不同壁面绕流特性的格子Boltzmann模拟研究

Lattice Boltzmann simulation research on characteristics of flow over different walls

为了探讨不同壁面的绕流特性,针对粘性流场中,不同壁面诱导的涡脱落现象以及升阻力系数等流场特性进行了格子Boltzmann数值研究。利用基于分子动理论的格子Boltzmann方法(LBM)求解Navier-Stokes方程,实现对流体运动的描述,针对不同的壁面条件,分别采用不同的格子Boltzmann流-固壁面处理方法。采用Half-way反弹边界条件来处理平直壁面,而曲壁面则采用LBM与有限差分法相结合的形式进行处理,计入了壁面与标准网格不重合对结果造成的影响。开发相应的计算程序,计算结果与已发表文献结果吻合良好,验证了数值模型的正确性。同时,探讨了进出口边界与钝体中心的距离对结果的影响。对比分析了不同壁面的绕流模型中升阻力系数、斯托罗哈数和涡量云图等,并进一步研究了雷诺数条件的影响。结果表明,不同壁面的绕流特性具有明显差异,且同时受雷诺数的显著影响;一般地,平直壁面对于来流作出的响应更迅速。

In order to investigate the flow characteristics of different walls, the vortex shedding and lift, drag coefficients induced by different walls are studied by using the lattice Boltzmann method in viscous fluid field. The flow motion is described by solving the Navier-Stokes equations using the lattice Boltzmann method（LBM） which is based on the kinetic theory. Different lattice Boltzmann schemes are adopted to deal with different walls. The plane wall is handled with the Half-way rebound boundary scheme, while the curved surface is processed in the form combining the LBM with the finite difference method （FDM）. The effects that the actual physical boundary and the standard grid lines do not overlap on the computational results are included. Corresponding codes are developed, and the numerical models are verified by comparing the results with public literatures. Meanwhile, the influence of the distance of inlet and outlet boundaries to bluff body center are discussed. The comparative analysis of the results of lift, drag coefficient, Strouhal number, vorticity contours and so on is presented. And, the effect of different Reynolds numbers is investigated. It shows that the wall structures obviously impact the flow characteristics which is also seriously influenced by the Reynolds number. Generally, a plane wall responds more quickly.