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

An adaptive (Lagrangian) boundary-element approach is proposed for the general three-dimensional simulation of con ned free surface ow of viscous incompressible uids. The method is stable as it includes remeshing capabilities of the deforming free surface, and thus can handle large deformations. A simple algorithm is developed for mesh re nement of the deforming free surface mesh. Smooth transition between large and small elements is achieved without signi cant degradation of the aspect ratio of the elements in the mesh. Several ow problems are presented to illustrate the utility of the approach, particularly as encountered in polymer processing. These problems illustrate the transient nature of the ow in the extrusion through circular and square dies, the lling of circular and square disks as in conventional injection molding, and the ow during gas-assisted injection molding inside a duct, with relevance to the important problem of viscous ngerin