Crossover from Intermittent to Continuum Dynamics for Locally Driven Colloids

TL;DR

This study investigates how a charged colloid driven through a disordered colloid assembly transitions from intermittent, heterogeneous motion to smooth, continuum-like behavior as the charge ratio increases, revealing a crossover in dynamics.

Contribution

It demonstrates the crossover from intermittent to continuum dynamics in driven colloids and characterizes the associated velocity fluctuations and response regimes.

Findings

Intermittent velocity fluctuations with 1/f noise at comparable charges.

Linear velocity-force relation with Gaussian fluctuations at high charge ratios.

Predictions for transient responses in different dynamical regimes.

Abstract

We simulate a colloid with charge q_d driven through a disordered assembly of interacting colloids with charge q and show that, for q_d \approx q, the velocity-force relation is nonlinear and the velocity fluctuations of the driven particle are highly intermittent with a 1/f characteristic. When q_d >> q, the average velocity ddrops, the velocity force relation becomes linear, and the velocity fluctuations are Gaussian. We discuss the results in terms of a crossover from strongly intermittent heterogeneous dynamics to continuum dynamics. We also make several predictions for the transient response in the different regimes.