Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 149663

149663 - Clogging: The Self-Sabotage of Suspensions Flows 

Clogging is a common obstacle encountered during the transport of suspensions and represents a significant energy and material cost across applications, including water purification, irrigation, biopharmaceutical processing, and aquifer recharge. Clogging can occur whenever a suspension, comprised of discrete particles dispersed in a liquid, flows through a confined geometry. It is a major issue in many engineering systems, such as filtration devices, additive manufacturing, or in bioengineering. A key issue in modeling and preventing clogging is that it involves a wide range of time and length scales. For instance, clogging can occur in microscale filters over a few months through the deposition of colloidal particles, or in macroscopic pipes transporting water through the clogging of transported particles in a few milliseconds.

Generally, clogging mechanisms include sieving, when particles are too large to pass a constriction; bridging, when particles jam each other at a constriction and form a stable arch; and aggregation, the successive deposition of small cohesive particles at a constriction. One or two of those mechanisms may be more common in certain systems, but generally, all of them happen during the clogging process, which adds to the complexity of establishing a general picture. One must thus consider the role of the different clogging mechanisms. This presentation will report our past and ongoing efforts to characterize, model, and prevent - or at least delay - the clogging of fluid systems.

First, we will consider clogging by bridging: the formation of a stable arch of particles at a constriction. In this case, our experiments show that clogging by bridging is primarily controlled by the constriction width and the volume fraction of the suspension. However, we also show that the geometry of the system can be tuned to delay the clogging of the constriction. The situation becomes even more challenging with anisotropic particles, particularly fibers, as used in additive manufacturing.

 Second, we will report how pulsatile flows can help mitigate clogging by aggregation of colloidal particles when compared to steady flows in microfluidic systems. We highlight experimentally the influence of the amplitude and the frequency of pulsation on clog mitigation in a microfluidic array of parallel channels. By combining macroscopic flow rate measurements with direct visualizations at the pore scale, one can correlate the observed clogging dynamics with the changes in flow rate. The direct visualizations reveal the role of the rearrangement of particles when subject to a dynamic shear environment.

Even if clogging can commonly occur in a fluid system, understanding the mechanisms and conditions of clog formation can lead to new design principles and improve the reliability of multiple engineering systems.

Presenting Author: Alban Sauret University of California Santa Barbara and University of Maryland College Park

Presenting Author Biography: Alban Sauret is an Associate Professor in the Department of Mechanical Engineering at UC Santa Barbara and a Visiting Associate Research Professor at the University of Maryland, College Park. He graduated with a BS and an MS in Physics from ENS Lyon and earned a Ph.D. in Mechanical Engineering from the University of Aix-Marseille in 2013. He worked as a Postdoctoral Fellow at Princeton University with Howard Stone from 2013 to 2014. He then spent four years as a tenured CNRS Research Scientist and a visiting research scholar at NYU Tandon School of Engineering. He joined UC Santa Barbara in 2018. His research lies at the intersection of fluid mechanics and soft matter, as it aims to understand the dynamics of multiphase systems. Alban Sauret was named a Soft Matter Emerging and Pioneering Investigator and elected a UC Regents Junior Faculty Fellow. He has received the NSF CAREER Award in 2020, the APS Milton van Dyke Award, and the APS DSOFT Gallery of Soft Matter Award. His research has been featured in various media outlets such as the Los Angeles Times, the Wall Street Journal, and Science Friday.

Authors:

Alban Sauret University of California Santa Barbara and University of Maryland College Park