Concentration-Dependent Diffusion Instability in Reactive Miscible Fluids

TL;DR

This paper investigates how concentration-dependent diffusion and neutralization reactions in miscible fluids lead to regular convective patterns in a Hele-Shaw cell, revealing a new mechanism for reaction-diffusion-driven flow instabilities.

Contribution

It introduces a novel chemoconvective pattern formation mechanism driven by concentration-dependent diffusion and neutralization in miscible fluids.

Findings

Experimental observation of regular cell-type convective patterns.

Theoretical explanation of the instability mechanism.

Identification of a new reaction-diffusion-driven flow instability.

Abstract

We report new 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 the frontal acid-base neutralization can give rise to formation of the 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 condition.