Precipitation induced filament pattern of injected fluid controlled by structured cell

TL;DR

This study investigates how injection rate and obstacles influence filament pattern formation during fluid precipitation in confined spaces, combining experiments and a mathematical model to control and predict these complex patterns.

Contribution

It demonstrates that injection rate and obstacle placement can reliably control filament patterns, supported by experimental results and a mathematical model.

Findings

High injection and low reaction rates produce filament patterns.

Injection rate controls the number of active filaments.

Structured obstacles straighten filament motion.

Abstract

Mixing of two fluids can lead to the formation of a precipitate. If one of the fluids is injected into a confined space filled with the other, a created precipitate disrupts the flow locally and forms complex spatiotemporal patterns. The relevance of controlling these patterns has been highlighted in the engineering and geological contexts. Here, we show that such injection patterns can be controlled consistently by injection rate and obstacles. Our experimental results revealed filament patterns for high injection and low reaction rates, and the injection rate can control the number of active filaments. Furthermore, appropriately spaced obstacles in the cells can straighten the motion of the advancing tip of the filament. A mathematical model based on a moving boundary adopting the effect of precipitation reproduced the phase diagram and the straight motion of filaments in structured cells. Our study clarifies the impact of the nonlinear permeability response on the precipitate density and that of the obstacles in the surrounding medium on the motion of the injected fluid with precipitation.