Year: 2025
Type: article
Abstract: The on-body flow and near-to-intermediate wake of a 6:1 prolate spheroid at a pitch angle of $\alpha = 10^{\circ }$ and a length-based Reynolds number, ${Re}_L = U_\infty L / \nu = 3 \times 10^4$ , are investigated using large eddy simulation (LES) across four stratification levels: ${\textit {Fr}} = U_{\infty }/ND = \infty , 6, 1.9$ and $1$ . A streamwise vortex pair, characteristic of non-zero $\alpha$ in unstratified flow over both slender and blunt bodies, is observed. At ${\textit {Fr}} = \infty$ (unstratified) and $6$ , the vortex pair has a lateral left–right asymmetry as has been reported in several previous studies of unstratified flow. However, at higher stratification levels of ${\textit {Fr}} = 1.9$ and $1$ , this asymmetry disappears and there is a complex combination of body-shed vorticity that is affected by baroclinicity and vorticity associated with internal gravity waves. Even at the relatively weak stratification of ${\textit {Fr}} = 6$ , the wake is strongly influenced by buoyancy from the outset: (a) the vertical drift of the wake is more constrained at ${\textit {Fr}} = 6$ than at ${\textit {Fr}} = \infty$ throughout the domain; and (b) the streamwise vortex pair loses coherence by $x/D = 10$ in the ${\textit {Fr}} = 6$ wake, unlike the ${\textit {Fr}} = \infty$ case. For the ${\textit {Fr}} = 1$ wake, flow separation characteristics differ significantly from those at ${\textit {Fr}} = \infty$ and $6$ , resulting in a double-lobed wake topology that persists throughout the domain.
Source: Journal of Fluid Mechanics
DOI: 10.1017/jfm.2025.204
Institution: University of California San Diego
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,550
Awards: G2558063343, G8876996369
OpenAlex ID: W4409951860