Self-Sustained Reaction Fronts in Porous Media

TL;DR

This paper experimentally investigates chemical wave propagation in porous media, revealing how flow direction and rate influence reaction front velocity, shape, and pinning phenomena, with implications for understanding reaction dynamics in disordered systems.

Contribution

It provides new experimental insights into the behavior of reaction fronts in porous media, highlighting the conditions for static, downstream, and upstream propagation, and the role of flow-disorder interactions.

Findings

Reaction fronts travel at constant velocity depending on flow direction and rate.

Fronts can remain static over a range of flow rates due to pinning.

Frozen fronts exhibit a sawtooth shape influenced by flow and reaction competition.

Abstract

We analyze experimentally chemical waves propagation in the disordered flow field of a porous medium. The reaction fronts travel at a constant velocity which drastically depends on the mean flow direction and rate. The fronts may propagate either downstream and upstream but, surprisingly, they remain static over a range of flow rate values. Resulting from the competition between the chemical reaction and the disordered flow field, these frozen fronts display a particular sawtooth shape. The frozen regime is likely to be associated with front pinning in low velocity zones, the number of which varies with the ratio of the mean flow and the chemical front velocities.