Direct numerical simulations of transitional supersonic base flows

Abstract

Transitional supersonic base flows at M = 2.46 are investigated using direct numerical simulations. Results are presented for Reynolds numbers based on the cylinder diameter ReD = 3 × 104-1 × 105. As a consequence of flow instabilities, coherent structures develop that have a profound impact on the global flow behavior. Simulations with various circumferential domain sizes are conducted to investigate the effect of coherent structures associated with different azimuthal modes on the mean flow, in particular on the base pressure, which determines the base drag. Temporal spectra reveal that frequencies found in the axisymmetric mode can be related to dominant higher modes present in the flow. ..