Deformed liquid marble formation: Experiments and computational modeling

TL;DR

This study combines experiments and computational modeling to understand how liquid marbles form when drops impact powder beds, revealing key relationships and developing a new mathematical model for the process.

Contribution

It introduces the first mathematical model for liquid marble formation via drop impact, integrating experimental data and surface viscous effects.

Findings

Good agreement between impact on powder beds and superhydrophobic surfaces

Development of a model capturing encapsulation and freezing thresholds

Simulations qualitatively match experimental features

Abstract

The formation of deformed liquid marbles via impact of drops onto powder beds is analysed using experimental and computational modelling approaches. Experimentally, particular attention is paid to determining a relationship between the maximum contact area of the spreading drops, which determines how much powder the drop's surface is able to harvest, and the drop's surface area when the powder (potentially) encapsulates and then immobilises (`freezes') the surface of the drop to form a liquid marble. Comparisons between impacts on powder beds to those on rigid and impermeable superhydrophobic substrates show good agreement for a range of parameters and motivate the development of the first mathematical model for the process of liquid marble formation via drop impact. The model utilises experimentally-determined functions to capture encapsulation and freezing thresholds and accounts for the powder's influence on the drop via a surface viscous mechanism. Simulations in the volume-of-fluid framework qualitatively recover many features of the experiments and highlight physical effects that should be incorporated into future analyses.