The effect of gravity and dimensionality on the impact of cylinders and spheres onto a wall in a viscous fluid
Abstract
As a solid body approaches a wall in a viscous fluid, the flow in the gap between them is dominated by the viscous effect and can be approximated by the lubrication theory. Here we show that without gravity, a cylinder comes to rest asymptotically at a finite separation from the wall, whereas with gravity, the cylinder approaches the wall asymptotically and contact does not happen in finite time. A cylinder approaches the wall much slower compared to a sphere under matching conditions, implying that the lubrication approximates hold longer before the molecular scale sets in. Our results further serve as a building block for analyzing particle interactions in close proximity, and provide analytic results for integrating the lubrication theory into the computations of Navier-Stokes equations. © Published by AIP Publishing.