Three-Dimensional Modeling of the Twin-Screw-Extruder with the Immersed Boundary Method

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The experimental design and optimization of twin-screw extruders (TSE) is often very expensive and time consuming. Three-dimensional, numerical process simulation is therefore of great importance for future technological progress in the plastics industry. It allows a wide variety of configurations to be analyzed and virtually optimized in a resource-efficient manner in a very short time and at low cost. Although there have already been promising developments and research activities in this field in recent years, the three-dimensional simulation of TSE remains a major challenge today. This is particularly due to the fact that moving, interlocking elements cannot easily be calculated by classical, body-fitted simulations. The continuous development of computer technology is accompanied by the development of new, powerful simulation methods. For example, the Immersed Boundary Method is a very promising simulation method for overcoming current limitations in the simulation of interlocking, moving elements. Therefore, the aim of this research project is the development and validation of a novel IBM solver in OpenFOAM for the three-dimensional simulation of single-phase flows in a TSE. The new solver is to be validated on the one hand within a controlled laboratory experiment by a novel measuring device and on the other hand on a real TSE as a scale-up to real process conditions for the first time. The results of this research project represent a further step towards computer-aided design and can be used in future to simulate various TSE configurations. Due to the complexity of the simulation, this has not been possible or only in a simplified way still today. Furthermore, this research project will pave the way for the future development of a coupled flow solver, which covers both solid particles in terms of the Discrete Element Method (DEM) and a flow simulation using a suitable IBM solver. Such a coupled CFD-DEM simulation is essential in order to map the melting process during extrusion and thus simulate all process zones of the TSE together in the future.