The Study Of Level Set Method For The Flow Filling Process In The Mold Of Polymer

The melt filling stage is one of the most important stages of the polymer molding; this stage involves the variation of the pressure and the movement of the front interface. In this stage, the pressure changes greatly, and the movement of the melt is complex. We are not able to use the traditional experiences and skills to control the movement of the melt accurately. So we can't ensure the quality and the properties of the products. We must know the flow pattern in order to take steps to ensure the quality of the product. From the simulation of the polymer filling stage, we will be able to predict the flow pattern of the polymer in the cavity, and the variation of both the pressure and the velocity. The simulating results will provide data for engineers to design items, optimize parameters and so on. Using the numerical method to simulate the mold process, we will break through the restraint of the traditional experiences, and provide a practical technical method which bases on the scientific analysis for the actual project.Taking the melt flow in the cavity for instance, by the basic theory of viscous fluid mechanics, we analysis the physical process of the melt filling. Based on the Hele-Shaw flow model and Level set method, we summarize the flow simulation of melt filling to the problem on solving the partial differential equation about the pressure and the velocity by the appropriate assumption. We adopt the power law model which is appropriate to describe the viscous property as the material model.As usual, the simulation for the melt interface is mainly done by the control volume method. Considering the advantages of the level set method on tracking the interface, we use the level set method to track the moving interface in this article, and the signal distance function is corrected by the re-initialization of the level set function. For the re-initialization of the level set equation and the discretion in space, The WENO(Weighted Essentially Non-Oscillatory) method is applied for ensuring the numerical accuracy, while the Runge-Kutta method is used for the discretion in time. At the same time, the pressure and the velocity are achieved by the finite difference method. For the melt in the cavity, we simulate its movement when there is one or two symmetrical injection ports. The numerical results show that the moving interface can be tracked accurately by using the level set method.