127 citations · 764 across the 38 of their papers we have counts for
10 papers · 1 filter
Generalized Golub-Kahan bidiagonalization for nonsymmetric saddle point systems
Andrei Dumitrasc, Carola Kruse, Ulrich Ruede
The generalized Golub-Kahan bidiagonalization has been used to solve saddle-point systems where the leading block is symmetric and positive definite. We extend this iterative metho…
Deflation for the off-diagonal block in symmetric saddle point systems
Andrei Dumitrasc, Carola Kruse, Ulrich Ruede
Deflation techniques are typically used to shift isolated clusters of small eigenvalues in order to obtain a tighter distribution and a smaller condition number. Such changes induc…
A decoupled numerical method for two-phase flows of different densities and viscosities in superposed fluid and porous layers
Yali Gao, Daozhi Han, Xiaoming He +1
In this article we consider the numerical modeling and simulation via the phase field approach of two-phase flows of different densities and viscosities in superposed fluid and por…
A stencil scaling approach for accelerating matrix-free finite element implementations
Simon Bauer, Daniel Drzisga, Marcus Mohr +3
We present a novel approach to fast on-the-fly low order finite element assembly for scalar elliptic partial differential equations of Darcy type with variable coefficients optimiz…
On the analysis of block smoothers for saddle point problems
Lorenz John, Ulrich Rüde, Barbara Wohlmuth +1
In this article, we discuss several classes of Uzawa smoothers for the application in multigrid methods in the context of saddle point problems. Beside commonly used variants, such…
A two-scale approach for efficient on-the-fly operator assembly in massively parallel high performance multigrid codes
Simon Bauer, Marcus Mohr, Ulrich Rüde +3
Matrix-free finite element implementations of massively parallel geometric multigrid save memory and are often significantly faster than implementations using classical sparse matr…
Highly sparse surface couplings for subdomain-wise isoviscous Stokes finite element discretizations
Markus Huber, Ulrich Rüde, Christian Waluga +1
The Stokes system with constant viscosity can be cast into different formulations by exploiting the incompressibility constraint. For instance the strain in the weak formulation ca…
Solution Techniques for the Stokes System: A priori and a posteriori modifications, resilient algorithms
Markus Huber, Lorenz John, Petra Pustejovska +3
This article proposes modifications to standard low order finite element approximations of the Stokes system with the goal of improving both the approximation quality and the paral…
Optimization of the Multigrid-Convergence Rate on Semi-structured Meshes by Local Fourier Analysis
B. Gmeiner, T. Gradl, F. Gaspar +1
In this paper a local Fourier analysis for multigrid methods on tetrahedral grids is presented. Different smoothers for the discretization of the Laplace operator by linear finite…
Boundary Conditions for Free Interfaces with the Lattice Boltzmann Method
Simon Bogner, Regina Ammer, Ulrich Rüde
In this paper we analyze the boundary treatment of the lattice Boltzmann method (LBM) for simulating 3D flows with free surfaces. The widely used free surface boundary condition of…