Modification of the SSG/LRR-Omega Model for Turbulent Boundary Layer Flows in an Adverse Pressure Gradient

Abstract

A modification of the RANS turbulence model SSG/LRR-omega for turbulent boundary layers in an adverse pressure gradient is presented. The modification is based on a wall law for the mean velocity, in which the log law is progressively eroded in an adverse pressure gradient and an extended wall law (designated loosely as a half-power law) emerges above the log law. An augmentation term for the half-power law region is derived from the analysis of the boundary-layer equation for the specific rate of dissipation omega. An extended data structure within the RANS solver provides, for each viscous wall point, the field points on a wall normal line. This enables the evaluation of characteristic boundary layer parameters for the local activation of the augmentation term. The modification is calibrated using a joint DLR/UniBw turbulent boundary layer experiment. The modified model yields an improved predictive accuracy for flow separation. Finally, the applicability of the modified model to a 3D wing-body configuration is demonstrated.