Effect of rotation on a developed turbulent stratified convection: The hydrodynamic helicity, the $\ensuremath{\alpha}$ effect, and the effective drift velocity Academic Article uri icon

abstract

  • An effect of rotation on a developed turbulent stratified convection is studied. Dependences of the hydrodynamic helicity, the $\ensuremath{\alpha}$ tensor, and the effective drift velocity of the mean magnetic field on the rate of rotation and an anisotropy of turbulent convection are found. It is shown that in an anisotropic turbulent convection the $\ensuremath{\alpha}$ effect can change its sign depending on the rate of rotation. The evolution of the $\ensuremath{\alpha}$ effect is much more complicated than that of the hydrodynamic helicity in an anisotropic turbulent convection of a rotating fluid. Different properties of the effective drift velocity of the mean magnetic field in a rotating turbulent convection are found: (i) a poloidal effective drift velocity can be diamagnetic or paramagnetic depending on the rate of rotation; (ii) there is a difference in the effective drift velocities for the toroidal and poloidal magnetic fields; (iii) a toroidal effective drift velocity can play a role of an additional differential rotation. The above effects and an effect of a nonzero divergence of the effective drift velocity of the toroidal magnetic field on a magnetic dynamo in a developed turbulent stratified convection of a rotating fluid are studied. Astrophysical applications of the obtained results are discussed.

publication date

  • February 27, 2003