A nonlinear low-Reynolds-number κ-ε model for turbulent separated and reattaching flows-I. Flow field computations

An improved version of nonlinear low-Reynolds-number κ-ε model is developed. In this model, the limiting near-wall behavior and nonlinear Reynolds stress representations are incorporated. Emphasis is placed on the adoption of R_y (κ ^{1 2} y v) instead of γ⁺ (≡_τ y v) in the low-Reynolds-number model for predicting turbulent separated and reattaching flows. The non-equilibrium effect is examined to describe recirculating flows away from the wall. The present model is validated by doing the benchmark problem of turbulent flow behind a backward-facing step. The predictions of the present model are cross-checked with the existing measurements and DNS data. The model performance is shown to be generally satisfactory.