中文摘要：

基于流体运动基本控制方程和Giesekus黏弹模型，在OpenFOAM流体计算开源平台上采用有限体积法编制了新求解器，同时采用体积分数法追踪多相流中的自由界面，并利用此求解器对溢流法水辅共注填充过程进行了仿真计算。系统地分析了内层熔体预填量对制品最终形态的影响，发现随着内层熔体预填量的增加，制件中空率减小，内层熔体的残余壁厚增加，皮层熔体则变化不明显；另外，基于熔体黏弹特质对结果进行了解释。还系统地进行了相关水辅共注实验，结果表明，其得到的结论和数值模拟所得结论相同。

英文摘要：

Based on the basic governing equations of fluid and Giesekus model, a new solver was built with the finite volume method on the open source platform named OpenFOAM for the fluid flow problems. The solver tracked the movement of free boundaries of muhiphase flow with the volume of fluid method. In this paper, the filling process of water-assisted co-injection molding was simulated by using the solver. This paper systematically analyzed the influence of inner melt pre-filled volume on the final form of product. The results show that the residual wall thickness of inner melt increases and the hollow ratio decreases with the increasing in the inner melt pre-filled volume, while the residual wall thickness of skin melt shows no remarkable change. Meanwhile, the paper explained the conclusions based on the intrinsically viscoelastic character. Finally, the experiments of overflow water-assisted co-injection were carried out and the conclusion of numerical simulation was verified.