Continuation and stability of rotating waves in the magnetized spherical Couette system: Secondary transitions and multistability

Abstract

Rotating waves (RW) bifurcating from the axisymmetric basic magnetized spherical Couette (MSC) flow are computed by means of Newton-Krylov continuation techniques for periodic orbits. In addition, their stability is analysed in the framework of Floquet theory. The inner sphere rotates whilst the outer is kept at rest and the fluid is subjected to an axial magnetic field. For a moderate Reynolds number $\mathrm{Re}=10^3$ (measuring inner rotation) the effect of increasing the magnetic field strength (measured by the Hartmann number $\mathrm{Ha}$) is addressed in the range $\mathrm{Ha}\in (0,80)$ corresponding to the working conditions of the HEDGEHOG experiment at Helmholtz-Zentrum Dresden-Rossendorf. The study reveals several regions of multistability of waves with azimuthal wave number $m=2,3,4$, and several transitions to quasiperiodic flows, i.e modulated rotating waves (MRW). These nonlinear flows can be classified as the three different instabilities of the radial jet, the return flow and the shear-layer, as found in previous studies. These two flows are continuously linked, and part of the same branch, as the magnetic forcing is increased. Midway between the two instabilities, at a certain critical $\mathrm{Ha}$, the nonaxisymmetric component of the flow is maximum.

arXiv commentPublished in the Proceedings of the Royal Society A journal. Contains 3 tables and 12 figures

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Cited by in corpus (7)

• Chaotic wave dynamics in weakly magnetised spherical Couette flows
• Experimental investigation of the return flow instability in magnetic spherical Couette flow
• Four-frequency solution in a magnetohydrodynamic Couette flow as a consequence of azimuthal symmetry breaking
• Bifurcation aspect of wide-gap spherical Couette flow emphasizing polygonal coherence and wave numbers observed over transitional Reynolds numbers
• High dimensional tori and chaotic and intermittent transients in magnetohydrodynamic Couette flows
• A thermal convection limit of spiral state in wide-gap spherical Couette flow
• Modulated rotating waves and triadic resonances in spherical fluid systems: The case of magnetized spherical Couette flow