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Convective, absolute and global azimuthal magnetorotational instabilities

Mishra, A.; Mamatsashvili, G.; Galindo, V.; Stefani, F.

We study the convective and absolute forms of azimuthal magnetorotational instability (AMRI) in a cylindrical Taylor–Couette (TC) flow with an imposed azimuthal magnetic field. We show that the domain of the convective AMRI is wider than that of the absolute AMRI. Actually, it is the absolute instability which is the most relevant and important for magnetic TC flow experiments. The absolute AMRI, unlike the convective one, stays in the device, displaying a sustained growth that can be experimentally detected. We also study the global AMRI in a TC flow of finite height using direct numerical simulation and find that its emerging butterfly-type structure – a spatio-temporal variation in the form of axially upward and downward travelling waves – is in a very good agreement with the linear analysis, which indicates the presence of two dominant absolute AMRI modes in the flow giving rise to this global butterfly pattern.

Keywords: absolute/convective instability; Taylor-Couette flow

  • Open Access Logo Journal of Fluid Mechanics 922(2021), R4
    DOI: 10.1017/jfm.2021.548
    Cited 1 times in Scopus
  • Lecture (Conference) (Online presentation)
    International Couette-Taylor Workshop 2021, 05.-09.07.2021, Enschede, Netherlands

Publ.-Id: 32890