A priori Analysis of Subgrid-Scale Heat Flux Vectors in High Pressure H2/O2 Mixing and Reacting Shear Layers

A Direct Numerical Simulation (DNS) database of supercritical, transitional H2/O2 mixing and reacting shear layers is analyzed in an a priori manner to obtain subgrid statistics relevant to Large Eddy Simulation (LES) engineering modeling. The DNS employs a real gas state equation, detailed chemistry, accurate property models, multicomponent, differential, and cross diffusion. The parallel simulations were conducted using eighth order central finite differencing in conjunction with a fourth order accurate Runge-Kutta time integration, on resolutions up to 135 million grid points, and used up to 2,016 processing cores. All simulations are for an ambient pressure of 100 atm and are relevant to rocket engine conditions. The particular focus of the study is on analyzing the subgrid heat flux vector which has thus far been nearly universally ignored in the literature. DNS provides a near “exact ” description of all of the scales of the flow. For this study the DNS database is filtered over a range of filter widths to provide the exact LES governing equations; including those terms requiring modeling. The filtered heat flux vector is extensively compared with th