Marker transport in a composite vortex

Using a coloring method, the pattern of the transport of a compact spot of markers in a composite vortex created by a uniformly rotating disk, which is located on the bottom of a cylindrical tank, is investigated. The markers were formed by droplets of an aqueous solution of uranyl or ink, which fell down on the free surface of the fluid. In a quiescent fluid, the spot of the markers was transformed into a slowly sinking cascade of vortices. The markers introduced at the center of the cavity on the composite-vortex surface formed a spiral branch. For a non-central introduction of the markers, two spiral branches were formed, one growing in the direction of the fluid rotation and the other growing in the direction, opposite to the rotation. The markers penetrate into the interior of the composite vortex along isolated cylindrical surfaces. The geometrical parameters of the flow are presented.