Stratified gravity currents in porous media

Pegler, Samuel S. and Huppert, Herbert E. and Neufeld, Jerome A. (2016) Stratified gravity currents in porous media. Journal of Fluid Mechanics, 791. pp. 329-357. ISSN 0022-1120, ESSN: 1469-7645 DOI 10.1017/jfm.2015.733

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Official URL: http://dx.doi.org/10.1017/jfm.2015.733

Abstract

We consider theoretically and experimentally the propagation in porous media of variable-density gravity currents containing a stably stratified density field, with most previous studies of gravity currents having focused on cases of uniform density. New thin-layer equations are developed to describe stably stratified fluid flows in which the density field is materially advected with the flow. Similarity solutions describing both the fixed-volume release of a distributed density stratification and the continuous input of fluid containing a distribution of densities are obtained. The results indicate that the density distribution of the stratification significantly influences the vertical structure of the gravity current. When more mass is distributed into lighter densities, it is found that the shape of the current changes from the convex shape familiar from studies of the uniform-density case to a concave shape in which lighter fluid accumulates primarily vertically above the origin of the current. For a constant-volume release, the density contours stratify horizontally, a simplification which is used to develop analytical solutions. For currents introduced continuously, the horizontal velocity varies with vertical position, a feature which does not apply to uniform-density gravity currents in porous media. Despite significant effects on vertical structure, the density distribution has almost no effect on overall horizontal propagation, for a given total mass. Good agreement with data from a laboratory study confirms the predictions of the model.

Item Type: Article
Uncontrolled Keywords: 2015AREP; IA70
Subjects: 03 - Mineral Sciences
99 - Other
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Journal of Fluid Mechanics
Volume: 791
Page Range: pp. 329-357
Identification Number: 10.1017/jfm.2015.733
Depositing User: Sarah Humbert
Date Deposited: 28 Apr 2016 11:52
Last Modified: 28 Apr 2016 11:52
URI: http://eprints.esc.cam.ac.uk/id/eprint/3651

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