Rotating Turbulent Thermal Convection and Solar Differential Rotation

TL;DR

This paper investigates how rotating turbulent thermal convection influences vorticity, angular momentum transport, and differential rotation in the solar polar region, revealing mechanisms behind solar differential rotation.

Contribution

It introduces a model linking microscopic vorticity effects to macroscopic solar differential rotation, highlighting the role of centrifugal forces and temperature gradients.

Findings

Vorticity varies with density, causing angular momentum transport.

Axial thermal convection can generate solar-like differential rotation.

Temperature gradients drive the energy source for differential rotation.

Abstract

The expansion of the rotating fluid will change the vorticity and rotational speed of the expanding region. In turbulent thermal convection, this microscopic effect is preserved. Tracking the fluid micelles shows that the average vorticity varies with density, producing vorticity transport and angular momentum transport from the low-density area to the high-density area, forming a macroscopic vorticity difference and rotational speed difference. Taking the axial thermal convection model of the solar polar region, it can generate axial differential rotation, and the centrifugal force difference generated by the axial differential rotation drives the meridional circulation, transporting angular momentum away from the axis of rotation, forming latitudinal differential rotation. The rotation of the fluid cell generates additional pressure and change the convection criterion. The temperature gradient in the solar troposphere is higher than in the non-rotating fluid model, It's the energy source of the differential rotating.