Momentumless and almost-momentumless wakes in a stratified fluid

Abstract

Extensive measurements have been made on the wakes of towed spheres and other bodies for steady horizontal motion in a stratified fluid. It has been proposed, and largely verified, that these bluff body wakes can serve as canonical cases for the decay of initially turbulent motions in the presence of a stable background density gradient and applications have ranged from oceanography and climate modelling to prediction of signatures from undersea objects. While experimental data on momentumless wakes has been available for more than 25 years, it has not been in such quantitative detail as the towed body case and so the two have been difficult to compare directly. Here the similarity and scaling behaviour of mean and turbulence quantities are reported for slender and blunt bodies, at, or close to momentum balance. Results are then compared with literature values, and with the standard towed configuration, to identify those features that are general and those that are not