Parallel<i>S<sub>n</sub></i>Sweeps on Unstructured Grids: Algorithms for Prioritization, Grid Partitioning, and Cycle Detection

Plimpton, Steven J.; Hendrickson, Bruce; Burns, Shawn P.; McLendon, William Clarence; Rauchwerger, Lawrence

doi:10.13182/nse150-267

Cited by 36 publications

(7 citation statements)

References 13 publications

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“…In 3D, this is no longer the case. Graph algorithms allow to recover such an ordering at the expense of lagging some intensities at the previous iteration in the source iteration method [61].…”

Section: Short Description Of the Discontinuous Finite Element (Dfe) Methodsmentioning

confidence: 99%

An asymptotic preserving method for the linear transport equation on general meshes

Anguill

Cargo

Enaux

et al. 2022

Journal of Computational Physics

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Section: Short Description Of the Discontinuous Finite Element (Dfe) Methodsmentioning

confidence: 99%

An asymptotic preserving method for the linear transport equation on general meshes

Anguill

Cargo

Enaux

et al. 2022

Journal of Computational Physics

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“…The first work published that sought to sweep a generally unstructured mesh with unstructured partitioning [39] described an algorithm that was potentially massively parallel, but scaling results were only investigated in the work to 256 processors. A follow-up work expanded on the algorithm and included scaling results to several thousand processors [40]. The mesh investigated in this work had some uniform structures, but an unstructured partitioning of the mesh was investigated.…”

Section: The Parallel Sweepermentioning

confidence: 99%

Performance Improvements for the Griffin Transport Solvers

Wang

Prince

Hanophy

et al. 2021

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Griffin is a Multiphysics Object-Oriented Simulation Environment (MOOSE) based reactor multiphysics analysis application jointly developed by Idaho National Laboratory and Argonne National Laboratory. Griffin includes a variety of deterministic radiation transport solvers for fixed source, k-eigenvalue, adjoint, and subcritical multiplication, as well as transient solvers for point-kinetics, improved quasi-static, and spatial dynamics. A code assessment performed in FY-20 identified two significant issues with the transport solvers in Griffin: first, the primary heterogeneous SN (discrete ordinates) transport solver based on continuous finite element methods required significant mesh refinement and higher memory usage compared to solvers based on the method of characteristic for equivalent accuracy. Second, the homogeneous PN (spherical harmonics expansion) transport solver did not adequately support spatial polynomial refinement, which is a feature usually required for problems with spatial homogenization and pronounced streaming, typical in fast or gas-cooled reactor systems. To address the first issue, the development effort focused on the more promising discontinuous finite element method (DFEM)-based SN transport solver in Griffin. The addition of an asynchronous parallel transport sweeper and coarse mesh finite difference (CMFD) acceleration have rendered a superior heterogeneous SN transport capability for multiphysics problems that requires far less computing resources in terms of both CPU time and memory usage. This is demonstrated with typical thermal-and fast-spectrum reactor benchmark problems, including 2D Transient Reactor Test (TREAT), 3D Advanced Burner Test Reactor (ABTR), and 2D and 3D Empire microreactor. Last year, it was challenging to run the 3-D Empire eigenvalue problem with Griffin. Currently, Griffin can execute the problem in 20 minutes on 1,536 CPUs with roughly 80% parallel efficiency on the INL Sawtooth machine. For the second issue, the development effort focused on a new transport solver based on the hybrid finite element PN method (HFEM-PN), equivalent to the variational nodal method, as well as a new diffusion solver based on HFEM-Diffusion. This solver is intended for homogenized domains with multiphysics coupling (i.e., supports mesh displacement, seamless temperature feedback, etc.). Initial calculations with the HFEM-Diffusion implementation show very good parallel efficiency for the residual evaluations with the 2D ABTR benchmark. A future development effort will be centered on further improvements to the CMFD, HFEM-PN, and DFEM diffusion solvers to ensure Griffin meets performance and software quality assurance requirements for advanced reactor design and analysis.iii

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“…Kerbyson et al in the paper [8] presented the first performance model for transport sweeps on unstructured meshes. A similar work has been carried out by Plimpton et al as described in the paper [9]. In the paper [10], Kumar et al explore scheduling strategies for a generalized sweep algorithm.…”

Section: Related Workmentioning

confidence: 99%

3D Cartesian Transport Sweep for Massively Parallel Architectures with PaRSEC

Moustafa

Faverge

Plagne

et al. 2015

2015 IEEE International Parallel and Distributed Processing Symposium

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High-fidelity nuclear power plant core simulations require solving the Boltzmann transport equation. In discrete ordinates methods, the most computationally demanding operation of this equation is the sweep operation. Considering the evolution of computer architectures, we propose in this paper, as a first step toward heterogeneous distributed architectures, a hybrid parallel implementation of the sweep operation on top of the generic task-based runtime system: PARSEC. Such an implementation targets three nested levels of parallelism: message passing, multi-threading, and vectorization. A theoretical performance model was designed to validate the approach and help the tuning of the multiple parameters involved in such an approach. The proposed parallel implementation of the Sweep achieves a sustained performance of 6.1 Tflop/s, corresponding to 33.9% of the peak performance of the targeted supercomputer. This implementation compares favorably with state-ofart solvers such as PARTISN; and it can therefore serve as a building block for a massively parallel version of the neutron transport solver DOMINO developed at EDF.

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ParallelS_nSweeps on Unstructured Grids: Algorithms for Prioritization, Grid Partitioning, and Cycle Detection

Cited by 36 publications

References 13 publications

An asymptotic preserving method for the linear transport equation on general meshes

An asymptotic preserving method for the linear transport equation on general meshes

Performance Improvements for the Griffin Transport Solvers

3D Cartesian Transport Sweep for Massively Parallel Architectures with PaRSEC

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ParallelSnSweeps on Unstructured Grids: Algorithms for Prioritization, Grid Partitioning, and Cycle Detection

Cited by 36 publications

References 13 publications

An asymptotic preserving method for the linear transport equation on general meshes

An asymptotic preserving method for the linear transport equation on general meshes

Performance Improvements for the Griffin Transport Solvers

3D Cartesian Transport Sweep for Massively Parallel Architectures with PaRSEC

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Product

Resources

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ParallelS_nSweeps on Unstructured Grids: Algorithms for Prioritization, Grid Partitioning, and Cycle Detection