Self-assembling clusters of particles on a shrinking liquid surface

TL;DR

This study investigates how synthetic particles self-assemble into clusters on a shrinking liquid surface, combining experiments and simulations to understand the dynamics and final configurations of the particles.

Contribution

It provides new experimental and numerical insights into particle self-assembly driven by a shrinking liquid boundary, a phenomenon inspired by natural puddle phenomena.

Findings

Particles tend to aggregate as the liquid surface shrinks.

Cluster sizes and numbers evolve with packing fraction.

Numerical simulations qualitatively match experimental results.

Abstract

After rainfall, pine needles often float on the surface of small puddles. As the water evaporates, they self-assemble into distinct clusters. Motivated by this natural phenomenon, we experimentally investigate the dynamic evolution of synthetic particles as the liquid surface shrinks in area. Our experiments demonstrate the tendency of particles to aggregate, forming distinct clusters as the liquid boundary shrinks. We systematically examine the emergence of these clusters and explore how their sizes and numbers evolve with changes in packing fraction. We also analyze particle rotation during the process and discuss the formation of the final configuration comprising clusters of various orientations. Complementary numerical simulations demonstrate qualitative agreement with our experimental findings. This study sheds additional light on the self-assembly of macroscopic particles in a dynamically evolving medium.