Context. Stellar convection zones are characterized by vigorous high-Reynolds number turbulence at low Prandtl numbers. Aims. We study the dynamo and differential rotation regimes at varying levels of viscous, thermal, and magnetic diffusion. Methods. We perform three-dimensional simulations of stratified fully compressible magnetohydrodynamic convection in rotating spherical wedges at various ...

The presence of an imposed external magnetic field may drastically influence the structure of thin accretion discs. The magnetic field energy is here assumed to be in balance with the thermal energy of the accretion flow. The vertical magnetic field, its toroidal component B tor at the disc surface (due to different rotation rates between disc and its magnetosphere), the turbulent magnetic Pran...

Using the field theoretic renormalization group technique in the two-loop approximation, turbulent Prandtl numbers are obtained in the general A model of passive vector advected by fully developed turbulent velocity field with violation of spatial parity introduced via continuous parameter ρ ranging from ρ = 0 (no violation of spatial parity) to |ρ| = 1 (maximum violation of spatial parity). Va...

Accurate numerical computations of the onset of thermal convection in wide rotating spherical shells are presented. Low-Prandtl-number (σ ) fluids, and non-slip boundary conditions are considered. It is shown that at small Ekman numbers (E), and very low σ values, the well-known equatorially trapped patterns of convection are superseded by multicellular outer-equatorially-attached modes. As a r...

This paper presents the results of an experimental investigation of heat transfer to the airflow in the square duct. The main purpose of this study is influence of square ducts on the convective heat transfer mechanism. Under this investigation friction factor and the Nusselt Number were calculated. The reason that square ducts increase the fluid flow turbulence near the wall and also increase ...

The nature of the primary instabilities that arise in a fluid contained in a fast rotating cylindrical annulus with slightly inclined plane top and bottom boundaries, radial gravity, and internal heating is numerically analyzed. It is shown that for moderate and high Prandtl numbers, the onset of convection is described by a competition of azimuthal thermal modes with different radial structure...

The linear instability of a barotropic flow with uniform horizontal shear in a stratified rotating fluid is investigated with respect to perturbations invariant in the alongflow direction. The flow can be inertially unstable if there is sufficiently strong anticyclonic shear, but only for sufficiently high Reynolds numbers Re. We determine the critical Reynolds numbers required for amplificatio...