强压缩湍流雷诺应力模型中压力应变快速项的探索

A STUDY ON THE RAPID PRESSURE-STRAIN RATE IN THE SECOND-MOMENT CLOSURE FOR TURBULENT FLOWS UNDERGOING STRONG COMPRESSIONS

对压力应变快速项的五个模型作了压缩性修正，即在模型中引入了由于平均流可压而导入的不为零的平均速度散度，并把五个模型计算所得的雷诺应力各向异性张量分量、平均湍能及压力应变快速项的值与快速畸变理论的计算结果作了比较．结果表明，包含湍流应变史效应的线性模型可达到四阶非线性模型的精度．

To clarify applicability of the existing models for the rapid pressure-strain correlation in the Reynolds-stress closures, modifications accounting for the nonzero divergence of the mean velocity have been set into five turbulence models. These are two models of Launder et al. (LRR1 and LRR2), model of Speziale et al. (SSG), model of Johansson et al. and model of Lee. Computations have been carried out with these models for compression process in the cylinder of an internal combustion engine. The calculation results of the mean turbulent kinetic energy, the anisotropy tensor of Reynolds stress and rapid pressure-strain have been compared with the analytical solutions of Rapid Distortion Theory(RDT) in order to identify a suitable model for turbulent flows undergoing strong compressions as in the engines. The results demonstrate that the linear model of Lee which includes the history effect of the total strain can even give the same accurate predictions as those of the Johansson's nonlinear models up to fourth order in the Reynolds-stress anisotropy tensor.