Reynolds stresses and meridional circulation from rotating cylinder simulations

¹ Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany e-mail: hupfer@kis.uni-freiburg.de
² Observatory, University of Helsinki, PO Box 14, 00014 University of Helsinki, Finland
³ Astronomy Division, Department of Physical Sciences, PO Box 3000, 90014 University of Oulu, Finland

Received: 28 April 2006
Accepted: 4 August 2006

Abstract

Aims.The latitude and depth dependences of Reynolds stresses are obtained from numerical simulations of a solar-type convection zone where the star is assumed to rotate with a uniform angular velocity.

Methods.A two-dimensional model, using a cylindrical annulus with axis perpendicular to the axis of rotation, is introduced as an approximation of a spherical section along the meridional plane. We solve the fully compressible Navier-Stokes equations numerically and use Cartesian and cylindrical geometries to simulate convection under the influence of rotation.

Results.For moderate Coriolis numbers both models yield strong extrema of the Reynolds stress component at low latitudes near the equator, and a meridional cell pattern is found in the cylindrical model. For Coriolis numbers larger than about 10 the flow becomes aligned with the direction of the rotation axis.