吸水口上自由表面旋涡的LES-LBM模拟

为了实现高雷诺数下自由表面旋涡生成与演化过程的数值模拟,将标准Smagorinsky亚格子应力模型引入到三维单相自由面格子Boltzmann方法中,建立结合大涡模拟的格子Boltzmann方法（LES-LBM）.当进口雷诺数分别为5×104和105时,考虑重力和科氏力的作用,采用LES-LBM对长方形水槽底部吸水口上方的自由表面旋涡的生成与演化过程进行数值计算,再现了自由表面旋涡发展过程中的典型流态,并根据其特点将自由表面旋涡的发展过程分为4个典型阶段.对比分析有、无科氏力作用下的高雷诺数流动算例,验证科氏力的作用.对自由表面旋涡发展过程中的B型（染色旋涡和挟物旋涡）和D型（连续吸气旋涡）自由表面旋涡的径向速度、切向速度以及轴向速度沿吸水口半径方向的分布规律进行重点分析.数值计算结果表明：采用结合大涡模拟的单相自由面格子Boltzmann方法,可以有效模拟高雷诺数下的自由表面旋涡生成与演化过程;验证了科氏力在诱导并促进自由表面旋涡发展过程中的作用;计算获得的自由表面旋涡内部流场的各速度分量沿径向的分布规律与试验结果定性一致,且几乎不随进口雷诺数的不同而改变.

Simulation of free surface vortex upon suction inlet based on LES-LBM

To realize the numerical simulation of the formation and evolution process of the free surface vortex in high Reynolds number flow issues,the standard Smagorinsky sub-grid stress model was introduced into the three dimensional of single-phase free surface lattice Boltzmann method,and the LES-LBM was established.Considered that the inlet Reynolds number were 5×104 and 105,the formation and evolution process of the free surface vortex upon suction inlet of rectangular water tank under the effect of gravity and Coriolis force was simulated by LES-LBM.The main flow features of the free surface vortex were represented in the process.According to the flow characteristics,the developing process was divided into four typical stages.By comparing the high Reynolds number flow problems with and without Coriolis force,the action of it was tested.The regularities of the radial velocity,tangential velocity and axial velocity of the B-type（Dye core Trash pulling core） and D-type（Full air core） free surface vortex along the direction of radial were mainly analyzed.The numerical simulation results show that the formation and evolution process of free surface vortex in high Reynolds number can be effectively simulated by LES-LBM.The effect of Coriolis force which promotes the free surface vortex production and development has been proved.The regularities of the velocity components of free surface vortex are qualitatively consistent with the experimental results and they barely change along with the variation of the inlet Reynolds number.