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An experimental investigation of chemically triggered convection is carried out. A two-layer system of miscible reactive fluids—the neutralization reaction between an acid and a base—is considered in a vertical Hele-Shaw cell. This system is subject to the action of gravity and vertical translational vibrations (modulated gravity). During the reaction, a less dense salt solution emerges in the reaction zone, thus triggering the buoyancy-driven convection in the form of concentration plumes rising in the upper layer. The particle image velocimetry is used as the method of study. The considered system is non-stationary, and a technique is developed for the processing of a long series of images registered during experiments. The evolution of the flow structures and of the convection intensity is analyzed. In the considered range of experimental parameters the vibrations slightly slow down the convection. [ABSTRACT FROM AUTHOR]

We report on chemoconvective pattern formation phenomena observed in a two-layer system of miscible fluids filling a vertical Hele-Shaw cell. We show both experimentally and theoretically that the concentration-dependent diffusion coupled with frontal acid-base neutralization can give rise to the formation of a local unstable zone low in density, resulting in a perfectly regular cell-type convective pattern. The described effect gives an example of yet another powerful mechanism which allows the reaction-diffusion processes to govern the flow of reacting fluids under gravity conditions. [ABSTRACT FROM AUTHOR]