Application of Artificial Fluid Properties for Stable and Accurate Large-Eddy Simulations of Compressible Turbulent Reactive Flows

摘要

In large-eddy simulations (LES) of turbulent reactive flows, typically employed numerical schemes suitable for proper resolution of turbulent structures are not appropriate for capturing steep scalar gradients. In the present work, artificial fluid properties (AFP) have been applied in local regions of sharp scalar variations alongside non-dissipative, explicit central difference schemes to ensure stability without compromising on accuracy. Simulation of a 1D laminar premixed flame using this approach shows that for grids in which there are very few points across the flame, AFP is needed for a stable and accurate flame solution. The dissipation introduced by AFP is verified to be insignificant in the case of a Taylor-Green vortex, in which steep scalar gradients are absent. Finally, a 3D compressible temporal mixing layer is validated by comparing the results from the AFPbased LES with those from dynamic Smagorinsky model-based LES and filtered direct numerical simulation (DNS). Overall, it is shown that the artificial properties provide adequate high wavenumber dissipation enabling stability on coarse grids and compensating for the unresolved sub-grid dissipation. Thus this numerical method is found to be a good candidate for high resolution LES of turbulent flows in which high scalar gradients are present.