Spatial inhomogeneity of kinetic and magnetic dissipations in thermal convection

Abstract

We investigate the inhomogeneity of kinetic and magnetic dissipations in thermal convection using high-resolution calculations. In statistically steady turbulence, the injected and dissipated energies are balanced. This means that a large amount of energy is continuously converted to internal energy via dissipation. As in thermal convection downflows are colder than upflows, the inhomogeneity of the dissipation potentially changes the convection structure. Our investigation on the inhomogeneity of the dissipation shows the following. 1. More dissipation is seen around the bottom of the calculation domain, and this tendency is promoted with the magnetic field. 2. The dissipation in the downflow is much larger than that in the upflow. The dissipation in the downflow is more than 80% of the total at maximum. This tendency is also promoted with the magnetic field. 3. Although 2D probability density functions of the kinetic and magnetic dissipations versus the vertical velocity are similar, the kinetic and magnetic dissipations are not well correlated. Our result suggests that the spatial inhomogeneity of the dissipation is significant and should be considered when modeling a small-scale strong magnetic field generated with an efficient small-scale dynamo for low-resolution calculations.

23 pages, 8 figures accepted for publication in The Astrophysical Journal

References in corpus (9)

• Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
• Extension of the MURaM radiative MHD code for coronal simulations
• High-resolution calculation of the solar global convection with the reduced speed of sound technique: II. Near surface shear layer with the rotation
• The Emergence of Solar Supergranulation as a Natural Consequence of Rotationally-Constrained Interior Convection
• Magnetic Prandtl number dependence of kinetic to magnetic dissipation ratio
• Efficient small-scale dynamo in solar convection zone
• The Role of Subsurface Flows in Solar Surface Convection: Modeling the Spectrum of Supergranular and Larger Scale Flows
• Solar overshoot region and small-scale dynamo with realistic energy flux
• Dissipation in dynamos at low and high magnetic Prandtl numbers

Cited by in corpus (1)

• Impacts of small-scale dynamo on rotating columnar convection in stellar convection zones