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(gzipped) PostScript## Viscosity-alpha and dynamo-alpha for magnetically driven compressible turbulence in Kepler disks
^{1} Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany^{2} Institute for Solar-Terrestrial Physics, P.O. Box 4026, 664033 Irkutsk, Russia
For a given isotropic and homogeneous field of The current helicity also changes
its sign with increasing shear. For a Kepler flow in the upper (lower)
disk plane, the sign is positive (negative). In our turbulence model
the current helicity of the fluctuations and the
-effect of dynamo theory are almost
always out of phase; the signs of all the quantities are in perfect
correspondence to the numerical simulations of Brandenburg (1998,
2000). The kinetic helicity has the The resulting ratio between the dynamo- and the viscosity- reveals the dynamo- amplitude as rather small compared with the turbulence intensity. This is in contrast to earlier results on the basis of a quantitative approximation but again is in agreement with recent results of numerical simulations.
Online publication: October 24, 2000 |