Numerical solution of turbulent flow past a backward facing step using a nonlinear K-epsilon model

Abstract The problem of turbulent flow past a backward facing step is important in many technological applications and has been used as a standard test case to evaluate the performance of turbulence models in the prediction of separated flows. It is well known that the commonly used K-e (and K-l ) models of turbulence yield inaccurate predictions for the reattachment point in this problem. By an analysis of the mean vorticity transport equation, it will be argued that the intrinsically inaccurate prediction of normal Reynolds stress differences by the K-e and K-l models is a major contributor to this problem. Computations using a new nonlinear k-e model (which alleviates this deficiency) are made with the TEACH program. Comparisons are made between the improved results predicted by this nonlinear k-e model and those obtained from the linear K-e model as well as from second-order closure models.