板坯连铸结晶器流场的格子法模拟

给出一种与现有传统数值方法不同的计算流体动力学介观模型。在该模型中,建立描述流体微团运动及碰撞规律的格子Boltzmann方程以及平衡分布函数,并依此求解出流体微团的分布函数,而流场的速度、压力等物理量可直接根据流体微团的分布函数统计求和而得。在此基础上计算了板坯连铸结晶器中心面内的二维流动,模拟出流场在高雷诺数条件下流动模态随时间的变化过程,得到与试验结果一致的流场结构,较真实地反映高雷诺数条件下结晶器内湍流的有漩性、非对称性及非定常性。结果表明随着流场雷诺数的提高,流动中物理量脉动成分的显著增强,打乱了原有对称性的大涡结构,使得流动呈现非对称性及非定常性。

LATTICE BOLTZMANN METHOD SIMULATION OF FLUID FLOW INSIDE CONTINUOUS SLAB CASTING MOLD

Lattice Boltzmann method, which is different from traditional macroscopic and microscopic models of computational fluid dynamics, is presented. The movement and collision of fluid micelle are controlled by lattice Boltzmann equation and equilibrium distribution functions, and distribution functions of fluid micelle can be solved from lattice Boltzmann equation. Thus physical quantities such as velocity and pressure are interpreted by the statistic sum form of distribution functions. Furthermore, the fluid flow in the 2D central plane of continuous slab casting mold is computed, especially the evolution with time of flow with high Reynolds number is simulated, and the simulated flow patterns are found to be in excellent agreement with the previous experiment results, which show that the turbulent flow with high Reynolds number inside the mold is swirly, asymmetric and unsteady. These results indicate that the fluctuation of quantity has been strengthened as long as Reynolds number is high enough, which destroys the symmetric eddy structure, and the fluid flow becomes asymmetric and unsteady.