High Rayleigh number convection in a porous medium containing a thin low-permeability layer

Hewitt, Duncan R. and Neufeld, Jerome A. and Lister, John R. (2014) High Rayleigh number convection in a porous medium containing a thin low-permeability layer. Journal of Fluid Mechanics, 756. pp. 844-869. ISSN 0022-1120, ESSN: 1469-7645 DOI 10.1017/jfm.2014.478

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Abstract

Porous geological formations are commonly interspersed with thin, roughly horizontal, low-permeability layers. Statistically steady convection at high Rayleigh number Ra is investigated numerically in a two-dimensional porous medium that is heated at the lower boundary and cooled at the upper, and contains a thin, horizontal, low-permeability interior layer. In the limit that both the dimensionless thickness h and permeability Π of the low-permeability layer are small, the flow is described solely by the impedance of the layer Ω=h/Π and by Ra. In the limit Ω→0 (i.e. h→0), the system reduces to a homogeneous Rayleigh–Darcy (porous Rayleigh–Bénard) cell. Two notable features are observed as Ω is increased: the dominant horizontal length scale of the flow increases; and the heat flux, as measured by the Nusselt number Nu, can increase. For larger values of Ω, Nu always decreases. The dependence of the flow on Ra is explored, over the range 2500⩽Ra⩽2×104. Simple one-dimensional models are developed to describe some of the observed features of the relationship Nu(Ω).

Item Type:	Article
Uncontrolled Keywords:	2014AREP; IA68;
Subjects:	99 - Other
Divisions:	02 - Geodynamics, Geophysics and Tectonics 99 - Other
Journal or Publication Title:	Journal of Fluid Mechanics
Volume:	756
Page Range:	pp. 844-869
Identification Number:	10.1017/jfm.2014.478
Depositing User:	Sarah Humbert
Date Deposited:	06 Feb 2015 17:08
Last Modified:	16 Feb 2015 18:27
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3222

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