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SUMMARY:Filling box flows in porous media - Chunendra Sahu\, BP Institute
DTSTART:20180301T113000Z
DTEND:20180301T123000Z
UID:TALK97975@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:Motivated from buoyancy/density-driven flows in confined sub-s
 urface environment\, e.g. carbon sequestration and geothermal energy recov
 ery\, a novel solution is presented for buoyant convection from an isolate
 d source in uniform and non-uniform porous media of \nfinite extents. In t
 he former case\, the problem is divided into three flow regimes: (i) a neg
 atively-buoyant plume\, (ii) gravity current comprising discharged plume f
 luid that forms when the plume reaches the bottom (impermeable) boundary\,
  and\, (iii) the subsequent ascending motion of this discharged plume flui
 d towards the source after the gravity current reaches the vertical side w
 alls. Analytical solutions are derived for all three regimes in a rectilin
 ear geometry with a line source and in an axisymmetric geometry with a poi
 nt source. By synthesizing the above three flow regimes\, a "fi\nlling box
 " model is developed that can predict the time needed for a source of dens
 e fluid to fi\nll the control volume up to the point of overflow as a func
 tion of the source and reservoir parameters.\n\nExtending the above result
 s to a nonuniform porous medium\, the effects of sudden permeability chang
 es in a \nfilling box flow are studied for the case of rectilinear geometr
 y. The porous medium consists of two thick horizontal layers of different 
 permeabilities. Two con\nfigurations are examined: a lower permeable mediu
 m on top of the higher permeability layer and vice-versa. While the flow d
 ynamics observed in the fi\nrst con\nfiguration are qualitatively similar 
 to the case of a uniform porous medium\, a signi\nficantly different  flow
  behaviour is observed in the latter con\nfiguration. Here not all of the 
 plume fluid enters the lower layer. Rather some significant fraction propa
 gates along the (horizontal) interface between the upper and lower layers 
 as an intrusive gravity current exhibiting \nfingering instabilities along
  its bottom surface. Depending on the source parameters and permeability r
 atio\, the gravity current can reach only a certain length before draining
  completely into the lower layer. Analytical solutions are presented for t
 his runout length and the corresponding \nfilling box time. Similitude exp
 eriments were then also performed to verify these predictions.\n
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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