Nanoscale simulations of directional locking

TL;DR

This study uses molecular dynamics simulations to demonstrate that directional locking of particles in obstacle lattices persists at the nanoscale with molecular diffusion, revealing potential for particle separation applications.

Contribution

It provides the first nanoscale simulation evidence that directional locking occurs with molecular diffusion, exploring how various parameters influence the effect.

Findings

Directional locking persists at the nanoscale with diffusion.

Particle size and flow conditions affect locking degree.

Potential application in nanoparticle separation techniques.

Abstract

When particles suspended in a fluid are driven through a regular lattice of cylindrical obstacles, the particle motion is usually not simply in the direction of the force, and in the high Peclet number limit particle trajectories tend to lock along certain lattice directions. By means of molecular dynamics simulations we show that this effect persists in the presence of molecular diffusion for nanoparticle flows, provided the Peclet number is not too small. We examine the effects of varying particle and obstacle size, the method of forcing, solid roughness, and particle concentration. While we observe trajectory locking in all cases, the degree of locking varies with particle size and these flows may have application as a separation technique.