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4 results on '"synchronized PIV"'

1. Advances in Hydraulics and Hydroinformatics Volume 2.

Author

Zhou, Jianguo, Zhang, Jianmin, Peng, Yong, Borthwick, Alistair, and Zhou, Jianguo

Subjects
History of engineering & technology, chute aerator, spillway bottom, air concentration, air bubble frequency, air bubble chord length, evolution of precipitation, model simulation, information entropy theory, desert-oasis areas, Tarim Basin, gravity wave model, dam-break flood, image processing technology, experimental study, cavitation bubble, high-speed photography, impact pressure, micro-jet, Ningxia-Inner Mongolia, Yellow River, riverbank collapse, BSTEM model, flood &amp, dry season, sediment transport, finite crest length weir, FGP (flaring gate pier), discharge coefficient, subcritical flow, river flow modeling, sediment transport simulation, automation of flow modeling, HEC-RAS controller, python scripting, three-dimensional aerator, multi-horizontal-submerged jets, energy dissipation, near-field vibration, fluctuating pressure, gate-opening modes, collapse near a wall, double cavitation bubble, tilt distribution cavitation, parallel cavitation, pseudopotential lattice Boltzmann model, numerical simulation, pooled stepped spillway, pool weir, flow property, surface-piercing propeller, artificial ventilation, hydrodynamic performance, LES-VOF method, flow-induced vibration, plane gate, numerical analysis, bridge scour, submerged flow, physical hydraulic modeling, ski-jump flow, spillway outlet, jet trajectory, experimental model, rainfall intensity distribution, two water jets, collision in air, Gaussian distribution, trajectory line, clogging, drip irrigation, flushing, particle size distribution, sediments, submerged jets, aerated flow, plunge pool, trapezoidal cross-section, U-shaped channel, radius-to-width ratio, slope coefficient, hydraulic characteristics, hydraulic jump, Froude number, stilling basin with shallow-water cushion (SBSWC), large eddy simulation, best depth, CFD-DEM coupling, hydrocyclone, particle shape, particle size, water and sediment separation, stepped dropshaft, flow region, central angle of step, free surface measurement, optical motion capturing, tank test, wave gauge, sloshing, offset jet, potential core, decay rate, k-ε model, abutment, overtopping flow, pressure flow, scour and velocity field, Y-shaped confluence channel, non-submerged rigid vegetation, longitudinal velocity, secondary flow, turbulent kinetic energy, wetland, lattice Boltzmann method, shallow lake, drag force, water-saving irrigation development level, Sichuan province, TOPSIS method, experiment, particle image velocimetry, 3D confined wall jet, mean flow, multiple bubble collapse, pressure wave energy, energy conversion rate, consistent particle method, solitary wave, submerged breakwater, breaking wave, vortex, free surface flow, embankment weir, bridge piers, turbulence, CFD, sediment, transforming mechanism, open channel bend, velocity distribution, PIV, hyporheic exchange, surface−groundwater flow process, influencing factors, orthogonal tests, sensitivity analysis, linearly moved irrigation system, application depth, moving speed, uniformity coefficient, tidal discharge, phase difference, tidal channel junction, flow division, fluvial acoustic tomography, wavelet analysis, DEM, hydrodynamic modelling, river bathymetry, floods, Bathy-supp, coherent vortex structure, backward-facing step, synchronized PIV, separation and reattachment, free shear layer, vortical evolution
Abstract

Summary: This Special Issue reports on recent research trends in hydraulics, hydrodynamics, and hydroinformatics, and their novel applications in practical engineering. The Issue covers a wide range of topics, including open channel flows, sediment transport dynamics, two-phase flows, flow-induced vibration and water quality. The collected papers provide insight into new developments in physical, mathematical, and numerical modelling of important problems in hydraulics and hydroinformatics, and include demonstrations of the application of such models in water resources engineering.

2. Experimental Investigation of Coherent Vortex Structures in a Backward-Facing Step Flow

Author

Dai Jiangyu, Qian Liao, Gao Ang, Wang Fangfang, Shiqiang Wu, and Senlin Zhu

Subjects
Critical distance, Geography, Planning and Development, Flow (psychology), 0207 environmental engineering, Geometry, vortical evolution, 02 engineering and technology, Aquatic Science, 01 natural sciences, Biochemistry, 010305 fluids & plasmas, free shear layer, symbols.namesake, 0103 physical sciences, Shear stress, 020701 environmental engineering, Water Science and Technology, Physics, Turbulence, backward-facing step, Reynolds number, separation and reattachment, Vortex, synchronized PIV, Shear (sheet metal), Particle image velocimetry, coherent vortex structure, symbols
Abstract

Coherent vortex structures (CVS) are discovered for more than half a century, and they are believed to play a significant role in turbulence especially for separated flows. An experimental study is conducted for a pressured backward-facing step flow with Reynolds number (Reh) being 4400 and 9000. A synchronized particle image velocimetry (PIV) system is developed for measurement of a wider range of velocity fields with high resolution. The CVS are proved to exist in the separation-reattachment process. For their temporal evolution, a life cycle is proposed that vortices form in the free shear layer, develop with pairings and divisions and finally shed at the reattachment zone, and sometimes new vortical structures are restructured with recovery of flow pattern. The CVS favor the free shear layer with frequent pairings and divisions particularly at the developing stage around x/h = 2~5 (x: distance from the step in flow direction, h: step height), which may contribute to the high turbulent intensity and shear stress there. A critical distance is believed to exist among CVS, which affects their amalgamation (pairing) and division events. Statistics show that the CVS are well organized in spatial distribution and show specific local features with the flow structures distinguished. The streamwise and vertical diameters (Dx and Dy) and width to height ratio (Dx/Dy) all obey to the lognormal distribution. With increase of Reh from 4400 to 9000, Dx decreases and Dy increases, but the mean diameter (D=0.5 × (Dx + Dy)) keeps around (0.28~0.29) h. As the increase of Reh, the vortical shape change toward a uniform condition, which may be contributed by enhancement of the shear intensity.

Published
2019

4. Experimental Investigation of Coherent Vortex Structures in a Backward-Facing Step Flow.

Author

Wang, Fangfang, Gao, Ang, Wu, Shiqiang, Zhu, Senlin, Dai, Jiangyu, and Liao, Qian

Subjects
PARTICLE image velocimetry, VORTEX shedding, LOGNORMAL distribution, REYNOLDS number, SHEARING force, FLOW separation
Abstract

Coherent vortex structures (CVS) are discovered for more than half a century, and they are believed to play a significant role in turbulence especially for separated flows. An experimental study is conducted for a pressured backward-facing step flow with Reynolds number (Reh) being 4400 and 9000. A synchronized particle image velocimetry (PIV) system is developed for measurement of a wider range of velocity fields with high resolution. The CVS are proved to exist in the separation-reattachment process. For their temporal evolution, a life cycle is proposed that vortices form in the free shear layer, develop with pairings and divisions and finally shed at the reattachment zone, and sometimes new vortical structures are restructured with recovery of flow pattern. The CVS favor the free shear layer with frequent pairings and divisions particularly at the developing stage around x/h = 2~5 (x: distance from the step in flow direction, h: step height), which may contribute to the high turbulent intensity and shear stress there. A critical distance is believed to exist among CVS, which affects their amalgamation (pairing) and division events. Statistics show that the CVS are well organized in spatial distribution and show specific local features with the flow structures distinguished. The streamwise and vertical diameters (Dx and Dy) and width to height ratio (Dx/Dy) all obey to the lognormal distribution. With increase of Reh from 4400 to 9000, Dx decreases and Dy increases, but the mean diameter (D=0.5 × (Dx + Dy)) keeps around (0.28~0.29) h. As the increase of Reh, the vortical shape change toward a uniform condition, which may be contributed by enhancement of the shear intensity. [ABSTRACT FROM AUTHOR]

Published
2019
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