Turbulent Compressible Convection with Rotation - Penetration above a Convection Zone

TL;DR

This study uses large eddy simulations to analyze how rotation rate, inclination, and stability influence turbulent compressible convection and the extent of penetration into stable layers in stellar convection zones.

Contribution

It provides new insights into the effects of rotation and stability on convective penetration in stellar zones through detailed 3D simulations.

Findings

Penetration distance increases with rotation rate when rotation is vertical.

Higher stability in the upper layer reduces upward penetration.

Resolution effects influence the estimated penetration depth.

Abstract

We perform Large eddy simulations of turbulent compressible convection in stellar-type convection zones by solving the Navi\'{e}r-Stokes equations in three dimensions. We estimate the extent of penetration into the stable layer above a stellar-type convection zone by varying the rotation rate ({\boldmath$\rm\Omega$}), the inclination of the rotation vector ($\theta$) and the relative stability ($S$) of the upper stable layer. The computational domain is a rectangular box in an f-plane configuration and is divided into two regions of unstable and stable stratification with the stable layer placed above the convectively unstable layer. Several models have been computed and the penetration distance into the stable layer above the convection zone is estimated by determining the position where time averaged kinetic energy flux has the first zero in the upper stable layer. The vertical grid spacing in all the model is non-uniform, and is less in the upper region so that the flows are better resolved in the region of interest. We find that the penetration distance increases as the rotation rate increases for the case when the rotation vector is aligned with the vertical axis. However, with the increase in the stability of the upper stable layer, the upward penetration distance decreases. Since we are not able to afford computations with finer resolution for all the models, we compute a number of models to see the effect of increased resolution on the upward penetration. In addition, we estimate the upper limit on the upward convective penetration from stellar convective cores.