Stratified near wake of a slender body

Motivated by applications in submersible hydrodynamics, the effect of density stratification on the wake of a slender body is numerically investigated. Large-eddy simulations with an immersed boundary method are employed to simulate the flow past a 6:1 prolate spheroid at zero angle of attack. The Reynolds number based on the minor-axis diameter is fixed to $Re_D=UD/\nu=10^5$, and different levels of stratification measured by $Fr = U/ND$ are compared: $Fr =2$ which is close the critical value of Froude number ($Fr_c = 6/\pi$) where the turbulence suppression in the wake is maximal; a moderately stratified case ($Fr= 4$) and the unstratified case ($Fr=\infty$). A trip placed near the nose of the body is used to force laminar-turbulent transition and the wake is simulated to $25D$. Preliminary results that include the evolution of the boundary layer, mean velocity and turbulence statistics will be presented.