Featured Research

from universities, journals, and other organizations

Granular Matter On The Boil Behaves Like Fluids

Date:
February 22, 2008
Source:
University of Twente
Summary:
When grains are shaken fiercely, they show behavior that can be compared to water on the boil. Convection takes place, with the typical rolling movement that can also be seen in water. For the first time, researchers show this phenomenon in granular matter using a high speed camera.

Granular convection, showing the same rolling movement that can be seen in water heating up.
Credit: Image courtesy of University of Twente

When grains are shaken fiercely, they show behaviour that can be compared to water on the boil. Convection takes place, with the typical rolling movement that can also be seen in water. For the first time, researcher Peter Eshuis of the University of Twente in The Netherlands shows this phenomenon in granular matter using a high speed camera. His research gains a better understanding of the behaviour of these materials that are often used and produced in industry.

Related Articles


Convection can be noticed in water when it nears the boiling point. Rolling movements then occur, to get rid of excess heat: heated fluid rises and cooler water falls, causing a roll. A similar and beautiful effect is seen in little balls shaken hard: starting with an eruption of rising fast balls that go down again, clusters are formed and a rotating movement starts. Just like in fluid, there are balls with lower energy clustering and with higher energy, moving fast. Analogous to the temperature of the boiling plate heating fluids, the shaking energy gives rise to phase transitions.

Before convection starts, at lower shaking intensities, the balls already show behaviour typical to fluids: in fluids this is called the Leidenfrost effect, when a droplet is ‘floating’ on a thin layer of gas. The same happens with vertically shaken balls: a packed cluster of balls ‘floats’ on a layer of fast moving balls. This layer is therefore called ‘granular gas’. Eshuis describes the transition from the Leidenfrost condition towards convection. This is not just a matter of rising the level of energy, he found out: there has to be an instability that causes the onset of convection. This instability causes some balls to cluster and others to free themselves.

Stagnation

Granular matter like grain, sugar, sand and pills, often give rise to unexpected effects during transport, processing or storage. This often causes stagnation in industrial processes or excessive energy consumption. Better understanding of the behaviour of the materials, like Eshuis presents in his thesis, helps to prevent these effect. He also proves that many phenomena like clustering of grains can be explained by treating and describing the materials like fluids.

Peter Eshuis (1980) studied Applied Physics at the University of Twente and did his PhD-research within the Physics of Fluids research group of prof. Detlef Lohse, part of the Institute of Mechanics, Processes and Control (IMPACT) of the University of Twente.


Story Source:

The above story is based on materials provided by University of Twente. Note: Materials may be edited for content and length.


Cite This Page:

University of Twente. "Granular Matter On The Boil Behaves Like Fluids." ScienceDaily. ScienceDaily, 22 February 2008. <www.sciencedaily.com/releases/2008/02/080217215051.htm>.
University of Twente. (2008, February 22). Granular Matter On The Boil Behaves Like Fluids. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2008/02/080217215051.htm
University of Twente. "Granular Matter On The Boil Behaves Like Fluids." ScienceDaily. www.sciencedaily.com/releases/2008/02/080217215051.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
First Etihad Superjumbo Flight in December

First Etihad Superjumbo Flight in December

AFP (Dec. 18, 2014) The first flight of Etihad Airways' long-awaited Airbus A380 superjumbo will take place later in December, the Abu Dhabi carrier said Thursday, also announcing its first Boeing 787 Dreamliner route. Duration: 01:09 Video provided by AFP
Powered by NewsLook.com
Ford Expands Air Bag Recall Nationwide

Ford Expands Air Bag Recall Nationwide

Newsy (Dec. 18, 2014) The automaker added 447,000 vehicles to its recall list, bringing the total to more than 502,000. 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