Turbulent stresses as a function of shear rate in a local disk model

WC Present local numerical models of accretion disk turbulence driven by the magnetorotational instability with varying shear rate. The resulting turbulent stresses are compared with predictions of a closure model in which triple correlations are modelled in terms of quadratic correlations. This local model uses live nondimensional parameters to describe the properties of the flow. We attempt to determine these Closure parameters for our simulations and find that the model does produce qualitatively correct behaviour. In addition, we present results concerning the shear rate dependency of the magnetic to kinetic energy ratio. We find both the turbulent stress ratio and the total stress to be strongly dependent on the shear rate. (C) 2009 WILEY-VCH Verlag GmbH & Co, KGaA, Weinheim