TY - JOUR
T1 - Scale variability in convection-driven MHD dynamos at low Ekman number
AU - Takahashi, Futoshi
AU - Matsushima, Masaki
AU - Honkura, Yoshimori
N1 - Funding Information:
and Applications Award (co-author), the ASEE/IIE Eugene L. Grant Award (co-author), and a NSF Presidential Young Investigator Award. Dr. Askin has consulted with a variety of industrial companies in the areas of facilities planning, quality improvement, and performance evaluation of manufacturing systems.
PY - 2008/4
Y1 - 2008/4
N2 - 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.
AB - 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.
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U2 - 10.1016/j.pepi.2008.03.005
DO - 10.1016/j.pepi.2008.03.005
M3 - Article
AN - SCOPUS:44349192595
SN - 0031-9201
VL - 167
SP - 168
EP - 178
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
IS - 3-4
ER -