Flow, transport and chemistry in porous media : numerical methods for coupled problems
Event details
| Date | 07.05.2009 |
| Hour | 14:15 |
| Speaker | Dr. Michel Kern |
| Location |
MAA112
|
| Category | Conferences - Seminars |
Understanding mass transfer phenomena in the subsurface is becoming increasingly important for environmental issues : predicting pollution and remediation strategies, assessing the feasibility of a
nuclear 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
situations. Flow simulations are based on Darcy's law, and require accurate methods (based on mixed finite elements) for computing the velocity in heterogeneous situations. Fractured media, where the
fractures play the role of preferential channels, can be handled by an extension of the substructuring technique used in domain decomposition. The velocity is the main input for the transport model, an advection-dispersion type equation, possibly with sharp fronts. Saltwater intrusion in an aquifer is a situation where flow and transport are coupled through the state equation for density. We devote a large part of the talk to the coupling of transport with chemistry. Under the hypo-
thesis of local equilibrium, the model couples transport PDEs with local algebraic equations. We give a formulation based on aqueous and fixed total concentrations, and show how the usual fixed point
problem can be solved using a Newton-Krylov method. This enables us to use a global formulation for the coupled problem, while keeping the transport and chemistry codes (usually written by different groups) separate. We illustrate our approach on standard test cases.
Links
Practical information
- General public
- Free
Contact
- Marco Discacciati & Alfio Quarteroni