Density currents in shear flows - a two-fluid model

Abstract

For an idealized inviscid flow, the results show that the density current becomes deeper and propagates relative to the environmental flow as the shear increases toward positive (i.e., the system-relative inflow speed decreases with height). When the effects of energy loss and negative vorticity generation are taken into account for the entire or physically constrained fractional depth of the upper-layer outflow, multiple solutions are found for two possible flow states: supercritical and subcritical, similar to that of Benjamin. The supercritical (or subcritical) state is characterized by a large (small) Froude number for the downstream upper-layer outflow, in which case the density current is shallower (or much shallower) and propagates slightly faster (or significantly slower) than the idealized inviscid one. -from Author