Fluid-Solid Reaction in Porous Media as a Chaotic Restart Process

Area of Science:

• Porous materials science
• Chemical reaction engineering
• Fluid dynamics

Background:

• Reactions at fluid-solid interfaces are crucial for porous materials.
• Solute transport limitations in pores can decrease reaction rates.
• The effect of chaotic mixing on surface reactions in porous media is not well understood.

Purpose of the Study:

• To investigate the impact of pore-scale chaotic mixing on reaction efficiency.
• To determine if chaotic mixing enhances reaction rates at fluid-solid interfaces.
• To understand the mechanisms behind enhanced reaction rates due to chaotic mixing.

Main Methods:

• Numerical simulations of fluid flow and solute transport in porous media.
• Analysis of reaction rates under chaotic and nonchaotic flow conditions.
• Modeling reaction rates using diffusive first-passage times and stochastic restart processes.

Main Results:

• Pore-scale chaotic mixing significantly increases reaction efficiency compared to nonchaotic flows.
• Reaction rates are accurately described by diffusive first-passage times influenced by Lagrangian chaos.
• A characteristic scaling of reaction efficiency with Péclet number was observed under chaotic mixing.

Conclusions:

• Chaotic mixing is a key factor in enhancing reaction efficiency at fluid-solid interfaces in porous materials.
• The findings suggest that reaction rates are largely independent of flow topology in chaotic regimes.
• This research highlights the broad relevance of chaotic mixing for various porous material applications.