Numerical prediction of separating and reattaching flows with a modified low-Reynolds-number k-ϵ model

We propose a new turbulence model which is modified from the low-Reynolds-number k-ε{lunate} model developed by Nagano and Tagawa. The main improvement is made by the introduction of the Kolmogorov velocity scale u_ε{lunate} ≡ (νε{lunate}) ^{1 4} instead of the friction velocity u_τ. We have also reevaluated the model constants in the transport equations. With these modifications, it is shown that the present model predicts quite successfully the separating and reattaching turbulent flows downstream of a backward-facing step at various Reynolds numbers, which have been very difficult to simulate with any previous k-ε{lunate} model.