Featured Research

from universities, journals, and other organizations

Streaming Sand Grains Help Define Essence Of A Liquid

Date:
June 25, 2009
Source:
National Science Foundation
Summary:
Researchers recently showed that dry granular materials such as sands, seeds and grains have properties similar to liquid, forming water-like droplets when poured from a given source. The finding could be important to a wide range of industries that use "fluidized" dry particles for oil refining, plastics manufacturing and pharmaceutical production.

In a first-time accomplishment, physicists from the Materials Research Science and Engineering Center at the University of Chicago used high-speed photography to measure minute levels of surface tension and detect droplet formation in flows of dry granular materials. The finding could be important to industries that use "fluidized" dry particles for oil refining, plastics manufacturing, pharmaceutical production and other mechanized processes.
Credit: Helge F. Gruetjen, John R. Royer, Scott R. Waitukaitis, and Heinrich M. Jaeger, The University of Chicago

University of Chicago researchers recently showed that dry granular materials such as sands, seeds and grains have properties similar to liquid, forming water-like droplets when poured from a given source. The finding could be important to a wide range of industries that use "fluidized" dry particles for oil refining, plastics manufacturing and pharmaceutical production.

Researchers previously thought dry particles lacked sufficient surface tension to form droplets like ordinary liquids. But, in a first-time accomplishment, physicists from the Materials Research Science and Engineering Center at the University of Chicago, led by Professor Heinrich M. Jaeger, used high-speed photography to measure minute levels of surface tension and detect droplet formation in flows of dry granular materials.

The science journal Nature reports the finding in its June 25 issue. The materials research center at the University of Chicago is supported by the National Science Foundation.

Until recently, studies of so-called "free falling granular streams" tracked shape changes in flows of dry materials, but were unable to observe the full evolution of the forming droplets or the clustering mechanisms involved.

"Previous studies of granular streams were able to detect clustering by performing experiments in vacuum and were able to establish that the clustering was not caused by the drag from the ambient air," said Jaeger. "However, the cause of the clustering remained a mystery."

But in this new experiment, researchers measured nanoscale forces that cause droplet formation using a special co-moving apparatus devised for a high-speed, $80,000 camera that captures images much like a skydiver might photograph a fellow jumper in free fall.

They observed falling 100-micrometer-diameter glass beads, or streaming sand, and found that forces as much as 100,000 times smaller than those that produce surface tension in ordinary liquids could cause droplet formation in granular streams and cause these dry streams to behave like an ultra-low-surface-tension liquid.

John Royer, the graduate student in physics at the University of Chicago, who developed the apparatus, and his colleagues also directly measured grain-to-grain interactions with an atomic force microscope.

"At first we thought grain-grain interactions would be far too weak to influence the granular stream," said Royer. "The atomic force microscopy surprised us by demonstrating that small changes in these interactions could have a large impact on the break up of the stream, conclusively showing that these interactions were actually controlling the droplet formation."

Researchers say understanding how dry materials coalesce could create greater efficiencies in their transportation and manipulation. The pharmaceutical production of pills, for example, could benefit by pouring equal amounts of a drug into a capsule every time while greatly reducing waste.

"Estimates show that we waste 60 percent of the capacity of many of our industrial plants due to problems related to the transport of these materials," said Jaeger. "Hence even a small improvement in our understanding of how granular media behave should have a profound impact for industry."

The researchers write in their report that these "experimental results open up new territory for which there currently is no theoretical framework."

"Our experiments ask two questions for which currently there is no established answer," said Jaeger. "Both questions are about how a liquid breaks apart. How does the break-up proceed in the ultra-low surface-tension limit and what happens in the ultra-low temperature limit when particles cease to move relative to each other?

"It is quite remarkable that a granular stream consisting of macroscopic particles provides a model system to explore it."


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Cite This Page:

National Science Foundation. "Streaming Sand Grains Help Define Essence Of A Liquid." ScienceDaily. ScienceDaily, 25 June 2009. <www.sciencedaily.com/releases/2009/06/090624152946.htm>.
National Science Foundation. (2009, June 25). Streaming Sand Grains Help Define Essence Of A Liquid. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2009/06/090624152946.htm
National Science Foundation. "Streaming Sand Grains Help Define Essence Of A Liquid." ScienceDaily. www.sciencedaily.com/releases/2009/06/090624152946.htm (accessed October 22, 2014).

Share This



More Matter & Energy News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) — Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) — Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) — As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com
What Is Magic Leap, And Why Is It Worth $500M?

What Is Magic Leap, And Why Is It Worth $500M?

Newsy (Oct. 22, 2014) — Magic Leap isn't publicizing much more than a description of its product, but it’s been enough for Google and others to invest more than $500M. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins