Patterned deposition at moving contact lines

TL;DR

This paper reviews recent experimental and modeling studies on the patterns formed by liquids and suspensions as they recede from solid surfaces, emphasizing mesoscopic hydrodynamic models and future research directions.

Contribution

It provides a comprehensive overview of recent advances in understanding patterned deposition at moving contact lines, focusing on mesoscopic hydrodynamic modeling approaches.

Findings

Different deposit structures depend on receding speed and wetting properties.

Complex liquids can form various structured deposits, including lines and hierarchical patterns.

Mesoscopic models help explain the formation of these patterns.

Abstract

When a simple or complex liquid recedes from a smooth solid substrate it often leaves a homogeneous or structured deposit behind. In the case of a receding non-volatile pure liquid the deposit might be a liquid film or an arrangement of droplets depending on the receding speed of the meniscus and the wetting properties of the system. For complex liquids with volatile components as, e.g., polymer solutions and particle or surfactant suspensions, the deposit might be a homogeneous or structured layer of solute - with structures ranging from line patterns that can be orthogonal or parallel to the receding contact line via hexagonal or square arrangements of drops to complicated hierarchical structures. We review a number of recent experiments and modelling approaches with a particular focus on mesoscopic hydrodynamic long-wave models. The conclusion highlights open question and speculates about future developments.