标题： 滴落撞击浅池时的涡环生成 显示英文标题

标题： Vortex Ring generation during drop impact into a shallow pool

摘要： 当一滴液体从适中的高度落入深度约为液滴半径的浅流体池中时，会生成两对涡环。 内对在撞击液体形成的陨石坑边缘形成，而外对则由扩展的波浪产生。 这些对中的每个环有一个短暂存在的环和一个持续存在的环。 每个环都有可测量的非零环量（尽管其符号与著名的深水液滴涡环相反），这种环量在波退去后仍持续存在。 此外，在某些条件下，它们会发展出典型的环状涡旋不稳定性。 尽管这些环具有良好的可重复性，但它们后期的发展对某些实验参数的变化非常敏感。 本文报告了区分这些液滴生成环的可重复方面并记录它们对材料和几何参数依赖性的实验。 显示英文摘要

摘要： When a drop falls from a moderate height into a shallow fluid pool whose depth is of the order of the drop-radius two pairs of vortex rings are generated. The inner pair forms at the edge of the crater created by the impacting drop while the outer pair is laid off from the spreading wave. One ring of each of these pairs is short-lived while the other persists. Each of the rings has a measureable non-zero circulation (whose sign, however, is opposite to that of the well-known deep-water drop vortex rings) which persists long after the wave has receded. Furthermore under certain conditions they develop instabilities typical to ring vortices. Although the rings are well reproducible, aspects of their later development are very sensitive to changes in some of the experimental parameters. This paper reports on experiments distinguishing reproducible aspects of these drop- generated rings and documenting their dependence on material and geometrical parameters.