Stochastic migrations of Marangoni surfers between two lobes of a dumbbell-shaped confinement

TL;DR

This study experimentally investigates the stochastic migration behavior of Marangoni surfers in a dumbbell-shaped chamber, revealing how aging and interactions influence their stability and distribution.

Contribution

It introduces a detailed experimental analysis of Marangoni surfer dynamics, modeling them as Chiral Active Particles and linking motility decay to migration stability.

Findings

Equal partitioning of disks is most stable.

Stretched exponential decay describes migration dynamics.

Decreased motility leads to aging effects in the system.

Abstract

We report an experimental investigation on the stochastic migration dynamics of Marangoni surfers (camphor-infused paper disks) between the two lobes of a dumbbell-shaped chamber. We characterize the migration dynamics using survival analysis for a given configuration with a unique disk count in each lobe. Qualitatively, all the configurations exhibit stretched exponential decay with time, ascribed to a disk s aging. A given configuration s stability decreases with increasing pairwise interactions. The most stable configuration is always the one with equal partitioning of disks between the lobes, i.e., exactly one-half of disks in each lobe for even-numbered systems but with one extra disk in either of the lobes for odd-numbered systems. Furthermore, we model a camphor disk as a Chiral Active Particle (CAP), as initially proposed by Cruz et al. and show that decreasing motility (or aging) indeed causes the stretched exponential behavior.