Improved Modeling Tools for High Speed Reacting Flows

Recent work in high speed reacting flows has identified three areas in which model improvements are needed. (1) Multi-element grid adaptation for fuel injection problems - h-refinement (cell splitting) procedures being utilized in our grid adaptation tool, CRISPr, produce large meshes after several levels of refinement. Point redistribution (r-refinement) techniques based on moving mesh concepts can improve efficiency and will be implemented. (2) Scalar fluctuation modeling for high speed flows - a generalized framework is operational which predicts local values of Prt and Sct and works with our compressibility-corrected k model. Application to basic jet/shear layer flows has indicated good overall performance, but application to fuel injection flow problems has indicated that further turbulence modeling upgrades are required, which will be addressed in this program. (3) Chemical kinetic efficiency enhancement - using point implicit methodology with an iterative chemical kinetic solver leads to load unbalances since more work is done in regions with stiff chemistry. A new "work per node" load balancing technique, has permitted us to analyze hydro-carbon chemical systems with a large number of species and reactions with much greater efficiency. We will incorporate this procedure into our multi-element unstructured code, and make it operate with grid adaptation techniques.