A numerical investigation about the effects of Reynolds number on the flow around an appended axisymmetric body of revolution

Large-eddy simulations for the case of an axisymmetric body of revolution with appendages are considered. The geometry is the benchmark case of the DARPA suboff body. The paper focuses on the effects of the Reynolds number on the structure of the boundary layer in the stern area as well as the near wake. For this purpose we compare results for two Reynolds numbers (based on the length of the body, L, and the free-stream velocity, U 1): Re-L D 12 x 10(6) and ReL D 1:2 x 10(6). Results are in good agreement with published experiments at the same Reynolds numbers. The boundary layer thickness over the stern increases substantially at both simulated Reynolds numbers, due to the adverse pressure gradient at the rear of the body. However, for the high Reynolds number case, a weaker peak of turbulent kinetic energy develops in the outer layer over the stern. Nonetheless, the associated bimodal distribution of the turbulent stresses in the wake is already very similar a few diameters downstream of the tail. First- and second-order moments demonstrate that junction vortices at the stern bring higher velocities and turbulence at the root of the appendages for both Reynolds numbers, with a more evident signature at Re-L D 12 x 10(6). An azimuthal readjustment of turbulent kinetic energy occurs in the wake, becoming more axisymmetric, with increasing values in the planes aligned with the stern appendages, due to turbulence coming from both the stern boundary layer and junction vortices.