Chemo-hydrodynamic patterns due to precipitation reactions


Abstract : Upon displacement of pollutant in soils or injection of CO2 in underground reservoirs for sequestration purposes, hydrodynamic instabilities may take place at the interface between the injected and displaced fluids. Such convective instabilities are also observed in material science technology when a solution of one reactant is injected into another one and a reaction takes place in the reaction zone. By combined theoretical and experimental approaches, we investigate the influence of chemical reactions on the efficiency of such displacements. In particular, we analyze to what extent chemo-hydrodynamic patterns due to the interplay between reactions and flows can reinforce mixing and spreading of the chemicals or on the contrary induce their trapping in localized area of the soils or reactor. The objective of the PhD thesis will be to study the specific case of precipitation reactions in presence of fingering phenomena due to gradients of viscosity or permeability. The model system we study experimentally are chemical gardens i.e. plant-like forms that develop when a solution of a metallic salt is injected into a solution of silica. Complex patterns are obtained, which result from a combination of precipitation, buoyancy, viscous fingering and mechanical effects. Analyzing these spatial structures by reaction-diffusion-convection models should yield insight into the relative importance of these various effects on the dynamics.
Promoteur/Supervisor : Prof. De Wit Anne
Email : adewit@ulb.ac.be
Site Web/Web site : http://www.ulb.ac.be/sciences/nlpc/
Centre de recherche/Research center : Nonlinear physical chemistry unit
Faculté/Faculty : Faculté des Sciences/Faculty of Sciences
Ecole doctorale/Graduate Colleges : Sciences/Science
Ecole doctorale thématique/Graduate School (French Only): Phénomènes non-linéaires, systèmes complexes et mécanique statistique



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