Buoyancy-driven flow around $A + B \rightarrow C$ reaction fronts propagating in Hele-Shaw cells: Parabolic flights experiments and numerical simulations

The dynamics of $A + B \rightarrow C$ reaction fronts is studied under modulated gravitational acceleration by means of a combination of parabolic flight experiments and numerical simulations. During modulated gravity the front position undergoes periodic modulation with an accelerated front propagation under hyper-gravity together with a slowing down under low gravity. The underlying reason for this is an amplification and a decay respectively, of the buoyancy-driven double vortex associated with the front propagation under standard gravitational acceleration, as explained by reaction-diffusion-convection simulations of an $A + B \rightarrow C$ front propagating in a thin layer. Deeper insights into the correlation between grey-value changes in the experimental shadowgraph images and characteristic changes in the concentration profiles are obtained by a numerical simulation of the imaging process.