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

双螺杆挤出机（TSE）的实验设计和优化通常是非常昂贵和耗时的。因此，三维数值工艺模拟对塑料工业未来的技术进步具有重要意义。它允许在很短的时间内以低成本以资源有效的方式分析和虚拟优化各种配置。虽然近年来在这一领域已经有了很好的发展和研究活动，但TSE的三维模拟仍然是当今的一个主要挑战。这尤其是由于这样一个事实，即移动的互锁元件不能容易地通过经典的贴体模拟来计算。计算机技术的不断发展伴随着新的、功能强大的仿真方法的发展。例如，浸没边界法是一种非常有前途的模拟方法，用于克服当前在模拟互锁、移动元件方面的局限性。因此，本研究项目的目的是在OpenFOAM中开发和验证一种新的IBM求解器，用于TSE中单相流的三维模拟。新的求解器是一个新的测量设备，一方面在一个受控的实验室实验，另一方面在一个真实的TSE作为一个规模扩大到真实的工艺条件的第一次验证。该研究项目的结果代表了计算机辅助设计的又一步，未来可用于模拟各种TSE配置。由于模拟的复杂性，这是不可能的，或者直到今天仍然只是以简化的方式。此外，该研究项目将为未来开发耦合流求解器铺平道路，该耦合流求解器包括离散元法（DEM）中的固体颗粒和使用合适的IBM求解器的流动模拟。这种耦合的CFD-DEM模拟是必不可少的，以便映射挤出过程中的熔化过程，从而在未来一起模拟TSE的所有工艺区。

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.