Effects of Low Mach-Number Correction in Turbulent Mixing Transition Simulations

Transition and turbulence decay with the Taylor-Green vortex have been effectively used to demonstrate emulation of high Reynolds-number (Re) physical dissipation through numerical convective effects of various non-oscillatory finite-volume algorithms for implicit large eddy simulation (ILES), e.g. using the Godunov-based Eulerian adaptive mesh refinement code xRAGE.  The inverse-chevron shock-tube simulations have been also used to assess xRAGE based ILES for shock driven turbulent mixing, compared with available simulation and laboratory data.  The previous assessments are extended to evaluate new directionally-unsplit high-order algorithms in xRAGE, including a correction to address the well-known issue of excessive numerical diffusion of shock-capturing (e.g., Godunov-type) schemes for low Mach numbers. Basic issues of transition to turbulence and turbulent  mixing are discussed, and results of simulations of high-Re  turbulent flow and mixing in canonical test cases are reported.  Compared to the directional-split cases, and for each grid resolution considered, unsplit results exhibit transition to turbulence with much higher effective Re -- and significantly more so with the low Mach number correction.