Wake Collapse in Stratified Fluid: Experimental Exploration of Scaling Characteristics

Abstract

Passage of a submerged self-propelled body or other mixing device produces a region of more or less homogeneous fluid, in a fluid having a stable vertical density gradient (stratified), which initially expands vertically and then falls back (collapses). Maximum expansion Z(2) at time t(2) after the start of mixing are dependent variables related to the diameter Z(1) of propeller or mixer and to the Väisälä-Brunt period T by T/t(2) = 2.5 and Z(2)t(2)/Z(1)T = 1.3. These scaling relations are first-order approximations.