Massively parallel transport sweeps on meshes with cyclic dependencies

Vermaak, Jan; Ragusa, Jean C.; Adams, Marvin L.; Morel, Jim E.

doi:10.1016/j.jcp.2020.109892

Cited by 24 publications

(5 citation statements)

References 21 publications

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“…However, they are most often optimized for regular geometries that have to be (semi-)structurally meshed to facilitate optimal marching (sweeping sequence) [41], which is also sensitive to boundary conditions, unless, e.g., orthogonality conditions between reflective surfaces hold [42]. These schemes may be extended to unstructured grids [43,44,45,46,47] but with understandably lower parallel efficiencies.…”

Section: Related Workmentioning

confidence: 99%

Deterministic radiative transfer equation solver on unstructured tetrahedral meshes: Efficient assembly and preconditioning

Jolivet

Badri

Favennec

2021

Journal of Computational Physics

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Section: Related Workmentioning

confidence: 99%

Deterministic radiative transfer equation solver on unstructured tetrahedral meshes: Efficient assembly and preconditioning

Jolivet

Badri

Favennec

2021

Journal of Computational Physics

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“…A previous attempt at modeling the core with PARCS is reported in [6], but the neutron flux comparison with the Serpent solution was not successful, especially in the outer fuel lattice region, due to the mismatch between PARCS mesh and the actual CROCUS fuel lattices. Furthermore, in line with the current efforts towards the use of more flexible numerical methodologies to implement deterministic neutron transport solvers capable of operating on unstructured meshes [7,8], the Laboratory for Reactor Physics and System Behaviour (LRS-EPFL) has started to develop new tools for reactor analysis based on the OpenFOAM finite-volume library [9,10], namely: the GeN-Foam multiphysics solver [11] and the OFFBEAT fuel behavior tool [12]. In particular, GeN-Foam is a multiphysics solver for the analysis of nuclear reactors that takes advantage of general finite-volume methodologies on unstructured meshes to provide enough flexibility for the study of non-conventional reactor designs, such as CROCUS.…”

Section: Introductionmentioning

confidence: 85%

Investigation and Validation of Unstructured Mesh Methodologies for Modeling Experimental Reactors

et al. 2022

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This paper summarizes a methodology developed at École Polytechnique Fédérale de Lausanne for the neutronic modeling of the CROCUS experimental reactor and proposes solutions to the challenges one may face while modeling a research reactor with a complex geometry. Indeed, the double-lattice configuration of CROCUS makes it difficult to use codes for neutron diffusion and transport relying on a structured mesh description. For this reason, and based on the available in-house competences, we decided to make use of the neutronic capabilities of the GeN-Foam multiphysics solver, which takes advantage of general finite volume methodologies on unstructured meshes to provide sufficient flexibility for the study of unconventional reactor designs. In this work, GeN-Foam is used to build a first SP3 model of CROCUS based on an unstructured mesh to have an explicit modeling of the double lattice and the water gap between the two lattices. Form functions are then used to reconstruct the intra-pin fission rates for validation against measured distributions. We also discuss the limitations of the SP3 approximation of neutron transport in regions with steep neutron flux gradients and the planned future developments.

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“…Note that a similar problem appears despite the parallel execution of different directions. It is called pipe fill or pipe drain (Vermaak et al 2021), and appears when the number of domains becomes large enough that there are inner regions which cannot start sweeping until outer regions are resolved. For an illustration of this effect, see Fig.…”

Section: The Sweep Algorithmmentioning

confidence: 99%

The Sweep Method for radiative Transfer in Arepo

Peter¹,

Klessen²,

Kanschat³

et al. 2022

Preprint

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We introduce the radiative transfer code Sweep for the cosmological simulation suite Arepo. Sweep is a discrete ordinates method in which radiation transport is carried out by a transport sweep across the entire computational grid. Since Arepo is based on an adaptive, unstructured grid, the dependency graph induced by the sweep dependencies of the grid cells is non-trivial. In order to solve the topological sorting problem in a distributed manner, we employ a task-based-parallelism approach. The main advantage of the sweep method is that the computational cost scales only with the size of the grid, and is independent of the number of sources or the distribution of sources in the computational domain, which is an advantage for radiative transfer in cosmological simulations, where there are large numbers of sparsely distributed sources. We successfully apply the code to a number of physical tests such as the expansion of HII regions, the formation of shadows behind dense objects, the scattering of light, as well as its behavior in the presence of periodic boundary conditions. In addition, we measure its computational performance with a focus on highly parallel, large-scale simulations.

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Massively parallel transport sweeps on meshes with cyclic dependencies

Cited by 24 publications

References 21 publications

Deterministic radiative transfer equation solver on unstructured tetrahedral meshes: Efficient assembly and preconditioning

Deterministic radiative transfer equation solver on unstructured tetrahedral meshes: Efficient assembly and preconditioning

Investigation and Validation of Unstructured Mesh Methodologies for Modeling Experimental Reactors

The Sweep Method for radiative Transfer in Arepo

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