黏弹性流体扩展及收缩流动的格子Boltzmann模拟分析

本文应用格子Boltzmann 方法(LBM)并结合Oldroyd-B 模型，讨论了不可压缩的 Navier-Stokes 方程和平流扩散本构方程的解耦及各自求解方法，以及两类问题的边界处理格式，实现了黏弹性流体在二维1:3 扩展流道以及3:1 收缩流道中的流动的数值模拟．获得了不同雷诺数Re 和维森伯格数Wi 以及黏度vs 下流动的流线分布，计算给出了漩涡的涡心位置和大小，并分析了参数Re、Wi 和vs 对流动特点的影响．模拟结果表明本文所采用模型和边界处理方法具有良好的精度和稳定性．

Simulation of Sudden Expansion and Contraction Flows for Viscoelastic Fluids Using the Lattice Boltzmann Method

In this paper, based on the lattice Boltzmann method (LBM) and the Oldroyd-B model, the plane 1:3 and 3:1 sudden expansion and contraction flow of viscoelastic fluid was studied numerically, the decoupling and solving methods of the incompressible Navier-Stokes equation and advection diffusion constitutive equations were discussed and the boundary processing format was given. The streamline patterns for sudden expansion and contraction flow of viscoelastic fluid with different Reynolds numbers Re, Weissenberg numbers Wi and viscosity vs were obtained. The positions of vortex center and the length of vortex were also listed, and the influences of those parameters on the sudden expansion and contraction flow were discussed. The results also confirmed that this method has satisfactory accuracy and stability.