An experimental study of the bulk properties of vortex rings translating through a stratified fluid

Experiments are carried out to find the bulk properties and some structural properties of vortex rings in a stratified fluid. Previous theoretical descriptions of vortex ring propagation speed in a homogeneous fluid are compared to experiment and developed for use in stratified fluids. Vortex rings are fired at oblique angles to the horizontal and at different speeds through a stratified fluid. The buoyancy frequency of the fluid is varied between different series of experiments. New models are proposed which predict the speeds and trajectories of vortex rings fired through a stratified fluid and these are compared to experiment. It is shown that these models perform well in high Froude number flows, but less well in low Froude number flows. (C) 2005 Elsevier SAS. All rights reserved.