Direct numerical simulation of molten pool convection in a 3D semicircular slice at different Prandtl numbers

Bian, Boshen; Villanueva, Walter; Dovizio, D.

doi:10.1016/j.nucengdes.2022.111772

Cited by 5 publications

(5 citation statements)

References 17 publications

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“…The Prandtl number is a material dependent parameter, representing the ratio of the momentum diffusion to heat diffusion. The computational model used in this work has been verified using a calculation performed by Goluskin and van der Poel [4] on a simplified internally heated 3D box with excellent agreement (see [3] for details).…”

Section: Governing Equations and Computational Domainmentioning

confidence: 87%

“…The thermo-fluid behaviour of the corium is characterized as an internally heated (IH) natural convection phenomenon, because of the absence of an external force and the presence of a decay heat source [3]. Different from forced convection flow, natural convection flow is mainly driven by the buoyancy force caused by the temperature difference, and controlled by the Rayleigh number, Ra, and the Prandtl number, Pr.…”

Section: Introductionmentioning

confidence: 99%

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Direct Numerical Simulation of an Internally Heated Natural Convection in a Hemispherical Geometry

Bian

Dovizio²,

Villanueva

2023

Preprint

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Section: Governing Equations and Computational Domainmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Direct Numerical Simulation of an Internally Heated Natural Convection in a Hemispherical Geometry

Bian

Dovizio²,

Villanueva

2023

Preprint

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“…But, it requires much more computational results than those of the RANS and LES models. Recently Bian et al (2022a), Bian et al (2022b) conducted a DNS of molten pool convection with Rayleigh number Ra = 10 11 in a hemispherical configuration using an open-source code Nek5000 (Fischer et al, 2016). The results of the thermo-fluid behavior, shown in Figures 2 and 3, are consistent with the observations in the BALI experiment, which are the RBC flow in the upper region, the damped flow in the lower region that facilitates thermal stratification, and the descending flow on the curved region that effectively transfer heat to the bottom.…”

Section: Introductionmentioning

confidence: 99%

“…Goluskin et al (2016) conducted a series of DNS simulations of internally heated natural convection with different Rayleigh numbers in a box geometry using Nek5000. We also used Nek5000 to analyze molten pool convection in different geometries (Bian et al, 2022). Since the DNS works usually demand large computational resources, it is necessary to compute the budget based on the scalability performance of the code.…”

Section: Introductionmentioning

confidence: 99%

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Scalability of Nek5000 on High-Performance Computing Clusters Toward Direct Numerical Simulation of Molten Pool Convection

2022

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In a postulated severe accident, a molten pool with decay heat can form in the lower head of a reactor pressure vessel, threatening the vessel’s structural integrity. Natural convection in molten pools with extremely high Rayleigh (Ra) number is not yet fully understood as accurate simulation of the intense turbulence remains an outstanding challenge. Various models have been implemented in many studies, such as RANS (Reynolds-averaged Navier–Stokes), LES (large-eddy simulation), and DNS (direct numerical simulation). DNS can provide the most accurate results but at the expense of large computational resources. As the significant development of the HPC (high-performance computing) technology emerges, DNS becomes a more feasible method in molten pool simulations. Nek5000 is an open-source code for the simulation of incompressible flows, which is based on a high-order SEM (spectral element method) discretization strategy. Nek5000 has been performed on many supercomputing clusters, and the parallel performance of benchmarks can be useful for the estimation of computation budgets. In this work, we conducted scalability tests of Nek5000 on four different HPC clusters, namely, JUWELS (Atos Bullsquana X1000), Hawk (HPE Apollo 9000), ARCHER2 (HPE Cray EX), and Beskow (Cray XC40). The reference case is a DNS of molten pool convection in a hemispherical configuration with Ra = 1011, where the computational domain consisted of 391 million grid points. The objectives are (i) to determine if there is strong scalability of Nek5000 for the specific problem on the currently available systems and (ii) to explore the feasibility of obtaining DNS data for much higher Ra. We found super-linear speed-up up to 65536 MPI-rank on Hawk and ARCHER2 systems and around 8000 MPI-rank on JUWELS and Beskow systems. We achieved the best performance with the Hawk system with reasonably good results up to 131072 MPI-rank, which is attributed to the hypercube technique on its interconnection. Given the current HPC technology, it is feasible to obtain DNS data for Ra = 1012, but for cases higher than this, significant improvement in hardware and software HPC technology is necessary.

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Sweden

Pázsit

2024

Global Progress on Molten Salt Reactors

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Direct numerical simulation of molten pool convection in a 3D semicircular slice at different Prandtl numbers

Cited by 5 publications

References 17 publications

Direct Numerical Simulation of an Internally Heated Natural Convection in a Hemispherical Geometry

Direct Numerical Simulation of an Internally Heated Natural Convection in a Hemispherical Geometry

Scalability of Nek5000 on High-Performance Computing Clusters Toward Direct Numerical Simulation of Molten Pool Convection

Sweden

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