All Outputs (73)

Efficient Implementation of ADER Discontinuous Galerkin Schemes for a Scalable Hyperbolic PDE Engine (2018)
Journal Article
Dumbser, M., Fambri, F., Tavelli, M., Bader, M., & Weinzierl, T. (2018). Efficient Implementation of ADER Discontinuous Galerkin Schemes for a Scalable Hyperbolic PDE Engine. Axioms, 7(3), Article 63. https://doi.org/10.3390/axioms7030063

In this paper we discuss a new and very efficient implementation of high order accurate arbitrary high order schemes using derivatives discontinuous Galerkin (ADER-DG) finite element schemes on modern massively parallel supercomputers. The numerical... Read More about Efficient Implementation of ADER Discontinuous Galerkin Schemes for a Scalable Hyperbolic PDE Engine.

Simulation of tsunamis with the exascale hyperbolic PDE engine ExaHyPE (2018)
Conference Proceeding
Rannabauer, L., Haas, S., Charrier, D., Weinzierl, T., & Bader, M. (in press). Simulation of tsunamis with the exascale hyperbolic PDE engine ExaHyPE.

A Multi-Core Ready Discrete Element Method With Triangles Using Dynamically Adaptive Multiscale Grids (2018)
Journal Article
Krestenitis, K., & Weinzierl, T. (2019). A Multi-Core Ready Discrete Element Method With Triangles Using Dynamically Adaptive Multiscale Grids. Concurrency and Computation: Practice and Experience, 31(19), Article e4935. https://doi.org/10.1002/cpe.4935

The simulation of vast numbers of rigid bodies of non‐analytical shapes and of tremendously different sizes that collide with each other is computationally challenging. A bottleneck is the identification of all particle contact points per time step.... Read More about A Multi-Core Ready Discrete Element Method With Triangles Using Dynamically Adaptive Multiscale Grids.

HPC Coding: The Power of L(o)osing Control (2018)
Other
Weinzierl, T. (in press). HPC Coding: The Power of L(o)osing Control

Fast DEM collision checks on multicore nodes (2018)
Conference Proceeding
Krestenitis, K., Weinzierl, T., & Koziara, T. (2018). Fast DEM collision checks on multicore nodes. In R. Wyrzykowski, J. . J. Dongarra, E. Deelman, & K. Karczewski (Eds.), Parallel processing and applied mathematics : 12th International conference, PPAM 2017, Lublin, Poland, September 10-13 ; revised selected papers. Part 1 (123-132). https://doi.org/10.1007/978-3-319-78024-5_12

Many particle simulations today rely on spherical or analytical particle shape descriptions. They find non-spherical, triangulated particle models computationally infeasible due to expensive collision detections. We propose a hybrid collision detecti... Read More about Fast DEM collision checks on multicore nodes.

An experience report on (auto-)tuning of mesh-based PDE solvers on shared memory systems (2018)
Conference Proceeding
Charrier, D. E., & Weinzierl, T. (2018). An experience report on (auto-)tuning of mesh-based PDE solvers on shared memory systems. In R. Wyrzykowski, J. . J. Dongarra, E. Deelman, & K. Karczewski (Eds.), Parallel processing and applied mathematics : 12th International Conference, PPAM 2017, Lublin, Poland, September 10-13, 2017 ; revised selected papers. Part I (3-13). https://doi.org/10.1007/978-3-319-78054-2_1

With the advent of manycore systems, shared memory parallelisation has gained importance in high performance computing. Once a code is decomposed into tasks or parallel regions, it becomes crucial to identify reasonable grain sizes, i.e. minimum prob... Read More about An experience report on (auto-)tuning of mesh-based PDE solvers on shared memory systems.

Quasi-matrix-free hybrid multigrid on dynamically adaptive Cartesian grids (2018)
Journal Article
Weinzierl, M., & Weinzierl, T. (2018). Quasi-matrix-free hybrid multigrid on dynamically adaptive Cartesian grids. ACM Transactions on Mathematical Software, 44(3), Article 32. https://doi.org/10.1145/3165280

We present a family of spacetree-based multigrid realizations using the tree’s multiscale nature to derive coarse grids. They align with matrix-free geometric multigrid solvers as they never assemble the system matrices, which is cumbersome for dynam... Read More about Quasi-matrix-free hybrid multigrid on dynamically adaptive Cartesian grids.

A Case Study for a New Invasive Extension of Intel's Threading Building Blocks (2018)
Conference Proceeding
Schreiber, M., & Weinzierl, T. (2018). A Case Study for a New Invasive Extension of Intel's Threading Building Blocks. In J. Weidendorfer, & C. Trinitis (Eds.), Proceedings of HiPEAC 2018 — 3rd COSH Workshop on Co-Scheduling of HPC Applications (COSH 2018) (21-26). https://doi.org/10.14459/2018md1428538

We study codes deploying multiple MPI ranks to one node where each rank is parallelised with TBB. A static assignment of cores to ranks here is disadvantageous if the load is not perfectly balanced, the runtime is subject to fluctuations or one MPI r... Read More about A Case Study for a New Invasive Extension of Intel's Threading Building Blocks.

Complex additive geometric multilevel solvers for Helmholtz equations on spacetrees (2017)
Journal Article
Reps, B., & Weinzierl, T. (2017). Complex additive geometric multilevel solvers for Helmholtz equations on spacetrees. ACM Transactions on Mathematical Software, 44(1), Article 2. https://doi.org/10.1145/3054946

We introduce a family of implementations of low-order, additive, geometric multilevel solvers for systems of Helmholtz equations arising from Schrödinger equations. Both grid spacing and arithmetics may comprise complex numbers, and we thus can apply... Read More about Complex additive geometric multilevel solvers for Helmholtz equations on spacetrees.

Form Follows Function - Do algorithms and applications challenge or drag behind the hardware evolution? (2016)
Conference Proceeding
Weinzierl, T. (2016). Form Follows Function - Do algorithms and applications challenge or drag behind the hardware evolution?.

Exascale roadmaps are dominated by predictions on hardware trends. At the same time, hardware-software co-design is a frequently cited phrase. It suggests that software development has an impact on the hardware evolution. Is this assumption valid? If... Read More about Form Follows Function - Do algorithms and applications challenge or drag behind the hardware evolution?.

Multiscale Storage, Parallelisation and Programming Paradigms for Spacetrees in Scientific Computing (2016)
Book
Weinzierl, T. (2016). Multiscale Storage, Parallelisation and Programming Paradigms for Spacetrees in Scientific Computing. Technischen Universität München

More than ten years ago, the Gordon Bell Prize was awarded for a seismic calibration code [2]. According to the authors, mesh generation based upon octrees was one key feature to achieve the reported performance. Octrees look back on a long tradition... Read More about Multiscale Storage, Parallelisation and Programming Paradigms for Spacetrees in Scientific Computing.

A Contact Detection Code using Triangles for Non-Spherical Particle Simulations (2016)
Conference Proceeding
Krestenitis, K., Weinzierl, T., & Koziara, T. (2016). A Contact Detection Code using Triangles for Non-Spherical Particle Simulations. In Proceedings of the 24th Conference on Computational Mechanics (ACME-2016): 31 March - 01 April 2016, Cardiff University, Cardiff (227-230)

We present a novel DEM (discrete element method) code with explicit time stepping. DEM codes simulate billions of small particles that interact with each other primarily through collisions. Different to state-of-the-art codes, we rely on triangulated... Read More about A Contact Detection Code using Triangles for Non-Spherical Particle Simulations.

On-the-fly memory compression for multibody algorithms (2016)
Conference Proceeding
Eckhardt, W., Glas, R., Korzh, D., Wallner, S., & Weinzierl, T. (2016). On-the-fly memory compression for multibody algorithms. In G. R. Joubert, H. Leather, M. Parsons, F. Peters, & M. Sawyer (Eds.), Parallel computing : on the road to exascale (421-430). https://doi.org/10.3233/978-1-61499-621-7-421

Memory and bandwidth demands challenge developers of particle-based codes that have to scale on new architectures, as the growth of concurrency outperforms improvements in memory access facilities, as the memory per core tends to stagnate, and as com... Read More about On-the-fly memory compression for multibody algorithms.

Two Particle-in-Grid Realisations on Spacetrees (2016)
Journal Article
Weinzierl, T., Verleye, B., Henri, P., & Roose, D. (2016). Two Particle-in-Grid Realisations on Spacetrees. Parallel Computing: Systems & Applications, 52, 42-64. https://doi.org/10.1016/j.parco.2015.12.007

The present paper studies two particle management strategies for dynamically adaptive Cartesian grids at hands of a particle-in-cell code. One holds the particles within the grid cells, the other within the grid vertices. The fundamental challenge fo... Read More about Two Particle-in-Grid Realisations on Spacetrees.

Integration of FULLSWOF2D and PeanoClaw: Adaptivity and Local Time-stepping for Complex Overland Flows (2015)
Conference Proceeding
Unterweger, K., Wittmann, R., Neumann, P., Weinzierl, T., & Bungartz, H. (2015). Integration of FULLSWOF2D and PeanoClaw: Adaptivity and Local Time-stepping for Complex Overland Flows. In M. Mehl, M. Bischoff, & M. Schäfer (Eds.), Recent trends in computational engineering - CE2014 : optimization, uncertainty, parallel algorithms, coupled and complex problems (181-195). https://doi.org/10.1007/978-3-319-22997-3_11

We propose to couple our adaptive mesh refinement software PeanoClaw with existing solvers for complex overland flows that are tailored to regular Cartesian meshes. This allows us to augment them with spatial adaptivity and local time-stepping withou... Read More about Integration of FULLSWOF2D and PeanoClaw: Adaptivity and Local Time-stepping for Complex Overland Flows.

Cache-Oblivious Spacetree Traversals (2015)
Book Chapter
Bader, M., & Weinzierl, T. (2015). Cache-Oblivious Spacetree Traversals. In M. Kao (Ed.), Encyclopedia of algorithms (1-6). Springer Verlag. https://doi.org/10.1007/978-3-642-27848-8_583-1

In scientific computing and related fields, mathematical functions are often approximated on meshes where each mesh cell contains a local approximation (e.g., using polynomials) of the represented quantity (density functions, physical quantities such... Read More about Cache-Oblivious Spacetree Traversals.

PaTriG – Particle Transport Simulation in Grids (2014)
Book Chapter
Weinzierl, T., Neumann, P., Unterweger, K., Verleye, B., & Wittmann, R. (2014). PaTriG – Particle Transport Simulation in Grids. In S. Wagner, A. Bode, H. Satzger, & M. Brehm (Eds.), High Performance Computing in Science and Engineering 2014 (128-129). Bayerische Akademie der Wissenschaften

Adaptivity - and Regular Cartesian Patches for the Shallow Water Equations and Vectorisation of an Augmented Riemann Solver for the Shallow Water Equations (2014)
Presentation / Conference
Bader, M., & Weinzierl, T. (2014, December). Adaptivity - and Regular Cartesian Patches for the Shallow Water Equations and Vectorisation of an Augmented Riemann Solver for the Shallow Water Equations. Paper presented at SIAM Annual Meeting, Chicago, IL

Block Fusion on Dynamically Adaptive Spacetree Grids for Shallow Water Waves (2014)
Journal Article
Weinzierl, T., Bader, M., Unterweger, K., & Wittmann, R. (2014). Block Fusion on Dynamically Adaptive Spacetree Grids for Shallow Water Waves. Parallel Processing Letters, 24(3), Article 1441006. https://doi.org/10.1142/s0129626414410060

Spacetrees are a popular formalism to describe dynamically adaptive Cartesian grids. Even though they directly yield a mesh, it is often computationally reasonable to embed regular Cartesian blocks into their leaves. This promotes stencils working on... Read More about Block Fusion on Dynamically Adaptive Spacetree Grids for Shallow Water Waves.

Hardware-aware block size tailoring on adaptive spacetree grids for shallow water waves (2014)
Conference Proceeding
Weinzierl, T., Wittmann, R., Unterweger, K., Bader, M., Breuer, A., & Rettenberger, S. (2014). Hardware-aware block size tailoring on adaptive spacetree grids for shallow water waves. In A. Größlinger, & H. Köstler (Eds.), HiStencils 2014 - Proceedings of the 1st international workshop on high-performance stencil computations (57-64)

Spacetrees are a popular formalism to describe dynamically adaptive Cartesian grids. Though they directly yield an adaptive spatial discretisation, i.e. a mesh, it is often more efficient to augment them by regular Cartesian blocks embedded into the... Read More about Hardware-aware block size tailoring on adaptive spacetree grids for shallow water waves.