Nonlinear development of convective patterns driven by a neutralization reaction in immiscible two-layer systems

Area of Science:

• Fluid Dynamics
• Chemical Engineering
• Pattern Formation

Background:

• Buoyancy-driven instabilities are crucial in various natural and industrial processes.
• Understanding reaction-induced instabilities in multiphase systems is complex.
• Previous models often neglect the impact of reaction byproducts like water.

Purpose of the Study:

• To theoretically and experimentally investigate buoyancy-driven instabilities in an immiscible two-layer system undergoing a neutralization reaction.
• To develop a novel mathematical model incorporating reaction-produced water.
• To establish a stability map predicting flow patterns based on initial concentrations.

Main Methods:

• Utilized a vertical Hele-Shaw cell for experiments and theoretical modeling.
• Defined a reaction-induced buoyancy number to predict flow patterns.
• Employed a reaction-diffusion-convection model within the Hele-Shaw approximation, including water production.

Main Results:

• Observed distinct flow patterns: cellular convection, fingering, and Rayleigh-Taylor convection, correlating with the reaction-induced buoyancy number.
• The novel model accurately predicted flow behavior, including the stabilizing effect of dynamically released water during reaction zone collapse.
• Experimental data showed good agreement with theoretical predictions, validating the developed model.

Conclusions:

• The study provides a comprehensive understanding of buoyancy-driven instabilities in reacting systems.
• The inclusion of water production in the model offers a more accurate representation of pattern formation.
• The stability map serves as a valuable tool for predicting and controlling flow patterns in such systems.