Pattern Formation Due to the Collision of the Vortex Ring on a Granular Layer

The erosion pattern of the granular layer due to the collision of a vortex ring was investigated experimentally and numerically. We mainly focused on the erosion depth h... and the position of the most deeply eroded surface of the granular layer, and their dependence on the size d of the granular material as well as on the strength of the vortex ring Reynolds number Re. Between a certain threshold strength of Re where erosion occurs and the highest Re tested in our experiment, the number of eroded depth, N... = h.../d, increases with Re. The position of the most deeply eroded contour, however, is found to be almost constant regardless of Re. These results are qualitatively reproduced by our numerical simulation. (ProQuest: ... denotes formulae/symbols omitted.)