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Colloidal transport phenomena in dynamic, pulsating porous materials
Sachit G Nagella1, Sho C Takatori1
1Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA, United States.
Aiche Journal. American Institute of Chemical Engineers
|December 11, 2023
Summary
Colloidal particle transport in dynamic porous media is enhanced by obstacle oscillations, exceeding normal diffusion. This enhanced diffusion depends on particle and hydrodynamic interactions.
Area of Science:
- Physics
- Colloid Science
- Soft Matter Physics
Background:
- Colloidal transport in static porous media is well-understood.
- Colloidal diffusion in dynamic, nonequilibrium porous environments remains poorly understood.
- Dynamic porous media present unique transport challenges.
Purpose of the Study:
- To investigate colloidal particle transport in a dynamic porous material.
- To understand the fundamental mechanisms of colloidal diffusion in nonequilibrium environments.
- To quantify the effect of obstacle motion on particle dispersion.
Main Methods:
- Taylor dispersion theory
- Brownian dynamics simulations
- Optical tweezer experiments
- Solving the Smoluchowski equation with a generalized dispersion framework
Main Results:
- Colloidal particle dispersion shows non-monotonic dependence on oscillation frequency.
- A maximum in dispersion was observed, exceeding Stokes-Einstein-Sutherland diffusivity.
- Enhanced transport is driven by direct and hydrodynamic interactions with moving obstacles.
Conclusions:
- Oscillating porous media can significantly enhance colloidal transport.
- Both direct interparticle and fluid-mediated hydrodynamic interactions are critical.
- This study provides fundamental insights into nonequilibrium transport phenomena.
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