中文摘要：

为了避免使用速度延拓法处理自由表面边界条件,更真实地反映非牛顿熔体的充模过程,耦合Navier-Stokes方程组,建立了三维实体气液两相流模型。采用基于SIMPLE算法的同位网格有限体积法求解流场物理量,并结合Level Set界面追踪技术实现了非等温熔体充模阶段的动态模拟。为防止出现三维情形下棋盘型压力场,利用同位网格动量插值技术,解决压力与速度失耦的问题。分析了充模过程中,流场物理量的变化情况,研究了注射速率、入口温度等对充模过程及熔体凝固层厚度的影响,得出了与实验相吻合的模拟结果。数值结果表明,三维实体气液两相流模型能更准确地描述聚合物熔体的充模过程;当注射速率较大、入口温度较高时,充模时间较短,熔体凝固层的厚度较小。

英文摘要：

In order to simulate the mold filling process of non-Newtonian fluid and calculate the velocity of free surface without Ghost method,a three dimensional mathematical model for incompressible gas-liquid two-phase flow coupled with Navier-Stokes equations is established.The governing equations are solved by the finite volume method on a non-staggered grid and the interpolation technique on the collocated grid is used for solving pressure-velocity decoupling problem.The melt interface evolution versus time is captured by the Level Set method and the physical quantities of the flow field,such as velocity,pressure,shear rate and temperature at each time step,are obtained with corresponding analysis.The effect of injection parameters,such as injection rate and inlet temperature,on the filling process and thickness of solidified layer are studied.The simulation result is in good agreement with the experimental data.Numerical results show that the three dimensional mathematical model for the gas-liquid two-phase flow can describe the filling process of polymer melt more precisely,and larger injection rate and higher inlet temperature lead to thinner solidified layer.