Two-Phase Model of Liquid-Liquid Interactions With Interface Capturing: Application to Water Assisted Injection Molding

Abstract

Abstract. In this paper, a two phase model to compute liquid-liquid flows is presented. We consider that one phase is a highly viscous thermodependent liquid (polymer phase), whereas the second one is a low viscosity low temperature fluid (water). The first part of this paper concerns capture of the interface between the water and the polymer (or determination of the phase field function). Classical VOF and Level set techniques have been implemented and were ameliorated using mesh adaptation techniques. To accurately determine the velocity field, a two-phase formulation is considered, based in the theory of mixtures, and we introduce a scalar parameter, the phase fraction quantifying the presence of each phase in each point of the computational domain. A friction type coupling between both phases is retained. Using the mixed finite element method within an eulerian framework, we calculate in a single system the whole kinematic variables for both liquids (velocity and pressure of each phase). Results are shown, for 2D and 3D parts.

Overview of the Experimental Trends in Water‐Assisted Injection Molding

“…They found the dependence of the residual wall thickness on the water pressure and melt temperature, which was consistent with the experimental data. Polynkin et al and Silva et al used the volume of fluid method to simulate the high‐pressure water penetration and successfully traced the polymer–water interface. Recently, Wang et al used this method to simulate the process of high‐pressure water penetration, and showed that the process of melt filling propelled by high‐pressure water was divided into three stages: initial filling, fast filling, and terminal filling, and the water had a little shear effect on the melt in the water‐penetrated zone.…”

“…Michaeli et al systematically investigated the injector technology, residual wall thickness, and hollow space formation during the WAIM process . In addition, some researchers simulated the WAIM process using interesting approaches . Liu first reviewed the development and progress of WAIM technology in 2009 .…”

Multi Criteria Adaptive Meshing for Polymers Processing in Rem3D^®

“…A -non unique-good adaptation functions combination should generate a close to "necessary and sufficient" refinement. A first approach, proposed by [6], consists in refining through the different interfaces air/polymer, polymer/water or polymer/polymer. This method is especially adapted to the fluid assisted injection molding, it enables to describe very thin polymer or fluid layers, this gives also a very good surface quality description, as shown in figure 2.…”

“…Fig. 3, Interface comparison between isotropic homogeneous mesh (b-d) and anisotropic adaptive meshing (e-g) [6] Fig. 2, Anisotropic adaptive meshing around interface [6] 1652…”