Numerical simulations of stellar convective dynamos. II. Field propagation in the convection zone

Journal Article · Mon Apr 01 00:00:00 EST 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163069· OSTI ID:5403652

Glatzmaier, G A

We present numerical simulations of nonlinear, three-dimensional, time-dependent, giant-cell stellar convection and magnetic field generation. The velocity, magnetic field, and thermodynamic variables satisfy the anelastic magnetohydrodynamic equations for a stratified, rotating, spherical shell of ionized gas. The interaction of rotation and convection produces a nonlinear transport of angular momentum that maintains a differential rotation in radius and latitude. At the surface, our simulated angular velocity peaks in the equatorial region in agreement with Doppler measurements of the solar surface rotation rate; below the surface, it decreases with depth in agreement with what is inferred from the rotational frequency splitting of solar oscillations. The interaction of rotation and convection also maintains left-handed helical fluid motions in the northern hemisphere and right-handed motions in the southern hemisphere. Magnetic fields are generated by the shearing and twisting effects of the differential rotation and helical motions and are destroyed by eddy diffusion. They in turn feedback onto the velocity and thermodynamic fields via the Lorentz force and Joule heating. Although we have not continued the computation long enough to simulate a complete magnetic cycle, our solutions demonstrate how the induced magnetic fields propagate away from the equator in the opposite direction inferred from the solar butterfly diagram. We suggest that, instead of operating in the turbulent convective region, the solar dynamo may be operating at the base of the convection zone where our simulated helicity has the opposite sign and a smaller amplitude.

• Research Organization: Los Alamos National Laboratory
• OSTI ID: 5403652
• Journal Information: Astrophys. J.; (United States), Vol. 291:1
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
SOLAR CYCLE
MAGNETOHYDRODYNAMICS
STAR MODELS
ANGULAR MOMENTUM
ANGULAR MOMENTUM TRANSFER
CONVECTION
DIFFUSION
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
NUMERICAL ANALYSIS
NUMERICAL SOLUTION
PLASMA
ROTATION
SIMULATION
THERMODYNAMICS
THREE-DIMENSIONAL CALCULATIONS
ENERGY TRANSFER
FLUID MECHANICS
HEAT TRANSFER
HYDRODYNAMICS
MASS TRANSFER
MATHEMATICAL MODELS
MATHEMATICS
MECHANICS
MOMENTUM TRANSFER
MOTION
640104* - Astrophysics & Cosmology- Solar Phenomena