Impact of a Viscous Liquid Drop

TL;DR

This paper uses simulations to study how viscous liquid drops impact dry surfaces, revealing the formation of a uniform-thickness pancake shape influenced by boundary layer dynamics.

Contribution

It introduces a simulation-based analysis of viscous drop impact, highlighting the boundary layer's role in shaping the final pancake form.

Findings

Impact results in a pancake shape with uniform thickness.

Boundary layer dynamics determine the pancake thickness.

Surface tension effects are significant at the rim.

Abstract

We simulate the impact of a viscous liquid drop onto a smooth dry solid surface. As in experiments, when ambient air effects are negligible, impact flattens the falling drop without producing a splash. The no-slip boundary condition at the wall produces a boundary layer inside the liquid. Later, the flattening surface of the drop traces out the boundary layer. As a result, the eventual shape of the drop is a "pancake" of uniform thickness except at the rim, where surface tension effects are significant. The thickness of the pancake is simply the height where the drop surface first collides with the boundary layer.