涡旋脉动的流体可视化和粒子成像测速(PIV)分析
This article treats of the flow motion over the so-called vortex ripples whichare generated by water oscillations above a sand bed. We focus mainly our experimentalworks on the morphology and the dynamics of transient flow patterns above real vortexripples. With the help of flow visualizations and Particle Image Velocimetry measurementswith a high-speed video CCD camera, we test numerical simulations, which predict theexistence of a secondary vortex with a streamlines representation. However, ourexperimental findings show only one vortical structure and validate the observations ofBagnold in 1946 (using real ripples but with no visualization and measurement) and SandAndersen & al. in 2004 (using model ripples) with respect to the existence of a transient jet.