Subjects -> COMPUTER SCIENCE (Total: 2313 journals)
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    - COMPUTER SCIENCE (1305 journals)
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COMPUTER SCIENCE (1305 journals)            First | 1 2 3 4 5 6 7 | Last

Showing 201 - 400 of 872 Journals sorted alphabetically
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Economics     Hybrid Journal   (Followers: 12)
Computational Geosciences     Hybrid Journal   (Followers: 17)
Computational Linguistics     Open Access   (Followers: 23)
Computational Management Science     Hybrid Journal  
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 11)
Computational Methods and Function Theory     Hybrid Journal  
Computational Molecular Bioscience     Open Access   (Followers: 1)
Computational Optimization and Applications     Hybrid Journal   (Followers: 9)
Computational Particle Mechanics     Hybrid Journal   (Followers: 1)
Computational Science and Techniques     Open Access  
Computational Statistics     Hybrid Journal   (Followers: 15)
Computational Statistics & Data Analysis     Hybrid Journal   (Followers: 35)
Computational Toxicology     Hybrid Journal  
Computer     Full-text available via subscription   (Followers: 141)
Computer Aided Surgery     Open Access   (Followers: 5)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Communications     Hybrid Journal   (Followers: 19)
Computer Engineering and Applications Journal     Open Access   (Followers: 8)
Computer Journal     Hybrid Journal   (Followers: 7)
Computer Methods in Applied Mechanics and Engineering     Hybrid Journal   (Followers: 25)
Computer Methods in Biomechanics and Biomedical Engineering     Hybrid Journal   (Followers: 10)
Computer Methods in Biomechanics and Biomedical Engineering : Imaging & Visualization     Hybrid Journal  
Computer Music Journal     Hybrid Journal   (Followers: 18)
Computer Physics Communications     Hybrid Journal   (Followers: 9)
Computer Science - Research and Development     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 15)
Computer Science and Information Technology     Open Access   (Followers: 12)
Computer Science Education     Hybrid Journal   (Followers: 15)
Computer Science Journal     Open Access   (Followers: 20)
Computer Science Review     Hybrid Journal   (Followers: 12)
Computer Standards & Interfaces     Hybrid Journal   (Followers: 3)
Computer Supported Cooperative Work (CSCW)     Hybrid Journal   (Followers: 8)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 9)
Computer-Aided Design and Applications     Hybrid Journal   (Followers: 6)
Computers     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 12)
Computers & Education     Hybrid Journal   (Followers: 92)
Computers & Electrical Engineering     Hybrid Journal   (Followers: 8)
Computers & Geosciences     Hybrid Journal   (Followers: 30)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 9)
Computers & Structures     Hybrid Journal   (Followers: 43)
Computers & Education Open     Open Access   (Followers: 2)
Computers & Industrial Engineering     Hybrid Journal   (Followers: 6)
Computers and Composition     Hybrid Journal   (Followers: 11)
Computers and Education: Artificial Intelligence     Open Access   (Followers: 3)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 7)
Computers and Geotechnics     Hybrid Journal   (Followers: 12)
Computers in Biology and Medicine     Hybrid Journal   (Followers: 11)
Computers in Entertainment     Hybrid Journal  
Computers in Human Behavior Reports     Open Access  
Computers in Industry     Hybrid Journal   (Followers: 7)
Computers in the Schools     Hybrid Journal   (Followers: 8)
Computers, Environment and Urban Systems     Hybrid Journal   (Followers: 11)
Computerworld Magazine     Free   (Followers: 2)
Computing     Hybrid Journal   (Followers: 2)
Computing and Software for Big Science     Hybrid Journal   (Followers: 1)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 31)
Computing Reviews     Full-text available via subscription   (Followers: 1)
Concurrency and Computation: Practice & Experience     Hybrid Journal  
Connection Science     Hybrid Journal  
Control Engineering Practice     Hybrid Journal   (Followers: 46)
Cryptologia     Hybrid Journal   (Followers: 3)
CSI Transactions on ICT     Hybrid Journal   (Followers: 2)
Cuadernos de Documentación Multimedia     Open Access  
Current Science     Open Access   (Followers: 116)
Cyber-Physical Systems     Hybrid Journal  
Cyberspace : Jurnal Pendidikan Teknologi Informasi     Open Access  
DAIMI Report Series     Open Access  
Data     Open Access   (Followers: 4)
Data & Policy     Open Access   (Followers: 3)
Data Science and Engineering     Open Access   (Followers: 6)
Data Technologies and Applications     Hybrid Journal   (Followers: 211)
Data-Centric Engineering     Open Access  
Datenbank-Spektrum     Hybrid Journal   (Followers: 1)
Datenschutz und Datensicherheit - DuD     Hybrid Journal  
Decision Analytics     Open Access   (Followers: 3)
Decision Support Systems     Hybrid Journal   (Followers: 13)
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 33)
Digital Biomarkers     Open Access   (Followers: 1)
Digital Chemical Engineering     Open Access  
Digital Chinese Medicine     Open Access  
Digital Creativity     Hybrid Journal   (Followers: 11)
Digital Experiences in Mathematics Education     Hybrid Journal   (Followers: 3)
Digital Finance : Smart Data Analytics, Investment Innovation, and Financial Technology     Hybrid Journal   (Followers: 3)
Digital Geography and Society     Open Access  
Digital Government : Research and Practice     Open Access   (Followers: 1)
Digital Health     Open Access   (Followers: 10)
Digital Journalism     Hybrid Journal   (Followers: 7)
Digital Medicine     Open Access   (Followers: 3)
Digital Platform: Information Technologies in Sociocultural Sphere     Open Access   (Followers: 1)
Digital Policy, Regulation and Governance     Hybrid Journal   (Followers: 2)
Digital War     Hybrid Journal   (Followers: 1)
Digitale Welt : Das Wirtschaftsmagazin zur Digitalisierung     Hybrid Journal  
Digitális Bölcsészet / Digital Humanities     Open Access   (Followers: 2)
Disaster Prevention and Management     Hybrid Journal   (Followers: 30)
Discours     Open Access   (Followers: 1)
Discourse & Communication     Hybrid Journal   (Followers: 26)
Discover Internet of Things     Open Access   (Followers: 2)
Discrete and Continuous Models and Applied Computational Science     Open Access  
Discrete Event Dynamic Systems     Hybrid Journal   (Followers: 3)
Discrete Mathematics & Theoretical Computer Science     Open Access   (Followers: 1)
Discrete Optimization     Full-text available via subscription   (Followers: 7)
Displays     Hybrid Journal  
Distributed and Parallel Databases     Hybrid Journal   (Followers: 2)
e-learning and education (eleed)     Open Access   (Followers: 39)
Ecological Indicators     Hybrid Journal   (Followers: 22)
Ecological Informatics     Hybrid Journal   (Followers: 3)
Ecological Management & Restoration     Hybrid Journal   (Followers: 15)
Ecosystems     Hybrid Journal   (Followers: 32)
Edu Komputika Journal     Open Access   (Followers: 1)
Education and Information Technologies     Hybrid Journal   (Followers: 53)
Educational Philosophy and Theory     Hybrid Journal   (Followers: 10)
Educational Psychology in Practice: theory, research and practice in educational psychology     Hybrid Journal   (Followers: 13)
Educational Research and Evaluation: An International Journal on Theory and Practice     Hybrid Journal   (Followers: 7)
Educational Theory     Hybrid Journal   (Followers: 9)
Egyptian Informatics Journal     Open Access   (Followers: 5)
Electronic Commerce Research and Applications     Hybrid Journal   (Followers: 5)
Electronic Design     Partially Free   (Followers: 125)
Electronic Letters on Computer Vision and Image Analysis     Open Access   (Followers: 10)
Elektron     Open Access  
Empirical Software Engineering     Hybrid Journal   (Followers: 8)
Energy for Sustainable Development     Hybrid Journal   (Followers: 13)
Engineering & Technology     Hybrid Journal   (Followers: 22)
Engineering Applications of Computational Fluid Mechanics     Open Access   (Followers: 23)
Engineering Computations     Hybrid Journal   (Followers: 3)
Engineering Economist, The     Hybrid Journal   (Followers: 4)
Engineering Optimization     Hybrid Journal   (Followers: 19)
Engineering With Computers     Hybrid Journal   (Followers: 5)
Enterprise Information Systems     Hybrid Journal   (Followers: 2)
Entertainment Computing     Hybrid Journal   (Followers: 2)
Environmental and Ecological Statistics     Hybrid Journal   (Followers: 7)
Environmental Communication: A Journal of Nature and Culture     Hybrid Journal   (Followers: 16)
EPJ Data Science     Open Access   (Followers: 10)
ESAIM: Control Optimisation and Calculus of Variations     Open Access   (Followers: 2)
Ethics and Information Technology     Hybrid Journal   (Followers: 64)
eTransportation     Open Access   (Followers: 1)
EURO Journal on Computational Optimization     Open Access   (Followers: 5)
EuroCALL Review     Open Access  
European Food Research and Technology     Hybrid Journal   (Followers: 8)
European Journal of Combinatorics     Full-text available via subscription   (Followers: 3)
European Journal of Computational Mechanics     Hybrid Journal   (Followers: 1)
European Journal of Information Systems     Hybrid Journal   (Followers: 85)
European Journal of Law and Technology     Open Access   (Followers: 18)
European Journal of Political Theory     Hybrid Journal   (Followers: 27)
Evolutionary Computation     Hybrid Journal   (Followers: 11)
Fibreculture Journal     Open Access   (Followers: 9)
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 5)
Fixed Point Theory and Applications     Open Access  
Focus on Catalysts     Full-text available via subscription  
Focus on Pigments     Full-text available via subscription   (Followers: 3)
Focus on Powder Coatings     Full-text available via subscription   (Followers: 5)
Forensic Science International: Digital Investigation     Full-text available via subscription   (Followers: 317)
Formal Aspects of Computing     Hybrid Journal   (Followers: 3)
Formal Methods in System Design     Hybrid Journal   (Followers: 6)
Forschung     Hybrid Journal   (Followers: 1)
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Databases     Full-text available via subscription   (Followers: 2)
Foundations and Trends® in Human-Computer Interaction     Full-text available via subscription   (Followers: 5)
Foundations and Trends® in Information Retrieval     Full-text available via subscription   (Followers: 30)
Foundations and Trends® in Networking     Full-text available via subscription   (Followers: 1)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 7)
Foundations and Trends® in Theoretical Computer Science     Full-text available via subscription   (Followers: 1)
Foundations of Computational Mathematics     Hybrid Journal  
Foundations of Computing and Decision Sciences     Open Access  
Frontiers in Computational Neuroscience     Open Access   (Followers: 23)
Frontiers in Computer Science     Open Access   (Followers: 1)
Frontiers in Digital Health     Open Access   (Followers: 4)
Frontiers in Digital Humanities     Open Access   (Followers: 7)
Frontiers in ICT     Open Access  
Frontiers in Neuromorphic Engineering     Open Access   (Followers: 2)
Frontiers in Research Metrics and Analytics     Open Access   (Followers: 4)
Frontiers of Computer Science in China     Hybrid Journal   (Followers: 2)
Frontiers of Environmental Science & Engineering     Hybrid Journal   (Followers: 3)
Frontiers of Information Technology & Electronic Engineering     Hybrid Journal  
Fuel Cells Bulletin     Full-text available via subscription   (Followers: 9)
Functional Analysis and Its Applications     Hybrid Journal   (Followers: 3)
Future Computing and Informatics Journal     Open Access  
Future Generation Computer Systems     Hybrid Journal   (Followers: 2)
Geo-spatial Information Science     Open Access   (Followers: 7)
Geoforum Perspektiv     Open Access  
GeoInformatica     Hybrid Journal   (Followers: 7)
Geoinformatics FCE CTU     Open Access   (Followers: 8)
GetMobile : Mobile Computing and Communications     Full-text available via subscription   (Followers: 1)
Government Information Quarterly     Hybrid Journal   (Followers: 28)
Granular Computing     Hybrid Journal  
Graphics and Visual Computing     Open Access  
Grey Room     Hybrid Journal   (Followers: 16)
Group Dynamics : Theory, Research, and Practice     Full-text available via subscription   (Followers: 15)
Groups, Complexity, Cryptology     Open Access   (Followers: 2)
HardwareX     Open Access  
Harvard Data Science Review     Open Access   (Followers: 3)
Health Services Management Research     Hybrid Journal   (Followers: 16)
Healthcare Technology Letters     Open Access  
High Frequency     Hybrid Journal  
High-Confidence Computing     Open Access   (Followers: 1)
Home Cultures     Full-text available via subscription   (Followers: 7)
Home Health Care Management & Practice     Hybrid Journal   (Followers: 1)

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Similar Journals
Journal Cover
Computational Particle Mechanics
Journal Prestige (SJR): 0.888
Citation Impact (citeScore): 2
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2196-4378 - ISSN (Online) 2196-4386
Published by Springer-Verlag Homepage  [2469 journals]
  • Lethe-DEM: an open-source parallel discrete element solver with load
           balancing

    • Free pre-print version: Loading...

      Abstract: Abstract Approximately \({75}\%\) of the raw material and \({50}\%\) of the products in the chemical industry are granular materials. The discrete element method (DEM) provides detailed insights of phenomena at particle scale, and it is therefore often used for modeling granular materials. However, because DEM tracks the motion and contact of individual particles separately, its computational cost increases nonlinearly \(O(n_\mathrm{p}\log (n_\mathrm{p}))\) – \(O(n_\mathrm{p}^2)\) (depending on the algorithm) with the number of particles ( \(n_\mathrm{p}\) ). In this article, we introduce a new open-source parallel DEM software with load balancing: Lethe-DEM. Lethe-DEM, a module of Lethe, consists of solvers for two-dimensional and three-dimensional DEM simulations. Load balancing allows Lethe-DEM to significantly increase the parallel efficiency by \(\approx {25}\) – \({70}\%\) depending on the granular simulation. We explain the fundamental modules of Lethe-DEM, its software architecture, and the governing equations. Furthermore, we verify Lethe-DEM with several tests including analytical solutions and comparison with other software. Comparisons with experiments in a flat-bottomed silo, wedge-shaped silo, and rotating drum validate Lethe-DEM. We investigate the strong and weak scaling of Lethe-DEM with \({1}\le n_\mathrm{c} \le {192}\) and \({32}\le n_\mathrm{c} \le {320}\) processes, respectively, with and without load balancing. The strong-scaling analysis is performed on the wedge-shaped silo and rotating drum simulations, while for the weak-scaling analysis, we use a dam-break simulation. The best scalability of Lethe-DEM is obtained in the range of \({5000}\le n_\mathrm{p}/n_\mathrm{c} \le {15{,}000}\) . Finally, we demonstrate that large-scale simulations can be carried out with Lethe-DEM using the simulation of a three-dimensional cylindrical silo with \(n_\mathrm{p}={4.3}\times 10^6\) on 320 cores.
      PubDate: 2022-05-20
       
  • A particle-based parallel scheme for material point method (MPM) using
           message passing interface (MPI)

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      Abstract: Abstract Material point method (MPM) requires a high computational cost associated with mapping information between a background grid and material particles even though it has a great advantage of solving large deformation problems. This paper presents a particle-based parallel scheme for MPM using message passing interface to effectively reduce the computational cost of MPM. Unlike grid-based parallel schemes, computational workloads are evenly distributed over the computing cores by partitioning material particles into balanced particle subsets. The particle-based parallel scheme guarantees an optimal load balancing between the computing cores because the same number of material particles are assigned to each core. The performance of the present particle-based parallel scheme is compared with that of a grid-based parallel scheme.
      PubDate: 2022-05-17
       
  • Statistical analysis of three-dimensional run-up heights using Gaussian
           process emulator of particle method

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      Abstract: Abstract This study presents that an emulator of a particle method has the potential to be applied for the statistical analysis of tsunami run-up phenomena. The emulator follows a Gaussian process to model a particle method specifically for estimating wave heights of tsunami run-up in front of buildings on the ground. In general, Gaussian processes have the advantage of designing statistical emulators to reduce the computational cost required by simulators. Although statistical analysis using computational models requires a considerable number of simulations, Gaussian process emulators can address this challenge. In contrast, particle methods are advantageous for simulating free-surface flow problems including tsunami run-up. The mesh-free methods discretize the Navier–Stokes and continuity equations without mesh generations as opposed to mesh methods, and thus they can simulate tsunami behaviors near ground buildings. In this study, we simplify tsunami run-up as three-dimensional dam-break problems where the collapse of a water column owing to gravity moves in a slope and impacts on two buildings. Although these problems are not exactly tsunami run-up phenomena, the study intends to show the possibility of applying the Gaussian process emulator for such phenomena. The sensitivity analysis of the wave heights is carried out using the emulator to observe how the run-up heights are influenced by the initial size of the water column. Consequently, it predicts the tendency of the wave heights based on the initial settings and demonstrates the effectiveness of the emulator for the run-up analysis. In addition, this study illustrates the frequency and quartiles of the run-up heights near ground structures, which can be applied for tsunami evacuation planning.
      PubDate: 2022-05-01
       
  • Packing simulation of thin flexible particles using a novel discrete
           element model

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      Abstract: Abstract In discrete element method simulations for industrial applications, long, flat, bendable particles are often approximated as rods with circular cross sections. However, such crude approximation of the particle geometry raises questions on the ability to reproduce the material bulk properties. Therefore, we describe a novel discrete element representation of flexible, flat, thin particles, consisting of a triangulated mass-spring model of the particle’s neutral plane, with the thickness of the particle incorporated in customised contact models. We validate the model with experiments of packing after gravitational deposition and sinusoidal excitation, where we show that the model correctly predicts the packing density for long, flexible, flat particles. Furthermore, we benchmark the model against a circular cross-sectional flexible rod model. Investigation of the dynamics of densification under vibrational compaction shows that the Kohlrausch–Williams–Watts stretched exponential law is well suited to describe the compaction dynamics of the described particles. The novel foil model provides insights in the bulk behaviour of flexible flat particles, otherwise difficult or even impossible to obtain theoretically or experimentally for random orientations. Applications of the model could include the modelling of fabrics, biological material like leaves, soft plastic, and paper.
      PubDate: 2022-05-01
       
  • Direct numerical simulation of atomization by jet impact using moving
           particle semi-implicit method with GPU acceleration

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      Abstract: Abstract Impinging atomization of two jets is numerically simulated using the GPU (Graphics Processing Unit) accelerated moving particle semi-implicit (MPS) method. The acceleration ratio of the GPU-accelerated code is 11.75, which proves the validity of GPU acceleration. Three jet impact modes under different impinging velocities are successfully simulated. The numerical simulations successfully capture the formation of liquid films, the breaking of liquid films into liquid filaments and the breaking of liquid filaments into droplets. Under the flapping-sheet mode, i.e., the atomization phenomena, simulated atomization parameters such as spray angle, jet breakup length and Sauter mean diameter (SMD) agree well the experiment results, which proves the validity of the GPU-accelerated MPS method in the simulations of atomization problem. Thereafter, the GPU-accelerated MPS code is applied to simulate the impact atomization of double jets under typical 16 working conditions. The impinging velocity and angle can affect the atomization to a great extent. With the increasement of the impinging velocity and angle, the spray angle increases while the jet breakup length and SMD decrease, which indicates that the atomization is intensified. When the impinging momentum ratio and jet diameter ratio are not equal to 1.0, defective atomization occurs. With the increasement of the impinging momentum ratio and jet diameter ratio, the spray angle is almost same and the breakup length and SMD increase.
      PubDate: 2022-05-01
       
  • Numerical and experimental research on the degradation mechanism in a
           dust-free crusher using DEM-CFD method

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      Abstract: Abstract Ultrafine crushing is a prerequisite for achieving efficient recycling of waste thermoset plastics. In order to address the problems of recycling including low utilization, this research investigates rigid thermoset polyurethane foam insulation board as the research object and selects an integrated dust-free crusher designed independently. The crushing tool adopts the mechanical physical method to break down the plastic. By optimizing the crushing process parameters, combined with the particle size distribution law of the thermosetting plastic recycled material and the discrete element parameter calibration method, a crushing model based on the Hertz–Mindlin (with bonding) theory is designed and carried out. The discrete element method–computational fluid dynamics (DEM–CFD) gas–solid coupling field numerical simulation is used to explore the degradation of the recycled material after the optimization of the mechanical equipment. The results are verified with spectroscopic characterization and response surface method tests. It was found that when the optimized parameters of a five-slice blade, a crushing time of 25 min, and a crusher speed of 5500 rpm are used, the network crosslink density of the waste thermoset plastics is successfully broken. Among the materials tested, the crosslink density of the 120 mesh recycled material is very small (0.00074 mol/cm3). Many renewable polymerized active groups are obtained, and the degradation yield reaches up to 80.34%.
      PubDate: 2022-05-01
       
  • A modified bond model for describing isotropic linear elastic material
           behaviour with the discrete element method

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      Abstract: Abstract Recently, the discrete element method is increasingly being used for describing the behaviour of isotropic linear elastic materials. However, the common bond models employed to describe the interaction between particles restrict the range of Poisson’s ratio that can be represented. In this paper, to overcome the restriction, a modified bond model that includes the coupling of shear strain energy of neighbouring bonds is proposed. The coupling is described by a multi-bond term that enables the model to distinguish between shear deformations and rigid-body rotations. The positive definiteness of the strain energy function of the modified bond model is verified. To validate the model, uniaxial tension, pure shear and pure bending tests are performed. Comparison of the particle displacements with continuum mechanics solution demonstrates the ability of the model to describe the behaviour of isotropic linear elastic material for values of Poisson’s ratio in the range \(0 \le \nu < 0.5\) .
      PubDate: 2022-05-01
       
  • Impact dynamics and power-law scaling behavior of wet agglomerates

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      Abstract: Abstract We investigate the impact dynamics of a single wet agglomerate composed of primary spherical particles impacting a flat plane by using three-dimensional discrete element method simulations. The primary particle is assumed to be rigid and interacted with its near-neighboring particles by introducing approximate analytical expressions of capillary cohesion forces and lubrication forces induced from the liquid in addition to their elastic and frictional interactions. The paper analyzes the mechanical strength, the deformation, and the connectivity of wet particle agglomerate during the impact as well as in its early-stage impact and the final-stage deposition. We show that the mechanical strength, deformation, and connectivity of granule strongly depend on the key parameters (the liquid–vapor surface tension, the liquid viscosity, and the impact speed of agglomerate). In particular, the early-stage strength and the height of wet agglomerate at its final-stage deposition nicely behave as a function of the Capillary–Stokes inertial number that combines the Capillary number and Stokes number, and the macroscopic strength of the agglomerate at its early-stage impact has the microscopic origin from the normal compressive forces between primary particles. These observations are consistent that represent the relationship between the rheological properties and the liquid properties and the impact conditions of wet granular materials.
      PubDate: 2022-05-01
       
  • Numerical analysis of the drag on a rigid body in an immersed granular
           flow

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      Abstract: Abstract The drag exerted on an object moving in a granular medium is subject to many studies: in dry grains, it depends on the stress – often due to gravity – inside the grains. For Froude numbers less than 10, the drag is independent of the velocity. In immersed grains, it is proportional to the apparent weight of the grains and it depends on both velocity and fluid viscosity. In this paper, the drag on a cylinder in dry and immersed granular flow is simulated with a multi-scale FEM-DEM model. The Janssen stress saturation effect before the flow and velocity independence of the drag are both reproduced. The semi-circular orientation of the stress field supports the hypothesis of a spherical zone of influence of the cylinder. This orientation does not significantly change upon flowing. The results show the velocity independence of the drag is due to particle friction. In the immersed case, the fluid contribution is negligible on its own. A dimensional analysis suggests that shear thickening should be taken into account. The transition between the quasi-static and the fluidized regime is accompanied by a decrease of the stress field downstream of the cylinder and a change in the shape of the shear zone.
      PubDate: 2022-05-01
       
  • Application of improved multiresolution technique for the MPS method to
           fluid lubrication

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      Abstract: Abstract In this study, we improve a multiresolution method to reduce the computation time of fluid lubrication simulation based on a particle method by applying an implicit algorithm for viscosity calculation. The present method is based on the moving particle simulation (MPS) method and the overlapping particle technique (OPT), which is a multiresolution method for particle methods under unsteady states. The MPS method is used to solve the Navier–Stokes equation. The OPT is used to reduce the number of required particles and reduce the computation time. We improve the OPT by applying an implicit method for viscosity calculation to eliminate restrictions regarding time increment due to the diffusion number. In addition, we enable the particle size to be changed significantly between subdomains in the OPT. To validate the proposed method, we simulate the fluid lubrication of line contact in two dimensions until the flow reached a steady state. Consequently, it is shown that the pressure obtained using the proposed method agrees well with that obtained using the Reynolds equation. The computation time of a particle simulation using the improved multiresolution method is significantly shorter than that of a single-resolution simulation. In addition, the effects of particle size and subdomain size are validated in the fluid lubrication simulation using the OPT.
      PubDate: 2022-05-01
       
  • Numerical simulation on the effect of particle shape on mechanical
           response of proppants in horizontal fractures

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      Abstract: Particle geometry significantly influences the mechanical characteristics of sand. Hence, understanding the mechanical response of different shaped granular particle pack under compressive stress is important for estimating their influence on fracture conductivity as reported by Mollanouri Shamsi et al. (in: SPE paper SPE-190024-MS presented at the SPE Western Regional Meeting held in Garden Grove, California, 2018). Consequently, when modeling the behavior of granular assemblies, it is crucial that they are appropriately simulated as accurate as possible. In this study, a clumped particle logic which combines two or more spherical particles and allows for overlap is adopted to model proppant particle shapes. Three groups of particles: Particle A, Particle B and Particle C with different sphericity and aspect ratio are generated randomly and assembled between two rough parallel fracture plates. The rough surfaces which adhere to normal distribution were generated using Gaussian distribution model. A discrete element method approach using linear contact model is then implemented to replicate the real particle shapes and their assembly. Then, the fracture closure condition on each proppant pack is simulated by uniaxial compression. Results show that particle shape influences mechanical response (unconfined pack bed height, packing porosity, constrained modulus and coordination number) of proppant pack in fractures. The proposed work provides an effective insight for understanding mechanics of proppant of different shape and how it later influences fracture. It also avails an avenue for optimizing proppant shape based on expected combinations of field operations. Graphical abstract
      PubDate: 2022-05-01
       
  • Waterfall Algorithm as a tool of investigation the geometrical features of
           granular porous media

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      Abstract: Abstract The paper describes the so-called Waterfall Algorithm, which may be used to calculate a set of parameters characterising the spatial structure of granular porous media, such as shift ratio, collision density ratio, consolidation ratio, path length and minimum tortuosity. The study is performed for 1800 different two-dimensional random pore structures. In each geometry, 100 individual paths are calculated. The impact of porosity and the particle size on the above-mentioned parameters is investigated. It was stated in the paper, that the minimum tortuosity calculated by the Waterfall Algorithm cannot be used directly as a representative tortuosity of pore channels in the Kozeny or the Carman meaning. However, it may be used indirect by making the assumption that a unambiguous relationship between the representative tortuosity and the minimum tortuosity exists. It was also stated, that the new parameters defined in the present study are sensitive on the porosity and the particle size and may be therefore applied as indicators of the geometry structure of granular media. The Waterfall Algorithm is compared with other methods of determining the tortuosity: A-Star Algorithm, Path Searching Algorithm, Random Walk technique, Path Tracking Method and the methodology of calculating the hydraulic tortuosity based on the Lattice Boltzmann Method. A very short calculation time is the main advantage of the Waterfall Algorithm, what meant, that it may be applied in a very large granular porous media.
      PubDate: 2022-05-01
       
  • Numerical study of general shape particles in a concentric annular duct
           having inner obstacle

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      Abstract: Abstract We have examined the behavior of solid particles in an annulus. A circular, square and elliptic shaped particle is analysed separately and in pairs. Behaviour of two circular particles moving inside two concentric moving cylinders having an internal obstacle is analysed. The interaction of particle with the fluid and circular obstacle is carried out inside a fixed circular mesh using an Eulerian approach. The coupled fluid and particles system is handled using fictitious boundary method. The hydrodynamic forces acting on the fictitious boundaries (particles) are calculated using an explicit volume integral approach. A collision model proposed by Glowinski et al. is used to prevent particle-wall, particle-particle and particle-obstacle overlapping and collision. The particulate flow is computed using multigrid finite element solver FEATFLOW.
      PubDate: 2022-05-01
       
  • Effect of particle angularity on flow regime transitions and segregation
           of bidisperse blends in a rotating drum

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      Abstract: Abstract Granular segregation is a phenomenon that occurs when mixing different-sized particles. This work aims at comparing the segregation pattern and intensity in a bidisperse blend of spherical, cubic and icosahedral particles with a size ratio of 1.5 in a rotating drum. A model based on the discrete element method is used to simulate the flow of particles at rotational speeds ranging from 15 RPM to 115 RPM. This model is validated for monodisperse cubic particles. Segregation is shown to decrease with increasing particle shape angularity for a given rotational speed as long as the flow remains in the same regime. For all three shapes, the same sequence of segregation pattern occurs as the rotational speed increases (from a classic core segregation to a mixed state, and then to inverse segregation), but the speed thresholds for the transitions are shape-dependent and linked to the total kinetic energy of particles, as evidenced by a proposed apparent Froude number. The slip at the wall and the ability to spin explain why rounder shapes are less efficient to transfer kinetic energy from the wall into translational motion of the particles. This triggers regime transitions at higher rotational speeds for rounder particles, but at the same apparent Froude numbers. The transitions between cascading and cataracting, and between cataracting and centrifuging, occur at \(Fr_\mathrm{{app}}\approx 0.20\) and 0.35, respectively, regardless of the particle shape.
      PubDate: 2022-05-01
       
  • Simulation investigation of mechanical and failure characteristics of
           jointed rock with different shapes of joint asperities under compression
           loading

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      Abstract: Abstract With the increase in the number of rock engineering projects, it has been recognized that the influence of joints on compressive damage of rock mass cannot be ignored. The existence of joints in the rock mass having complex surface configurations significantly influences its damage properties. Hence, a particle flow code (PFC2D) was used to investigate the effects of joint surface configuration on mechanical properties of jointed rock when compressed. In this study, a hybrid model with parallel bond model (PBM) and flat-joint model (FJM) was applied to simulate granite material and the complex surface configuration was simplified into four types of shapes (i.e., rectangle, trapezoid, ellipse and triangle). The shape effect on deformation and failure modes of jointed rock was discussed. The numerical results show that joint asperity diminished mechanical property of jointed rock and is prone to damage. It is reflected that strength and elastic modulus markedly decreased and asperity degradation. In addition, because of the asperity asynchronous degradation, the joint surface exhibited inconsistent displacement. The joint asperity shape affected the failure properties of jointed rock. Three failure modes of the joint asperities were observed. Finally, the shape feature of the asperities (angle, radius ratios and side length) on the deformation and degradation of joint asperity was discussed.
      PubDate: 2022-04-27
       
  • Evaluating DualSPHysics performance implemented in the study of heat
           transfer in multiphase systems with applications in nuclear reactors

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      Abstract: Abstract For this work, we condense current endeavors and improvements in the expansion of applications of the DualSPHysics code to nuclear reactor safety analysis, that includes the analysis of very complex multiphysical phenomena, involving, in some cases, a highly nonlinear deformation. Computational fluid dynamic (CFD) codes have been developed to analyze some phenomena in nuclear reactors with very good performance; however, this kind of method, based on a well-defined mesh, presents some restrictions when physical phenomena like thermal expansion change the dimensions of the system. The smoothed particle hydrodynamics (SPH) formulation could represent an option to analyze with more precision some physical phenomena in nuclear reactors where a rigid mesh cannot fully represent the system. The DualSPHysics code has shown to be a real and robust alternative, since it involves a free mesh approach, and the numerical method is very well parallelized in both computational and graphical processing units (CPU and GPU). Five cases have been chosen and studied to validate the developments in the code. The results show an exceptionally good approximation with other simulation approaches and with experimental observations. Based on the analyzed cases, the potential applications for nuclear reactors are discussed. As a result, a development path for the DualSPHysics code has been identified as a starting point to further apply the code in nuclear safety analysis as an innovative technique in the field.
      PubDate: 2022-04-26
       
  • A random algorithm for 3D modeling of solid particles considering
           elongation, flatness, sphericity, and convexity

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      Abstract: Abstract Generating particles with specific shape characteristics is regarded as a critical issue in the research of granular materials. Improving the particle generation method to consider more comprehensive shape descriptors becomes a central challenge in this field. We described a novel solution for parametrically generate non-convex particles to meet this challenge. First, to conveniently capture particle characteristics, this work established estimation functions of 3D shape parameters (elongation, flatness, sphericity, and convexity). Then, the present study proposed a novel stochastic algorithm for generating non-convex particles. (This algorithm successfully controls the above particle shape parameters.) Finally, this work verified the mechanical properties of the generated particles are similar to those of realistic-shaped particles, by comparing the numerical results of three-dimensional compression of granular materials. The proposed algorithm has a good performance in controlling particle shape parameters and generate particles quickly.
      PubDate: 2022-04-15
       
  • Material and particle size sensitivity analysis on coefficient of
           restitution in low-velocity normal impacts

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      Abstract: Abstract In many granular processes, impacts play a crucial role. These impacts are often described by the coefficient of restitution (COR). This COR does not only depend on impact velocity but also on the material pairing, the shape of impacting bodies, number of impacts, etc. This paper analyzes and compares the sensitivity of the COR for often seen material pairings metal–metal and metal–polymer. For experimental investigations, a steel sphere impacts different planar material probes in a defined manner, e.g., a sphere–wall contact is reproduced. While the metal–metal impacts show a significant dependency on impact velocity, the metal–polymer impacts show only little influence of the impact velocity. Also, repeated impacts onto the same spot have a significant influence on metal–metal impacts, while metal–polymer impacts are not affected. To gain insights not only about the macroscopic behavior of impacts but also about the microscopic behavior, finite element simulations are performed using an efficient 2D axisymmetric model and viscoelastic and elastic–viscoplastic material models. A good agreement between experiments and FEM simulations are achieved for the utilized material pairings. Then, the influence of the sphere’s size is studied. Afterward, a deeper look into the energy dissipation process during contact is investigated. Finally, the contact duration and normal force in the contact zone are studied experimentally.
      PubDate: 2022-04-11
       
  • 2D SPH simulation of an anaerobic digester

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      Abstract: Abstract Understanding the hydrodynamics within the anaerobic digester tank of a wastewater treatment plant is of high importance to ensure sufficient mixing and subsequently a homogeneous distribution of the substrates. In this paper, we demonstrate a two-dimensional computational fluid dynamics simulation of a real-world case study focusing on both, the methodology and the operation of mixing. For this work, DualSPHysics, a Lagrangian solver, has been explored as an alternative to the more commonly used Eulerian solvers in studying the slow-moving dynamics inside a digester tank. This choice of a Lagrangian solver is primarily due to the inherent accounting for advection within the formulation, thus allowing for subsequent modelling of anaerobic digestion processes. A comparison has been made between the simulations from the two methods (Eulerian and Lagrangian), highlighting the benefits and the shortcomings of using smoothed particle hydrodynamics. Concerning operational mixing, the case relies on a draft tube, the effect of which on the velocity profiles has been studied based on the presence of low-velocity zones and Lagrangian coherent structures. Removing the draft tube results in an increase in low-velocity zones by 21.38% while the amount of dead volume increases from 0.52 to 1.2%.
      PubDate: 2022-04-02
       
  • Quantitative evaluation of SPH in TIG spot welding

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      Abstract: Abstract While the application of the Smoothed Particle Hydrodynamics (SPH) method for the modeling of welding processes has become increasingly popular in recent years, little is yet known about the quantitative predictive capability of this method. We propose a novel SPH model for the simulation of the tungsten inert gas (TIG) spot welding process and conduct a thorough comparison between our SPH implementation and two finite element method (FEM)-based models. In order to be able to quantitatively compare the results of our SPH simulation method with grid-based methods, we additionally propose an improved particle to grid interpolation method based on linear least-squares with an optional hole-filling pass which accounts for missing particles. We show that SPH is able to yield excellent results, especially given the observed deviations between the investigated FEM methods and as such, we validate the accuracy of the method for an industrially relevant engineering application.
      PubDate: 2022-04-01
       
 
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