Séminaire du LHyGes
Intervenant : Marco DENTZ, Research Professor, Hydrogeology Group - Universitat Politechnica de Calalunia, Dpt of Geosciences - Institute of Environmental Assessment and Water Research (IDAEA-CSIC) - Barcelone (Espagne)
Titre : "Mixing in Heterogeneous Porous Media"
Lieu : EOST, 1 rue Blessig, amphi 2
Résumé :
Solute dispersion and mixing are key processes for the prediction of the fate of contaminants in geological media. Dispersion informs on the speed by which the solute spreads in a medium, while mixing describes the process that leads to dilution of a dissolved substance. Solute mixing is a central process for the understanding of chemical reaction rates in heterogeneous media. Traditionally the terms mixing and spreading have been used synonymously.
While this is a valid assumption for homogeneous media, it is in general not true for heterogeneous environments.
The mixing dynamics are governed by the creation and destruction of concentration contrast. We quantify these dynamics by the scalar dissipation rate for Darcy-scale transport through heterogeneous porous media.
In order to quantify the mechanisms of mixing in terms of the heterogeneous medium properties, we relate deformation properties of porous media flow to the evolution of the entropy of the solute distribution. Finally, we present a mixing model for porous media transport based on the Lagrangian stretching dynamics of a materal line.