**Previous
abstract** **Next
abstract**

**Session 69 - The Solar Dynamo and Helioseismology.**

*Display session, Thursday, June 13*

*Tripp Commons, *

## [69.07] Angular Momentum Transport in Turbulent Compressible Convection

*N. E. Hurlburt (Lockheed-Martin Solar and Astrophysics Lab.), N. H. Brummell, J. Toomre (JILA, U. Colorado)*
We consider the dynamics of compressible convection within a curved
local segment of a rotating spherical shell, aiming to resolve the
disparity between the differential rotation profiles predicted by
previous laminar simulations (angular velocity constant on cylinders)
and those deduced from helioseismic inversion of the observed
frequency splitting of p modes. By limiting the horizontal extent of
the domain under study, we can utilize the available spatial degrees
of freedom on current supercomputers to attain more turbulent flows
than in the full shell. Our previous study of three-dimensional
convection within a slab geometry of an f-plane neglected the effects
of curvature, and thus did not admit the generation of Rossby
waves. These waves propagate in the longitudinal direction and thus
produce rather different spectral characteristics and mean flows in
the north-south and east-west directions. By considering motions in a
curvilinear geometry in which the Coriolis parameter varies with
latitude, we admit the possibility of Rossby waves which couple to the
turbulent convection. Here we present simulations with Rayleigh
numbers in excess of 10^6, and Prandtl numbers less than 0.1 in such
a curved local segment of a spherical shell using a newly developed
code based on compact finite differences. This computational domain
takes the form of a curved, periodic channel in longitude with
stress-free sidewalls in latitude and radius. Despite the differences
in geometry and boundary conditions, the flows maintain similarities
with those of our previous f-plane simulations. The surface flows
form broad, laminar networks which mask the much more turbulent flows
of the interior. The dynamics within this turbulent region is
controlled by the interactions of a tangled web of strong vortex
tubes. These interactions are further complicated by the effects of
curvature. The differential rotation generated by the turbulent
convection typically increases with depth and attains a maximum at the
base of the layer of about 10 % over the imposed rotation rate.

**Program
listing for Thursday**