavenumber k 2 = 0 (2D AAF) of streamlined bridge decks in free stream turbulence are investigated based on Ribner’s three-dimensional aerodynamic theory. The misunderstandings of and internal relationship between the three kinds of admittances are clarified theoretically. Using wind tunnel tests in large-scale spire-generated turbulence, generalized coherence models of buffeting forces are proposed by the introduction of the reduced separation to take into account the three-dimensional effects of turbulent flow. Then, the closed-form expressions of admittances of the gust-loading on streamlined bridge deck are derived provided that the floating parameters in generalized coherence models are determined experimentally. Compared with previous numerical solution, the proposed closed-form models can explicitly divide the 3D one- and two-wavenumber AAFs into two parts, the gust-independent 2D AAF and the gust-related correction factors, providing us a new insight into both the effects of turbulence and cross geometry of the streamlined bridge decks. Experimental results confirm that the 2D AAF depends only on the cross-section geometry and the streamwise wavenumber k 1 . In contrast, the spanwise correction factors of 3D AAF are mainly determined by the dimension of the girder and the statistical characteristics of the gusts, including the decay parameter and integral length scales. This approach proposed in this paper can be extended to line-like structures with complicated cross-section shapes, such as twin-box girder.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.014
      Issue No: Vol. 78 (2018)
       
  • Current blockage and extreme forces on a jacket model in focussed wave
           groups with current
    • Authors: H. Santo; P.H. Taylor; A.H. Day; E. Nixon; Y.S. Choo
      Pages: 24 - 35
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): H. Santo, P.H. Taylor, A.H. Day, E. Nixon, Y.S. Choo
      This paper documents large laboratory-scale measurements of hydrodynamic force time histories on a realistic 1:80 scale space-frame jacket structure exposed to combined waves and in-line current. The aim is to investigate the fluid flow (and the associated hydrodynamic force) reduction relative to ambient fluid flow due to the presence of the jacket structure as an obstacle array, interpreted as wave–current blockage. Transient focussed wave groups, and embedded wave groups in a smaller regular wave background are generated in a towing tank, and the jacket is towed under different speeds opposite to the wave direction to simulate wave loading with different in-line uniform currents. The measurements are compared with numerical predictions using Computational Fluid Dynamics (CFD), with the actual jacket represented in a three-dimensional numerical wave tank as a porous tower modelled as a uniformly distributed Morison stress field. Good agreement is achieved, both in terms of incident surface elevation as well as total force time histories, all using a single set of Morison drag ( C d ) and inertia ( C m ) coefficients. Substantial force reduction is observed under transient large crest relative to prediction from the present industry design guideline with the same Morison coefficients. We demonstrate the generality of our findings: without influence of Keulegan–Carpenter (KC) number effect, a single invariant set of C d and C m is all that is required to numerically explain and reproduce the measured total force time histories on a realistic jacket model for a large range of wave heights and non-zero current speeds.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.015
      Issue No: Vol. 78 (2018)
       
  • Rotating elliptic cylinders in a uniform cross flow
    • Authors: Kim Boon Lua; Hao Lu; T.T. Lim
      Pages: 36 - 51
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Kim Boon Lua, Hao Lu, T.T. Lim
      Numerical simulation of flow past a two-dimensional rotating cylinder of different thickness ratios at Re = 200 has been carried out to investigate how incremental changes in the cross-section of a cylinder from a circle to a thin ellipse affect their lift and drag characteristics as well as flow structures. In contrast to past studies, the present work considers velocity ratios up to 2.5, where vortex shedding of a circular cylinder completely ceases. Results show that a decreasing thickness generally leads to lower mean lift magnitude, but a non-monotonic change in mean drag with a local minimum at a thickness ratio of approximately 0.375. Interestingly, at velocity ratio 2.5, such minimum drag changes sign and turns into a positive thrust; this event occurs at a much smaller velocity ratio than the case of a circular cylinder. Detailed analysis on vorticity contours and surface pressure distributions reveals that the thrust generation is a result of the competition between a prevailing negative pressure below the cylinder due to rotational motion, and a suction effect from a “hovering vortex” formed above the cylinder. Additionally, as the thickness reduces, the wake transits from a von-Kármán type to a separated flow dictated by the two edges of the elliptic cylinder. And the crests and troughs in the transient aerodynamic forces become highly related to the instantaneous geometric angle of attack, which can be attributed to a projection effect.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.023
      Issue No: Vol. 78 (2018)
       
  • A fully-coupled generalized model for multi-directional wind loads on tall
           buildings: A development of the quasi-steady theory
    • Authors: Wei Cui; Luca Caracoglia
      Pages: 52 - 68
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Wei Cui, Luca Caracoglia
      This study examines in detail the quasi-steady aerodynamic theory, which is widely applied in wind engineering for the evaluation of wind loads. The authors propose an alternative approach and a novel generalized aerodynamic formulation for the wind-induced dynamic response of a bluff body. The proposed formulation is applied to the dynamic analysis of tall buildings, considering multi-directional wind loads, aerodynamic damping and aerodynamic stiffness effects, and inter-modal structural coupling. Dimensionless Fourier transformation is used in the formulation to provide a general “unified formula” and new insights on the modeling and estimation of wind loads. One numerical example is presented to verify the validity of the formula; numerical simulations are compared against literature data (wind tunnel test results) for a benchmark building structure.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.008
      Issue No: Vol. 78 (2018)
       
  • Comparative analysis of the effect of different nose lengths on train
           aerodynamic performance under crosswind
    • Authors: Zhengwei Chen; Tanghong Liu; Zhenhua Jiang; Zijian Guo; Jie Zhang
      Pages: 69 - 85
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Zhengwei Chen, Tanghong Liu, Zhenhua Jiang, Zijian Guo, Jie Zhang
      This study investigated the aerodynamic performances of four trains with different nose lengths (4, 7, 9 and 12 m) under strong crosswind using the detached eddy simulation (DES) method. The variations in the aerodynamic force coefficients with different nose lengths were analyzed. The pressure distribution on the train surface, vortex development around the train, and velocity field variation around the train with increases in the nose length were compared and discussed. The results indicated that in a strong wind environment, the aerodynamic drag coefficient was largest for the tail car, whereas the side force coefficient, lift coefficient and roll moment coefficient were largest for the head car. When the nose length of the train increased from 4 m to 12 m, the total drag coefficient of the train decreased by 19.0% and the side force, lift and roll moment coefficient decreased by 10.6%, 21.7% and 7.3%, respectively. In the horizontal section of the train head part and tail part, the largest pressure coefficient decreased in a logarithmic manner with increases in the nose length. The nose length significantly affects the pressure coefficient on the windward side of the head car and the leeward side of the tail car. With an increase in the nose length, on the leeward side of the train, the shedding length and influence width range of vortex were reduced; the strength of the spiral shedding and interaction effect of two vortices in the rear nose weakened, and their distinction was more notable, meanwhile, the wake impact ranges in the vertical and longitudinal directions decreased.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.016
      Issue No: Vol. 78 (2018)
       
  • Interaction of waves with a body floating on polynya between two
           semi-infinite ice sheets
    • Authors: Z.F. Li; Y.Y. Shi; G.X. Wu
      Pages: 86 - 108
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Z.F. Li, Y.Y. Shi, G.X. Wu
      The interaction of waves with a two-dimensional body floating on polynya between two semi-infinite ice sheets is investigated, based on a hybrid method utilizing a simple source function and eigenfunction matching. The ice sheet is modelled as a continuous thin elastic plate with uniform properties, while the fluid flow is described by the velocity potential. In the polynya, an integral equation is established by using the simple source function. In the two exterior ice covered regions, the potential is expanded in terms of eigenfunctions which satisfy the governing equation and all boundary conditions apart from that on the interface with the inner region. The unknown coefficients in the expansion and the boundary integral equation in the inner region are solved together by enforcing the continuity conditions of the pressure and normal velocity on the interface. The effectiveness and accuracy of the hybrid method is demonstrated through comparison with published results for a submerged cylinder and a floating rectangular body. Simulations are then carried out for a floating elliptical cylinder. Extensive results for the hydrodynamic force and motion response are provided, and the effects of ice draught as well as the body shape are investigated.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.019
      Issue No: Vol. 78 (2018)
       
  • Parametric study on confinement effect on a fuel assembly dynamical
           behavior under axial flow
    • Authors: Guillaume Ricciardi
      Pages: 109 - 125
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Guillaume Ricciardi
      Nuclear industry needs tools to design reactor cores in case of earthquake. Simulation using a fluid–structure model of the core subjected to a seismic excitation has been proposed. A parametric study has been conducted to observe the effect of confinement length and elasticity modulus on the added stiffness effect. The modeling used to make the parametric study showed good agreement with experimental results. Simulations showed that the added stiffness reaches a maximum for a confinement around 20 mm, and that the added stiffness should be negligible in a real core configuration.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.022
      Issue No: Vol. 78 (2018)
       
  • High-resolution computational fluid dynamics predictions for the static
           and dynamic stall of a finite-span OA209 wing
    • Authors: Rohit Jain; Arnaud Le Pape; Amanda Grubb; Michel Costes; François Richez; Marilyn Smith
      Pages: 126 - 145
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Rohit Jain, Arnaud Le Pape, Amanda Grubb, Michel Costes, François Richez, Marilyn Smith
      High-resolution computational fluid dynamics (CFD) predictions of static and dynamic stall of a finite-span ONERA OA209 wing were validated against the wind tunnel test measurements. The freestream Mach number was 0.16 and the Reynold number was 1 million. For the dynamic stall study, a sinusoidal pitching motion was prescribed. The CFD modeling approaches employed were — Delayed Detached Eddy Simulation (DDES) modeling using the NASA OVERFLOW flow solver, Unsteady Reynolds-averaged Navier–Stokes (URANS) modeling using the ONERA elsA flow solver, and DDES modeling using the NASA FUN3D flow solver. The flow was modeled as both fully turbulent and transitional. A comparative study between predictions and the wind-tunnel test data for pre- and post-stall measurements was carried out that included wing section lift and moment, surface pressure, and velocity field at chordwise and spanwise planes. The high spatial and temporal resolutions employed resulted in good correlations with the test data, in particular with the inclusion of DDES modeling along with a turbulence transition model. The CFD modeling parameters thus establish were applied to a deep and a light stall cases, and were found to accurately capture the wing section loads, demonstrating its generalizability in capturing the stall dynamics.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.012
      Issue No: Vol. 78 (2018)
       
  • Stability of helical tubes conveying fluid
    • Authors: François Gay-Balmaz; Dimitri Georgievskii; Vakhtang Putkaradze
      Pages: 146 - 174
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): François Gay-Balmaz, Dimitri Georgievskii, Vakhtang Putkaradze
      We study the linear stability of elastic collapsible tubes conveying fluid, when the equilibrium configuration of the tube is helical. A particular case of such tubes, commonly encountered in applications, is represented by quarter- or semi-circular tubular joints used at pipe’s turning points. The stability theory for pipes with non-straight equilibrium configurations, especially for collapsible tubes, allowing dynamical change of the cross-section, has been elusive as it is difficult to accurately develop the dynamic description via traditional methods. We develop a methodology for studying the three-dimensional dynamics of collapsible tubes based on the geometric variational approach. We show that the linear stability theory based on this approach allows for a complete treatment for arbitrary three-dimensional helical configurations of collapsible tubes by reduction to an equation with constant coefficients. We discuss new results on stability loss of straight tubes caused by the cross-sectional area change. Finally, we develop a numerical algorithm for computation of the linear stability using our theory and present the results of numerical studies for both straight and helical tubes.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.020
      Issue No: Vol. 78 (2018)
       
  • Study of a C-wing configuration for passive drag and load alleviation
    • Authors: S.N. Skinner; H. Zare-Behtash
      Pages: 175 - 196
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): S.N. Skinner, H. Zare-Behtash
      Non-planar wing configurations are often hypothesised as a means for improving the aerodynamic efficiency of large transport aircraft; C-wings may have the ability to exploit and unify drag reduction, aeroelasticity, and dynamics and control but their capacity to do so is ambiguous. The purpose of this work is to provide an experimental demonstration with the aim of verifying the C-wing configurations practical application. Thus, the main objective of this investigation is to quantify the C-wing’s ability for drag and load alleviation relative to a planar wing of equivalent wingspan, lift, and root bending moment at R e = 1 . 5 × 1 0 6 . Surface clay flow visualisations have been used to provide insight into the flow over the wing surface. Aerodynamic performance metrics show that despite the C-wing operating with a 19 . 1 % higher wing wetted area, a peak total drag reduction of 9 . 5 % at α = 6 ° is achieved in addition to a 1 . 1 % reduction in the wing root bending moment for equivalent lift. Force platform measurements in combination with laser vibrometry enabled a detailed understanding of the vibrational characteristics between the model and the wind tunnel. It is shown that the C-wing can passively attenuate buffet induced vibrations of the main-wing by up to 68 . 6 % whilst simultaneously reducing total drag without a significant increase in wing weight or root bending moment.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.018
      Issue No: Vol. 78 (2018)
       
  • Methodology for wave force monitoring of bottom-mounted cylinder using the
           measurement of the wave surface elevation around the body surface
    • Authors: Jiabin Liu; Anxin Guo; Hui Li; Hui Hu
      Pages: 197 - 214
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Jiabin Liu, Anxin Guo, Hui Li, Hui Hu
      This paper presents a methodology to estimate the wave force on a bottom-mounted cylinder using the measured signals of wave surface elevation around the body surface of the cylinder. Based on the potential theory, the formulae are derived in a general manner for bottom-mounted cylinders of arbitrary cross section. Considering the difficulty of decomposing the signal of wave surface elevation measured by wave gauges, a linear estimation method is developed to achieve an approximate estimation of the wave loads on cylinders. A hydrodynamic experiment was conducted on a circular cylinder in a random wave field to validate the effectiveness of the proposed method. The horizontal wave forces and bending moments directly measured by force balance are employed for the validation of the proposed estimated results using the measurement of the wave surface elevation by wave gauges. Error analysis is also conducted in the frequency domain to investigate the effects of the linear approximation. The analysis results indicate that the proposed method can effectively estimate the wave loads acting on the cylinder. The linear approximation method slightly underestimates the wave loads of the difference-frequency component, while overestimating that in the sum-frequency region.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2018.01.001
      Issue No: Vol. 78 (2018)
       
  • Vortex-induced vibrations of three tandem cylinders in laminar cross-flow:
           Vibration response and galloping mechanism
    • Authors: Weilin Chen; Chunning Ji; John Williams; Dong Xu; Lihong Yang; Yuting Cui
      Pages: 215 - 238
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Weilin Chen, Chunning Ji, John Williams, Dong Xu, Lihong Yang, Yuting Cui
      Vortex-induced vibrations (VIV) of three tandem cylinders are numerically studied using the immersed boundary method. Cylinders are free to vibrate in the cross-flow direction. The Reynolds number is Re = 100 and the reduced velocity is U r = 3 ∼ 80 . Six spacing ratios are selected in the range L ∕ D = 1 . 2 ∼ 5 . 0 . The mass ratio is m ∗ = 2 . 0 , while the damping ratio is set as zero for achieving large vibration amplitudes. The characteristics of the vibration amplitude, drag and lift forces, lift frequency, phase difference between displacement and lift, and the wake patterns are discussed. It is found that, in the case with small L ∕ D , large-amplitude vibrations of the cylinders are excited due to strong wake-cylinder interference. However, in the cases with large L ∕ D , the vibration responses of the upstream cylinder resemble those of an isolated cylinder indicating vanishing interference from the downstream cylinders. While, the two downstream cylinders attain large vibration amplitudes even at high reduced velocities. A wake pattern, T+S, i.e. the cylinders alternately shed triple vortices and a single vortex in a vibration cycle, is observed. This wake pattern is caused by the asymmetric vibration of the cylinders and transverse dislocation of the equilibrium positions. With increasing L ∕ D , two different vibration patterns are observed: wake-induced galloping (WG) for the small- L ∕ D case ( L ∕ D = 1 . 2 ) and vortex-induced vibration (VIV) for the moderate- to large- L ∕ D cases ( L ∕ D = 1 . 5 ∼ 5 . 0 ). The major characteristic feature of WG, distinct to VIV, are the divergent vibrations of the cylinders with the increasing reduced velocity. The mechanism of WG is elucidated by analyzing the complex but stable interactions between vortices and cylinders. Three pivotal factors are identified: the ‘perfect’ timing between vortex-shedding and cylinder motion, the transverse dislocation of the equilibrium positions, and the low and decreasing vibration frequency.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.017
      Issue No: Vol. 78 (2018)
       
  • A harmonic piecewise linearisation-wavelet transforms method for
           identification of non-linear vibration “black box” systems:
           Application in wind-induced vibration of a high-rise building
    • Authors: Dongmei Huang; Ledong Zhu; Weixin Ren; Quanshun Ding
      Pages: 239 - 262
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Dongmei Huang, Ledong Zhu, Weixin Ren, Quanshun Ding
      In this work, a harmonic piecewise linearisation-wavelet transform method is proposed for identification of some kind of non-linear/linear vibration “black box” systems. The proposed method firstly looks at the non-linear vibration system as piecewise linear, and then identifies the time-varying damping ratio and frequency by the segmented amplitude log analysis and wavelet transform method, secondly it obtains the relationship between damping and frequency to time or amplitude by least squares method, and finally establishes its non-linear oscillation governing equation. The proposed harmonic piecewise linearisation-wavelet transform method is verified by two numerical examples and then is used to identify the wind-induced cross-wind non-linear/linear aerodynamic parameters of Shanghai’s World Financial Centre by aeroelastic model vibration measurement wind tunnel test. The results show that the proposed harmonic piecewise linearisation-wavelet transform method is feasible for identification of some kind of non-linear/linear “black box” vibration systems, including in a flexible high-rise building subjected to strong wind: in this case, the non-linear/linear aeroelasticity effect cannot be ignored, which would generate additional weak non-linear damping and negative aerodynamic stiffness.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.021
      Issue No: Vol. 78 (2018)
       
  • Flow noise in planar sonar applications
    • Authors: Christian Henke
      Pages: 263 - 276
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Christian Henke
      In this paper an investigation of flow noise in sonar applications is presented. Based on a careful identification of the dominant coupling effects, the acoustic noise at the sensor position resulting from the turbulent wall pressure fluctuations is modelled with a system of hydrodynamic, bending and acoustic waves. We describe for the first time an analytical solution of the problem which is based on a biorthogonal system which can be solved in the spectral domain without the usual simplifying assumptions. Finally, it is demonstrated that the analytical solution describes the flow noise generation and propagation mechanisms of the considered sea trials.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2018.01.007
      Issue No: Vol. 78 (2018)
       
  • Numerical investigation of large-scale vortices in an array of cylinders
           in axial flow
    • Authors: Laurent De Moerloose; Pieter Aerts; Jeroen De Ridder; Jan Vierendeels; Joris Degroote
      Pages: 277 - 298
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Laurent De Moerloose, Pieter Aerts, Jeroen De Ridder, Jan Vierendeels, Joris Degroote
      Axial flow around an array of cylinders is commonly encountered in nuclear reactors and heat exchangers. This geometry is subject to important flow instabilities. The chaotic flow fluctuations due to turbulence are not the only source of vortex structures: large-scale vortices have also been observed, both experimentally and numerically. The periodic pressure fluctuations caused by the coherent vortex structures are possibly a source of fretting and fatigue in the aforementioned applications. In order to comprehend this phenomenon, Large-Eddy Simulations are performed on a numerical domain containing a single rigid cylinder with periodic boundary conditions, representative for a cylinder in an infinite square array. The research in this paper mainly focuses on the influence of the cylinder spacing, which is analysed by calculating the Cross Spectral Density (CSD) function of the cylinder wall pressure for different cylinder spacings. The spectral analysis shows that the amplitude of the pressure fluctuations increases up to a well-determined intercylinder gap, after which it decreases exponentially for incrementing gap size. With the weakening of the instability, the location on the cylinder circumference where the maximum pressure amplitude occurs, changes as well. Finally, it is shown that the coherent vortices are transported as a whole at a convection speed which is dependent on the cylinder spacing. An updated model for this convection speed is proposed.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2018.01.002
      Issue No: Vol. 78 (2018)
       
  • VIV analysis of a single elastically-mounted 2D cylinder: Parameter
           Identification of a single-degree-of-freedom multi-frequency model
    • Authors: Riccardo Pigazzini; Giorgio Contento; Simone Martini; Thomas Puzzer; Mitja Morgut; Andrea Mola
      Pages: 299 - 313
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Riccardo Pigazzini, Giorgio Contento, Simone Martini, Thomas Puzzer, Mitja Morgut, Andrea Mola
      A novel single-degree-of-freedom multi-frequency model (sdof-mf) for the prediction of the Vortex Induced Vibrations (VIV) of an elastically mounted circular cylinder in two-dimensional cross flow is presented. The proposed model treats the total hydrodynamic force as sum of conventional Morison-like inertia and drag terms related to the cylinder motion in still fluid plus additional harmonics that account for the lift force induced by vortex shedding. Amplitudes, frequencies and phase lags of these harmonics are identified using a Parameter Identification (PI) procedure applied to time domain data of vortex induced forces, here obtained via CFD simulations. The proposed sharp identification via PI of the independent frequencies of the vortex shedding fluid force is the peculiarity of the proposed method. The model is assessed considering a wide range of flow regimes, including lock-in conditions. From the overall results, the proposed sdof-mf model exhibits promising but consistent capabilities in the reproduction of the vortex shedding forces and cylinder motion, in terms of both amplitudes and frequencies.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.005
      Issue No: Vol. 78 (2018)
       
  • Parametric study of flow-induced vibrations in cylinder arrays under
           single-phase fluid cross flows using POD-ROM
    • Authors: Elisabeth Longatte; Erwan Liberge; Marie Pomarede; Jean-François Sigrist; Aziz Hamdouni
      Pages: 314 - 330
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Elisabeth Longatte, Erwan Liberge, Marie Pomarede, Jean-François Sigrist, Aziz Hamdouni
      Modeling numerically Flow-Induced Vibrations in heat exchangers at a microscopic scale requires high computational resources and time which are still unreachable. Therefore model reduction is investigated in the present work in order to address the issue of simulation computational time reduction. In the framework of POD-Galerkin projection methods, the purpose is to propose optimal a posteriori reduction strategies enabling error control on approximation as well as Reduced-Order Model (ROM) interpolation to deal with sensitivity analysis of solutions to parameter perturbations. A multi-phase fluid–solid POD-Galerkin-based method is proposed for modeling flows and vibrations in cylinder arrangements under single-phase fluid cross-flows. Moreover a single-POD basis method is evaluated in the context of ROM interpolation. This work is a first step in the development of robust ROM describing fluid and solid dynamics in the presence of turbulence, heat transfer effects and large magnitude structure displacements and deformations.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2017.12.011
      Issue No: Vol. 78 (2018)
       
  • Stability analysis of rectangular parallel plates interacting with
           internal fluid flow and external supersonic gas flow
    • Authors: S.A. Bochkarev; S.V. Lekomtsev
      Pages: 331 - 342
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): S.A. Bochkarev, S.V. Lekomtsev
      In this paper, we analyze the dynamic stability of deformable rectangular plates (single and two parallel) that interact simultaneously with the external supersonic gas flow and the internal flow of an ideal fluid. The mathematical formulation of the dynamics of elastic structures is made using the variational principle of virtual displacements, which includes the expression for the work done by aero- and hydro-dynamic forces. The motion of the liquid in the case of small perturbations is described by the equations of potential theory, which are converted to a weak form using the Bubnov–Galerkin method. Numerical solution of the problem is based on the application of the procedures of the finite element method to the coupled system of equations. The estimation of stability involves computation and analysis of complex eigenvalues, obtained at gradually growing velocity of the fluid or gas flow. The diagrams showing the mutual influence of fluid and gas flow velocities on the boundary of aero-hydroelastic stability, are constructed and the effects of the kinematic boundary conditions specified at the edges of the structure and the height of the fluid layer are evaluated. It has been established that the violation of smoothness of the obtained dependences and stability diagrams can be attributed either to a change in the vibration mode, or to a change in the type of stability loss.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.009
      Issue No: Vol. 78 (2018)
       
  • An experimental study to investigate the validity of the independence
           principle for vortex-induced vibration of a flexible cylinder over a range
           of angles of inclination
    • Authors: Banafsheh Seyed-Aghazadeh; Yahya Modarres-Sadeghi
      Pages: 343 - 355
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Banafsheh Seyed-Aghazadeh, Yahya Modarres-Sadeghi
      Vortex-induced vibration of an inclined flexible cylinder placed at different angles of inclination with respect to the incoming flow is studied experimentally. The tests were conducted in a re-circulating water tunnel and the angles of inclination were varied from 0° to 60° with increments of 15°. Dynamic response of the system in terms of the amplitude and frequency of oscillations is studied in the reduced velocity range of 2.3–13.9 and the Reynolds number range of R e = 320 –1610. The validity of the Independence Principle (IP), which states that the behavior of an inclined cylinder is essentially driven by the normal component of the incoming flow velocity, is investigated for this range of reduced velocities and angles of inclination. Based on the onset of oscillations and the magnitudes of modal weight contributions, it is shown that the dynamic response of the system is different from that of a completely vertical cylinder for all angles of inclination larger than 15°. Even for the small angle of inclination of 15°, for the normal reduced velocity range of 2 to 6, where the onset of oscillations and the magnitude of modal weight contributions are similar to those observed for a vertical cylinder, the frequency response and the excited structural modes are different. It is concluded that the onset of oscillations and the magnitudes for the modal weight contributions are not sufficient indicators of the validity of the IP, and that the modal response in terms of the excited structural modes and the frequencies should also be considered. In general, it is shown that the IP is not valid even at reduced velocities where the modal weight contributions are similar for the inclined and vertical cylinders.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.004
      Issue No: Vol. 78 (2018)
       
  • The flow-induced vibration of an elliptical cross-section at varying
           angles of attack
    • Authors: J.S. Leontini; M.D. Griffith; D. Lo Jacono; J. Sheridan
      Pages: 356 - 373
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): J.S. Leontini, M.D. Griffith, D. Lo Jacono, J. Sheridan
      This paper presents a study of the flow-induced vibration of an elliptical cross section at various angles of attack immersed in a free stream. The body is elastically-mounted and constrained to move only in the cross-stream direction. Two-dimensional direct numerical simulations are used to study the system response as a function of the spring stiffness and the angle of attack. The elliptical cross section used has an aspect ratio Γ = 1 . 5 . This aspect ratio is large enough so that the deformation from a circular cylinder is obvious, but not so large that the geometry is not related to the cylinder. Because of this, the impact of the symmetry of the system on the flow-induced vibration is studied without also introducing other complexities such as sharp corners or fixed separation points. The body is light with a mass ratio (body mass to displaced fluid mass) of one. The results show a surprisingly wide range of different flow regimes. For small angles (where the body is slightly streamlined) the flow behaviour is similar to that of a cylinder. However, for large angles, where the body is far from symmetric with respect to the wake centreline, the flow can be markedly different with distinct asymmetric modes, including one which is period-doubled. For angles where the body regains its symmetry (aligned across the flow and slightly bluff), an asymmetric mode continues to exist, apparently the result of a spontaneous symmetry breaking that is dependent on Reynolds number. Large-amplitude oscillations persist for very low stiffness or high reduced velocity, and this is explained in terms of the dependence of a critical mass on the angle of attack.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2017.12.013
      Issue No: Vol. 78 (2018)
       
  • 3D ISPH erosion model for flow passing a vertical cylinder
    • Authors: Dong Wang; Songdong Shao; Shaowu Li; Yang Shi; Taro Arikawa; Hongqian Zhang
      Pages: 374 - 399
      Abstract: Publication date: April 2018
      Source:Journal of Fluids and Structures, Volume 78
      Author(s): Dong Wang, Songdong Shao, Shaowu Li, Yang Shi, Taro Arikawa, Hongqian Zhang
      In this paper a 3D incompressible Smoothed Particle Hydrodynamics (ISPH) erosion model is proposed to simulate the scouring process around a large vertical cylinder. The erosion model is based on the turbidity water particle concept and the sediment motion is initiated when the fluid bottom shear stress exceeds the critical value. The previous 2D SPH sediment initiation model is expanded by combining the effects of both transverse and longitudinal sloping beds in a practical 3D situation. To validate the developed model, a laboratory flume experiment was carried out to study the clear water scouring around a vertical cylinder under unidirectional current, in which high-speed video cameras were used for the real-time monitoring of sediment movement. The 3D ISPH results are compared with the experimental data with good agreement in terms of the scouring patterns and scales. Besides, the computed flow velocity field suggests that both the horseshoe vortices and lee-wake flows around the cylinder have been realistically simulated.

      PubDate: 2018-02-26T05:31:53Z
      DOI: 10.1016/j.jfluidstructs.2018.01.003
      Issue No: Vol. 78 (2018)
       
  • A numerical investigation on piezoelectric energy harvesting from
           Vortex-Induced Vibrations with one and two degrees of freedom
    • Authors: Guilherme R. Franzini; Lucas O. Bunzel
      Pages: 196 - 212
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Guilherme R. Franzini, Lucas O. Bunzel
      This paper presents numerical investigations into the dynamics of a rigid cylinder, mounted on elastic supports fitted with piezoelectric harvesters and subjected to the Vortex-Induced Vibrations (VIV) phenomenon. Hydrodynamic loads are considered by wake-oscillators models, whereas linear constitutive equations are adopted aiming at coupling the solid and electric oscillators. The main objective is to highlight the influence of an additional structural degree of freedom (namely, in-line oscillations) on the dynamics of the fluid–solid-electric system. For a particular set of dimensionless parameters that define the harvester circuits, oscillation amplitudes, electric tension and harvested power are obtained for different reduced velocities. Among other findings, the simultaneous presence of in-line and cross-wise oscillations can be emphasized to lead to a marked increase in the maximum energy harvesting efficiency. In addition to this analysis, a sensitivity study with respect to the influence of the dimensionless quantities that characterize the piezoelectric harvesters is carried out. The study shows that the energy harvesting efficiency can be increased by up to 50 % for a particular reduced velocity.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.007
      Issue No: Vol. 77 (2018)
       
  • On the role of flow transition in laminar separation flutter
    • Authors: Caleb J. Barnes; Miguel R. Visbal
      Pages: 213 - 230
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Caleb J. Barnes, Miguel R. Visbal
      This work explores self-sustained pitching oscillations of a NACA0012 airfoil operating at low-to-moderate Reynolds numbers in which the aerodynamic flow is in a transitional regime. One-degree of freedom (DOF) pitching oscillations were explored over a range of Reynolds numbers ( 7 . 7 × 1 0 4 < Re c ≤ 2 . 0 × 1 0 5 ) using high-order implicit large-eddy simulation coupled with structural dynamics. Limit-cycle oscillation is observed at all Reynolds numbers tested but requires a disturbance to initiate at the highest flow speeds identifying a bifurcation in possible solution states. In all cases, aerodynamic loading is dominated by primarily two features. Negative aerodynamic damping is largely provided by suction beneath a separation bubble located behind the elastic axis. This feature induces a moment that reinforces the pitch-rate at small angles of incidence and is directly influenced by flow transition at different Reynolds numbers. Open trailing edge separation on the opposite surface transitions and reattaches immediately preceding the largest angles of incidence. This process imparts a spike in the pitching moment that opposes the pitch-rate and briefly damps oscillations. Transition of the detached shear layer occurs at smaller angles of incidence as Reynolds number is increased, attenuating oscillation amplitude as Reynolds number is increased.

      PubDate: 2018-02-05T03:49:15Z
      DOI: 10.1016/j.jfluidstructs.2017.12.009
      Issue No: Vol. 77 (2018)
       
  • Global force and moment in rectangular tanks through a modal method for
           wave sloshing
    • Authors: M. Antuono; C. Lugni
      Pages: 1 - 18
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): M. Antuono, C. Lugni
      Basing on a modal description of the sloshing phenomenon, formulas for the global force and moment acting on two-dimensional rectangular tanks are proposed. These are extensively validated through comparison with experimental data for roll motions at different angles of excitement. Moreover, to extend the applicability of the modal method to the most violent breaking cases, a diffusive variant of the scheme is proposed. This relies on the use of a proper diffusive term in the continuity equation and allows for the overcoming of some numerical issues related to the sloshing dynamics in very shallow waters. Finally, a qualitative description of the interaction between diffusion, dispersion and nonlinearities has been proposed for the present modal scheme, along with a physical interpretation of the diffusive term.

      PubDate: 2017-12-12T07:02:52Z
      DOI: 10.1016/j.jfluidstructs.2017.11.004
      Issue No: Vol. 77 (2017)
       
  • A coupled BE–FE–BE study for investigating the effect of earthquake
           frequency content and predominant period on seismic behavior of
           base-isolated concrete rectangular liquid tanks
    • Authors: Mohammad Reza Shekari
      Pages: 19 - 35
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Mohammad Reza Shekari
      Main purpose of this study is to numerically simulate a three-dimensional soil–structure–liquid interaction problem in order to scrutinize the dynamic behavior of base-isolated concrete rectangular tanks under horizontal seismic excitations. It has been deduced that in many earthquakes, the isolation systems reduce the earthquake effects on structures by lengthening their fundamental natural periods against excessive drifts of the superstructure. However, in exceptional cases of the soil stiffness and shaking frequency, the base-isolation systems could have noxious effects. Therefore, the numerical seismic response of rectangular liquid tank system isolated by bilinear bearings is investigated under three real earthquakes with different frequency characteristics in this paper. To this end, finite shell elements for tank wall and boundary elements for liquid and soil are used. Subsequently, fluid–structure–soil equations of motion are coupled with isolator governing equation in the time domain, to gain the whole system response. For different concrete tanks from slender to broad ones, the variations of base forces, sloshing responses, shell radial displacements, and hydrodynamic pressures are illustrated under various system parameters such as the flexibility of the isolation system and the soil properties, to censoriously scrutinize the effects of various system parameters on the utility of the base-isolators. From the analyses, author has concluded that the base-isolation effect is intimately dependent on the earthquake characteristics and may amplify or control the structural responses.

      PubDate: 2017-12-12T07:02:52Z
      DOI: 10.1016/j.jfluidstructs.2017.11.003
      Issue No: Vol. 77 (2017)
       
  • A numerical investigation of Vortex-Induced Vibration response
           characteristics for long flexible cylinders with time-varying axial
           tension
    • Authors: Yuchao Yuan; Hongxiang Xue; Wenyong Tang
      Pages: 36 - 57
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Yuchao Yuan, Hongxiang Xue, Wenyong Tang
      Vortex-Induced Vibration (VIV) for flexible cylinders is a typical fluid–structure interaction problem, and it becomes more complex when the time-varying axial tension effect is considered. An available force–decomposition model is proposed in this paper to investigate the cross-flow VIV response characteristics with time-varying tension. VIV hydrodynamic forces are all based on forced vibration experimental data, and structural stiffness will be updated at each time step to take the tension variation into account. Firstly, this VIV model is compared against the published experimental results of a small-scale cylinder with constant and time-varying tensions. Next, 60 cases of a long flexible cylinder are designed to investigate the time-varying tension effect comprehensively. Several new phenomena such as amplitude modulation, time-lag, frequency transition, mode jump and multi-frequencies response superposition are captured in the response comparison with the constant tension case. The effects of initial phase, amplitude and frequency of the varying tension are respectively discussed in detail. The Mathieu-type resonance between VIV and time-varying tension excitation is proved existent. The response displacement and strain will enlarge significantly at ω T = 2 ω C T , to which enough attention needs to be paid.

      PubDate: 2017-12-12T07:02:52Z
      DOI: 10.1016/j.jfluidstructs.2017.12.004
      Issue No: Vol. 77 (2017)
       
  • Inverse method for hydrodynamic load reconstruction on a flexible
           surface-piercing hydrofoil in multi-phase flow
    • Authors: J.C. Ward; C.M. Harwood; Y.L. Young
      Pages: 58 - 79
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): J.C. Ward, C.M. Harwood, Y.L. Young
      An inverse method for reconstruction of the in situ steady-state hydrodynamic load distribution using limited strain measurements is developed and validated on a rectangular, flexible surface-piercing hydrofoil in fully-wetted (FW) and fully-ventilated (FV) flows. The hydrofoil is used as a canonical proxy to more complex hydrodynamic lifting surfaces such as marine propulsors and turbines. The approach involves using a forward fluid–structure interaction (FSI) model to predict the hydroelastic response for given operating conditions. The inverse problem is solved as an optimization problem to determine unknown operating conditions. The forward FSI model consists of a nonlinear lifting line (LL) fluid solver with considerations for free surface, ventilation, and viscous effects, and a solid finite element method (FEM) solver using 1-D beam elements representing the spanwise bending and twisting deformations. The coupled FSI model was validated using data collected during towing tank experiments at the University of Michigan. Predictions of the lift and moment coefficients, as well as spanwise bending and twisting deformations agreed well with experimental results in FW and in FV flows. The inverse problem is formulated as an optimization problem to determine the unknown operating conditions that will minimize the difference between the measured and predicted deformations. To avoid non-uniqueness problems often encountered by inverse problems, a dynamic constraint using the measured wetted natural frequencies was added to help regularize the problem and speed up the solution process. A sequential quadratic programming algorithm was used as the optimizer for the inverse problem. The experimental studies showed that the inverse FSI model accurately determined the unknown operating conditions (angle of attack and immersed aspect ratio) for a given a known flow speed and a limited number of strain measurements in both FW and FV conditions. The converged results were used to reconstruct a 3-D hydrodynamic load distribution on the foil and to predict the cavity shape for FV operating conditions, which were found to agree well with experimental measurements and observations.

      PubDate: 2017-12-12T07:02:52Z
      DOI: 10.1016/j.jfluidstructs.2017.12.001
      Issue No: Vol. 77 (2017)
       
  • Self-sustaining turbulent wake characteristics in fluid–structure
           interaction of a square cylinder
    • Authors: T.P. Miyanawala; R.K. Jaiman
      Pages: 80 - 101
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): T.P. Miyanawala, R.K. Jaiman
      We present a numerical study on the fluid–structure interaction of a square cylinder at subcritical Reynolds numbers 1400 ≤ R e ≤ 10 , 000 . Variation in spatial and temporal structures during the self-sustaining regeneration cycle are investigated via a three-dimensional Navier–Stokes flow coupled with a freely vibrating square cylinder at relatively low mass ratio. We employ a variational fluid–structure interaction formulation based on the recently developed partitioned iterative scheme and the dynamic subgrid-scale turbulence model. To begin, we assess the response amplitudes, the synchronization regimes and the vortex shedding patterns against the experimental measurements for the flow-induced vibration of a square cylinder at zero incidence angle. Of particular interest is to predict and analyze the synchronization regimes and the associated wake structures for a range of reduced velocity. The vibration of the cylinder provides an avenue for the merging of smaller eddies in the vicinity of the cylinder and there are relatively more clustered spanwise rollers and streamwise ribs as compared to the stationary counterpart. We provide a comparative assessment of Reynolds stress distributions in the near-wake region between the VIV lock-in case and its stationary counterpart. We find that the spatial symmetry of the shearing process in the wake shifts to the temporal symmetry of Reynolds stress when the cylinder is free to vibrate. Consequently, in the vibrating case, the competition between the mean shear growth and damping results in a relatively lower frequency shearing as compared to the stationary cylinder. We introduce a representative control volume in the near-wake region to assess the kinetic energy and enstrophy evolution for the stationary and vibrating configurations. We examine the core reason of the matching of periodic wake frequency with the vibrating cylinder frequency through the development of near-wake flow structures and the kinetic energy evolution. By combining these results with the self-sustained process of coherent vortex structure development, we finally explain the formation of intermediate hairpin-like structures in close proximity to the vibrating cylinder and the absence of them in the stationary cylinder.

      PubDate: 2017-12-26T23:38:13Z
      DOI: 10.1016/j.jfluidstructs.2017.11.002
      Issue No: Vol. 77 (2017)
       
  • A new analytical approach for modeling the added mass and hydrodynamic
           interaction of two cylinders subjected to large motions in a potential
           stagnant fluid
    • Authors: Romain Lagrange; Xavier Delaune; Philippe Piteau; Laurent Borsoi; José Antunes
      Pages: 102 - 114
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Romain Lagrange, Xavier Delaune, Philippe Piteau, Laurent Borsoi, José Antunes
      A potential theory is presented for the problem of two moving circular cylinders, with possibly different radii, large motions, immersed in an perfect stagnant fluid. We show that the fluid force is the superposition of an added mass term, related to the time variations of the potential, and a quadratic term related to its spatial variations. We provide new simple and exact analytical expressions for the fluid added mass coefficients, in which the effect of the confinement is made explicit. The self-added mass (resp. cross-added mass) is shown to decrease (resp. increase) with the separation distance and increase (resp. decreases) with the radius ratio. We then consider the case in which one cylinder translates along the line joining the centers with a constant speed. We show that the two cylinders are repelled from each other, with a force that diverges to infinity at impact. We extend our approach to the case in which one cylinder is imposed a sinusoidal vibration. We show that the force on the stationary cylinder and the vibration displacement have opposite (resp. identical) axial (resp. transverse) directions. For large vibration amplitudes, this force is strongly altered by the nonlinear effects induced by the spatial variations of the potential. The force on the vibrating cylinder is in phase with the imposed displacement and is mainly driven by the added mass term. The results of this paper are of particular interest for engineers who need to understand the essential features associated with the vibration of a solid body in a still fluid.

      PubDate: 2017-12-26T23:38:13Z
      DOI: 10.1016/j.jfluidstructs.2017.12.002
      Issue No: Vol. 77 (2017)
       
  • Effects of attachments on aerodynamic characteristics and vortex-induced
           vibration of twin-box girder
    • Authors: Shujin Laima; Hui Li; Wenli Chen; Jinping Ou
      Pages: 115 - 133
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Shujin Laima, Hui Li, Wenli Chen, Jinping Ou
      An experimental investigation was carried out on the effects of attachments on the aerodynamic characteristics and vortex-induced vibration (VIV) of a twin-box girder. In the study, the flow pattern, pressure distribution, vortex shedding frequency, and VIV of five models, namely Model A (twin-box girder without attachments), Model B (twin-box girder with handrails and crash barriers), Model C (twin-box girder with handrails, crash barriers, and wind barriers), Model D (twin-box girder with maintenance rails), and Model E (twin-box girder with full ancillaries), are compared with a bare deck in detail. The results demonstrate that, owing to the large leading flow separation induced by the attachments, the flow characteristics and VIVs of the twin-box girder with attachments differ considerably from the bare twin-box girder. Because of the large porous ratio, the handrails and crash barriers exert relatively weak influences on the surface pressure distribution. However, the leading wind barrier and maintenance rail generate large flow separation at the leading edges, resulting in larger pressure fluctuations, a wider wake, and larger scale vortex with lower shedding frequency than that of the bare deck. Furthermore, owing to the large leading flow separation, the vertical VIV induced by the motion-induced vortex in the gap is suppressed. However, a torsional VIV is generated by the large-scale alternately shedding vortex in the wake of the downstream box girder.

      PubDate: 2017-12-26T23:38:13Z
      DOI: 10.1016/j.jfluidstructs.2017.12.005
      Issue No: Vol. 77 (2017)
       
  • Role of skin friction drag during flow-induced reconfiguration of a
           flexible thin plate
    • Authors: Awan Bhati; Rajat Sawanni; Kaushik Kulkarni; Rajneesh Bhardwaj
      Pages: 134 - 150
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Awan Bhati, Rajat Sawanni, Kaushik Kulkarni, Rajneesh Bhardwaj
      We investigate drag reduction due to the flow-induced reconfiguration of a flexible thin plate in presence of skin friction drag at low Reynolds Number. The plate is subjected to a uniform free stream and is tethered at one end. We extend existing models in the literature to account for the skin friction drag. The total drag on the plate with respect to a rigid upright plate decreases due to flow-induced reconfiguration and further reconfiguration increases the total drag due to increase in skin friction drag. A critical value of Cauchy number ( C a ) exists at which the total drag on the plate with respect to a rigid upright plate is minimum at a given Reynolds number. The reconfigured shape of the plate for this condition is unique, beyond which the total drag increases on the plate even with reconfiguration. The ratio of the skin friction drag coefficient for a horizontal rigid plate and form drag coefficient for an upright rigid plate ( λ ) determines the critical Cauchy number ( C a c r ). We propose modification in the drag scaling with free stream velocity ( F x ∝ U n ) in presence of the skin friction drag. The following expressions of n are found for 0 . 01 ≤ R e ≤ 1 , n = 4 ∕ 5 + λ ∕ 5 for 1 ≤ C a < C a c r and n = 1 + λ ∕ 5 for C a c r ≤ C a ≤ 300 , where R e is Reynolds number. We briefly discuss the combined effect of the skin friction drag and buoyancy on the drag reduction. An assessment of the feasibility of experiments is presented in order to translate the present model to physical systems.

      PubDate: 2017-12-26T23:38:13Z
      DOI: 10.1016/j.jfluidstructs.2017.12.003
      Issue No: Vol. 77 (2017)
       
  • Experimental assessment of an active L-shaped tab for dynamic stall
           control
    • Authors: A. Zanotti; G. Gibertini
      Pages: 151 - 169
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): A. Zanotti, G. Gibertini
      An experimental activity was performed on a NACA 23012 pitching airfoil to investigate the effectiveness of an active trailing edge L-shaped tab for deep dynamic stall control. The active control system, based on the use of micro pneumatic actuators, was designed to control the deployment and retraction of the tab along the oscillating cycle. In particular, the tab was designed to behave as a Gurney flap when deployed as its end prong protrudes at the airfoil trailing edge, while in retracted position the tab behaves as a trailing edge flap. The L-shaped tab design presents interesting features to be employed on rotor blades, due to an easier integration at the trailing edge with respect to a deployable Gurney flap. Wind tunnel tests were carried out considering two pitching cycles producing deep dynamic stall regime. Unsteady pressure measurements were performed at the model midspan section to obtain the phase-averaged aerodynamic loads curves. The tests results showed that the deployment of the tab during the upstroke produces a conspicuous increase of lift with respect to the clean airfoil case, corresponding to a higher level of available thrust on the retreating blade. The retraction of the tab before stall onset does not introduce a valuable effect in terms of pitching moment peak reduction with respect to clean airfoil. Moreover, the active control system produces a conspicuous reduction of the negatively-damped portions of the pitching cycles and of the negative aerodynamic damping peak that could account for stall flutter divergence.

      PubDate: 2017-12-26T23:38:13Z
      DOI: 10.1016/j.jfluidstructs.2017.11.010
      Issue No: Vol. 77 (2017)
       
  • Numerical study of vortex-induced vibrations of a flexible cylinder in an
           oscillatory flow
    • Authors: Bowen Fu; Lu Zou; Decheng Wan
      Pages: 170 - 181
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Bowen Fu, Lu Zou, Decheng Wan
      The vortex-induced vibrations of a flexible cylinder oscillating harmonically in still water have been numerically simulated using a CFD method based on the strip theory. The algorithm PIMPLE in OpenFOAM is adopted to compute the flow field while the small-displacement Bernoulli–Euler bending beam theory is used to model the cylinder. Two ends of the flexible cylinder are forced to oscillate harmonically. The simulation results have been compared with experimental results and further analyzed. Features such as the hysteresis phenomenon and the build-up–lock-in–die-out cycle are observed in the cross-flow vibration. The in-line vibrations consist of three components, the low-frequency oscillation, the first-natural-frequency vibration during the cylinder reversal, and the second-natural-frequency vibration due to vortex shedding. The butterfly-shaped trajectory has been observed. Detailed wavelet analyses of the vibrations have been given at the end.

      PubDate: 2017-12-26T23:38:13Z
      DOI: 10.1016/j.jfluidstructs.2017.12.006
      Issue No: Vol. 77 (2017)
       
  • Galloping oscillation of a circular cylinder firmly combined with
           different shaped fairing devices
    • Authors: Hanxu Zheng; Jiasong Wang
      Pages: 182 - 195
      Abstract: Publication date: February 2018
      Source:Journal of Fluids and Structures, Volume 77
      Author(s): Hanxu Zheng, Jiasong Wang
      The galloping oscillation of a circular cylinder combined with different fairing devices is numerically studied. The fairing devices are integrated with a circular cylinder that is supported by a spring and a damper. An unsteady Reynolds-averaged Navier–Stokes (URANS) model corrected with the arbitrary Lagrange Euler (ALE) method is used as the governing model of the fluid flow while the governing equations are solved with a total variation diminishing (TVD) finite volume method (FVM). The SST turbulence model is used. The fluid–structure-interaction (FSI) simulations are performed under the reduced velocities ranging from 3 to 25. The simulation results are validated with the available experimental and numerical results with a short-tail fairing device. The influences of the shapes and the characteristic lengths of the fairing devices on the galloping oscillation are discussed. The shape of the fairing devices are found to influence the vortex shedding patterns in the wake of the flow field while the characteristic length decides the galloping behavior of the cylinder at different reduced velocities. The fairing devices with the smallest characteristic length have the best vibration suppression performance in the present study.

      PubDate: 2017-12-26T23:38:13Z
      DOI: 10.1016/j.jfluidstructs.2017.12.010
      Issue No: Vol. 77 (2017)
       
  • Model-less forecasting of Hopf bifurcations in fluid-structural systems
    • Authors: Amin Ghadami; Carlos E.S. Cesnik; Bogdan I. Epureanu
      Pages: 1 - 13
      Abstract: Publication date: January 2018
      Source:Journal of Fluids and Structures, Volume 76
      Author(s): Amin Ghadami, Carlos E.S. Cesnik, Bogdan I. Epureanu
      Predicting critical transitions and post-transition dynamics of complex systems is a unique challenge. In this paper, a novel approach is introduced to forecast Hopf bifurcations and the post-bifurcation dynamics of nonlinear fluid-structural systems. The forecasting method is model-less and uses measurements of the system response collected only in the pre-bifurcation regime. To demonstrate the method, it is applied to a cantilever high aspect ratio wing exposed to gust loads as perturbations. To generate surrogate measurements required for forecasting bifurcations in this large-dimensional complex system, a nonlinear strain-based finite element formulation coupled with unsteady aerodynamics is used to model the fluid–structure interaction. Results show that the method successfully forecasts the linear flutter speed and the amplitude of the limit cycle oscillations that occur in the post-bifurcation regime. The procedure is shown to be time efficient, model-less, and to require only few measurements, which makes the proposed forecasting method a unique tool for nonlinear analysis of complex systems.

      PubDate: 2017-10-26T07:04:31Z
      DOI: 10.1016/j.jfluidstructs.2017.09.005
      Issue No: Vol. 76 (2017)
       
  • Aeroelastic response and energy harvesting from a cantilevered
           piezoelectric laminated plate
    • Authors: D.M. Tang; E.H. Dowell
      Pages: 14 - 36
      Abstract: Publication date: January 2018
      Source:Journal of Fluids and Structures, Volume 76
      Author(s): D.M. Tang, E.H. Dowell
      A new nonlinear computational model and code for a piezoelectric–aeroelastic coupled system has been developed. A cantilevered piezoelectric laminated plate in yawed flow ( β ≤ 9 0 0 ) and inverted yawed flow ( β > 9 0 0 ) with a rotated vortex lattice aerodynamic model and new inextensible beam and plate theory is considered in this computational model. For the linear piezoelectric–aeroelastic model a critical flutter or a divergence phenomenon is found for yaw angles β ≤ 9 0 0 or β > 9 0 0 respectively. The divergence speed is independent of the piezoelectric force. Beyond the linear flutter speed, a limit cycle oscillation (LCO) was found for β ≤ 9 0 0 and a large static deflection has been observed for β > 9 0 0 . The power extraction from the piezoelectric network depends on the LCO amplitude, the LCO mode shape and the resistive load, R, for β ≤ 9 0 0 . As flow velocity and resistive load increase, the power extraction increases. From a power efficiency analysis, the best power efficiency is found for a flag like plate when β = 0 0 . This is because this configuration provides the largest LCO amplitude and the best LCO mode shape with a larger bending curvature.

      PubDate: 2017-10-26T07:04:31Z
      DOI: 10.1016/j.jfluidstructs.2017.09.007
      Issue No: Vol. 76 (2017)
       
  • Experimental investigation on spatial attitudes, dynamic characteristics
           and environmental conditions of rain–wind-induced vibration of stay
           cables with high-precision raining simulator
    • Authors: Yaojun Ge; Ying Chang; Linshan Xu; Lin Zhao
      Pages: 60 - 83
      Abstract: Publication date: January 2018
      Source:Journal of Fluids and Structures, Volume 76
      Author(s): Yaojun Ge, Ying Chang, Linshan Xu, Lin Zhao
      Rain–wind-induced vibrations (RWIVs) are one of the most important phenomena affecting the performance of stay cables. The phenomena of RWIVs of cable models were successfully reproduced using a high-precision raining simulator, which has refined control of rainfall intensity and simulation of raindrop size and distribution, through wind tunnel tests considering coupling effects of wind velocity and rain intensity. Some main parameters influencing RWIVs, such as cable inclined angle, wind yaw angle, vibration frequency, vibration damping ratio, wind speed and rainfall intensity, were investigated and compared with those obtained under traditional artificial wind–rain testing conditions. The worst combination of conditions for RWIVs could be determined as two unfavorable environmental states: low wind speeds (2.1 ∼ 6.2 m/s) coupled with high rainfall intensities (50 ∼ 80 mm/h), and high wind speeds (6.9 ∼ 10.7 m/s) coupled with low rainfall intensities (10 ∼ 40 mm/h). Finally, the mechanism of rivulet formation during RWIVs is discussed and some conclusions are given.

      PubDate: 2017-10-26T07:04:31Z
      DOI: 10.1016/j.jfluidstructs.2017.09.006
      Issue No: Vol. 76 (2017)
       
 
 
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