Fluid flow aspects of twin-screw extruder process: numerical simulations of TSE rheomixing

This paper presents a brief review of the twin-screw extruder (TSE) process, analyses the fluid flow aspects of a new application of TSE in rheomixing casting, and simulates fundamental micro-mechanisms of the rheological behaviour of metallurgical alloys. The TSE is widely used as a mixing tool in the polymer industry. The numerical simulation of the TSE process is complex and there are only few simulation packages to provide an insight into TSE processing for viscoelastic flows. This study involves the systematic analysis of flow features of immiscible alloys in the TSE rheomixing process, the establishment of a simplified flow field, and simulation of the microstructure of immiscible alloy drops by the piecewise linear interface construction/volumeof-fluid method. It is noted that the microstructure of immiscible alloys is strongly influenced by the viscosity of the system, which dominates the interaction between droplets. The numerical results show good qualitative agreement with experimental results, and are useful for further optimization design of prototypical rheomixing processes.