Hypersonic Flow Predictions Using Linear and Nonlinear Turbulence Closures

Abstract

Two- and three-dimensional hypersonic flow cases are computed using linear one-equation closures and a nonlinear two-equation model, where the anisotropy tensor is modeled as a cubic function of mean strain and vorticity tensors. The latter is found to excel in predicting bypass transition, whereas the one-equation R t model is very good at heat-transfer prediction. Both closures excel in predicting pressure distributions; however, the nonlinear model is found to overpredict heat-transfer. This suggests that in separated flow regions with simultaneously low mean-flow kinetic energy (and therefore low strain magnitude) and high temperature gradients, overpredicted levels of turbulence length scale can lead to rather small errors in the turbulent shear stress, while at the same time leading to a large overprediction of the turbulent heat fluxes