PROPERTIES OF MAGNETIC HELICITY FLUX IN TURBULENT DYNAMOS
We study the flux of small-scale magnetic helicity in simulations of driven statistically homogeneous magneto-hydrodynamic turbulence in a periodic box with an imposed large-scale shear. The simulations show that in the regime of strong dynamo action the eddy-scale magnetic helicity flux has only tw...
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| Veröffentlicht in: | The Astrophysical journal 2014-01, Vol.780 (2), p.1-10 |
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| creator | Vishniac, Ethan T Shapovalov, Dmitry |
| description | We study the flux of small-scale magnetic helicity in simulations of driven statistically homogeneous magneto-hydrodynamic turbulence in a periodic box with an imposed large-scale shear. The simulations show that in the regime of strong dynamo action the eddy-scale magnetic helicity flux has only two significant terms: advective motion driven by the large-scale velocity field and the Vishniac-Cho (VC) flux which moves helicity across the magnetic field lines. The contribution of all the other terms is negligible. The VC flux is highly correlated with the large-scale electromotive force and is responsible for large-scale dynamo action, while the advective term is not. The VC flux is driven by the anisotropy of the turbulence. We derive analytical expressions for it in terms of the small-scale velocity or magnetic field. These expressions are used to predict the existence and strength of dynamo action for different turbulent anisotropies and tested against the results of the simulations. |
| doi_str_mv | 10.1088/0004-637X/780/2/144 |
| format | Article |
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The simulations show that in the regime of strong dynamo action the eddy-scale magnetic helicity flux has only two significant terms: advective motion driven by the large-scale velocity field and the Vishniac-Cho (VC) flux which moves helicity across the magnetic field lines. The contribution of all the other terms is negligible. The VC flux is highly correlated with the large-scale electromotive force and is responsible for large-scale dynamo action, while the advective term is not. The VC flux is driven by the anisotropy of the turbulence. We derive analytical expressions for it in terms of the small-scale velocity or magnetic field. These expressions are used to predict the existence and strength of dynamo action for different turbulent anisotropies and tested against the results of the simulations.</description><identifier>ISSN: 0004-637X</identifier><identifier>EISSN: 1538-4357</identifier><identifier>DOI: 10.1088/0004-637X/780/2/144</identifier><language>eng</language><publisher>United States</publisher><subject>ANISOTROPY ; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ; ELECTROMOTIVE FORCE ; Fluid dynamics ; Flux ; HELICITY ; MAGNETIC FIELDS ; MAGNETOHYDRODYNAMICS ; PERIODICITY ; Rotating generators ; SIMULATION ; TURBULENCE ; Turbulent flow</subject><ispartof>The Astrophysical journal, 2014-01, Vol.780 (2), p.1-10</ispartof><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c388t-2d5e1b3f19bb1753b53ceef145a18f0bc0ec4a1d9e1558d19152e1e7fb50ae83</citedby><cites>FETCH-LOGICAL-c388t-2d5e1b3f19bb1753b53ceef145a18f0bc0ec4a1d9e1558d19152e1e7fb50ae83</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>230,314,776,780,881,27903,27904</link.rule.ids><backlink>$$Uhttps://www.osti.gov/biblio/22348241$$D View this record in Osti.gov$$Hfree_for_read</backlink></links><search><creatorcontrib>Vishniac, Ethan T</creatorcontrib><creatorcontrib>Shapovalov, Dmitry</creatorcontrib><title>PROPERTIES OF MAGNETIC HELICITY FLUX IN TURBULENT DYNAMOS</title><title>The Astrophysical journal</title><description>We study the flux of small-scale magnetic helicity in simulations of driven statistically homogeneous magneto-hydrodynamic turbulence in a periodic box with an imposed large-scale shear. The simulations show that in the regime of strong dynamo action the eddy-scale magnetic helicity flux has only two significant terms: advective motion driven by the large-scale velocity field and the Vishniac-Cho (VC) flux which moves helicity across the magnetic field lines. The contribution of all the other terms is negligible. The VC flux is highly correlated with the large-scale electromotive force and is responsible for large-scale dynamo action, while the advective term is not. The VC flux is driven by the anisotropy of the turbulence. We derive analytical expressions for it in terms of the small-scale velocity or magnetic field. These expressions are used to predict the existence and strength of dynamo action for different turbulent anisotropies and tested against the results of the simulations.</description><subject>ANISOTROPY</subject><subject>ASTROPHYSICS, COSMOLOGY AND ASTRONOMY</subject><subject>ELECTROMOTIVE FORCE</subject><subject>Fluid dynamics</subject><subject>Flux</subject><subject>HELICITY</subject><subject>MAGNETIC FIELDS</subject><subject>MAGNETOHYDRODYNAMICS</subject><subject>PERIODICITY</subject><subject>Rotating generators</subject><subject>SIMULATION</subject><subject>TURBULENCE</subject><subject>Turbulent flow</subject><issn>0004-637X</issn><issn>1538-4357</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2014</creationdate><recordtype>article</recordtype><recordid>eNqFkM1Og0AYRSdGE2v1CdyQuHGDzDc_MLOsSFsSCk1Lk3Y1gekQMW1Rhi58eyE1br2bm5uc3MVB6BHwC2AhPIwxc30abL1AYI94wNgVGgGnwmWUB9do9EfcojtrP4ZJpBwhuVxly2iVx9HayabOYjJLozwOnXmUxGGc75xpstk6cerkm9XrJonS3HnbpZNFtr5HN1VxsObht8con0Z5OHeTbBaHk8TVVIjOJXtuoKQVyLKEgNOSU21MBYwXICpcamw0K2AvDXAu9iCBEwMmqEqOCyPoGD1dbhvb1crqujP6XTenk9GdIoQyQRj01POF-mybr7OxnTrWVpvDoTiZ5mwVBCCkD7TP_yjm2Od-MLzSC6rbxtrWVOqzrY9F-60Aq0G8GjyqQavqxSuievH0B-x7b1Q</recordid><startdate>20140110</startdate><enddate>20140110</enddate><creator>Vishniac, Ethan T</creator><creator>Shapovalov, Dmitry</creator><scope>AAYXX</scope><scope>CITATION</scope><scope>7TG</scope><scope>KL.</scope><scope>8FD</scope><scope>H8D</scope><scope>L7M</scope><scope>OTOTI</scope></search><sort><creationdate>20140110</creationdate><title>PROPERTIES OF MAGNETIC HELICITY FLUX IN TURBULENT DYNAMOS</title><author>Vishniac, Ethan T ; Shapovalov, Dmitry</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c388t-2d5e1b3f19bb1753b53ceef145a18f0bc0ec4a1d9e1558d19152e1e7fb50ae83</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2014</creationdate><topic>ANISOTROPY</topic><topic>ASTROPHYSICS, COSMOLOGY AND ASTRONOMY</topic><topic>ELECTROMOTIVE FORCE</topic><topic>Fluid dynamics</topic><topic>Flux</topic><topic>HELICITY</topic><topic>MAGNETIC FIELDS</topic><topic>MAGNETOHYDRODYNAMICS</topic><topic>PERIODICITY</topic><topic>Rotating generators</topic><topic>SIMULATION</topic><topic>TURBULENCE</topic><topic>Turbulent flow</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Vishniac, Ethan T</creatorcontrib><creatorcontrib>Shapovalov, Dmitry</creatorcontrib><collection>CrossRef</collection><collection>Meteorological & Geoastrophysical Abstracts</collection><collection>Meteorological & Geoastrophysical Abstracts - Academic</collection><collection>Technology Research Database</collection><collection>Aerospace Database</collection><collection>Advanced Technologies Database with Aerospace</collection><collection>OSTI.GOV</collection><jtitle>The Astrophysical journal</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Vishniac, Ethan T</au><au>Shapovalov, Dmitry</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>PROPERTIES OF MAGNETIC HELICITY FLUX IN TURBULENT DYNAMOS</atitle><jtitle>The Astrophysical journal</jtitle><date>2014-01-10</date><risdate>2014</risdate><volume>780</volume><issue>2</issue><spage>1</spage><epage>10</epage><pages>1-10</pages><issn>0004-637X</issn><eissn>1538-4357</eissn><abstract>We study the flux of small-scale magnetic helicity in simulations of driven statistically homogeneous magneto-hydrodynamic turbulence in a periodic box with an imposed large-scale shear. The simulations show that in the regime of strong dynamo action the eddy-scale magnetic helicity flux has only two significant terms: advective motion driven by the large-scale velocity field and the Vishniac-Cho (VC) flux which moves helicity across the magnetic field lines. The contribution of all the other terms is negligible. The VC flux is highly correlated with the large-scale electromotive force and is responsible for large-scale dynamo action, while the advective term is not. The VC flux is driven by the anisotropy of the turbulence. We derive analytical expressions for it in terms of the small-scale velocity or magnetic field. These expressions are used to predict the existence and strength of dynamo action for different turbulent anisotropies and tested against the results of the simulations.</abstract><cop>United States</cop><doi>10.1088/0004-637X/780/2/144</doi><tpages>10</tpages><oa>free_for_read</oa></addata></record> |
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| subjects | ANISOTROPY ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ELECTROMOTIVE FORCE Fluid dynamics Flux HELICITY MAGNETIC FIELDS MAGNETOHYDRODYNAMICS PERIODICITY Rotating generators SIMULATION TURBULENCE Turbulent flow |
| title | PROPERTIES OF MAGNETIC HELICITY FLUX IN TURBULENT DYNAMOS |
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