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Interaction of large- and small-scale dynamos in isotropic turbulent flows from GPU-accelerated simulations

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Väisälä, Miikka
dc.contributor.author Pekkilä, Johannes
dc.contributor.author Käpylä, Maarit
dc.contributor.author Rheinhardt, Matthias
dc.contributor.author Shang, Hsien
dc.contributor.author Krasnopolsky, Ruben
dc.date.accessioned 2021-03-22T07:12:20Z
dc.date.available 2021-03-22T07:12:20Z
dc.date.issued 2021-02
dc.identifier.citation Väisälä , M , Pekkilä , J , Käpylä , M , Rheinhardt , M , Shang , H & Krasnopolsky , R 2021 , ' Interaction of large- and small-scale dynamos in isotropic turbulent flows from GPU-accelerated simulations ' , The Astrophysical Journal , vol. 907 , no. 2 , 83 . https://doi.org/10.3847/1538-4357/abceca en
dc.identifier.issn 0004-637X
dc.identifier.other PURE UUID: cecff1e8-7971-49af-b1dd-3ac18c863e67
dc.identifier.other PURE ITEMURL: https://research.aalto.fi/en/publications/cecff1e8-7971-49af-b1dd-3ac18c863e67
dc.identifier.other PURE LINK: http://www.scopus.com/inward/record.url?scp=85101613843&partnerID=8YFLogxK
dc.identifier.other PURE FILEURL: https://research.aalto.fi/files/54087723/arxiv_draft.pdf
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/103291
dc.description | openaire: EC/H2020/818665/EU//UniSDyn
dc.description.abstract Magnetohydrodynamical (MHD) dynamos emerge in many different astrophysical situations where turbulence is present, but the interaction between large-scale dynamos (LSDs) and small-scale dynamos (SSDs) is not fully understood. We performed a systematic study of turbulent dynamos driven by isotropic forcing in isothermal MHD with magnetic Prandtl number of unity, focusing on the exponential growth stage. Both helical and nonhelical forcing was employed to separate the effects of LSD and SSD in a periodic domain. Reynolds numbers (ReM) up to ≈250 were examined and multiple resolutions used for convergence checks. We ran our simulations with the Astaroth code, designed to accelerate 3D stencil computations on graphics processing units (GPUs) and to employ multiple GPUs with peer-to-peer communication. We observed a speedup of ≈35 in single-node performance compared to the widely used multi-CPU MHD solver Pencil Code. We estimated the growth rates from both the averaged magnetic fields and their power spectra. At low ReM LSD growth dominates, but at high ReM SSD appears to dominate in both helically and nonhelically forced cases. Pure SSD growth rates follow a logarithmic scaling as a function of ReM. Probability density functions of the magnetic field from the growth stage exhibit SSD behavior in helically forced cases even at intermediate ReM. We estimated mean field turbulence transport coefficients using closures like the second-order correlation approximation (SOCA). They yield growth rates similar to the directly measured ones and provide evidence of α quenching. Our results are consistent with the SSD inhibiting the growth of the LSD at moderate ReM, while the dynamo growth is enhanced at higher ReM. en
dc.format.extent 18
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher IOP Publishing Ltd.
dc.relation info:eu-repo/grantAgreement/EC/H2020/818665/EU//UniSDyn
dc.relation.ispartofseries Astrophysical Journal en
dc.relation.ispartofseries Volume 907, issue 2 en
dc.rights openAccess en
dc.title Interaction of large- and small-scale dynamos in isotropic turbulent flows from GPU-accelerated simulations en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department Academia Sinica
dc.contributor.department Professorship Korpi-Lagg Maarit
dc.contributor.department Department of Computer Science en
dc.identifier.urn URN:NBN:fi:aalto-202103222569
dc.identifier.doi 10.3847/1538-4357/abceca
dc.type.version acceptedVersion

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