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Natural convection and the evolution of a reactive porous medium

Ritchie, Lindsey Thomson and Pritchard, David (2011) Natural convection and the evolution of a reactive porous medium. Journal of Fluid Mechanics, 673. pp. 286-317. ISSN 0022-1120

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    Abstract

    We describe a mathematical model of buoyancy-driven flow and solute transport in a saturated porous medium, the porosity and permeability of which evolve through precipitation and dissolution as a mineral is lost or gained from the pore fluid. Imposing a vertically varying equilibrium solubility creates a density gradient which can drive convective circulation. We characterise the onset of convection using linear stability analysis, and explore the further development of the coupled reaction–convection system numerically. At low Rayleigh numbers, the effect of the reaction–permeability feedback is shown to be destabilising through a novel reaction–diffusion mechanism; at higher Rayleigh numbers, the precipitation and dissolution have a stabilising effect. Over longer time scales, reaction–permeability feedback triggers secondary instabilities in quasi-steady convective circulation, leading to rapid reversals in the direction of circulation. Over very long time scales, characteristic patterns of porosity emerge, including horizontal layering as well as the development of vertical chimneys of enhanced porosity. We discuss the implications of these findings for more comprehensive models of reactive convection in porous media.

    Item type: Article
    ID code: 30753
    Keywords: fluid mechanics, porus medium, natural convection, geophysical flows , geological flows, Mechanical engineering and machinery
    Subjects: Technology > Mechanical engineering and machinery
    Department: Faculty of Science > Mathematics and Statistics
    Related URLs:
      Depositing user: Pure Administrator
      Date Deposited: 06 May 2011 05:15
      Last modified: 14 Dec 2012 11:35
      URI: http://strathprints.strath.ac.uk/id/eprint/30753

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