Nav: Home

Study shows how rough microparticles can cause big problems

October 12, 2017

New research from North Carolina State University, MIT and the University of Michigan finds that the surface texture of microparticles in a liquid suspension can cause internal friction that significantly alters the suspension's viscosity - effectively making the liquid thicker or thinner. The finding can help address problems for companies in fields from biopharmaceuticals to chemical manufacturing.

"We heard about problems companies were having with pumping suspensions and became curious about what was causing these problems," says Lilian Hsiao, an assistant professor of chemical and biomolecular engineering at NC State and lead author of a paper on the work. "Given the ubiquity of these types of fluids in the industry, we were surprised that no one had systematically looked at the role of surface roughness before. That turns out to be a really important factor in how these particle-laden fluids flow."

Using a combination of simulations and laboratory experiments, the researchers found that what was slowing down the suspensions was friction. Specifically, the friction becomes significant when enough particles suspended in the liquid bump into each other. And the rougher the surface of the particles, the more friction they generate when they come into contact.

"It takes energy to pump a liquid suspension through a pipe or tube, and the friction created by interaction between particles dissipates a lot of that energy," Hsiao says. "This dissipation slows down the movement of the suspension or, if the particles are very rough, can even stop it completely." A video demonstrating the difference between suspensions with rough particles and suspensions with smooth particles can be found at https://www.youtube.com/watch?v=oXRl2IdwdhY.

This insight gives industries a couple of options: They can reduce friction by engineering the particles to have smoother surfaces, or they can increase the amount of energy devoted to moving the suspension through the pipe.

However, the researchers also found that adding energy to a suspension that contains rough particles can also cause the suspension to expand. This is because rough particles simply take up more space than smooth ones when tumbling in suspension. The end result is that putting more shear stress into the system can cause catastrophic clogging if the suspension expands too much.

"This is a fundamental advance in our understanding of the physics of suspensions in flow, and should help engineers and scientists address the manufacturing challenges that caught our attention in the first place," Hsiao says.

"We're now looking at ways to use the principles we discovered here to make the friction work in our favor."
-end-
The paper, "Rheological state diagrams for rough colloids in shear flow," is published in the journal Physical Review Letters. The paper was co-authored by Safa Jamali of MIT, and Emmanouil Glynos, Peter Green, Ronald Larson and Michael Solomon of Michigan.

The work was done with support from the National Science Foundation, under grant number 1232937, and the U.S. Army Research Office, under award number W911NF10-1-0518.

North Carolina State University

Related Engineering Articles:

Engineering a new cancer detection tool
E. coli may have potentially harmful effects but scientists in Australia have discovered this bacterium produces a toxin which binds to an unusual sugar that is part of carbohydrate structures present on cells not usually produced by healthy cells.
Engineering heart valves for the many
The Wyss Institute for Biologically Inspired Engineering and the University of Zurich announced today a cross-institutional team effort to generate a functional heart valve replacement with the capacity for repair, regeneration, and growth.
Geosciences-inspired engineering
The Mackenzie Dike Swarm and the roughly 120 other known giant dike swarms located across the planet may also provide useful information about efficient extraction of oil and natural gas in today's modern world.
Engineering success
Academically strong, low-income would-be engineers get the boost they need to complete their undergraduate degrees.
HKU Engineering Professor Ron Hui named a Fellow by the UK Royal Academy of Engineering
Professor Ron Hui, Chair Professor of Power Electronics and Philip Wong Wilson Wong Professor of Electrical Engineering at the University of Hong Kong, has been named a Fellow by the Royal Academy of Engineering, UK, one of the most prestigious national academies.
Engineering a better biofuel
The often-maligned E. coli bacteria has powerhouse potential: in the lab, it has the ability to crank out fuels, pharmaceuticals and other useful products at a rapid rate.
Pascali honored for contributions to engineering education
Raresh Pascali, instructional associate professor in the Mechanical Engineering Technology Program at the University of Houston, has been named the 2016 recipient of the Ross Kastor Educator Award.
Scaling up tissue engineering
A team at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A.
Engineering material magic
University of Utah engineers have discovered a new kind of 2-D semiconducting material for electronics that opens the door for much speedier computers and smartphones that also consume a lot less power.
Engineering academic elected a Fellow of the IEEE
A University of Bristol academic has been elected a Fellow of the world's largest and most prestigious professional association for the advancement of technology.

Related Engineering Reading:

Basic Machines and How They Work
by Naval Education And Training Program (Author)

Engineering: An Illustrated History from Ancient Craft to Modern Technology (100 Ponderables)
by Tom Jackson (Editor) (Author), Tom Jackson (Editor)

101 Things I Learned® in Engineering School
by John Kuprenas (Author), Matthew Frederick (Author)

Practical Electronics for Inventors, Fourth Edition
by Paul Scherz (Author), Simon Monk (Author)

Engineering: A Very Short Introduction
by David Blockley (Author)

Mechanical Engineering Reference Manual for the PE Exam, 13th Ed
by Michael R. Lindeburg PE (Author)

The Engineering Book: From the Catapult to the Curiosity Rover, 250 Milestones in the History of Engineering (Sterling Milestones)
by Marshall Brain (Author)

Civil Engineering Reference Manual for the PE Exam, 15th Ed
by Michael R. Lindeburg PE (Author)

Studying Engineering: A Road Map to a Rewarding Career (Fourth Edition)
by Raymond B. Landis (Author)

The Beginner's Guide to Engineering: Mechanical Engineering
by Mark Huber (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Why We Hate
From bullying to hate crimes, cruelty is all around us. So what makes us hate? And is it learned or innate? This hour, TED speakers explore the causes and consequences of hate — and how we can fight it. Guests include reformed white nationalist Christian Picciolini, CNN commentator Sally Kohn, podcast host Dylan Marron, and writer Anand Giridharadas.
Now Playing: Science for the People

#482 Body Builders
This week we explore how science and technology can help us walk when we've lost our legs, see when we've gone blind, explore unfriendly environments, and maybe even make our bodies better, stronger, and faster than ever before. We speak to Adam Piore, author of the book "The Body Builders: Inside the Science of the Engineered Human", about the increasingly amazing ways bioengineering is being used to reverse engineer, rebuild, and augment human beings. And we speak with Ken Thomas, spacesuit engineer and author of the book "The Journey to Moonwalking: The People That Enabled Footprints on the Moon" about...