Chemical production on a deforming substrate

The interplay between chemical reaction and substrate deformation is discussed by adapting Ranz's formulation for scalar mixing to the case of a reactive mixture between segregated reactants, initially separated by an interface whose thickness may not be vanishingly small. Experiments in a simple shear flow demonstrate the existence of three regimes depending on the Damkohler number Da = t(s)/t(c) where t(s) is the mixing time of the interface width and t(c) is the chemical time. Instead of treating explicitly the chemical cross-term, we rationalize these different regimes by globalizing it as a production term involving a flux which depends on the rate at which the reaction one is fed by the reactants, a formulation valid for Da > 1. For Da < 1, the reactants interpenetrate before they react, giving rise to a 'diffusio-chemical' regime where chemical production occurs within a substrate whose width is controlled by molecular diffusion.

Automated summary

This study discusses the interplay between chemical reaction and substrate deformation by adapting Ranz's formulation for scalar mixing to the case of a reactive mixture between segregated reactants. Experiments in a simple shear flow demonstrate the existence of three regimes depending on the Damkohler number. For Da > 1, the different regimes are rationalized by globalizing the chemical cross-term as a production term involving a flux. For Da < 1, the reactants interpenetrate before they react, giving rise to a 'diffusio-chemical' regime where chemical production occurs within a substrate controlled by molecular diffusion.