基于格子Boltzmann方法的挤出胀大的数值模拟

将单相格子Boltzmann方法(lattice Boltzmann method, LBM)引入到粘弹流体的瞬态挤出胀大的数值模拟中，建立了基于双分布函数的自由面粘弹性流动格子Boltzmann模型．分析得到的流道中流动速度分布和构型张量结果与理论解十分吻合．对粘弹流体瞬态挤出胀大过程进行了模拟，并分析了运动粘度比和剪切速率对挤出胀大率的影响，得到的胀大率结果与理论分析和其它模拟结果基本一致．表明给出的LBM可以捕捉挤出胀大的瞬态效应．

Numerical Simulation of Extrudate Swell Based on Lattice Boltzmann Method

LBM (lattice Boltzmann method) is applied to the transient extrusion swell simulation of viscoelastic fluid. The LBM model for the free-surface flow of viscoelastic fluid is established based on the Bi-distribution function. The numerical results of velocity and conformation tensor in the channel are in good agreement with the analytical solutions. The transient swell process is simulated, and the influences of the kinematic viscosity ratio and the shear rate on the swelling ratio are analyzed. The predicted swelling ratio agrees well with the analytical and other numerical solutions. It show that the given LBM can capture the transient behavior of the extrusion swell process.