Prediction of turbulent boundary layers in adverse pressure gradients

Abstract

A second-moment closure proposed by Shima and Kobayashi (2007) is applied to turbulent boundary layers in adverse pressure gradients. The computation adopts a very simple 'standard' model for the £ transport equation. In spite of the simple scale-determining equation, the closure reproduces a case that is often used for testing turbulence models, i. e. the Samuel-Joubert flow in which a standard log law region exists. The model is also tested in equilibrium boundary layers of a recent DNS, in which the velocity profile in the log law region shifts downward from the standard law and the slope in that region becomes higher than that for the zero pressure gradient flow. The present model gives reasonable predictions for mild and moderate pressure gradient cases, but fails to capture a mean velocity profile for a strong gradient case. The Launder-Sharma k-ε model is also tested in these cases, and the performance is discussed.