On Reynolds-stress expressions and near-wall scaling parameters for predicting wall and homogeneous turbulent shear flows

In this paper, a new type of two-equation turbulence model that incorporates some essential characteristics of second-order closure models is proposed. The present model belongs to a nonlinear k-ε model taking into account low-Reynolds-number effects originating from the physical requirements, and is applicable to complex turbulent flows with separation and reattachment. The model successfully predicts both wall-turbulent and homogeneous shear flows, the latter of which has been very difficult to simulate with existing two-equation turbulence models. Channel flows with injection and suction at wall surfaces and separated and reattaching flows downstream of a backward-facing step are also calculated. Comparisons of the computational results with the measurements and the direct numerical simulation data indicate that the present model is effective in calculating complex turbulent flows of technological interest. Furthermore, the parameters for scaling the near-wall region in the low-Reynolds-number model functions are re-evaluated, yield-ing some insights into the near-wall scaling parameters for application to complex turbulent flows.