arXiv subjects

Dominik Bartuschat

Publications and source records attributed to Dominik Bartuschat.

5 recordsLinked to original sources

arXiv2018

A Scalable and Modular Software Architecture for Finite Elements on Hierarchical Hybrid Grids

In this article, a new generic higher-order finite-element framework for massively parallel simulations is presented. The modular software architecture is carefully designed to exploit the resources of modern and future supercomputers. Combining an unstructured topology with structured grid refinement facilitates high geometric adaptability and matrix-free multigrid implementations with excellent performance. Different abstraction levels and fully distributed data structures additionally ensure high flexibility, extensibility, and scalability. The software concepts support sophisticated load balancing and flexibly combining finite element spaces. Example scenarios with coupled systems of PDEs show the applicability of the concepts to performing geophysical simulations.

cs.MS↗

arXiv2018

A Scalable Multiphysics Algorithm for Massively Parallel Direct Numerical Simulations of Electrophoresis

In this article we introduce a novel coupled algorithm for massively parallel direct numerical simulations of electrophoresis in microfluidic flows. This multiphysics algorithm employs an Eulerian description of fluid and ions, combined with a Lagrangian representation of moving charged particles. The fixed grid facilitates efficient solvers and the employed lattice Boltzmann method can efficiently handle complex geometries. Validation experiments with more than $70\,000$ time steps are presented, together with scaling experiments with over ${4\cdot10^{6}}$ particles and ${1.96\cdot10^{11}}$ grid cells for both hydrodynamics and electric potential. We achieve excellent performance and scaling on up to $65\,536$ cores of a current supercomputer.

cs.CE↗

arXiv2015

Two Computational Models for Simulating the Tumbling Motion of Elongated Particles in Fluids

Suspensions with fiber-like particles in the low Reynolds number regime are modeled by two different approaches that both use a Lagrangian representation of individual particles. The first method is the well-established formulation based on Stokes flow that is formulated as integral equations. It uses a slender body approximation for the fibers to represent the interaction between them directly without explicitly computing the flow field. The second is a new technique using the 3D lattice Boltzmann method on parallel supercomputers. Here the flow computation is coupled to a computational model of the dynamics of rigid bodies using fluid-structure interaction techniques. Both methods can be applied to simulate fibers in fluid flow. They are carefully validated and compared against each other, exposing systematically their strengths and weaknesses regarding their accuracy, the computational cost, and possible model extensions.

cs.CE↗

arXiv2014

Parallel Multiphysics Simulations of Charged Particles in Microfluidic Flows

The article describes parallel multiphysics simulations of charged particles in microfluidic flows with the waLBerla framework. To this end, three physical effects are coupled: rigid body dynamics, fluid flow modelled by a lattice Boltzmann algorithm, and electric potentials represented by a finite volume discretisation. For solving the finite volume discretisation for the electrostatic forces, a cell-centered multigrid algorithm is developed that conforms to the lattice Boltzmann meshes and the parallel communication structure of waLBerla. The new functionality is validated with suitable benchmark scenarios. Additionally, the parallel scaling and the numerical efficiency of the algorithms are analysed on an advanced supercomputer.

cs.CE↗

arXiv2014

Simulation of a Hard-Spherocylinder Liquid Crystal with the pe

The pe physics engine is validated through the simulation of a liquid crystal model system consisting of hard spherocylinders. For this purpose we evaluate several characteristic parameters of this system, namely the nematic order parameter, the pressure, and the Frank elastic constants. We compare these to the values reported in literature and find a very good agreement, which demonstrates that the pe physics engine can accurately treat such densely packed particle systems. Simultaneously we are able to examine the influence of finite size effects, especially on the evaluation of the Frank elastic constants, as we are far less restricted in system size than earlier simulations.

physics.comp-ph↗