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SUMMARY:Transport in heterogeneous porous media - Dr Diogo Bolster\, Dept.
  of Geotechnical Engineering\, Polytechnic University of Catalunya
DTSTART:20080306T113000Z
DTEND:20080306T123000Z
UID:TALK10255@talks.cam.ac.uk
CONTACT:Anne Alexander
DESCRIPTION:In practice\, many porous media of interest\, particularly in 
 the natural world\, are highly heterogeneous. Often field scale data displ
 ays significantly different behaviour to simple laboratory experiments and
  homogeneous mathematical models. It is well known that medium heterogenei
 ties on a local scale have an important impact on the effective large scal
 e behaviour of solute transport.  Therefore\, understanding the influence 
 of hetereogeneity on flow and transport processes within a porous medium i
 s critical to a better understanding of real life observations. Using stoc
 hastic modelling techniques\, we have developed upscaled 'homogeneous' mat
 hematical models that aim to capture the influence of heterogeneity. In th
 is seminar we present the results on three areas of interest: \n\na) The i
 nfluence of spatial heterogeneities and temporal fluctuations on the trans
 port of a passive solute\, which has practical implications for the transp
 ort of subsurface contaminants. In particular we examine the enhanced mixi
 ng that is observed and quantify it by calculating effective dispersion co
 efficients that depend on the properties of the medium and flow. \n\nb) Th
 e influence of heterogeneities on multiphase flow. We study Buckley Levere
 tt (idealised immiscible two phase displacement) flow in a heterogeneous p
 orous medium under the influence of a temporally fluctuating flow field.  
 We also examine the influence of buoyancy\, which appears to significantly
  enhance 'mixing'. This project is motivated by a desire to understand the
  influence of heterogeneities on multiphase flow\, which has specific appl
 ications in CO2 sequestration and oil recovery.\n\nc) The effect that vari
 able flow paths (in heterogeneous and some homogeneous media) have on cont
 aminant transport. Often\, on the macroscale\, the diffusion/dispersion of
  a passive tracer appears to behave in a non-Fickian manner. Using simple 
 models we attempt to explain/quantify these observations by considering th
 e fact that within a porous medium parcels that have been displaced over t
 he the same distance in one dimension can have traveled along different fl
 ow paths and thus very different distances. While locally all transport wi
 ll be Fickian these varying flow paths can lead to highly non-Fickian beha
 viour on the large scale. 
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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