Nonlinear Physical Chemistry Unit
Service de Chimie Physique et Biologie
Théorique
Hydrodynamically unstable liquid-liquid interfaces influenced by chemical reactions underly many industrial applications. Our objective is a theoretical study of pattern formation due to the coupling between chemical reactions at interfaces and hydrodynamical instabilities (or also chemically driven interfacial convection, CDIC). Our focus is on understanding the underlying physical mechanisms which can range from Rayleigh-Bénard, Rayleigh-Taylor and double-diffusive to Marangoni instabilities. Our goal is to analyze by combined analytical and numerical analysis how a simple A+B->S chemical reaction can trigger and influence these various hydrodynamical instabilities in a two-layer system contained in a Hele-Shaw cell. Related experiments are performed in the group of Kerstin Eckert in Dresden and Veronique Pimienta in Toulouse. Our combined work takes place in the framework of the international collaboration Chemo-hydrodynamic instabilities at interfaces sponsored by ESA and national space agencies (Prodex, DLR, CNES, Hungarian Space Agency).
Chemically-driven convection in the lower layer of a system of two immiscible fluids brought into contact, each phase containing the reactant of a simple A+B->C reaction. The set-up oriented vertically in the gravity field shows buoyancy-driven convection when the heavier species A initially contained in the upper layer crosses the interface and starts to react with the lighter B to produce the product C of intermediate density.
References:
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D.A Bratsun, Y. Shi, K. Eckert and A. De Wit, Control of chemo-hydrodynamic pattern formation by localized cooling, Europhys. Lett, 69, 746-752 (2005).
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D.A. Bratsun and A. De Wit, On Marangoni convective patterns driven by an exothermic chemical reaction in two-layer systems", Phys. Fluids, 16, 1082-1096 (2004).