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Seminar: Fluid Mechanics

Magnetorotational turbulence in quasi-Keplerian shear flows

Speaker: Anna Guseva
Organization: University of Bremen
Time: 2017-11-16 10:30
Place: Teknikringen 8

Abstract

Magnetorotational instability (MRI) is thought to be a powerful source of turbulence in astrophysical accretion disks. Keplerian angular velocity profile of these disks ? ? r?3/2 is hydrodynamically stable; yet external magnetic fields can create the instability via magnetic tension in the field lines. In- spired by recent experiments of magnetized Taylor-Couette flow, we study MRI driven by azimuthal magnetic field in conducting fluid sheared between two co-rotating cylinders. In this talk I will show how the flow transits from laminar to periodic waves and then eventually becomes chaotic. Resulting turbulence appears to be effective in transporting angular momentum out- wards. We will see how Reynolds, Maxwell and viscous stresses contribute to the total angular momentum transport. Finally, I will demonstrate under which conditions this turbulence becomes self-sustained even in the absense of imposed external magnetic field.