h1

%0 Thesis
%A Klimach, Harald
%T Parallel multi-scale simulations with octrees and coupled applications; 1st edition
%V 1
%I Rheinisch-Westfälische Technische Hochschule Aachen
%V Dissertation
%C Siegen
%M RWTH-2016-07385
%@ 978-3-936533-82-8
%B Simulation Techniques in Siegen
%P 1 Online-Ressource (xv, 185 Seiten) : Illustrationen, Diagramme
%D 2016
%Z Auch veröffentlicht auf dem Publikationsserver der RWTH Aachen University
%Z Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2016
%X Physical simulations often require the consideration of many phenomena and scales. For example in aeroacoustic problems, both, the flow generatingthe noise and the sound wave propagation needs to be considered. This work investigates numerical approaches to such problems on large distributed and parallel computing systems. The coupling framework KOP is parallelized as far as possible and to overcome fundamental scalability limits a new framework APES is developed. Both implementations utilize high-order discretizations, as these allow for accurate simulations with less degrees of freedoms than lower order methods. This property of high-order methodsis an important feature for modern supercomputing systems, as memory to represent degrees of freedom in a simulation is a scarce resource. The presented methods enable the transient simulation of multi-scale setups but detailed resolutions still require large amounts of computational resources. A focus is put on the efficient utilization of modern computing systems to address this need. Besides the scalability of the implementations, the importance of single core optimization and vectorization is illustrated. KOP uses discrete points to realize the coupling and allows for the interaction between domains with differing discretizations and solved equation systems. Arbitrary mesh configurations are supported and both, structuredand unstructured mesh solvers are available in the framework. In both framworksexplicit time integration methods are deployed to resolve the timedependent simulations. The coupling allows for a varying time step widthover the participating domains by a sub-cycling method. Various conservationlaws can be solved by the presented frameworks ranging from Maxwell’s equations and linearized Euler equations to full compressible Navier-Stokesequations. A fully distributed coupling approach is developed that allows for coupling of those in a large-scale simulation to solve, for example, aeroacousticproblems.APES enables high-order discretizations in the spectral regime. It involvesa fully scalable toolchain for mesh-based simulations featuring a meshgeneration and a post-processing tool to support the solvers. The common foundation of these tools is an Octree representation for the mesh, andthis work specifically covers the generation of high-order geometry approximationsin the developed mesh generator Seeder. This robust mechanismworks for arbitrarily complex surfaces and offers a practical way to tackleengineering tasks with spectral element discretizations.
%F PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
%9 Dissertation / PhD ThesisBook
%U https://publications.rwth-aachen.de/record/670169