Analysis of Simulations of Topologically Changing Three-Dimensional Separated Flows

The paper summarizes puzzling results from transonic flow simulations around a hemisphere-cylinder configuration and tries to shed some light on the temporal-spatial numerical resolution requirements. We recall an invariant definition of vortices and show examples where sensitivity to initial conditions of separating shear layers exist and where (Ma → 0)-uniqueness problems occur in compressible flow simulations of steady, separated flows. Aspects of a numerical simulation and its topological analysis of the onset of unsteadiness, periodicity and three-dimensionality of the flow around a sphere are also considered.

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