分层Reynolds应力模式

本文根据切变湍流结构的特征提出一种分层Reynolds应力模式。在切变湍流中存在湍能生成项达到狭峰的极大值层次(本文称它为活跃层),根据这一特征,在活跃层中保留微分Reynolds应力模式,但它可以简化为常微分方程。在两层活跃层之间以及活跃层和壁面之间的Reynolds应力分布,用满足衔接相容条件的多项式近似。时均湍流场将由以上得到的Reynolds应力代入Reynolds方程求出。用本方法计算了两个比较复杂的湍流例子,结果表明,本方法较常用的k-ε模式有明显的优越性,它的计算时间并不比k-ε模式多,而计算结果与实测结果的吻合则较k-ε模式好得多。另一方面本方法较之完全的微分Reynolds应力模式可大大节省计算时间。

A REGIONAL REYNOLDS STRESS MODEL

A regional Reynolds stress model has been proposed in the paper based on the structure features of the turbulent shear flow. In turbulent shear flows there exist regions in which the production of turbulent energy reaches maxima and we call such regions as vital layers. The differential Reynolds stress model is applied in the vital layers, thus the transportation and redistribtron of Reynolds stress are included in these layers. Distribution of Reynolds stress outside vital layers is approximated by function fitting. The mean velocity and pressure fields are then solved from the averaged Navier-Stokes equation with the given Reynolds stress field stated above. The results of two testing cases of complex turbulent flows indicate that the present model is much better than usual k-e model, since the, numerical results of the present method are in better agreement with experimental data, the computing time, however, is much less titan that by use of k-e method. On the other hand, the present method can save CPU time in comparison with full Reynolds stress model.