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Publisher: Springer-Verlag (Total: 2352 journals)

 Showing 1201 - 1400 of 2352 Journals sorted alphabetically J. of Clinical Immunology       (Followers: 14, SJR: 1.332, h-index: 75) J. of Clinical Monitoring and Computing       (Followers: 1, SJR: 0.661, h-index: 37) J. of Clinical Psychology in Medical Settings       (Followers: 13, SJR: 0.46, h-index: 34) J. of Cluster Science       (SJR: 0.416, h-index: 31) J. of Coal Science and Engineering (China)       (SJR: 0.188, h-index: 8) J. of Coastal Conservation       (Followers: 7, SJR: 0.474, h-index: 25) J. of Coatings Technology and Research       (Followers: 5, SJR: 0.425, h-index: 25) J. of Combinatorial Optimization       (Followers: 5, SJR: 1.093, h-index: 34) J. of Communications Technology and Electronics       (Followers: 2, SJR: 0.29, h-index: 16) J. of Community Genetics       (Followers: 1, SJR: 0.727, h-index: 14) J. of Community Health       (Followers: 8, SJR: 0.921, h-index: 44) J. of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology       (Followers: 9, SJR: 1.087, h-index: 74) J. of Comparative Physiology B : Biochemical, Systemic, and Environmental Physiology       (Followers: 4, SJR: 1.126, h-index: 59) J. of Compassionate Health Care       (Followers: 3) J. of Computational Analysis and Applications       (SJR: 0.291, h-index: 19) J. of Computational Electronics       (Followers: 4, SJR: 0.511, h-index: 20) J. of Computational Neuroscience       (Followers: 25, SJR: 1.068, h-index: 60) J. of Computer and Systems Sciences Intl.       (SJR: 0.27, h-index: 13) J. of Computer Science and Technology       (Followers: 5, SJR: 0.437, h-index: 31) J. of Computer Virology and Hacking Techniques       (Followers: 6, SJR: 0.151, h-index: 2) J. of Computer-Aided Molecular Design       (Followers: 2, SJR: 0.995, h-index: 78) J. of Computers in Education       (Followers: 12) J. of Computing in Higher Education       (Followers: 13, SJR: 0.363, h-index: 21) J. of Consumer Policy       (Followers: 7, SJR: 0.704, h-index: 30) J. of Contemporary Mathematical Analysis       (SJR: 0.237, h-index: 5) J. of Contemporary Physics (Armenian Academy of Sciences)       (Followers: 11, SJR: 0.197, h-index: 6) J. of Contemporary Psychotherapy       (Followers: 6, SJR: 0.397, h-index: 23) J. of Control Theory and Applications       (Followers: 2, SJR: 0.359, h-index: 19) J. of Control, Automation and Electrical Systems       (Followers: 10, SJR: 0.231, h-index: 9) J. of Crop Science and Biotechnology       (Followers: 7) J. of Cross-Cultural Gerontology       (Followers: 6, SJR: 0.631, h-index: 29) J. of Cryptographic Engineering       (Followers: 5, SJR: 0.989, h-index: 11) J. of Cryptology       (Followers: 3, SJR: 1.443, h-index: 55) J. of Cultural Economics       (Followers: 4, SJR: 0.539, h-index: 29) J. of Database Marketing & Customer Strategy Management       (Followers: 9, SJR: 0.149, h-index: 8) J. of Derivatives & Hedge Funds       (Followers: 8, SJR: 0.114, h-index: 5) J. of Developmental and Physical Disabilities       (Followers: 8, SJR: 0.574, h-index: 29) J. of Digital Imaging       (Followers: 10, SJR: 0.578, h-index: 35) J. of Direct Data and Digital Marketing Practice       (Followers: 8, SJR: 0.154, h-index: 6) J. of Dynamical and Control Systems       (Followers: 2, SJR: 0.4, h-index: 26) J. of Dynamics and Differential Equations       (SJR: 1.418, h-index: 31) J. of Earth Science       (Followers: 10, SJR: 0.483, h-index: 16) J. of Earth System Science       (Followers: 49, SJR: 0.448, h-index: 32) J. of East Asian Linguistics       (Followers: 6, SJR: 0.537, h-index: 20) J. of Echocardiography       (Followers: 4, SJR: 0.22, h-index: 3) J. of Ecology and Environment       (Followers: 1) J. of Economic Growth       (Followers: 29, SJR: 3.273, h-index: 63) J. of Economic Interaction and Coordination       (SJR: 0.263, h-index: 12) J. of Economics       (Followers: 17, SJR: 0.418, h-index: 23) J. of Economics and Finance       (Followers: 6, SJR: 0.272, h-index: 19) J. of Educational Change       (Followers: 7, SJR: 0.961, h-index: 21) J. of Elasticity       (Followers: 6, SJR: 0.851, h-index: 45) J. of Electroceramics       (SJR: 0.577, h-index: 57) J. of Electronic Materials       (Followers: 5, SJR: 0.609, h-index: 75) J. of Electronic Testing       (Followers: 2, SJR: 0.372, h-index: 27) J. of Electronics (China)       (Followers: 4, SJR: 0.112, h-index: 9) J. of Elementary Science Education       (Followers: 9) J. of Elliptic and Parabolic Equations J. of Engineering Mathematics       (SJR: 0.347, h-index: 37) J. of Engineering Physics and Thermophysics       (Followers: 1, SJR: 0.288, h-index: 11) J. of Engineering Research       (Followers: 1, SJR: 0.145, h-index: 5) J. of Engineering Thermophysics       (Followers: 4, SJR: 0.763, h-index: 9) J. of Environmental Studies and Sciences       (Followers: 2) J. of Ethology       (Followers: 2, SJR: 0.609, h-index: 25) J. of Evolution Equations       (SJR: 0.826, h-index: 26) J. of Evolutionary Biochemistry and Physiology       (SJR: 0.145, h-index: 11) J. of Evolutionary Economics       (Followers: 9, SJR: 0.492, h-index: 52) J. of Experimental and Theoretical Physics       (Followers: 3, SJR: 0.458, h-index: 39) J. of Experimental Criminology       (Followers: 50, SJR: 1.445, h-index: 28) J. of Failure Analysis and Prevention       (Followers: 5, SJR: 0.261, h-index: 15) J. of Family and Economic Issues       (Followers: 6, SJR: 0.396, h-index: 32) J. of Family Violence       (Followers: 38, SJR: 0.639, h-index: 56) J. of Financial Services Marketing       (Followers: 3, SJR: 0.273, h-index: 10) J. of Financial Services Research       (Followers: 24, SJR: 0.572, h-index: 36) J. of Fixed Point Theory and Applications       (SJR: 0.644, h-index: 13) J. of Fluorescence       (Followers: 3, SJR: 0.465, h-index: 56) J. of Food Measurement and Characterization       (SJR: 0.307, h-index: 4) J. of Food Science and Technology       (Followers: 6, SJR: 0.441, h-index: 29) J. of Forest Research       (Followers: 3, SJR: 0.495, h-index: 27) J. of Forestry Research       (Followers: 4, SJR: 0.304, h-index: 14) J. of Fourier Analysis and Applications       (Followers: 1, SJR: 1.18, h-index: 42) J. of Friction and Wear       (Followers: 7, SJR: 0.373, h-index: 7) J. of Fusion Energy       (Followers: 3, SJR: 0.387, h-index: 19) J. of Gambling Studies       (Followers: 7, SJR: 1.171, h-index: 57) J. of Gastroenterology       (Followers: 12, SJR: 1.651, h-index: 88) J. of Gastrointestinal Cancer       (Followers: 4, SJR: 0.304, h-index: 39) J. of Gastrointestinal Surgery       (Followers: 8, SJR: 1.64, h-index: 99) J. of General Internal Medicine       (Followers: 18, SJR: 1.804, h-index: 134) J. of General Plant Pathology       (SJR: 0.554, h-index: 22) J. of Genetic Counseling       (Followers: 6, SJR: 0.902, h-index: 39) J. of Genetics       (Followers: 5, SJR: 0.458, h-index: 28) J. of Geodesy       (Followers: 9, SJR: 2.173, h-index: 56) J. of Geographical Sciences       (Followers: 1, SJR: 0.8, h-index: 23) J. of Geographical Systems       (Followers: 4, SJR: 0.822, h-index: 39) J. of Geometric Analysis       (Followers: 2, SJR: 1.491, h-index: 27) J. of Geometry       (Followers: 1, SJR: 0.272, h-index: 15) J. of Global Optimization       (Followers: 4, SJR: 0.992, h-index: 60) J. of Global Policy and Governance       (Followers: 11) J. of Grid Computing       (Followers: 1, SJR: 1.414, h-index: 37) J. of Happiness Studies       (Followers: 25, SJR: 0.881, h-index: 39) J. of Hematopathology       (Followers: 4, SJR: 0.2, h-index: 13) J. of Heuristics       (Followers: 4, SJR: 1.308, h-index: 50) J. of High Energy Physics       (Followers: 18, SJR: 1.052, h-index: 153) J. of Homotopy and Related Structures       (SJR: 0.232, h-index: 2) J. of Housing and the Built Environment       (Followers: 8, SJR: 0.648, h-index: 28) J. of Huazhong University of Science and Technology [Medical Sciences]       (SJR: 0.344, h-index: 19) J. of Ichthyology       (Followers: 3, SJR: 0.304, h-index: 10) J. of Immigrant and Minority Health       (Followers: 13, SJR: 0.759, h-index: 37) J. of Inclusion Phenomena and Macrocyclic Chemistry       (Followers: 1, SJR: 0.331, h-index: 46) J. of Indian Council of Philosophical Research J. of Indian Philosophy       (Followers: 12, SJR: 0.127, h-index: 12) J. of Industrial Microbiology and Biotechnology       (Followers: 16, SJR: 0.966, h-index: 80) J. of Industry, Competition and Trade       (Followers: 8, SJR: 0.327, h-index: 15) J. of Infection and Chemotherapy       (Followers: 1, SJR: 0.673, h-index: 46) J. of Information Technology       (Followers: 56, SJR: 1.474, h-index: 55) J. of Information Technology Teaching Cases       (Followers: 9) J. of Infrared, Millimeter and Terahertz Waves       (Followers: 2, SJR: 1.25, h-index: 36) J. of Inherited Metabolic Disease       (Followers: 2, SJR: 1.389, h-index: 77) J. of Inorganic and Organometallic Polymers and Materials       (Followers: 9, SJR: 0.338, h-index: 33) J. of Insect Behavior       (Followers: 8, SJR: 0.569, h-index: 39) J. of Insect Conservation       (Followers: 10, SJR: 0.872, h-index: 43) J. of Intelligent and Robotic Systems       (Followers: 3, SJR: 0.629, h-index: 43) J. of Intelligent Information Systems       (Followers: 1, SJR: 0.691, h-index: 43) J. of Intelligent Manufacturing       (Followers: 3, SJR: 1.397, h-index: 54) J. of Interventional Cardiac Electrophysiology       (SJR: 0.93, h-index: 43) J. of Intl. Business Studies       (Followers: 35, SJR: 4.208, h-index: 130) J. of Intl. Entrepreneurship       (Followers: 9, SJR: 0.549, h-index: 23) J. of Intl. Migration and Integration / Revue de l integration et de la migration internationale       (Followers: 13, SJR: 0.308, h-index: 13) J. of Intl. Relations and Development       (Followers: 21, SJR: 0.793, h-index: 22) J. of Labor Research       (Followers: 19, SJR: 0.394, h-index: 27) J. of Logic, Language and Information       (Followers: 7, SJR: 0.288, h-index: 25) J. of Low Temperature Physics       (Followers: 3, SJR: 0.531, h-index: 52) J. of Machinery Manufacture and Reliability       (Followers: 2, SJR: 0.203, h-index: 7) J. of Mammalian Evolution       (Followers: 5, SJR: 1.134, h-index: 37) J. of Mammary Gland Biology and Neoplasia       (Followers: 2, SJR: 2.252, h-index: 83) J. of Management and Governance       (Followers: 14, SJR: 0.805, h-index: 33) J. of Management Control       (Followers: 4, SJR: 0.605, h-index: 6) J. of Marine Science and Application       (Followers: 2, SJR: 0.439, h-index: 11) J. of Marine Science and Technology       (Followers: 3, SJR: 0.235, h-index: 19) J. of Maritime Archaeology       (Followers: 21, SJR: 0.228, h-index: 8) J. of Market-Focused Management       (Followers: 2) J. of Marketing Analytics       (Followers: 4) J. of Material Cycles and Waste Management       (Followers: 3, SJR: 0.449, h-index: 22) J. of Materials Engineering and Performance       (Followers: 23, SJR: 0.544, h-index: 40) J. of Materials Science       (Followers: 21, SJR: 0.836, h-index: 123) J. of Materials Science : Materials in Electronics       (Followers: 5) J. of Materials Science : Materials in Medicine       (Followers: 5) J. of Mathematical Biology       (Followers: 11, SJR: 1.011, h-index: 71) J. of Mathematical Chemistry       (Followers: 4, SJR: 0.497, h-index: 45) J. of Mathematical Fluid Mechanics       (Followers: 8, SJR: 1.22, h-index: 22) J. of Mathematical Imaging and Vision       (Followers: 5, SJR: 0.901, h-index: 53) J. of Mathematical Modelling and Algorithms       (Followers: 2, SJR: 0.414, h-index: 23) J. of Mathematical Sciences       (SJR: 0.272, h-index: 23) J. of Mathematics Teacher Education       (Followers: 18, SJR: 1.062, h-index: 20) J. of Maxillofacial and Oral Surgery       (Followers: 3) J. of Mechanical Science and Technology       (Followers: 6, SJR: 0.589, h-index: 26) J. of Medical and Biological Engineering       (Followers: 1, SJR: 0.387, h-index: 18) J. of Medical Humanities       (Followers: 22, SJR: 0.299, h-index: 18) J. of Medical Systems       (Followers: 1, SJR: 0.717, h-index: 44) J. of Medical Toxicology       (Followers: 6, SJR: 0.874, h-index: 28) J. of Medical Ultrasonics       (Followers: 2, SJR: 0.18, h-index: 13) J. of Medicine and the Person J. of Membrane Biology       (Followers: 2, SJR: 0.738, h-index: 82) J. of Micro-Bio Robotics       (SJR: 0.28, h-index: 3) J. of Microbiology       (Followers: 8, SJR: 0.741, h-index: 43) J. of Mining Science       (Followers: 4, SJR: 0.317, h-index: 16) J. of Molecular Evolution       (Followers: 9, SJR: 0.952, h-index: 108) J. of Molecular Histology       (Followers: 4, SJR: 0.755, h-index: 48) J. of Molecular Medicine       (Followers: 14, SJR: 2.165, h-index: 113) J. of Molecular Modeling       (Followers: 4, SJR: 0.466, h-index: 50) J. of Molecular Neuroscience       (Followers: 11, SJR: 0.988, h-index: 69) J. of Mountain Science       (Followers: 3, SJR: 0.418, h-index: 15) J. of Muscle Research and Cell Motility       (Followers: 1, SJR: 1.264, h-index: 55) J. of Nanoparticle Research       (Followers: 3, SJR: 0.583, h-index: 84) J. of Natural Medicines       (SJR: 0.602, h-index: 28) J. of Near-Death Studies       (Followers: 2) J. of Nephrology       (Followers: 4, SJR: 0.689, h-index: 55) J. of Network and Systems Management       (SJR: 0.466, h-index: 26) J. of Neural Transmission       (Followers: 2, SJR: 1.034, h-index: 86) J. of Neuro-Oncology       (Followers: 3, SJR: 1.274, h-index: 90) J. of Neuroimmune Pharmacology       (Followers: 1, SJR: 1.662, h-index: 45) J. of Neurology       (Followers: 17, SJR: 1.429, h-index: 105) J. of NeuroVirology       (Followers: 1, SJR: 0.979, h-index: 69) J. of Nondestructive Evaluation       (Followers: 11, SJR: 0.863, h-index: 27) J. of Nonlinear Science       (Followers: 1, SJR: 1.887, h-index: 42) J. of Nonverbal Behavior       (Followers: 5, SJR: 0.723, h-index: 47) J. of Nuclear Cardiology       (SJR: 1.024, h-index: 68) J. of Nutrition, Health and Aging       (Followers: 26, SJR: 0.919, h-index: 60) J. of Obstetrics and Gynecology of India       (Followers: 5, SJR: 0.214, h-index: 6) J. of Occupational Rehabilitation       (Followers: 16, SJR: 0.811, h-index: 51) J. of Ocean Engineering and Marine Energy       (Followers: 2) J. of Ocean University of China (English Edition)       (Followers: 1, SJR: 0.237, h-index: 11) J. of Oceanography       (Followers: 10, SJR: 0.796, h-index: 52) J. of Ocular Biology, Diseases, and Informatics       (SJR: 0.183, h-index: 11) J. of Optical and Fiber Communications Reports       (Followers: 4) J. of Optics       (Followers: 7, SJR: 0.214, h-index: 8) J. of Optimization Theory and Applications       (Followers: 5, SJR: 0.898, h-index: 65) J. of Ornithology       (Followers: 24) J. of Orofacial Orthopedics / Fortschritte der Kieferorthopädie       (SJR: 0.574, h-index: 33) J. of Orthopaedic Science       (Followers: 6, SJR: 0.708, h-index: 48)
 Experiments in Fluids   [SJR: 1.088]   [H-I: 82]   [13 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1432-1114 - ISSN (Online) 0723-4864    Published by Springer-Verlag  [2352 journals]
• Transient gas viscosity measurement using tunable diode laser absorption
spectroscopy
• Authors: Rongkang Gao; Sean O’Byrne; Suzanne L. Sheehe; Joseph Kurtz; Jong-Leng Liow
Abstract: Abstract We have designed and implemented a non-intrusive method for measuring gas viscosity coefficients of gases with accessible absorbing transitions based on transient tunable diode laser absorption spectroscopy (TDLAS) in a 20 µm hollow-core photonic crystal fiber (HC-PCF). As the system contains no moving parts and can be used with a fiber of arbitrary length, it is suitable for viscosity measurements at elevated temperature and under low-density conditions. The gas flow through HC-PCF is driven by a known, constant pressure gradient imposed by gas in two gas cells at either end of the fiber. Infrared radiation from a diode laser is coupled to the fiber to be guided through the gas. A photodetector is placed at the fiber exit to measure the change of light intensity due to absorption from the molecular species. The path-averaged number density of the flow undergoing this transient process can be monitored in real time by TDLAS, based on the Beer–Lambert law, relating absorbance to gas concentration. An existing numerical model describing the time-varying local number density distribution is applied for the numerical determination of viscosity coefficient, by relating the viscosity to the time required for the gas flowing through the fiber to reach a steady state. This measurement method is validated by measuring the viscosity of CO2 as a reference gas at room temperature and inlet pressure ranging from 29 to 3.6 kPa, extending the lower limit of viscosity measurements to pressures below 10 kPa, where laboratory data are lacking. The experimental outcomes are in reasonable agreement with the theoretical value, confirming the effectiveness of this new measurement technique.
PubDate: 2017-10-16
DOI: 10.1007/s00348-017-2438-3
Issue No: Vol. 58, No. 11 (2017)

• Effects of slot jet and its improved approach in a high-load compressor
• Authors: Jiaguo Hu; Rugen Wang; Renkang Li; Peigen Wu
Abstract: Abstract Experimental investigations are conducted in this paper to study a slot jet approach. Measurements inside a high-load compressor cascade were performed to evaluate its gains and reveal its mechanisms. Further, an improved approach is developed on the basis of the individual slot jet approach. Experiments shows that the individual slot jet is highly efficient at reducing trailing-edge separation by directly speeding up separated fluids, but it is not so efficient at reducing the corner stall. To further reduce the corner stall, the improved approach introduces a vortex generator into the flow field. The individual slot jet partly reduces corner stall by restricting the passage vortex and concentrating the separation at the cascade corner, which happens to offer convenient conditions for the vortex generator to further reduce flow loss. The vortex generator, which produces a counter-rotating vortex to counteract the passage vortex, prevents the formation of the end-wall cross flow. Therefore, both the trailing-edge separation and corner stall are significantly suppressed, so that the improved approach achieves more powerful flow control effects.
PubDate: 2017-10-12
DOI: 10.1007/s00348-017-2437-4
Issue No: Vol. 58, No. 11 (2017)

• Particle image velocimetry measurements in an anatomical vascular model
fabricated using inkjet 3D printing
• Authors: Kenneth I. Aycock; Prasanna Hariharan; Brent A. Craven
Abstract: Abstract For decades, the study of biomedical fluid dynamics using optical flow visualization and measurement techniques has been limited by the inability to fabricate transparent physical models that realistically replicate the complex morphology of biological lumens. In this study, we present an approach for producing optically transparent anatomical models that are suitable for particle image velocimetry (PIV) using a common 3D inkjet printing process (PolyJet) and stock resin (VeroClear). By matching the index of refraction of the VeroClear material using a room-temperature mixture of water, sodium iodide, and glycerol, and by printing the part in an orientation such that the flat, optical surfaces are at an approximately 45 $$^{\circ }$$ angle to the build plane, we overcome the challenges associated with using this 3D printing technique for PIV. Here, we summarize our methodology and demonstrate the process and the resultant PIV measurements of flow in an optically transparent anatomical model of the human inferior vena cava.
PubDate: 2017-10-07
DOI: 10.1007/s00348-017-2403-1
Issue No: Vol. 58, No. 11 (2017)

• Characterizing free-surface expressions of flow instabilities by tracking
submerged features
• Authors: Tracy L. Mandel; Itay Rosenzweig; Hayoon Chung; Nicholas T. Ouellette; Jeffrey R. Koseff
Abstract: Abstract Under unidirectional flow, complex bottom roughness such as seagrass canopies can induce Kelvin–Helmholtz (KH) shear instabilities, and these vortices can impact the free surface and leave a signature with an inherent frequency. Therefore, one approach to inferring the presence and properties of submerged ecosystems may be to look at the behavior of the water surface. We present an imaging-based laboratory method developed to characterize this canopy-induced shear instability. Much like a lens, a curving free surface refracts light at the interface (Moisy et al., Exp Fluids 46:1021–1036, 2009). Using cameras placed above the length of a flume, the water surface slope is measured by tracking the apparent distortion of submerged model vegetation in a series of images, manifested as a slight shimmering over time. We demonstrate that the synthetic Schlieren technique can: (1) measure the spectral signature of the canopy-induced shear instability on the free surface, (2) provide high-resolution spatial information on the development of the instability over the entire canopy length, and (3) measure the propagation speed and length scale of the coherent KH rollers at the surface and detect distinguishable differences in these properties for varying canopy geometry.
PubDate: 2017-10-05
DOI: 10.1007/s00348-017-2435-6
Issue No: Vol. 58, No. 11 (2017)

• Surface obstacles in pulsatile flow
• Authors: Ian A. Carr; Michael W. Plesniak
Abstract: Abstract Flows past obstacles mounted on flat surfaces have been widely studied due to their ubiquity in nature and engineering. For nearly all of these studies, the freestream flow over the obstacle was steady, i.e., constant velocity, unidirectional flow. Unsteady, pulsatile flows occur frequently in biology, geophysics, biomedical engineering, etc. Our study is aimed at extending the comprehensive knowledge base that exists for steady flows to considerably more complex pulsatile flows. Characterizing the vortex and wake dynamics of flows around surface obstacles embedded in pulsatile flows can provide insights into the underlying physics in all wake and junction flows. In this study, we experimentally investigate the wake of two canonical obstacles: a cube and a circular cylinder with an aspect ratio of unity. Our previous studies of a surface-mounted hemisphere in pulsatile flow are used as a baseline for these two new, more complex geometries. Phase-averaged PIV and hot-wire anemometry are used to characterize the dynamics of coherent structures in the wake and at the windward junction of the obstacles. Complex physics occur during the deceleration phase of the pulsatile inflow. We propose a framework for understanding these physics based on self-induced vortex propagation, similar to the phenomena exhibited by vortex rings.
PubDate: 2017-10-05
DOI: 10.1007/s00348-017-2436-5
Issue No: Vol. 58, No. 11 (2017)

• Stereoscopic particle image velocimetry investigations of the mixed
convection exchange flow through a horizontal vent
• Authors: Kevin Varrall; Hugues Pretrel; Samuel Vaux; Olivier Vauquelin
Abstract: Abstract The exchange flow through a horizontal vent linking two compartments (one above the other) is studied experimentally. This exchange is here governed by both the buoyant natural effect due to the temperature difference of the fluids in both compartments, and the effect of a (forced) mechanical ventilation applied in the lower compartment. Such a configuration leads to uni- or bi-directional flows through the vent. In the experiments, buoyancy is induced in the lower compartment thanks to an electrical resistor. The forced ventilation is applied in exhaust or supply modes and three different values of the vent area. To estimate both velocity fields and flow rates at the vent, measurements are realized at thermal steady state, flush the vent in the upper compartment using stereoscopic particle image velocimetry (SPIV), which is original for this kind of flow. The SPIV measurements allows the area occupied by both upward and downward flows to be determined.
PubDate: 2017-09-26
DOI: 10.1007/s00348-017-2434-7
Issue No: Vol. 58, No. 10 (2017)

• Experimental analysis on the dynamic wake of an actuator disc undergoing
• Authors: W. Yu; V. W. Hong; C. Ferreira; G. A. M. van Kuik
PubDate: 2017-09-26
DOI: 10.1007/s00348-017-2432-9
Issue No: Vol. 58, No. 10 (2017)

• Generalization of the PIV loss-of-correlation formula introduced by Keane
• Authors: Sven Scharnowski; Kristian Grayson; Charitha M. de Silva; Nicholas Hutchins; Ivan Marusic; Christian J. Kähler
Abstract: Abstract In 2D particle image velocimetry (PIV), the loss-of-correlation due to out-of-plane motion or light-sheet mismatch has two effects. First, it reduces the probability of detecting a valid vector. Second, it increases the uncertainty measured in velocity fields. The loss-of-correlation is commonly determined by the $$F_\mathrm {O}$$ factor, which was initially proposed by Keane and Adrian (Appl Sci Res 49:191–215, 1992). However, the present study demonstrates that the validity of the original $$F_\mathrm {O}$$ definition is confined to cases with identical laser intensity profiles. As light sheets usually differ in width and shape, the proposed definition is of limited use in reality. To overcome this restriction, a new definition for $$F_\mathrm {O}$$ is proposed which covers the effect of light-sheet pairs with different shapes and widths. The proposed improvement was validated by means of synthetic PIV images based on various light-sheet profiles. The loss-of-correlation for the images was compared to the theoretical solution based on the light-sheet profiles. The results show that the new definition of $$F_\mathrm {O}$$ accurately predicts the loss-of-correlation for all tested laser mismatches and agrees with the old definition for the ideal case involving identical light sheets. Based on the revised $$F_\mathrm {O}$$ definition, prediction of loss-of-correlation due to light-sheet mismatches and misalignment is now possible using a laser profiling camera. This allows the optimization of a laser prior to any PIV measurements. For the case of out-of-plane motion, the loss-of-correlation can also be estimated from the correlation function of the PIV images. Thus, it is possible to optimize the laser alignment to match the flow conditions while setting up an experiment. These findings help experimentalists to understand and control the sources of errors associated with out-of-plane effects and help to minimize the measurement uncertainty.
PubDate: 2017-09-26
DOI: 10.1007/s00348-017-2431-x
Issue No: Vol. 58, No. 10 (2017)

• A laser sheet self-calibration method for scanning PIV
• Authors: Anna N. Knutsen; John M. Lawson; James R. Dawson; Nicholas A. Worth
Abstract: Abstract Knowledge of laser sheet position, orientation, and thickness is a fundamental requirement of scanning PIV and other laser-scanning methods. This paper describes the development and evaluation of a new laser sheet self-calibration method for stereoscopic scanning PIV, which allows the measurement of these properties from particle images themselves. The approach is to fit a laser sheet model by treating particles as randomly distributed probes of the laser sheet profile, whose position is obtained via a triangulation procedure enhanced by matching particle images according to their variation in brightness over a scan. Numerical simulations and tests with experimental data were used to quantify the sensitivity of the method to typical experimental error sources and validate its performance in practice. The numerical simulations demonstrate the accurate recovery of the laser sheet parameters over range of different seeding densities and sheet thicknesses. Furthermore, they show that the method is robust to significant image noise and camera misalignment. Tests with experimental data confirm that the laser sheet model can be accurately reconstructed with no impairment to PIV measurement accuracy. The new method is more efficient and robust in comparison with the standard (self-) calibration approach, which requires an involved, separate calibration step that is sensitive to experimental misalignments. The method significantly improves the practicality of making accurate scanning PIV measurements and broadens its potential applicability to scanning systems with significant vibrations.
PubDate: 2017-09-26
DOI: 10.1007/s00348-017-2428-5
Issue No: Vol. 58, No. 10 (2017)

• Design and implementation of a hot-wire probe for simultaneous velocity
and vorticity vector measurements in boundary layers
• Authors: S. Zimmerman; C. Morrill-Winter; J. Klewicki
Abstract: Abstract A multi-sensor hot-wire probe for simultaneously measuring all three components of velocity and vorticity in boundary layers has been designed, fabricated and implemented in experiments up to large Reynolds numbers. The probe consists of eight hot-wires, compactly arranged in two pairs of orthogonal ×-wire arrays. The ×-wire sub-arrays are symmetrically configured such that the full velocity and vorticity vectors are resolved about a single central location. During its design phase, the capacity of this sensor to accurately measure each component of velocity and vorticity was first evaluated via a synthetic experiment in a set of well-resolved DNS fields. The synthetic experiments clarified probe geometry effects, allowed assessment of various processing schemes, and predicted the effects of finite wire length and wire separation on turbulence statistics. The probe was subsequently fabricated and employed in large Reynolds number experiments in the Flow Physics Facility wind tunnel at the University of New Hampshire. Comparisons of statistics from the actual probe with those from the simulated sensor exhibit very good agreement in trend, but with some differences in magnitude. These comparisons also reveal that the use of gradient information in processing the probe data can significantly improve the accuracy of the spanwise velocity measurement near the wall. To the authors’ knowledge, the present are the largest Reynolds number laboratory-based measurements of all three vorticity components in boundary layers.
PubDate: 2017-09-26
DOI: 10.1007/s00348-017-2433-8
Issue No: Vol. 58, No. 10 (2017)

• Aerodynamic features of a two-airfoil arrangement
• Authors: Thierry M. Faure; Laurent Hétru; Olivier Montagnier
Abstract: Abstract The interaction between two foils occurs in many aerodynamic or hydrodynamic applications. Although the characteristics of many airfoils are well documented, there is a limited amount of data for multiple airfoils in interaction and for large values of the angle of attack. This paper presents measurements of the turbulent flow around a two-airfoil T-tail type arrangement and the aerodynamic coefficients, for an incompressible flow at moderate Reynolds number. The study focuses mainly on large angles of attack, corresponding to detached flows on the airfoils, large wakes and involving vortex shedding. Phase averages of velocity fields are made building the flow time development relative to the vortex shedding. The understanding of the change in the tail lift coefficient versus angle of attack, between a two-airfoil arrangement and a single airfoil, is discussed in relation with the position and width of the wing wake and the pathlines of the shedding vortices.
PubDate: 2017-09-26
DOI: 10.1007/s00348-017-2429-4
Issue No: Vol. 58, No. 10 (2017)

• Composition-independent mean temperature measurements in laminar diffusion
flames using spectral lineshape information
• Authors: D. Zelenak; V. Narayanaswamy
Abstract: Abstract Temperature is an important thermochemical property in combusting flows that holds the key to uncovering pollutant formation, flame extinction, and heat release. In a practical combustion environment, the local composition is typically unknown, which hinders the effectiveness of many traditional non-intrusive thermometry techniques. This study aims to offset this limitation by developing a laser-based thermometry technique that does not require prior knowledge of the local composition. Two methods for obtaining temperature are demonstrated in this work, both of which make use of the spectral line broadening of an absorbing species (krypton) seeded into the flow. In the first method, the local Doppler broadening is extracted from an excitation scan to yield the corresponding temperature, while the second method utilizes compositional scaling information of the collisional broadening and collisional shift to determine the temperature. Both methods are demonstrated by measuring the radial temperature profile of a steady laminar CH4/N2 diffusion flame with an air co-flow. The accuracy of the temperature measurements obtained using both methods are evaluated using corresponding temperature profiles determined from computational simulations.
PubDate: 2017-09-26
DOI: 10.1007/s00348-017-2430-y
Issue No: Vol. 58, No. 10 (2017)

• Wake characterization methods of a circulation control wing
• Authors: Y. El Sayed Mohamed; R. Semaan; S. Sattler; R. Radespiel
Abstract: Abstract We propose a three-pronged methodology to characterise the wake behind a circulation control wing. The study relies on time-resolved particle image velocimetry (TR-PIV) measurements in a water tunnel for a range of blowing intensities. The first method is the well-known proper orthogonal decomposition (POD). The second tool is a new implementation of the power spectrum. Finally, a modified Q-criterion vortex detection and quantification method is presented. The results show the complementary advantage of the three methods in analysing wake flows with varying conditions.
PubDate: 2017-09-16
DOI: 10.1007/s00348-017-2424-9
Issue No: Vol. 58, No. 10 (2017)

• An axisymmetric inertia-gravity wave generator
• Authors: P. Maurer; S. J. Ghaemsaidi; S. Joubaud; T. Peacock; P. Odier
Abstract: Abstract There has been a rich interplay between laboratory experimental studies of internal waves and advancing understanding of their role in the ocean and atmosphere. In this study, we present and demonstrate the concept for a new form of laboratory internal wave generator that can excite axisymmetric wave fields of arbitrary radial structure. The construction and operation of the generator are detailed, and its capabilities are demonstrated through a pair of experiments using a Bessel function and a bourrelet (i.e., ring-shaped) configuration. The results of the experiments are compared with the predictions of an accompanying analytical model.
PubDate: 2017-09-15
DOI: 10.1007/s00348-017-2423-x
Issue No: Vol. 58, No. 10 (2017)

• Experimental evidence of inter-blade cavitation vortex development in
Francis turbines at deep part load condition
• Authors: K. Yamamoto; A. Müller; A. Favrel; F. Avellan
PubDate: 2017-09-15
DOI: 10.1007/s00348-017-2421-z
Issue No: Vol. 58, No. 10 (2017)

• Plane boundary effects on characteristics of propeller jets
• Authors: Maoxing Wei; Yee-Meng Chiew; Shih-Chun Hsieh
Abstract: Abstract The flow properties of a propeller jet in the presence of a plane bed boundary were investigated using the particle image velocimetry technique. Three clearance heights, Z b = 2D p, D p, and 0.5D p, where D p = propeller diameter, were used to examine boundary effects on the development of the jet. In each case, the mean flow properties and turbulence characteristics were measured in a larger field of view than those used in past studies. Both the streamwise and transverse flow fields were measured to obtain the three-dimensional characteristics of the propeller jet. Similar to a confined offset jet, the propeller jet also exhibits a wall attachment behavior when it is placed near a plane boundary. As a result, in contrast to its unconfined counterpart, the confined propeller jet features three regions, namely the free jet, impingement and wall jet regions. The study shows that the extent of each region varies under different clearance heights. The development of the mean flow and turbulence characteristics associated with varying clearance heights are compared to illustrate boundary effects in these regions. In the impingement region, the measured transverse flow fields provide new insights on the lateral motions induced by the impingement of the swirling jet. In the wall jet region, observations reveal that the jet behaves like a typical three-dimensional wall jet and its axial velocity profiles show good agreement with the classical wall jet similarity function.
PubDate: 2017-09-14
DOI: 10.1007/s00348-017-2425-8
Issue No: Vol. 58, No. 10 (2017)

• Experimental investigation of Görtler vortices in hypersonic ramp
flows
• Authors: Amit Roghelia; Herbert Olivier; Ivan Egorov; Pavel Chuvakhov
Abstract: Abstract A sharp leading-edge ramp model with 15°, 20°, and 25° ramp angles is experimentally investigated at a freestream Mach number 7.7 and a unit Reynolds number 4.2 × 106 m−1 in the Aachen Shock Tunnel TH2. The objective of this paper is to analyze Görtler vortices in terms of shear layer length, flow curvature, and vortex related parameters. The spanwise heat flux variation caused by it and the streamwise heat flux enhancement during its tenure are also studied. Thermocouples, pressure sensors, schlieren imagery, and infrared imaging are used for the investigation. The boundary layer on the flat plate until separation is laminar. An important outcome is that the arc length at reattachment is constant irrespective of the ramp angle. Characteristic boundary layer thicknesses at different Mach number show that the momentum thickness is insensitive to compressibility and is used to determine the Görtler number. A model is presented to determine the Görtler number in terms of ramp angle and a constant based on separation angle, arc length, momentum thickness, and Reynolds number. The half of the vortex wavelength is equal to the boundary layer thickness just before reattachment. The length scale required for breakdown of Görtler vortices decreases with rising ramp angle and is analogous to peak heating length. The streamwise heat flux enhancement occurs during the tenure of Görtler vortices and the enhancement rises with ramp angle. Although the visibility of Görtler vortices through temperature variation is distinct, the spanwise heat flux variation is not too high. Moreover, the spanwise heat flux variation rises marginally with ramp angle.
PubDate: 2017-09-14
DOI: 10.1007/s00348-017-2422-y
Issue No: Vol. 58, No. 10 (2017)

• Simultaneous schlieren photography and soot foil in the study of
detonation phenomena
• Authors: Mark Kellenberger; Gaby Ciccarelli
Abstract: Abstract The use of schlieren photography has been essential in unravelling the complex nature of high-speed combustion phenomena, but its line-of-sight integration makes it difficult to decisively determine the nature of multi-dimensional combustion wave propagation. Conventional schlieren alone makes it impossible to determine in what plane across the channel an observed structure may exist. To overcome this, a technique of simultaneous high-speed schlieren photography and soot foils was demonstrated that can be applied to the study of detonation phenomena. Using a kerosene lamp, soot was deposited on a glass substrate resulting in a semi-transparent sheet through which schlieren source light could pass. In order to demonstrate the technique, experiments were carried out in mixtures of stoichiometric hydrogen–oxygen at initial pressures between 10 and 15 kPa. Compared to schlieren imaging obtained without a sooted foil, high-speed video results show schlieren images with a small reduction of contrast with density gradients remaining clear. Areas of high temperature cause soot lofted from the foil to incandescence strongly, resulting in the ability to track hot spots and flame location. Post-processing adjustments were demonstrated to make up for camera sensitivity limitations to enable viewing of schlieren density gradients. High-resolution glass soot foils were produced that enable direct coupling of schlieren video to triple-point trajectories seen on the soot foils, allowing for the study of three-dimensional propagation mechanisms of detonation waves.
PubDate: 2017-09-14
DOI: 10.1007/s00348-017-2420-0
Issue No: Vol. 58, No. 10 (2017)

• Coupling temporal and spatial gradient information in high-density
unstructured Lagrangian measurements
• Authors: Jaime G. Wong; Giuseppe A. Rosi; Amirreza Rouhi; David E. Rival
Abstract: Abstract Particle tracking velocimetry (PTV) produces high-quality temporal information that is often neglected when computing spatial gradients. A method is presented here to utilize this temporal information in order to improve the estimation of spatial gradients for spatially unstructured Lagrangian data sets. Starting with an initial guess, this method penalizes any gradient estimate where the substantial derivative of vorticity along a pathline is not equal to the local vortex stretching/tilting. Furthermore, given an initial guess, this method can proceed on an individual pathline without any further reference to neighbouring pathlines. The equivalence of the substantial derivative and vortex stretching/tilting is based on the vorticity transport equation, where viscous diffusion is neglected. By minimizing the residual of the vorticity-transport equation, the proposed method is first tested to reduce error and noise on a synthetic Taylor–Green vortex field dissipating in time. Furthermore, when the proposed method is applied to high-density experimental data collected with ‘Shake-the-Box’ PTV, noise within the spatial gradients is significantly reduced. In the particular test case investigated here of an accelerating circular plate captured during a single run, the method acts to delineate the shear layer and vortex core, as well as resolve the Kelvin-Helmholtz instabilities, which were previously unidentifiable without the use of ensemble averaging. The proposed method shows promise for improving PTV measurements that require robust spatial gradients while retaining the unstructured Lagrangian perspective.
PubDate: 2017-09-14
DOI: 10.1007/s00348-017-2427-6
Issue No: Vol. 58, No. 10 (2017)

• Influence of condensation on heat flux and pressure measurements in a
detonation-based short-duration facility
• Authors: S. Haase; H. Olivier
Abstract: Abstract Detonation-based short-duration facilities provide hot gas with very high stagnation pressures and temperatures. Due to the short testing time, complex and expensive cooling techniques of the facility walls are not needed. Therefore, they are attractive for economical experimental investigations of high-enthalpy flows such as the flow in a rocket engine. However, cold walls can provoke condensation of the hot combustion gas at the walls. This has already been observed in detonation tubes close behind the detonation wave, resulting in a loss of tube performance. A potential influence of condensation at the wall on the experimental results, like wall heat fluxes and static pressures, has not been considered so far. Therefore, in this study the occurrence of condensation and its influence on local heat flux and pressure measurements has been investigated in the nozzle test section of a short-duration rocket-engine simulation facility. This facility provides hot water vapor with stagnation pressures up to 150 bar and stagnation temperatures up to 3800 K. A simple method has been developed to detect liquid water at the wall without direct optical access to the flow. It is shown experimentally and theoretically that condensation has a remarkable influence on local measurement values. The experimental results indicate that for the elimination of these influences the nozzle wall has to be heated to a certain temperature level, which exclusively depends on the local static pressure.
PubDate: 2017-09-07
DOI: 10.1007/s00348-017-2419-6
Issue No: Vol. 58, No. 10 (2017)

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