CONSISTENT SCALING LAWS IN ANELASTIC SPHERICAL SHELL DYNAMOS

Yadav, Rakesh K.; Gastine, Thomas; Christensen, Ulrich R.; Duarte, Lucia D. V.,

doi:10.1088/0004-637X/774/1/6

Title: CONSISTENT SCALING LAWS IN ANELASTIC SPHERICAL SHELL DYNAMOS

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Abstract

Numerical dynamo models always employ parameter values that differ by orders of magnitude from the values expected in natural objects. However, such models have been successful in qualitatively reproducing properties of planetary and stellar dynamos. This qualitative agreement fuels the idea that both numerical models and astrophysical objects may operate in the same asymptotic regime of dynamics. This can be tested by exploring the scaling behavior of the models. For convection-driven incompressible spherical shell dynamos with constant material properties, scaling laws had been established previously that relate flow velocity and magnetic field strength to the available power. Here we analyze 273 direct numerical simulations using the anelastic approximation, involving also cases with radius-dependent magnetic, thermal, and viscous diffusivities. These better represent conditions in gas giant planets and low-mass stars compared to Boussinesq models. Our study provides strong support for the hypothesis that both mean velocity and mean magnetic field strength scale as a function of the power generated by buoyancy forces in the same way for a wide range of conditions.

Authors:

Yadav, Rakesh K.; Gastine, Thomas; Christensen, Ulrich R. ^[1]; Duarte, Lucia D. V., ^[2]

Max-Planck-Institut fuer Sonnensystemforschung, Max Planck Strasse 2, D-37191 Katlenburg-Lindau (Germany)
Also at the Technische Universitaet Braunschweig (Germany)

Publication Date:: Sun Sep 01 00:00:00 EDT 2013

OSTI Identifier:: 22133996

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 774; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COMPUTERIZED SIMULATION; CONVECTION; MAGNETIC FIELDS; PLANETS; SCALING LAWS; SPHERICAL CONFIGURATION; STARS; VELOCITY

Citation Formats


                    Yadav, Rakesh K., Gastine, Thomas, Christensen, Ulrich R., and Duarte, Lucia D. V.,. CONSISTENT SCALING LAWS IN ANELASTIC SPHERICAL SHELL DYNAMOS.  United States: N. p., 2013. 
        Web.  doi:10.1088/0004-637X/774/1/6.

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                    Yadav, Rakesh K., Gastine, Thomas, Christensen, Ulrich R., & Duarte, Lucia D. V.,. CONSISTENT SCALING LAWS IN ANELASTIC SPHERICAL SHELL DYNAMOS.  United States.  https://doi.org/10.1088/0004-637X/774/1/6

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                    Yadav, Rakesh K., Gastine, Thomas, Christensen, Ulrich R., and Duarte, Lucia D. V.,. 2013.  
        "CONSISTENT SCALING LAWS IN ANELASTIC SPHERICAL SHELL DYNAMOS".  United States.  https://doi.org/10.1088/0004-637X/774/1/6.

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@article{osti_22133996,

  title        = {CONSISTENT SCALING LAWS IN ANELASTIC SPHERICAL SHELL DYNAMOS},

  author       = {Yadav, Rakesh K. and Gastine, Thomas and Christensen, Ulrich R. and Duarte, Lucia D. V.,},

  abstractNote = {Numerical dynamo models always employ parameter values that differ by orders of magnitude from the values expected in natural objects. However, such models have been successful in qualitatively reproducing properties of planetary and stellar dynamos. This qualitative agreement fuels the idea that both numerical models and astrophysical objects may operate in the same asymptotic regime of dynamics. This can be tested by exploring the scaling behavior of the models. For convection-driven incompressible spherical shell dynamos with constant material properties, scaling laws had been established previously that relate flow velocity and magnetic field strength to the available power. Here we analyze 273 direct numerical simulations using the anelastic approximation, involving also cases with radius-dependent magnetic, thermal, and viscous diffusivities. These better represent conditions in gas giant planets and low-mass stars compared to Boussinesq models. Our study provides strong support for the hypothesis that both mean velocity and mean magnetic field strength scale as a function of the power generated by buoyancy forces in the same way for a wide range of conditions.},

  doi          = {10.1088/0004-637X/774/1/6},

  url          = {https://www.osti.gov/biblio/22133996},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 1,

  volume       = 774,

  place        = {United States},

  year         = {Sun Sep 01 00:00:00 EDT 2013},

  month        = {Sun Sep 01 00:00:00 EDT 2013}

}

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