基于格子Boltzmann方法的方通道湍流的大涡模拟

基于格子Boltzmann方程的大涡模拟方法,对以摩擦速度、方通道水利直径为特征尺度,雷诺数为300的直方通道内湍流流动进行数值计算.利用多松弛时间格子Boltzmann方法来模拟流场的流动,切应力改善亚格子应力模型来模化滤波后的非封闭项.将模化后的亚格子应力与格子Boltzmann方法中的松弛时间相关联,使得松弛时间当地化,从而能够准确地模拟湍流.对湍流的平均流向速度、平均二次流速度以表征湍流强度的均方根速度以及不同截面流向瞬时涡做了计算和评估.计算结果与直接数值模拟、实验数据相吻合,证明了格子Boltzmann方法在计算通道湍流中的精度.

Large eddy simulation of square duct turbulence based on the lattice Boltzmann method

Large eddy simulation(LES),based on the lattice Boltzmann equation (LBE),was used to study the square duct turbulent flow at a shear Reynolds number equal to 300 based on the hydraulic diameter and the friction velocity.The flow field was simulated by the multiple relaxation time lattice Boltzmann equation.The non-closure term after filtering was modeled by the shear improved Smagorinsky sub-grid stress model.To combine the lattice Boltzmann and large eddy simulation,the subgrid scales turbulent viscosity was related to the subgrid-scale relaxation time.Then the effective relaxation times were computed locally.The turbulent statistics quantities,including the mean streamwise velocity,mean second velocity,the root-mean-square velocity and the instantaneous streamwise voriticity on different sections,were computed.The comparison result,with the DNS and experimental data,shows that the LES based on the LBE can be used to study the bounded turbulent flow.