紊流冲击射流数学研究中的壁面函数法

使用低雷诺数 k-ε模型、标准 k-ε模型和改进的 k-ε模型计算了半封闭圆形冲击射流的紊流流场 ,并将结果作了对比。其中 ,改进的 k-ε模型在其模化过程中重新考虑了 ε方程中的脉动压力扩散项。结果表明 :低雷诺数 k-ε模型、标准 k-ε模型的计算结果很差 ,而改进的 k-ε模型的结果却要好得多 ,特别是对紊动能的改进尤其明显。因此可以认为 :标准 k-ε模型的计算结果很差是由于它在模化中没有考虑脉动压力扩散项 ,而并不是文献中所认为的是由于在近壁区使用了壁面函数法。

EFFECT OF WALL FUNC TION IN NUMERICAL STUDY ON TURBULENT IMPINGING JET

A low Reynolds number k-ε　model is used in the numerical study on a circular semi-confined turbulent impinging jet . The result is compared with that of the standard k-ε　model and a refined k-ε　model, which re-consi-dered the fluctuating pressure diffusion term in the dissipation rate equation (ε-equation) through modeling. It shows that the low Reynolds number k-ε　model and the standard k-ε　model yield very poor performance, while the predicting ability of the refined k-ε　model is much improved , especially for the turbulent kinetic energy k. So it can be concluded that the poor performance of the standard k-ε　model is owing to the incorrect considering the effect of the fluctuating pressure diffusion term rather than the use of the wall function near the wall just as presumed in the reference.