Stochastic jetting and dripping in confined soft granular flows

TL;DR

This paper uncovers new stochastic jetting and dripping behaviors in confined soft granular flows, driven by individual grain chaos, with implications for modeling tissue dynamics and soft matter systems.

Contribution

It introduces novel dynamical modes in soft granular flows, linking microscopic chaos to macroscopic flow phenomena, and suggests microfluidic emulsions as models for biological tissue behavior.

Findings

Observation of stable granular jets and avalanching dynamics.

Non-Gaussian distribution of cluster sizes in flow.

Resemblance of droplet rearrangements to cancer cell unfolding.

Abstract

We report new dynamical modes in confined soft granular flows, such as stochastic jetting and dripping, with no counterpart in continuum viscous fluids. The new modes emerge as a result of the propagation of the chaotic behaviour of individual grains -- here, monodisperse emulsion droplets to the level of the entire system as the emulsion is focused into a narrow orifice by an external viscous flow. We observe avalanching dynamics and the formation of remarkably stable jets -- singlefile granular chains -- which occasionally break, resulting in a non-Gaussian distribution of cluster sizes. We find that the sequences of droplet rearrangements that lead to the formation of such chains resemble unfolding of cancer cell clusters in narrow capillaries, overall demonstrating that microfluidic emulsion systems could serve to model various aspects of soft granular flows, including also tissue dynamics at the meso-scale.