Vortex Dynamics and Bifurcation of Buoyant Jets in Crossflow

A model is developed which predicts the integral behavior of buoyant or nonbuoyant jets in crossflow with the superimposed effect of the counterrotating internal vortex structure which exists in a plane normal to the jet trajectory. Despite some real fluid effects, such as finite vortex core size and turbulent growth, classical irrotational vortex pair theory is an adequate first-order model for the motions induced in the surrounding fluid. If these outside motions are constrained—either by a fluid boundary or by the effects of density stratification—then a repulsive force mechanism is created. This force leads to bifurcation of the bent-over jet into two separate elements with undiluted fluid in between. The theory shows excellent agreement with available experimental data for homogenous crossflow of finite depth. An application to hypothetical cases of stratified crossflow predicts different environmental conditions under which jet bifurcation can occur.