Scale variability in convection-driven MHD dynamos at low Ekman number

Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

We have undertaken a numerical study of convection-driven MHD dynamos in a rapidly rotating spherical shell with the Ekman number, E, down to 2 × 1 0- 6 and the magnetic Prandtl number, Pm, down to 0.2. We focus on the characteristic scales of the flow and the magnetic field. Smaller-scale convection vortices responsible for generating the magnetic field appear at lower Ekman numbers, while the scale of the magnetic field shows less variation compared with the flow. As a result, scale separation between the flow and the magnetic field occurs as the Ekman number is decreased. Scale separation helps dynamos to maintain the magnetic field at P m < 1 through increase in the effective value of the magnetic Reynolds number.

Original languageEnglish
Pages (from-to)168-178
Number of pages11
JournalPhysics of the Earth and Planetary Interiors
Volume167
Issue number3-4
DOIs
Publication statusPublished - Apr 1 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science

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