RädlerFest: Alpha Effect and Beyond

Session

Session 10

16 Feb 2011, 11:00

Wenner-Gren Center, floor 7, Hörsalen (Wenner Gren Center)

275. The onset of strongly localized thermal convection in rotating spherical shells

Prof. Andrew Soward

16/02/2011, 11:00

The onset of instability of a Boussinesq fluid within a rapidly rotating spherical shell is considered, when a thin unstable layer lies adjacent to the inner sphere boundary, radius r_i . This layer, which is of radial extent O(ε^2 r_i ), sits beneath the remaining (stably stratified) fluid. The variable stratification is effected by a combination of differential heating between the...

276. α-effect and large-scale dynamos from convection simulations

Dr Petri Käpylä (University of Helsinki)

16/02/2011, 11:30

The results for the α-effect as a function of rotation rate are consistent with earlier numerical studies, i.e. increasing magnitude as rotation increases and approximately cos θ latitude profile for moderate rotation. Turbulent diffusivity, η_t, is proportional to the square of the turbulent vertical velocity in all cases. Whereas ηt decreases approximately inversely proportional to...

277. Dynamo action and magnetic buoyancy in convection with vertical shear

Dr Gustavo Guerrero

16/02/2011, 12:00

One of the existing hypothesis on sunspot formation is the buoyant emergence of magnetic flux tubes created by the strong radial shear at the tachocline. In this scenario, the magnetic field has to exceed a threshold value before it becomes buoyant and emerges through the convection zone up to the surface. However, several physical constrains are required to be fulfilled for this model...