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SUMMARY:Flow\, transport and chemistry in porous media : numerical methods
  for coupled problems
DTSTART:20090507T141500
DTSTAMP:20260916T043954Z
UID:4ea5855e90da1e0ffca5114e4997428cf4ab785b4acf7b7963a7cb27
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Michel Kern\nUnderstanding mass transfer phenomena in the 
 subsurface is becoming increasingly important for environmental issues : p
 redicting pollution and remediation strategies\, assessing the feasibility
  of a\nnuclear underground storage site or a carbon dioxide sequestration 
 site. These studies usually involve interaction between several phenomena\
 , such as reactive transport. In this talk\, we present numerical methods 
 both for the basic models and for handling coupled\nsituations. Flow simul
 ations are based on Darcy's law\, and require accurate methods (based on m
 ixed finite elements) for computing the velocity in heterogeneous situatio
 ns. Fractured media\, where the\nfractures play the role of preferential c
 hannels\, can be handled by an extension of the substructuring technique u
 sed in domain decomposition. The velocity is the main input for the transp
 ort model\, an advection-dispersion type equation\, possibly with sharp fr
 onts. Saltwater intrusion in an aquifer is a situation where flow and tran
 sport are coupled through the state equation for density. We devote a larg
 e part of the talk to the coupling of transport with chemistry. Under the 
 hypo-\nthesis of local equilibrium\, the model couples transport PDEs with
  local algebraic equations. We give a formulation based on aqueous and fix
 ed total concentrations\, and show how the usual fixed point\nproblem can 
 be solved using a Newton-Krylov method. This enables us to use a global fo
 rmulation for the coupled problem\, while keeping the transport and chemis
 try codes (usually written by different groups) separate. We illustrate ou
 r approach on standard test cases. 
LOCATION:MAA112
STATUS:CONFIRMED
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