RädlerFest: Alpha Effect and Beyond

Session

Session 4

Feb 14, 2011, 4:00 PM

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

257. Helicity generation and α-effect in MHD Taylor-Couette flows

Markus Gellert

2/14/11, 4:00 PM

Helical magnetic background fields with adjustable pitch angle are imposed on a conducting fluid in a differentially rotating cylindrical container. The small-scale kinetic and current helicities are calculated for various field geometries, and shown to have the opposite sign as the helicity of the large-scale field. These helicities and also the corresponding $\alpha$-effect scale with...

258. α effect from buoyancy instability

Piyali Chatterjee

2/14/11, 4:30 PM

A strong toroidal field can exist in form of a magnetic layer in the overshoot region below the solar convection zone. This motivates a more detailed study of the magnetic buoyancy instability with rotation. We calculate the alpha effect due to helical motions caused by a disintegrating magnetic layer in a rotating density-stratified system with angular velocity Omega making an angle...

259. What wavelets can bring to study MHD flows?

Marie Farge

2/14/11, 5:00 PM

We have proposed a wavelet based method, called Coherent Vorticity Extraction (CVE), to extract coherent fluctuations out of fully developed turbulent flows. We will explain its principles and illustrate its use in the context of 3D fluid turbulence. We will then extract coherent vorticity sheets and coherent current sheets from DNS data of 3D forced incompressible MHD turbulence. We...