Waves in the magnetized spherical Couette problem.


Waves in the magnetized spherical Couette problem.

Garcia Gonzalez, F.; Seilmayer, M.; Giesecke, A.; Stefani, F.

Experiments on the magnetized spherical Couette system are presently being carried out at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). A liquid metal (GaInSn) is confined within two differentially rotating spheres and exposed to a magnetic field parallel to the axis of rotation. Bifurcation diagrams for rotating waves, obtained with continuation methods when only the magnetic field is increased, are presented. This allows us to carefully investigate the time-scales of the nonlinear saturation of the radial jet, return flow, and shear layer instabilities, as found in previous studies. In addition, modulated rotating waves, obtained at secondary bifurcations, are exhaustively studied by means of direct numerical simulations, with main focus on their spatio-temporal symmetries. We find that at moderate differential rotation the modulated rotating waves give rise to several types of chaotic flows, but only for the radial jet instability. With this study we reveal how the flow patterns and time-scales depend on the magnetic field, reproducing thus different physical situations of the HZDR experiments.

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    Alexander von Humboldt Colloquium “Research without Borders – Alexander von Humboldt’s Legacy Today”, 11.-13.04.2019, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-30360
Publ.-Id: 30360