Collapse of a homogeneous fluid mass in a stratified fluid

Abstract

In an experimental study of the turbulent wake behind an object moving horizontally in a stratified liquid, Schooley and Stewart [1] found that the growth of the wake is suppressed in the vertical direction as the well-mixed, nearly homogeneous fluid in the wake seeks to its own level of density. Thus, in the immediate vicinity of the body, the wake grows uniformly in all transverse directions, but after a certain distance behind the body, it begins to shrink in height and to spread in horizontal width at a rate faster than that in a homogeneous fluid. Wu [2], utilizing the fact that the longitudinal variation of a wake boundary is relatively small compared with the transversel variation, conducted two-dimensional experiments on the gravitational collapse of a homogeneous fluid mass in a stratified fluid. The homogeneous fluid is originally confined in a hollow circular cylinder and has the same density as the ambient stratified fluid at the level of the horizontal axis of the cylinder. At the time t = 0, the cylinder is removed and the vertical collapse of the homogeneous fluid within is then recorded cinematically as a function of time. Related studies have been reported in [3], [4)], and [5].