Extended Subadiabatic Layer in Simulations of Overshooting Convection

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dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.authorKäpylä, Petri J.en_US
dc.contributor.authorRheinhardt, Matthiasen_US
dc.contributor.authorBrandenburg, Axelen_US
dc.contributor.authorArlt, Raineren_US
dc.contributor.authorKäpylä, Maarit J.en_US
dc.contributor.authorLagg, Andreasen_US
dc.contributor.authorOlspert, Nigulen_US
dc.contributor.authorWarnecke, Jörnen_US
dc.contributor.departmentDepartment of Computer Scienceen
dc.contributor.groupauthorCentre of Excellence Research on Solar Long-Term Variability and Effects, ReSoLVEen
dc.contributor.groupauthorProfessorship Vehtari Akien
dc.contributor.organizationStockholm Universityen_US
dc.contributor.organizationUniversity of Potsdamen_US
dc.contributor.organizationMax Planck Institute for Solar System Researchen_US
dc.date.accessioned2018-08-01T13:29:46Z
dc.date.available2018-08-01T13:29:46Z
dc.date.issued2017-08-20en_US
dc.description.abstractWe present numerical simulations of hydrodynamic overshooting convection in local Cartesian domains. We find that a substantial fraction of the lower part of the convection zone (CZ) is stably stratified according to the Schwarzschild criterion while the enthalpy flux is outward directed. This occurs when the heat conduction profile at the bottom of the CZ is smoothly varying, based either on a Kramers-like opacity prescription as a function of temperature and density or a static profile of a similar shape. We show that the subadiabatic layer arises due to nonlocal energy transport by buoyantly driven downflows in the upper parts of the CZ. Analysis of the force balance of the upflows and downflows confirms that convection is driven by cooling at the surface. We find that the commonly used prescription for the convective enthalpy flux being proportional to the negative entropy gradient does not hold in the stably stratified layers where the flux is positive. We demonstrate the existence of a non-gradient contribution to the enthalpy flux, which is estimated to be important throughout the convective layer. A quantitative analysis of downflows indicates a transition from a tree-like structure where smaller downdrafts merge into larger ones in the upper parts to a structure in the deeper parts where a height-independent number of strong downdrafts persist. This change of flow topology occurs when a substantial subadiabatic layer is present in the lower part of the CZ.en
dc.description.versionPeer revieweden
dc.format.extent1-6
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationKäpylä, P J, Rheinhardt, M, Brandenburg, A, Arlt, R, Käpylä, M J, Lagg, A, Olspert, N & Warnecke, J 2017, ' Extended Subadiabatic Layer in Simulations of Overshooting Convection ', Astrophysical Journal Letters, vol. 845, no. 2, L23, pp. 1-6 . https://doi.org/10.3847/2041-8213/aa83aben
dc.identifier.doi10.3847/2041-8213/aa83aben_US
dc.identifier.issn2041-8205
dc.identifier.issn2041-8213
dc.identifier.otherPURE UUID: 7b80237b-66d3-418b-be13-a9e06b93a729en_US
dc.identifier.otherPURE ITEMURL: https://research.aalto.fi/en/publications/7b80237b-66d3-418b-be13-a9e06b93a729en_US
dc.identifier.otherPURE LINK: http://www.scopus.com/inward/record.url?scp=85028452048&partnerID=8YFLogxKen_US
dc.identifier.otherPURE FILEURL: https://research.aalto.fi/files/26502919/K_pyl_2017_ApJL_845_L23.pdfen_US
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/32821
dc.identifier.urnURN:NBN:fi:aalto-201808014222
dc.language.isoenen
dc.relation.ispartofseriesAstrophysical Journal Lettersen
dc.relation.ispartofseriesVolume 845, issue 2en
dc.rightsopenAccessen
dc.subject.keywordconvectionen_US
dc.subject.keywordhydrodynamicsen_US
dc.subject.keywordturbulenceen_US
dc.titleExtended Subadiabatic Layer in Simulations of Overshooting Convectionen
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi
dc.type.versionpublishedVersion
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