Some Properties of the Kinetic Energy Flux and Dissipation in Turbulent Stellar Convection Zones

TL;DR

This paper analyzes turbulent flow in stellar convection zones, examining energy transport and dissipation, and presents a boundary value approach compatible with stellar evolution models, validated by simulations.

Contribution

It introduces a boundary value framework for turbulent convection in stars, aligning theoretical analysis with simulations and addressing boundary treatment in stellar models.

Findings

Good agreement between theory and simulation.

Highlights importance of boundary conditions.

Provides a practical approach for stellar evolution codes.

Abstract

We investigate simulated turbulent flow within thermally driven stellar convection zones. Different driving sources are studied, including cooling at the top of the convectively unstable region, as occurs in surface convection zones; and heating at the base by nuclear burning. The transport of enthalpy and kinetic energy, and the distribution of turbulent kinetic energy dissipation are studied. We emphasize the importance of global constraints on shaping the quasi-steady flow characteristics, and present an analysis of turbulent convection which is posed as a boundary value problem that can be easily incorporated into standard stellar evolution codes for deep, efficient convection. Direct comparison is made between the theoretical analysis and the simulated flow and very good agreement is found. Some common assumptions traditionally used to treat quasi-steady turbulent flow in stellar models are briefly discussed. The importance and proper treatment of convective boundaries are indicated.