Numerical and theoretical study of a buoyant localized disturbance in irrotational shear flows

Abstract

The evolution of a buoyant vortex in stagnant and irrotational shear flows is studied using both computational and theoretical tools. The evolution is described in terms of the two relevant time scales, associated with the shear and the buoyancy (viscous effects, although included, are considered to be relatively small). Computations show that a strong shear causes the buoyant vortex to propagate to a lesser extent in the vertical direction and to spread further in the lateral direction, compared to a disturbance placed in a base-flow characterized by weak or no shear. Another effect of shear is an earlier splitting of the buoyant mass of fluid into a vortex ring, resulting in a lower value ..