Engineered Porous Membranes

This thrust develops models to understand how membrane geometry, texture, and surface charge distribution influence water and ion transport through pores and heterogeneous porous media. The chemical physics of the fluid are encoded in free energy functionals, providing direct access to equilibrium thermodynamic properties. Conservation laws are then imposed to describe fluid transport and the internal stresses generated within the solid matrix.

Motivation

Many public utility applications benefit from improved control of species transport in porous media. Surface texture and non-uniform pore properties can be exploited to regulate flow, enhance mixing, and filter ions and colloids by charge and size. This thrust focuses on electrokinetic phenomena as mechanisms for manipulating flow in porous media.

Applications include:

• Enhanced oil recovery via electrochemical gradients
• Electro-remediation of contaminated soils
• Desalination and water purification
• Blue energy harvesting from osmotic mixing fronts
• Membrane distillation

Key Innovations

A central contribution of our group is integrating transport mechanics with classical density functional theory (cDFT), which captures finite-size effects and density fluctuations in molecular and colloidal systems. Rather than resolving individual particles explicitly, cDFT models ensemble-averaged density fields—enabling larger system sizes and longer timescales than molecular dynamics at moderate computational cost.

We are also developing hybrid Brownian dynamics–cDFT methods, in which a reduced number of particles are explicitly tracked while interactions are represented through cDFT-derived forces.

At the mesoscale, we have developed two complementary frameworks:

1. Poromechanical network models — constructed using Voronoi tessellation and Delaunay triangulation to generate interacting elastic and pore networks.
2. Continuum free-energy formulations — in which fluid and solid phases are encoded in a Helmholtz free energy functional with gradient energy terms generating texture and interfaces.

Key Findings

A systematic study of electrokinetic flow in charge-patterned corrugated nanochannels (Petersen et al., 2026) demonstrated:

• Flow gating via discontinuous transitions in bulk flow
• Selective ionic current control
• Ionic diode behavior with near-perfect charge selectivity

These results establish a design framework for electrokinetic control in engineered pores and nanochannels.