The destabilization of an erodible sediment bed by a reproducible impulsive phenomenon is studied experimentally. For this, a specific setup is designed to produce a well-controlled isolated vortex, advected over a uniform sand bed. Particle image velocimetry (PIV) measurements are performed to get fluid flow information; suspended particles images are also recorded. A new measurement technique, based on a stereo-correlation method, provides a precise reconstruction of the bedform morphology over time. Strong turbulent structures (namely sweep events) are evidenced in a near-wall region, where particles are mainly dislodged. The sediment plume follows the vortex: in particular, the upward velocity inside maintains the suspension phenomenon. However, the dispersion process seems to be not dependent on the vortex parameters. Then, the bed morphology is investigated: a scour hole is dug as the vortex hits the granular layer. Its dynamics is described by a typical scour law, even if the initial perturbation is transient. Another area, where the particles settled, can be observed: it behaves like a ripple, with a logarithmic growth of its crest. This deposition region has a specific geometry, studied here by a Fourier contour approach. Finally, a pickup rate is also derived from the morphological data: it appears independent of the vortex and bedform features.

实验研究了可再现的冲动现象使可蚀沉渣床失稳的现象。为此，设计了一种特殊的装置来产生一个受控良好的隔离涡流，该涡流平移在均匀的沙床上。进行粒子图像测速（PIV）测量以获取流体流量信息。悬浮颗粒图像也被记录下来。一种基于立体相关方法的新测量技术，可以随着时间的推移精确重建床形。在近壁区域，主要是颗粒被驱除，证实了强烈的湍流结构（即扫掠事件）。沉积物羽流跟随涡流：特别是内部的向上速度保持了悬浮现象。但是，分散过程似乎并不依赖于涡旋参数。然后，研究床的形态：在涡旋撞击颗粒层时挖出冲刷孔。即使最初的扰动是短暂的，它的动力学也由典型的冲刷定律描述。可以观察到粒子沉降的另一个区域：其行为像波纹，其波峰对数增长。该沉积区域具有特定的几何形状，此处通过傅立叶轮廓方法进行研究。最后，还从形态学数据中得出了拾取速率：它的出现与涡旋和床形特征无关。该沉积区域具有特定的几何形状，此处通过傅立叶轮廓方法进行研究。最后，还从形态学数据中得出了拾取速率：它的出现与涡旋和床形特征无关。该沉积区域具有特定的几何形状，此处通过傅立叶轮廓方法进行研究。最后，还从形态学数据中得出了拾取速率：它的出现与涡旋和床形特征无关。