WaLBerla: HPC software design for computational engineering simulations

Feichtinger, Christian; Donath, S.; Köstler, Harald; Götz, Jan; Rüde, Ulrich

doi:10.1016/j.jocs.2011.01.004

Cited by 84 publications

(73 citation statements)

References 19 publications

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“…Hereby, the flow variables are assumed constant along the y-axis, and the channel is rotated by an angle α about the y-axis. The test cases have been realized using the waLBerla (Feichtinger et al, 2011; framework.…”

Section: Numerical Resultsmentioning

confidence: 99%

Boundary conditions for free interfaces with the lattice Boltzmann method

Bogner

Ammer

Rüde

2015

Journal of Computational Physics

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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 Körner et al. (2005) is shown to be first order accurate. The article presents a new free surface boundary scheme that is suitable for second order accurate simulations based on the LBM. The new method takes into account the free surface position and its orientation with respect to the computational lattice. Numerical experiments confirm the theoretical findings and illustrate the different behavior of the original method and the new method.

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Section: Numerical Resultsmentioning

confidence: 99%

Boundary conditions for free interfaces with the lattice Boltzmann method

Bogner

Ammer

Rüde

2015

Journal of Computational Physics

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“…The Widely Applicable Lattice-Boltzmann from Erlangen (waLBerla) (Feichtinger et al, 2011) is a massively parallel framework for simulating multiphase flows based on the lattice-Boltzmann method. The flow simulator can be coupled to a rigid body dynamics solver (PE, physics engine) (Iglberger and Rüde, 2011) using an explicit fluid-structure interaction technique, with the goal of, for example, simulating particulate flows or suspensions as they appear in many technical, environmental, or biophysical applications.…”

mentioning

confidence: 99%

Multiphysics simulations: challenges and opportunities.

Keyes¹,

McInnes²,

Woodward³

et al. 2012

149

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We consider multiphysics applications from algorithmic and architectural perspectives, where "algorithmic" includes both mathematical analysis and computational complexity and "architectural" includes both software and hardware environments. Many diverse multiphysics applications can be reduced, en route to their computational simulation, to a common algebraic coupling paradigm. Mathematical analysis of multiphysics coupling in this form is not always practical for realistic applications, but model problems representative of applications discussed herein can provide insight. A variety of software frameworks for multiphysics applications have been constructed and refined within disciplinary communities and executed on leading-edge computer systems. We examine several of these, expose some commonalities among them, and attempt to extrapolate best practices to future systems. From our study, we summarize challenges and forecast opportunities.

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“…However, there are a few major differences to other approaches: [55] and [56] both implement the lattice-Boltzmann method on top of a highly optimised octree grid implementation. I.e., the solver itself had to be developed more or less from scratch in a way that is adapted to the grid structure and its specific memory-optimal traversal in the Peano framework [57] or waLBerla [58]. Also, [56] provides a solver on statically adaptive meshes, which allows for much more sophisticated solutions in terms of run-time optimisation per core and on massively parallel hardware.…”

Section: Discussionmentioning

confidence: 99%

“…Even in worst-case tests where we assumed full dynamical adaptivity in every fine grid time step, we observe good performance and scalability. The flexibility and minimal invasiveness of the p4est mesh comes with an acceptable overhead when compared to specialised versions such as [58,57].…”

Section: Discussionmentioning

confidence: 99%

Towards Lattice-Boltzmann on Dynamically Adaptive Grids — Minimally-Invasive Grid Exchange in Espresso

Lahnert¹,

Burstedde²,

Holm³

et al. 2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Abstract. We present the minimally-invasive exchange of the regular Cartesian grid in the lattice-Boltzmann solver of ESPResSo by a dynamically-adaptive octree grid. Octree grids are favoured by computer scientists over other grid types as they are very memory-efficient. In addition, they represent a natural generalisation of regular Cartesian grids, such that most discretisation details of a regular grid solver can be maintained. Optimised codes, however, require a special tree-oriented grid traversal, which typically conflicts with existing simulation codes using various iterators, some for only parts of the grid, e.g., boundaries. ESPResSo is a large software package developed for soft-matter simulations involving fluid flow, electrostatic, and electrokinetic effects, and molecular dynamics. The currently used regular Cartesian grid hinders the simulation of realistic domain sizes and significant time periods, a problem that can be solved using grid adaptivity. In a first step, we focus on the lattice-Boltzmann flow solver in ESPResSo.p4est is a grid framework, that already provides dynamically adaptive quadtree and octree grids together with high-level interfaces for flexible grid traversals with direct neighbour access in all grid components. In this paper, we first describe extensions of p4est that were necessary to fulfill certain application requirements. The second part of our work consists of the minimally-invasive changes in ESPResSo preserving the expertise accumulated in the software's implementation over years. Our numerical results demonstrate physical correctness of the implementation, good parallel scalability and low overhead of the dynamical grid adaptivity. These are prerequisites to actually profit from grid adaptivity in terms of being able to simulate larger domains over longer time periods with limited computational resources. Thus, the current status forms a solid basis for further steps such as the development of refinement criteria, the setup of more realistic application scenarios, and a GPU implementation.

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WaLBerla: HPC software design for computational engineering simulations

Cited by 84 publications

References 19 publications

Boundary conditions for free interfaces with the lattice Boltzmann method

Boundary conditions for free interfaces with the lattice Boltzmann method

Multiphysics simulations: challenges and opportunities.

Towards Lattice-Boltzmann on Dynamically Adaptive Grids — Minimally-Invasive Grid Exchange in Espresso

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