The technique of semidefinite programming is used to replace direct numerical simulations and time integrations turbulent flows with an optimization problem which easier solve but returns only upper bounds the averages simulation would have produced. This idea applied rotating Rayleigh-B\'enard convection at infinite Prandtl number. obtained are not sharp they reproduce qualitative behavior res...

LOWTO MODERATE-PRANDTL NUMBER FLUIDS Guy Metcalfe Division of Building, Construction and Engineering CSIRO Highett, Victoria AUSTRALIA R.P. Behringer Dept. of Physics and Center for Nonlinear and Complex Systems Duke University Durham, North Carolina USA to be given at the 12th Australasian Fluid Mechanics Conference, Sydney Australia December 10{15 1995 ABSTRACT Super uid mixtures have Prandtl...

We investigate the behavior of the magnetic Prandtl number (ratio of microscopic viscosity to resistivity) for accretion sources. Generally this number is very small in standard accretion disk models, but can become larger than unity within ∼ 50 Schwarzschild radii of the central mass. Recent numerical investigations suggest a marked dependence of the level of MHD turbulence on the value of the...