Frozen fronts in cellular flows

TL;DR

This study investigates how reaction fronts behave in cellular flows with and without disorder, revealing that fronts tend to freeze or pin to flow structures across various conditions, with implications for natural and engineered systems.

Contribution

The paper demonstrates that front pinning occurs widely in cellular flows, regardless of boundary conditions, and introduces experimental evidence of front freezing in both ordered and disordered flow configurations.

Findings

Fronts freeze or pin to flow separatrices over a range of winds.

Freezing is common in disordered cellular flows.

Pinning occurs independently of boundary conditions.

Abstract

We present experiments on the behavior of reaction fronts in ordered and disordered cellular flows with imposed winds. Fronts in a chain of alternating vortices are found to freeze (pin to the separatrix) for a wide range of imposed winds that grows nonlinearly with the characteristic strength of the underlying vorticity. Experiments in spatially-disordered flows demonstrate that freezing of fronts is common to cellular flows; furthermore, it is not dependent on boundary conditions. We therefore anticipate similar pinning in a wide range of cellular flows and front-producing systems.