Deposit Growth in the Wetting of an Angular Region with Uniform Evaporation

TL;DR

This paper models solvent evaporation-driven flow and solute deposition near a sharp corner in a drying drop with uniform evaporation, revealing distinct deposit patterns compared to dry-surface evaporation.

Contribution

It extends previous models by analyzing uniform evaporation effects on solute deposition at a corner, highlighting differences from dry-surface evaporation profiles.

Findings

Uniform evaporation causes more singular early-time deposit growth.

Intermediate-time deposition is nearly uniform across a range of angles.

Contrast between acute and obtuse angles is more pronounced with uniform evaporation.

Abstract

Solvent loss due to evaporation in a drying drop can drive capillary flows and solute migration. The flow is controlled by the evaporation profile and the geometry of the drop. We predict the flow and solute migration near a sharp corner of the perimeter under the conditions of uniform evaporation. This extends the study of Ref. 6, which considered a singular evaporation profile, characteristic of a dry surrounding surface. We find the rate of the deposit growth along contact lines in early and intermediate time regimes. Compared to the dry-surface evaporation profile of Ref. 6, uniform evaporation yields more singular deposition in the early time regime, and nearly uniform deposition profile is obtained for a wide range of opening angles in the intermediate time regime. Uniform evaporation also shows a more pronounced contrast between acute opening angles and obtuse opening angles.