Stability of particles inside yield-stress fluid Poiseuille flows

Chaparian, Emad and Tammisola, Outi (2020) Stability of particles inside yield-stress fluid Poiseuille flows. Journal of Fluid Mechanics, 885. 1038. ISSN 0022-1120 (https://doi.org/10.1017/jfm.2019.1038)

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Abstract

The stability of neutrally and non-neutrally buoyant particles immersed in a plane Poiseuille flow of a yield-stress fluid (Bingham fluid) is addressed numerically. Particles being carried by the yield-stress fluid can behave in different ways: they might (i) migrate inside the yielded regions or (ii) be transported without any relative motion inside the unyielded region if the yield stress is large enough compared to the buoyancy stress and the other stresses acting on the particles. Knowing the static stability of particles inside a bath of quiescent yield-stress fluid (Chaparian & Frigaard, J.A Fluid Mech., vol.A 819, 2017, pp.A 311-351), we analyse the latter behaviour when the yield-stress fluid Poiseuille flow is host to two-dimensional particles. Numerical experiments reveal that particles lose their stability (i.e. break the unyielded plug and sediment/migrate) with smaller buoyancy compared to the sedimentation inside a bath of quiescent yield-stress fluid, because of the inherent shear stress in the Poiseuille flow. The key parameter in interpreting the present results is the position of the particle relative to the position of the yield surface in the undisturbed flow (in the absence of any particle): the larger the portion of a particle located inside the undisturbed sheared regions, the more likely is the particle to be unstable. Yet, we find that the core unyielded plug can grow locally to some extent to contain the particles. This picture holds even for neutrally buoyant particles, although they are strictly stable when they are located wholly inside the undisturbed plug. We propose scalings for all cases.

  • Item type:Article
    ID code:84362
    Dates:
    Date
    Event
    7 January 2020
    Published
    5 December 2019
    Accepted
    Notes:Funding Information: E.C. gratefully acknowledges the support of a Linné FLOW PostDoc grant during the course of this study. O.T. acknowledges the support of the Swedish Research Council through grant VR 2017-0489. Publisher Copyright: © The Author(s), 2020. Chaparian, E., & Tammisola, O. (2020). Stability of particles inside yield-stress fluid Poiseuille flows. Journal of Fluid Mechanics, 885, A45. doi:10.1017/jfm.2019.1038
    Subjects:Science > Physics
    Science > Mathematics
    Department:Faculty of Engineering > Mechanical and Aerospace Engineering
    Depositing user: Pure Administrator
    Date deposited:23 Feb 2023 09:16
    Last modified:11 Apr 2024 02:38
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/84362
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