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An Isaac Newton Institute Workshop

Supported by the European Commission, Sixth Framework Programme - Marie Curie Conferences and Training Courses - MSCF-CT-2003-503674 <br><br> Large-Scale Computation in Astrophysics

Mach number dependence of the onset of dynamo action

Authors: Nils Erland L. Haugen (NTNU), Axel Brandenburg (NORDITA), ntony J. Mee (Univ. Newcastle)

Abstract

The effect of compressibility on the onset of nonhelical turbulent dynamo action is investigated using both direct simulations as well as simulations with shock-capturing viscosities, keeping however the regular magnetic diffusivity. It is found that the critical magnetic Reynolds number for the onset of dynamo activity increases from about 35 in the subsonic regime to about 70 in the supersonic regime. Although the shock structures are sharper in the high resolution direct simulations compared to the low resolution shock-capturing simulations, the magnetic field looks roughly similar in both cases and does not show shock structures. Similarly, the onset of dynamo action is not significantly affected by the shock-capturing viscosity.

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