部分平均Navier-Stokes方法模拟超声速斜面空腔流动

采用部分平均Navier-Stokes (PANS)方法对超声速斜面空腔流动进行了数值模拟研究,评估其对于超声速非定常湍流模拟的性能,并与雷诺平均N-S(RANS),脱体涡模拟(DES)的计算结果及实验数据进行对比.研究表明:模化湍动能比例全场可变的PANS方法预测的速度、壁面压力和摩擦力系数分布与DES的结果非常接近,都与实验值吻合得较好,优于RANS的计算结果;非定常雷诺平均N-S(URANS)计算的自由剪切层近乎为二维稳态的,而DES和PANS方法可以求解出更为丰富的流动结构;模化湍动能比例全场统一的PANS方法虽然可以求解出相比RANS更多尺度的流动结构,但在近壁区不能回归到RANS模型,预测的湍流边界层的速度型偏离对数律,后续的流动计算也偏离实验数据. 

Partially averaged Navier-Stokes method for simulation of supersonic flow over a ramped-cavity

Partially averaged Navier-Stokes (PANS) model was adopted to numerically investigate the supersonic ramped-cavity flow. The objective of current study is to assess the capability of PANS method in the prediction of unsteady supersonic turbulent flow. Comparison of PANS, Reynolds averaged Navier-Stokes (RANS) and detached eddy simulation (DES) results with the available experimental data shows that: (1) velocity profiles, wall-pressure and skin-friction coefficient distributions predicted by PANS model with variable unresolved-to-total ratio of kinetic energy are consistent with DES results; and (2) both of PANS results with variable unresolved-to-total ratio of kinetic energy and DES results are in good agreement with the experimental data and superior to those predicted by RANS; and (3) unsteady Raynolds averaged Navier-Stokes (URANS) model predicts two dimensional steady geometries of free shear layer, while DES and PANS resolve more abundant flow structures; and (4) PANS model with constant unresolved-to-total ratio of kinetic energy cannot return to RANS model in the near-wall region despite it can resolve more scales of motion compared with RANS; and the predicted velocity profiles of upstream turbulent boundary layer mismatch the log law, thus downstream flow simulation deviates a lot from the experiment.