Convective velocity suppression via the enhancement of subadiabatic layer: Role of the effective Prandtl number
arXiv:1711.05960 · doi:10.3847/1538-4357/aa9b7f
Abstract
It has recently been recognized that the convective velocities achieved in the current solar convection simulations might be over-estimated. The newly-revealed effects of the prevailing small-scale magnetic field within the convection zone may offer possible solutions to this problem. The small-scale magnetic fields can reduce the convective amplitude of small-scale motions through the Lorentz-force feedback, which concurrently inhibits the turbulent mixing of entropy between upflows and downflows. As a result, the effective Prandtl number may exceed unity inside the solar convection zone. In this paper, we propose and numerically confirm a possible suppression mechanism of convective velocity in the effectively high-Prandtl number regime. If the effective horizontal thermal diffusivity decreases (the Prandtl number accordingly increases), the subadiabatic layer which is formed near the base of the convection zone by continuous depositions of low entropy transported by adiabatically downflowing plumes is enhanced and extended. The global convective amplitude in the high-Prandtl thermal convection is thus reduced especially in the lower part of the convection zone via the change in the mean entropy profile which becomes more subadiabatic near the base and less superadiabatic in the bulk.
arXiv comment17 pages, 13 figures, accepted for publication in ApJ
References in corpus (31)
- Astrophysical magnetic fields and nonlinear dynamo theory
- Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
- Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
- A solar surface dynamo
- Detection of Equatorward Meridional Flow and Evidence of Double-Cell Meridional Circulation inside the Sun
- Structure and Evolution of Giant Cells in Global Models of Solar Convection
- Solar differential rotation and meridional flow: The role of a subadiabatic tachocline for the Taylor-Proudman balance
- Anomalously Weak Solar Convection
- Meridional Circulation in Solar and Stellar Convection Zones
- A simulation of convective dynamo in the solar convective envelope: maintenance of the solar-like differential rotation and emerging flux
- Zonal flow regimes in rotating anelastic spherical shells: an application to giant planets
- Meridional circulation in the solar convection zone: time-distance helioseismic inferences from four years of HMI/SDO observations
- Seismic Sounding of Convection in the Sun
- Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles
- High-resolution calculation of the solar global convection with the reduced speed of sound technique: II. Near surface shear layer with the rotation
- Confirmation of bistable stellar differential rotation profiles
- The Mass Mixing Length in Convective Stellar Envelopes
- The Spectral Amplitude of Stellar Convection and its Scaling in the High-Rayleigh-Number Regime
- Helioseismic Imaging of Fast Convective Flows Throughout the Near-Surface Shear Layer
- High-resolution calculations of the solar global convection with the reduced speed of sound technique: I. The structure of the convection and the magnetic field without the rotation
- Stellar mixing length theory with entropy rain
- Extended subadiabatic layer in simulations of overshooting convection
- On the cause of solar-like equatorward migration in global convective dynamo simulations
- 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
- Velocity Amplitudes in Global Convection Simulations: The Role of the Prandtl Number and Near-Surface Driving
- Solar overshoot region and small-scale dynamo with realistic energy flux
- Convection-driven spherical shell dynamos at varying Prandtl numbers
- Meridional circulation dynamics from 3D MHD global simulations of solar convection
- Impact of MHD Turbulence on Thermal Wind Balance in the Sun
- Double-Cell Type Solar Meridional Circulation Based on Mean-Field Hydrodynamic Model
Cited by in corpus (22)
- Solar inertial modes: Observations, identification, and diagnostic promise
- Generation solar-like differential rotation
- Consequences of high effective Prandtl number on solar differential rotation and convective velocity
- Theory of solar oscillations in the inertial frequency range: Linear modes of the convection zone
- Overshooting in simulations of compressible convection
- Small-scale dynamos: From idealized models to solar and stellar applications
- Star-in-a-box simulations of fully convective stars
- Effects of a subadiabatic layer on convection and dynamos in spherical wedge simulations
- Theory of solar oscillations in the inertial frequency range: Amplitudes of equatorial modes from a nonlinear rotating convection simulation
- Driving Solar Giant Cells through the Self-Organization of Near-Surface Plumes
- Transition from anti-solar to solar-like differential rotation: Dependence on Prandtl number
- Non-Boussinesq low-Prandtl number convection with a temperature-dependent thermal diffusivity
- Small-scale dynamos in simulations of stratified turbulent convection
- Prandtl number dependence of compressible convection: Flow statistics and convective energy transport
- Breaking Taylor-Proudman balance by magnetic field in stellar convection zone
- Three-dimensional non-kinematic simulation of post-emergence evolution of bipolar magnetic regions and Babcock-Leighton dynamo of the Sun
- Turbulent Prandtl number from isotropically forced turbulence
- Global Turbulent Solar Convection: a Numerical Path Investigating Key Force Balances in the context of the Convective Conundrum
- Simulations of entropy rain-driven convection
- Impacts of small-scale dynamo on rotating columnar convection in stellar convection zones
- Helioseismological determination of the subsurface spatial spectrum of solar convection: Demonstration using numerical simulations
- Scale-resolved turbulent Prandtl number for Rayleigh-Bénard convection at