Particles accelerate the detachment of viscous liquids

TL;DR

This study reveals that even a single particle within a viscous filament significantly accelerates droplet detachment by perturbing the thinning process, providing insights into particulate effects on fluid detachment dynamics.

Contribution

It demonstrates how individual particles influence viscous filament thinning and accelerates droplet detachment, extending understanding of particulate effects in fluid dynamics.

Findings

Single particles perturb filament thinning and accelerate detachment.

Particle size correlates with the degree of acceleration.

Insights applicable to dense suspensions and previous observations.

Abstract

During detachment of a viscous fluid extruded from a nozzle a filament linking the droplet to the latter is formed. Under the effect of surface tension the filament thins until pinch off and final detachment of the droplet. In this paper we study the effect of the presence of individual particles trapped in the filament on the detachment dynamics using granular suspensions of small volume fractions ({\phi} < 6%). We show that even a single particle strongly modifies the detachment dynamics. The particle perturbs the thinning of the thread and a large droplet of fluid around the particle is formed. This perturbation leads to an acceleration of the detachment of the droplet compared to the detachment ob- served for a pure fluid. We quantify this acceleration for single particles of different sizes and link it to similar ob- servations for suspensions of small volume fractions. Our study also gives more insight into particulate effects on de- tachment of more dense suspensions and allows to explain the accelerated detachment close to final pinch off observed previously (Bonnoit et al 2012)