Inclined 6:1 prolate spheroid wake characteristics in a stratified background*

Initially-turbulent wakes of bluff and streamlined bodies have been studied and simulated in a stratified ambient, and there are conflicting findings on the possible power-law evolution of early- and late-wake profiles.  Moreover, when bodies travel at incidence, breaking the axisymmetry, there are a number of ways in which non-general properties might be found.

Here, both stereo-PIV (2D3C) and tomo-PIV (3D3C) experiments are conducted on the wake of a 6:1 spheroid in uniform and stratified backgrounds. The inclination angle, $\theta$, is varied from $0^\circ - 20^\circ$, over a range of Reynolds numbers, Re$ = \{1.25, 2.5, 5, 10, 20\} \times 10^3$, and internal Froude numbers, Fr $=\{4, 8, 16, 32, 64, \infty \}$,

At non-zero $\theta$, the wake is a combination of the usual drag wake and coherent streamwise vortices, deviating from self-similar wake models.  In stratified environments, the inclined wake generates large-scale internal wave undulations, even at relatively weak background stratification.