396 citations · 934 across the 12 of their papers we have counts for
14 papers
An adaptive stabilized trace finite element method for surface PDEs
Timo Heister, Maxim A. Olshanskii, Vladimir Yushutin
The paper introduces an adaptive version of the stabilized Trace Finite Element Method (TraceFEM) designed to solve low-regularity elliptic problems on level-set surfaces using a s…
Efficient distributed matrix-free multigrid methods on locally refined meshes for FEM computations
Peter Munch, Timo Heister, Laura Prieto Saavedra +1
This work studies three multigrid variants for matrix-free finite-element computations on locally refined meshes: geometric local smoothing, geometric global coarsening, and polyno…
Robust preconditioning for a mixed formulation of phase-field fracture problems
Timo Heister, Katrin Mang, Thomas Wick
In this work, we consider fracture propagation in nearly incompressible and (fully) incompressible materials using a phase-field formulation. We use a mixed form of the elasticity…
The deal.II finite element library: design, features, and insights
Daniel Arndt, Wolfgang Bangerth, Denis Davydov +7
deal.II is a state-of-the-art finite element library focused on generality, dimension-independent programming, parallelism, and extensibility. Herein, we outline its primary design…
Comparison Between Algebraic and Matrix-free Geometric Multigrid for a Stokes Problem on Adaptive Meshes with Variable Viscosity
Thomas C. Clevenger, Timo Heister
Problems arising in Earth's mantle convection involve finding the solution to Stokes systems with large viscosity contrasts. These systems contain localized features which, even wi…
A Flexible, Parallel, Adaptive Geometric Multigrid method for FEM
Thomas C. Clevenger, Timo Heister, Guido Kanschat +1
We present the design and implementation details of a geometric multigrid method on adaptively refined meshes for massively parallel computations. The method uses local smoothing o…
A new formulation for coupled magma/mantle dynamics
Juliane Dannberg, Rene Gassmöller, Ryan Grove +1
Many open problems in the Earth sciences can only be understood by modelling the porous flow of melt through a viscously deforming solid rock matrix. However, the system of equatio…
Parallel solution, adaptivity, computational convergence, and open-source code of 2d and 3d pressurized phase-field fracture problems
Timo Heister, Thomas Wick
We present a scalable, parallel implementation of a solver for the solution of a phase-field model for quasi-static brittle fracture. The code is available as open source. Numerica…
Efficient discretizations for the EMAC formulation of the incompressible Navier-Stokes equations
Sergey Charnyi, Timo Heister, Maxim A. Olshanskii +1
We study discretizations of the incompressible Navier-Stokes equations, written in the newly developed energy-momentum-angular momentum conserving (EMAC) formulation. We consider l…
High Accuracy Mantle Convection Simulation through Modern Numerical Methods. II: Realistic Models and Problems
Timo Heister, Juliane Dannberg, Rene Gassmöller +1
Computations have helped elucidate the dynamics of Earth's mantle for several decades already. The numerical methods that underlie these simulations have greatly evolved within thi…
On conservation laws of Navier-Stokes Galerkin discretizations
Sergey Charnyi, Timo Heister, Maxim A. Olshanskii +1
We study conservation properties of Galerkin methods for the incompressible Navier-Stokes equations, without the divergence constraint strongly enforced. In typical discretizations…
Unconditional long-time stability of a velocity-vorticity method for the 2D Navier-Stokes equations
Timo Heister, Maxim A. Olshanskii, Leo G. Rebholz
We prove unconditional long-time stability for a particular velocity-vorticity discretization of the 2D Navier-Stokes equations. The scheme begins with a formulation that uses the…
Clone and graft: Testing scientific applications as they are built
Bruno Turcksin, Timo Heister, Wolfgang Bangerth
This article describes our experience developing and maintaining automated tests for scientific applications. The main idea evolves around building on already existing tests by clo…
Finitely presented groups related to Kaplansky's Direct Finiteness Conjecture
Ken Dykema, Timo Heister, Kate Juschenko
We consider a family of finitely presented groups, called Universal Left Invertible Element (or ULIE) groups, that are universal for existence of one--sided invertible elements in…