Characterization of the flow past a truncated square cylinder in a duct under a spanwise magnetic field

Vincent Dousset, Alban Potherat

    Research output: Contribution to journalArticle

    13 Citations (Scopus)

    Abstract

    We study the flow of an electrically conducting fluid past a truncated square cylinder in a rectangular duct under the influence of an externally applied homogeneous magnetic field oriented along the cylinder axis. Our aim is to bridge the gap between the non-magnetic regime, where we previously found a complex set of three-dimensional recirculations behind the cylinder (Dousset & Pothérat, J. Fluid Mech., vol. 653, 2010, pp. 519–536) and the asymptotic regime of dominating Lorentz force analysed by Hunt & Ludford (J. Fluid. Mech., vol. 33, 1968, pp. 693–714). The latter regime is characterized by a remarkable structure known as Hunt’s wake in the magnetohydrodynamics community, where the flow is deflected on either side of a stagnant zone, right above the truncated cylinder as if the latter would span the full height of the duct. In steady flows dominated by the Lorentz force, with negligible inertia, we provide the first numerical flow visualization of Hunt’s wake. In regimes of finite inertia, a thorough topological analysis of the steady flow regimes reveals how the Lorentz force gradually reorganizes the flow structures in the hydrodynamic wake of the cylinder as the Hartmann number Ha (which gives a non-dimensional measure of the magnetic field) is increased. The nature of the vortex shedding follows from this rearrangement of the steady structures by the magnetic field. As Ha is increased, we observe that the vortex street changes from a strongly symmetric one to the alternate procession of counter-rotating vortices typical of the non-truncated cylinder wakes.
    Original languageEnglish
    Pages (from-to)341-367
    Number of pages27
    JournalJournal of Fluid Mechanics
    Volume691
    DOIs
    Publication statusPublished - Jan 2012

    Fingerprint

    ducts
    Lorentz force
    Ducts
    Magnetic fields
    wakes
    Steady flow
    magnetic fields
    Fluids
    Vortex flow
    steady flow
    inertia
    numerical flow visualization
    Vortex shedding
    Flow structure
    Flow visualization
    Magnetohydrodynamics
    vortex streets
    Hartmann number
    conducting fluids
    vortex shedding

    Bibliographical note

    © Cambridge University Press 2011

    Keywords

    • high-Hartmann-number flows
    • vortex streets
    • wakes

    Cite this

    Characterization of the flow past a truncated square cylinder in a duct under a spanwise magnetic field. / Dousset, Vincent; Potherat, Alban.

    In: Journal of Fluid Mechanics, Vol. 691, 01.2012, p. 341-367.

    Research output: Contribution to journalArticle

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