一种基于冯卡门尺度的湍流模式在模拟稳态和非稳态流动问题中的应用

采用尺度自适应模型(SAS)对稳态和非稳态流动进行了数值仿真。SAS模型有效解决了传统脱体涡数值模拟(DES)方法在网格加密过程中引发的“附面层速度型偏离对数率”的问题;同时,SAS模型的尺度自解效应也赋予了该方法类LES特征,可以在不出现非物理解的前提下有效地释放当地脉动。通过高雷诺数平板边界层模拟,SAS方法在附面层内模拟的速度型分布与理论值贴合得很好,说明该方法对于稳态流动的求解并未偏离RANS模型;同时,在串联双圆柱算例中,SAS方法对于圆柱表面压力分布的预测精度高于其他稳态和非稳态模型,Q云图也显示出该方法的类LES特征。算例结果证明了SAS方法有着一定的工程使用价值。

APPLICATION OF A TURBULENCE MODEL BASED ON VON KARMEN LENGTH SCALE IN STEADY AND UNSTEADY FLOW SIMULATION

The Scale-Adaptive Simulation (SAS) model has been applied to numerical simulation for steady and unsteady flows. By using SAS, the problem of velocity profiles within the boundary layer deviating from the law of wall during the process of grid refinement using traditional Detached Eddy Simulation method (DES) could be avoided. Meanwhile, this method displays the LES-like characteristics because of the effect of the automatic adjustment of scale in SAS, which makes it possible that the method avoids any non-physics and detects the local pulsation well. In the simulation of the boundary layer of flat plate at a high Reynolds number, the velocity profile within the boundary layer matches excellently with theoretical values, which illustrates that this method does not deviate from the RANS model in solving steady flows. The study case of two tandem circular cylinders shows that SAS predicts the pressure distribution at the surfaces of cylinders more accurately than other steady and unsteady flow models. Furthermore, Q contours show its LES-like characteristics. Therefore, the numerical results prove that the SAS method can be applied to engineering practice.