Mean velocity profiles and total shear stress profiles in adverse-pressure-gradient turbulent boundary layers considering history effect

Abstract: This study focuses on developing a predictive model for mean velocity profiles and total shear stress profiles in turbulent boundary layers subjected to adverse pressure gradients, especially with history effects. Based on universal near-wall similarity, a new scaling using friction velocity modified by Clauser pressure gradient parameter is introduced to restore streamwise self-similarity. Furthermore, an estimation-correction model is developed, explicitly incorporating a streamwise derivative for pressure gradient, which effectively captures history effect beyond the reach of Reynolds-averaged Navier-Stokes equations. A detailed analysis is conducted on the corrected model of total shear stress, which is decomposed into four parts, in which the latter two parts correspond to non-equilibrium effect, and they are considered the first-order history effect. Generally, they tend to offset each other, but in downstream region, their combined effect is significantly stronger, accounting for up to approximately half of the total stress. Validation against multiple DNS/LES datasets across a wide range of pressure gradients and Reynolds numbers demonstrates model's accuracy in predicting both mean velocity profiles and total shear stress profiles.