Validation of RANS turbulence models for subsonic turbulent boundary layer flows under families of pressure gradients

Abstract

The behavior of turbulent boundary layer (TBL) flows subjected to adverse-pressure gradients (APG) at high Reynolds numbers has not yet been fully understood, despite its great importance for many practical engineering applications. In particular, the effects of pressure gradients on the mean velocity profiles are still under debate, e.g., existence of log-law and half-power-law (sqrt-law), history effects, or non-equilibrium effects. At the same time, the predictive accuracy of the existing Reynolds averaged Navier-Stokes (RANS) turbulence models for such flows is also questionable because these models are mainly calibrated for simple canonical flows including a flat-plate TBL at a zeropressure gradient (ZPG). Therefore, the validation of RANS models for well-defined TBL flow experiments at APG is a crucial task to ensure reliable predictions and to obtain insights into further model improvements. However, such validations are still rare in the literature due to the lack of carefully designed experiments that are intended to be used as test cases for computational fluid dynamics (CFD).