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TY  - THES
AU  - Helmig, Jan
TI  - Boundary-conforming finite element methods for complex rotating domains
PB  - Rheinisch-Westfälische Technische Hochschule Aachen
VL  - Dissertation
CY  - Aachen
M1  - RWTH-2021-09694
SP  - 1 Online-Ressource : Illustrationen
PY  - 2021
N1  - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2022
N1  - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021
AB  - Simulation technology has become a very powerful tool to describe and predict physical processes like complex flow. Many of these simulation techniques – and among those the finite element method (FEM) – require the generation of a discrete version of the domain of interest, the computational mesh. Such meshes cannot be chosen arbitrarily, but have to satisfy certain quality criteria. Boundary-conforming meshes, which are aligned with the domain boundary, have significant advantages in terms of accuracy and efficiency. However, with increasing complexity of the domain, generating such meshes can be very time-consuming. This is especially true for applications with complex moving domains, e.g., caused by rotating parts and small geometric features. The example considered within this thesis are twin-screw extruders (TSEs). The particular challenge for a TSE is the co-rotating deformation of the computational domain with very small gap sizes between the individual parts. To allow the use of boundary-conforming meshes for TSEs with convex screw shapes we develop an efficient, tailor-made mesh update method. It makes the need for remeshing and projections of solutions obsolete. In addition, a spline-based meshing technique that extends the previously described method to screw shapes of arbitrarycomplexity is presented. A sliding mesh approach based on Nitsche’s method to account for discontinuities of the screw design in axial direction complements both methods. The proposed meshing concepts are then used to simulate the flow of polymer melts in TSEs. Mathematical and numerical models describing such flows are also discussed. This includes non-Newtonian models to accurately describe the flow behavior of polymer melts. 2D and 3D test cases verify the presented methods including convergence studies and comparisons with experiments. Furthermore, cases evaluating complex, unsteady temperature-dependent flow of polymer melt inside TSEs with multiple screw elements show the potential of the presented methods to industrial applications.
LB  - PUB:(DE-HGF)11
DO  - DOI:10.18154/RWTH-2021-09694
UR  - https://publications.rwth-aachen.de/record/834178
ER  -