Nanoparticle dispersion in porous media: Effects of array geometry and flow orientation

Area of Science:

• Physics
• Fluid Dynamics
• Materials Science

Background:

• Understanding particle transport in ordered structures is crucial for applications like filtration and microfluidics.
• Previous studies often simplified array geometry or flow conditions.

Purpose of the Study:

• To investigate how array geometry and flow orientation influence the transport of finite-sized particles in ordered arrays.
• To elucidate the underlying mechanisms governing particle dispersion under various flow conditions.

Main Methods:

• Utilized Stokesian dynamics simulations to model particle behavior.
• Examined transport in ordered arrays of nanoposts with varying geometry and volume fractions.
• Analyzed particle diffusion and dispersion under quiescent and flowing conditions.

Main Results:

• Quiescent diffusion was found to be independent of array geometry within the studied volume fraction range.
• Longitudinal dispersion strongly depended on the incident flow direction relative to the array's lattice vectors.
• Taylor-Aris behavior was observed for flow aligned with lattice directions.
• Nonmonotonic dependence of the dispersion coefficient on Péclet number occurred for perturbed flow orientations due to competing effects.

Conclusions:

• Array geometry has a limited impact on quiescent diffusion but significantly influences dispersion under flow.
• Flow orientation is a critical parameter determining particle transport characteristics in ordered arrays.
• The complex interplay between directional locking and velocity variations dictates dispersion behavior in non-aligned flow conditions.