  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.
