Abstract
The backward-facing step (BFS) is a heuristic example, allowing for complex phenomena to arise in a simple geometry. Particle Image Velocimetry (PIV) investigations of mean-velocity distributions of backward-facing step flow with steady inlet condition were carried out and good agreement was obtained between current and previously published results for 50 ≤ Re ≤ 400. This confirms that the current experimental capabilities can provide detailed and accurate velocity information. The flow behaviour downstream the step depends on the strength of separated shear layer, which the circulation depends on the bulk flow, recirculation zone length and vortex formation time. Since the vortex formation process is governed by the circulation flux convected along the wall layer from the step, for Re ≤ 400, all of the circulation contained in the shear layer is drawn into the recirculation region. Thus, in a case where the shear layer characteristics are modified (e.g. in higher Reynolds number and unsteady flows), the balance of circulation is modified that would result in shedding.
Highlights
The backward-facing step (BFS) is a heuristic example, allowing for complex phenomena to arise in a simple geometry
Since the vortex formation process is governed by the circulation flux convected along the wall layer from the step, for Re 400, all of the circulation contained in the shear layer is drawn into the recirculation region
Results of Particle Image Velocimetry (PIV) investigations of steady laminar flows over an expansion ratio 2:1 backward-facing step (BFS) at 50 Re 400 are summarized here
Summary
The backward-facing step (BFS) is a heuristic example, allowing for complex phenomena to arise in a simple geometry. Et al [2] performed Laser-Doppler measurements of velocity distribution and reattachment length downstream of a BFS mounted in a 18:1 aspect ratio (step span/step height) channel for a wide range of Reynolds number, 70 < Re < 8000 They reported that the length of the recirculating flow region in the immediate vicinity of the BFS (primary vortex) has strong, non-linear dependence on the Reynolds number. EPJ Web of Conferences on how to handle the different flow parameters in a case where circulation must shed (e.g. turbulent, pulsatile flow) For this purpose, steady inlet flows for 50 Re 400 are experimentally investigated by using particle image velocimeter (PIV)
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