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P. Williams (Los Alamos National Laboratory)
We discuss turbulent elasticity within the context of the angular momentum balance of the solar convective zone (SCZ). The concept of a turbulent elasticity is complementary to the notion of a turbulent viscosity. In the case of turbulent viscosity, the small-scale stochastic component of the turbulent fluid motions behaves like molecules in ordinary viscous fluids to create an effective viscous response of the stress. Likewise, in the case of turbulent elasticity, the small-scale stochastic component of the magnetic field behaves like polymers in solution in viscoelastic fluids to create an effective elastic response of the fluid to stress. This elastic response creates hoop-stresses in azimuthal shear flow. We demonstrate that the hoop-stresses generated by turbulent elasticity induce a component to the meridional flow in the SCZ that is ``clockwise'' in the usual terminology, that is to say, north to south at the surface and south to north at the base of the convective zone, for the northern hemisphere. This meridional flow is in opposition to the meridional flow that is induced by inertia. In fact it is commonly observed in the secondary flow phenomena of viscoelastic fluids in the laboratory that elastic forces act oppositely to inertial forces. We thus argue that the addition of a turbulent elasticity may help solve the so-called ``Taylor number puzzle.'' One additional effect of an effective elasticity is the purely elastic (as opposed to viscous) response of the fluid to shear on timescales shorter than the elastic relaxation time. The fluid should thus support transverse shear waves, which are essentially Alvfén waves in a spatially stochastic field. Our model should thus make testable predictions about the solar oscillation spectrum.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.