NekRS, a GPU-accelerated spectral element Navier–Stokes solver

Fischer, Paul; Kerkemeier, Stefan; Min, Misun; Lan, Yu-Hsiang; Phillips, Malachi; Rathnayake, Thilina; Merzari, Elia; Tomboulides, Ananias; Karakus, Ali; Chalmers, Noel; Warburton, Tim

doi:10.1016/j.parco.2022.102982

Cited by 78 publications

(36 citation statements)

References 38 publications

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“…DNS of the three-dimensional incompressible Navier–Stokes equations were carried out using the CPU-based spectral element solver (Fischer, Lottes & Kerkemeier 2008) and its GPU equivalent (Fischer et al. 2022). The method involves the discretisation of the domain into hexahedral macro-elements, where the solution is expanded using a tensor product of th-order polynomials defined by the values at the Gauss–Lobatto–Legendre (GLL) nodes of the same order.…”

Section: Methodsmentioning

confidence: 99%

Asymmetric wakes in flows past circular cylinders confined in channels

Aljubaili

Zahtila

et al. 2023

J. Fluid Mech.

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In this paper, we investigate the flow past a circular cylinder confined in a channel at a blockage ratio of $\beta =0.7$ (the ratio of the cylinder diameter and the channel height) for Reynolds numbers between ${\textit {Re}}=300$ and $3900$ using direct numerical simulation (DNS). We show for varying Reynolds numbers a wide range of wake dynamics occur as the spanwise domain length is changed. At a lower Reynolds number of ${\textit {Re}}=300$ , a reverse von Kármán wake alongside either a top- or bottom-biased asymmetry was observed at different spanwise locations. The asymmetry was structurally similar the two-dimensional asymmetry studied by prior investigators, and was found to be a result of the confinement effect. Further, wake-jumping between the two intermittent states was present. For larger Reynolds numbers, ${\textit {Re}}=1000$ and $3900$ , these asymmetric structures were found to become dominant. We also examine the dependence of the asymmetries on the spanwise domain. For small spanwise domains the asymmetries were uniformly orientated across the span. In contrast, for sufficiently large spanwise domains, the asymmetry flips its orientation at different spanwise locations. Comparisons of flow statistics demonstrate good agreement between the different spanwise domains, which suggests the same mechanism maintains the asymmetry in both cases. Further analysis at ${\textit {Re}}=1000$ found the number of times the wake flips is dependent on the initial conditions, with a wake that flips zero (purely asymmetric), two and four times being observed. These structures were also determined to remain stable over time scales of $1000D/U$ .

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Section: Methodsmentioning

confidence: 99%

Asymmetric wakes in flows past circular cylinders confined in channels

Aljubaili

Zahtila

et al. 2023

J. Fluid Mech.

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“…We present a few plots that reflect work in salient kernels, such as the advection operator, which is largely communication-free, and the pressure-Poisson coarse-grid solve, which is highly communication-intensive. Detailed, kernel-by-kernel, break downs are presented in [9,10] and are available in every logfile generated by NekRS. Further, it is important to note that NekRS supports multiple versions of all of its high-intensity kernels and communication utilities.…”

Section: Test Casesmentioning

confidence: 99%

“…Timestepping is based Nek5000's second-order characteristics method with one substep [11,12] and the timestep size is ∆t = 1.2e-3 (CFL=1.82). Pressure preconditioning is based on p-multigrid with CHEBYSHEV+ASM smoothing and hypre AMG for coarse grid solve [9]. Tolerances for pressure and velocity are 1e-4 and 1e-6, respectively.…”

Section: Test Casesmentioning

confidence: 99%

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Nek5000/RS Performance on Advanced GPU Architectures

Min¹,

Lan²,

Fischer³

et al. 2022

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“…As evident in the chart, the new examples demonstrate a variety of NEAMS applications and physics phenomena: MOOSE (open source physics modules and framework), Griffin [4] (reactor physics), Pronghorn [5] (engineering scale fluids), SAM [6] (systems scale fluids), Nek5000 [7] (computational fluid dynamics), Sockeye [8] (heat pipe analysis), Bison [9] (fuel performance and heat conduction), and Cardinal [10] (multiphysics application coupling the NekRS CFD solver [11] to MOOSE).…”

Section: Neams Models Recently Added To the Virtual Test Bedmentioning

confidence: 99%

NEAMS Advanced Reactor Model Contributions to the NRIC Virtual Test Bed

Shemon

Giudicelli

Abou-Jaoude

2022

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The U.S. Department of Energy (DOE) Office of Nuclear Energy's Advanced Modeling and Simulation (NEAMS) Program develops models of advanced reactor phenomena to demonstrate code applicability to challenging physics problems, drive code development through user assessment, and perform code verification and validation. Meanwhile, the U.S. DOE's National Reactor Innovation Center (NRIC) hosts an open-source website and associated GitHub repository called the Virtual Test Bed (VTB) on which computational models for advanced reactors are documented and shared with the reactor community.Several NEAMS advanced reactor models (including input files, documentation, and discussion of results) have recently been contributed to the NRIC VTB. The open sharing of these models benefits the reactor community by providing "best practice" examples using NEAMS tools for advanced reactor physics problems. This report summarizes and provides links to these new models, which include modeling phenomena important to liquid metal cooled fast reactors, molten salt reactors, high temperature gas-cooled reactors, and microreactors. This document is an overview report of NEAMS activities that have recently contributed to the VTB. Details of individual work done by the modeling teams have been or will be published in separate reports.

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NekRS, a GPU-accelerated spectral element Navier–Stokes solver

Cited by 78 publications

References 38 publications

Asymmetric wakes in flows past circular cylinders confined in channels

Asymmetric wakes in flows past circular cylinders confined in channels

Nek5000/RS Performance on Advanced GPU Architectures

NEAMS Advanced Reactor Model Contributions to the NRIC Virtual Test Bed

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