Exploring buoyancy-driven effects in chemo-hydrodynamic oscillations sustained by bimolecular reactions

Abstract

Exotic dynamics, previously associated only with reactions involving complex kinetics, have been observed even with simple bimolecular reactions A + B → C, when coupled with hydrodynamical flows. Numerical studies in two-dimensional reactors have shown that oscillatory dynamics can emerge from an antagonistic coupling between chemically-driven buoyancy and Marangoni convective flows, induced by changes in density and surface tension, respectively, as the reaction occurs. Here, we investigate reactions increasing both surface tension and density, leading to a cooperative coupling between the flows and show how, in this configuration, buoyancy-driven contribution dampens spatio-temporal oscillations of concentration. We finally identify the key parameters controlling the onset and persistence of the oscillatory instability, namely the density and surface tension gradients, and the systems height.