Computational study of the inviscid, nonlinear physics of supersonic base flows

The entrainment, reattachment location, and base pressure are all significantly affected by the large scale, inviscid, turbulent structures present in the free shear layer formed in supersonic base flows. This study is aimed at better understanding the spatial evolution of large scale, inviscid, three-dimensional structures present in these compressible shear layers and their effects on supersonic base flow. An unsteady Euler flow solver is used to study these structures. Results from this work are in qualitative agreement with previous temporally evolving computations and experiments. The planar mixing layer is shown to be primarily two-dimensional in the early stages of development while becoming more three-dimensional in the latter stages of development. The forcing used in this simulation includes a wider range of scales than most computations which, in turn, gives rise to a broad range of eddy scales as evidenced by the flow visualizations. Initial mean flow computations were also made for the blunt base geometry. These computations predicted the average base pressure magnitude reasonably well, although they show a radial variation in base pressure which is not consistent with experiments, but is common in many previous computations.