Van der Waals interaction between a moving nano-cylinder and a liquid thin film

TL;DR

This paper investigates how a moving nano-cylinder interacts with a thin liquid film, analyzing deformation and stability influenced by parameters like film thickness and probe speed, using numerical models based on lubrication and van der Waals forces.

Contribution

It introduces a numerical approach combining lubrication and van der Waals models to study dynamic probe-liquid interactions, highlighting effects of physical and geometrical parameters.

Findings

Film thickness and probe speed affect the threshold for jump-to-contact instability.

Numerical deformation profiles reveal parameter sensitivities.

Results support using nano-probes to measure thin film properties.

Abstract

We study the static and dynamic interaction between a horizontal cylindrical nano-probe and a thin liquid film. The effects of the physical and geometrical parameters, with a special focus on the film thickness, the probe speed, and the distance between the probe and the free surface are analyzed. Deformation profiles have been computed numerically from a Reynolds lubrication equation, coupled to a modified Young-Laplace equation, which takes into account the probe/liquid and the liquid/substrate non-retarded van der Waals interactions. We have found that the film thickness and the probe speed have a significant effect on the threshold separation distance below which the jump-to-contact instability is triggered. These results encourage the use of horizontal cylindrical nano-probes to scan thin liquid films, in order to determine either the physical or geometrical properties of the latter, through the measurement of interaction forces.