Turbulent magnetic dynamo excitation at low magnetic Prandtl number

Details Turbulent magnetic dynamo excitation at low magnetic Prandtl number Turbulent magnetic dynamo excitation at low magnetic Prandtl number

2005-12-06

arxiv.org/abs/astro-ph/0512134v1

Astronomy and Astrophysics

Astrophysics

8 pages, 8 figures, to appear in Physics of Plasmas

Scientific paper

10.1063/1.2179055

Planetary and stellar dynamos likely result from turbulent motions in magnetofluids with kinematic viscosities that are small compared to their magnetic diffusivities. Laboratory experiments are in progress to produce similar dynamos in liquid metals. This work reviews recent computations of thresholds in critical magnetic Reynolds number above which dynamo amplification can be expected for mechanically-forced turbulence (helical and non-helical, short wavelength and long wavelength) as a function of the magnetic Prandtl number $P_M$. New results for helical forcing are discussed, for which a dynamo is obtained at $P_M=5\times10^{-3}$. The fact that the kinetic turbulent spectrum is much broader in wavenumber space than the magnetic spectrum leads to numerical difficulties which are bridged by a combination of overlapping direct numerical simulations and subgrid models of magnetohydrodynamic turbulence. Typically, the critical magnetic Reynolds number increases steeply as the magnetic Prandtl number decreases, and then reaches an asymptotic plateau at values of at most a few hundred. In the turbulent regime and for magnetic Reynolds numbers large enough, both small and large scale magnetic fields are excited. The interactions between different scales in the flow are also discussed.

Affiliated with

Also associated with

No associations

Rating

Turbulent magnetic dynamo excitation at low magnetic Prandtl number does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Turbulent magnetic dynamo excitation at low magnetic Prandtl number, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Turbulent magnetic dynamo excitation at low magnetic Prandtl number will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-697443