Nanoscale flow past a colloidal cylinder confined in a slit channel: Lubrication theory and molecular dynamics analysis

Abstract

Plane Poiseuille flow past a nanoscale cylinder that is arbitrarily confined (i.e., symmetrically or asymmetrically confined) in a slit channel is studied via hydrodynamic lubrication theory and molecular dynamics simulations, considering cases where the cylinder remains static or undergoes thermal motion. Lubrication theory predictions for the drag force and volumetric flow rate are in close agreement with molecular dynamics simulations of flows having molecularly thin lubrication gaps, despite the presence of significant structural forces induced by the crystalline structure of the modeled solid. While the maximum drag force is observed in symmetric confinement, i.e., when the cylinder is equidistant from both channel walls, the drag decays significantly as the cylinder moves away from the channel centerline and approaches a wall. Hence, significant reductions in the mean drag force on the cylinder and hydraulic resistance of the channel can be observed when thermal motion induces random off-center displacements. Analytical expressions and numerical results in this work provide useful insights into the hydrodynamics of colloidal solids and macromolecules in confinement.

Crossover from shear-driven to thermally activated drainage of liquid-infused microscale capillaries

“…It is necessary to model the effects of random thermal motion when surface defects have dimensions smaller than 100 nm and become comparable to the nanoscale thermal fluctuations of the liquid interface. The interplay between thermal motion and nanoscale surface features can lead to nontrivial wetting processes that are induced by thermal fluctuations of the contact line [17][18][19][20][21][22][23][24][25][26]. A few different approaches have been proposed to model the effect thermal motion and nanoscale surface defects s d ≤ 1 nm have on the dynamics of wetting.…”

“…The interplay between thermal motion and nanoscale surface features can lead to nontrivial wetting processes that are induced by thermal fluctuations of the contact line [17][18][19][20][21][22][23][24][25][26]. A few different approaches have been proposed to model the effect thermal motion and nanoscale surface defects s d ≤ 1 nm have on the dynamics of wetting.…”