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

Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura

doi:10.1016/j.pepi.2008.03.005

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

DOI Web Site Web Site 被引用文献5件

書誌事項

公開日: 2008-04

権利情報

https://www.elsevier.com/tdm/userlicense/1.0/

DOI

10.1016/j.pepi.2008.03.005

公開者: Elsevier BV

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説明

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.