FINITE-ELEMENT MODELING OF FREE-SURFACE VISCOELASTIC FLOWS WITH PARTICULAR APPLICATION TO RUBBER MIXING

Internal mixers are used extensively in industry for mixing the compon ents of rubber compounds. In these operations, in order to achieve eff ective mixing, the mixer chamber is always partially filled. This inev itably results in the appearance of multiple free surfaces in flow fie lds inside rubber mixer chambers. Mathematical modelling of such a flo w regime is not a simple task and requires a great deal of effort. Tra ditional free surface flow-modelling techniques, which are mainly base d on the use of volume-of-fluid or pseudo-density approaches in an Eul erian framework, are not flexible enough to cope with this problem. In this paper we describe a new method for the numerical modelling of fr ee surface flows. In this method the pseudo-density approach is extend ed to a special Lagrangian framework along the trajectories of the flu id particles. We show that the developed scheme can very effectively s imulate viscoelastic free surface flows encountered in rubber-mixing p rocesses.