运用低雷诺数非线性k-ε模型研究湍流分离流动

PREDICTION OF TURBULENT SEPARATED FLOWS WITH A LOW REYNOLDS NUMBER NONLINEAR K-ε MODEL

给出了一个低雷诺数非线性ｋ－ε湍流模型，其中采用了一个非线性雷诺应力表达式并引入了两个考虑湍流近壁效应的修正函数。应用该模型和标准ｋ－ε模型计算了两种不同膨胀比的后台阶分离流。与实测结果比较表明，低雷诺数非线性模型结果较标准ｋ－ε模型结果有明显改进，它对流场的各特征量包括分离—再附长度、时均速度及各雷诺应力分量均给出了较好的预测。

A new low Reynolds number nonlinear K-ε model is presented,in which two correction functions for the near-wall flow and a nonlinear expression for the Reynolds stress are incorporated.Several backstep separated flows with two different expansion ratios are numerically studied by using the above model and a standard K-ε model.In comparision with experimental data,the results obatined show that the predictions of the presented nonlinear model are obviously improved over these of the standard K-ε model in respect of various flow parameters,such as reattachment length,time mean velocities and Reynolds stress components.Also,the presented model is the partial differential Reynolds stress model in prediction of the Reynolds stress components.