Vortex rings are enthralling manifestation of fluid flow! Here, we generate mushroom shaped fluidic structures by the velocity induced by a propelling vortex ring.
Vortex ring inside water is made to impinge on a perforated plate with 25% porosity. As understood by the Biot-Savart law, the vortex ring induces a velocity field (O ~ 0.01 m/s) around it due to its circulation. To see the effect of this induced field, a layer of dye is carefully spread over the perforated surface.
As the vortex ring approaches, we see beautiful mushrooms visualized by the dye emerging out of the holes. The vortex ring catches up with the mushrooms at later stages.
At far downstream, the dancing mushrooms unite to form another vortex ring!