An adaptive boundary-element approach for 3D transient free surface cavityflow, as applied to polymer processing

An adaptive (Lagrangian) boundary-element approach is proposed for the gene ral three-dimensional simulation of confined free surface flow of viscous i ncompressible fluids. The method is stable as it includes remeshing capabil ities of the deforming free surface, and thus can handle large deformations . A simple algorithm is developed for mesh refinement of the deforming free surface mesh. Smooth transition between large and small elements is achiev ed without significant degradation of the aspect ratio of the elements in t he mesh. Several flow problems are presented to illustrate the utility of t he approach, particularly as encountered in polymer processing. These probl ems illustrate the transient nature of the flow in the extrusion through ci rcular and square dies, the filling of circular and square disks as in conv entional injection molding, and the flow during gas-assisted injection mold ing inside a duct, with relevance to the important problem of viscous finge ring. Copyright (C) 2001 John Wiley & Sons, Ltd.