LARGE EDDY SIMULATIONS OF THE 3D SUBSONIC INCOMPRESSIBLE ANDTURBULENT FLOW OVER A FIXED RE-ENTRY CAPSULE AT RE = 10 000

摘要

Large eddy simulations (LES) of the 3D turbulent flowrnover a fixed re-entry capsule at Re = 104 and at a 180u000ernangle of attack have been performed with the axisymmetricrnversion of a combined spectral/stabilized finite elementrnincompressible flow solver called SFELES. Thesernsimulations allow the visualization of a large recirculatingrnzone in the wake of the capsule, which is characterizedrnby a meandering ‘fish tail' flapping motion. The detachmentrnof the boundary layer at the sphere-cone junctionrnof the capsule appears also clearly, resulting in arnstrong shear layer and a fully separated flow surface inrnthe aft conical part of the capsule. Due to the developmentrnof Kelvin-Helmholtz instabilities, this shear layerrnrolls up and give rise to a vortex ring shedding. The mainrnfrequencies of these phenomena are captured by meansrnof power spectrum densities (PSD) associated with therntemporal evolution of local physical variables. The aerodynamicrncoefficients are also computed and their PSDrnreveal that the static stability of the capsule is characterizedrnby low frequencies related to the ‘fish tail' flappingrnmotion of the wake and to some instabilities in the shearrnlayer.