Model-Invariant Hybrid Computations of Separated Flows for RCA Standard Test Cases

摘要

NASA's Revolutionary Computational Aerosciences discipline has identified several smooth-body separated flows as standard test cases to emphasize the challenge these flows present for computational methods and their importance to the aerospace community. Results of computations of two of these test cases, the NASA hump and the FAITH experiment, are presented. The computations were performed with the model-invariant hybrid LES-RANS formulation, implemented in the NASA code VULCAN-CPD. The model-invariant formulation employs gradual LES-RANS transitions and compensation for model variation to provide more accurate and efficient hybrid computations. Comparisons revealed that the LES-RANS transitions of the present computations were sufficiently gradual that the compensating terms were unnecessary. Agreement with experiment was achieved only after reducing the turbulent viscosity to mitigate the effect of numerical dissipation. The streamwise evolution of peak Reynolds shear stress provided a measure of turbulence dynamics in separated flows useful for evaluating the computations.