Large-scale magnetic fields at high Reynolds numbers in magnetohydrodynamic simulations

• Autores: H. Hotta, M. Rempel, T. Yokoyama
• Localización: Science, ISSN 0036-8075, Vol. 351, Nº 6280, 2016, págs. 1427-1430
• Idioma: inglés
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• Resumen

  • The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity (Embedded Imagesquare centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities—that is, large Reynolds numbers.