An improved k-ω-φ-α turbulence model applied to near-wall, separated and impinging jet flows and heat transfer

摘要

A turbulence model based on elliptic blending concept, referred to as improved k-omega-phi-alpha model compared against the original k-omega-phi-alpha model developed previously, is developed and verified. This model consists of four governing equations. Among them the k and omega equations are based on the Wilcox's k-omega model with some modifications and improvements according to the original k-omega-phi-alpha model, and the phi and alpha equations are extracted from the original k-omega-phi-alpha model directly without any change. The improved k-omega-phi-alpha model is applied to near-wall, separated and impinging jet flows and convective heat transfer, i.e. the 2D fully developed channel flow, the 2D backward-facing step flow, the 2D impinging jet flow, and the convective heat transfer in the 2D fully developed channel flow and the 2D impinging jet flow. The computational results are compared with available DNS and experimental data and also to those computed using the original k-omega-phi-alpha model and the popular Menter's SST k-omega model. It is shown that the improved k-omega-phi-alpha model has better numerical stability, higher computational efficiency and more concise form than the original k-omega-phi-alpha model. In addition, compared with the original k-omega-phi-alpha model, the improved k-omega-phi-alpha model can yield similar velocity profiles in the fully developed channel flow and step flow and friction and pressure coefficients in the step flow and very close temperature profiles in the fully developed channel flow. Moreover, it shows significant improvements on the predictions for the fluid flow and heat transfer in the impinging jet flow. As a whole, the improved k-omega-phi-alpha model predicts better results than both of the original k-omega-phi-alpha model and the SST k-omega model. (C) 2018 Elsevier Ltd. All rights reserved.