Featured Research

from universities, journals, and other organizations

Grains And Liquids Demonstrate Similar Cohesion Effects

Date:
June 19, 2008
Source:
CNRS
Summary:
What if sand flowed like water? Researchers have just demonstrated that even without an attractive force between grains in flowing sand, they have a cohesion similar to that of liquids.

Glass beads flowing from a funnel.
Credit: Copyright CNRS 2008 Yacine Amarouchene

What if sand flowed like water? Researchers at Centre de Physique Moléculaire Optique et Hertzienne (CNRS/ Université Bordeaux  have just demonstrated that even without an attractive force between grains in flowing sand, they have a cohesion similar to that of liquids.

How do grains flow out of an emptying silo? Or And what about sugar poured out by a pastry chef?  Like liquids, grains can flow, but there is no attraction between the grains to ensure trigger cohesion. However, by studying the waves that form and propagate on the surface of flowing sand, the physicists have observed telltale signs of cohesion. Like the very small ripples that form on the surface of water, these waves point to the existence of a “taut elastic skin” on the surface of volumes of grain surfaces. This “skin” on flowing grain flows is its surface tension.

The surface of a liquid is similar to an elastic membrane under tension, which causes, for example, the pressure on the interior of soap bubbles. This “surface tension” is due to cohesion forces between molecules in the liquid.

By measuring wave propagation speed, the researchers have shown that this cohesion effect is a result of reduces a decrease in air pressure between flowing grains. Therefore, when a mass of grains flows, there is a depressed area at the middle of the pressure is reduced within the flow, which bringing pulls straying grains back towards the mass. These results are goingshould improve our understanding of the details of what happens on a very small scale in grain flows – these materials may bewhich are common, but they are not yet well understood.


Story Source:

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


Journal Reference:

  1. Amarouchene et al. Capillarylike Fluctuations at the Interface of Falling Granular Jets. Physical Review Letters, 2008; 100 (21): 218001 DOI: 10.1103/PhysRevLett.100.218001

Cite This Page:

CNRS. "Grains And Liquids Demonstrate Similar Cohesion Effects." ScienceDaily. ScienceDaily, 19 June 2008. <www.sciencedaily.com/releases/2008/06/080611185948.htm>.
CNRS. (2008, June 19). Grains And Liquids Demonstrate Similar Cohesion Effects. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2008/06/080611185948.htm
CNRS. "Grains And Liquids Demonstrate Similar Cohesion Effects." ScienceDaily. www.sciencedaily.com/releases/2008/06/080611185948.htm (accessed September 30, 2014).

Share This



More Matter & Energy News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Argentina's Tax Evaders Detected, Hunted Down by Drones

Argentina's Tax Evaders Detected, Hunted Down by Drones

AFP (Sep. 30, 2014) — Argentina doesn't only have Lionel Messi the footballer, it has now also acquired "Mesi" the drone system which monitors undeclared mansions, swimming pools and soy fields to curb tax evasion in the country. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Do Video Games Trump Brain Training For Cognitive Boosts?

Do Video Games Trump Brain Training For Cognitive Boosts?

Newsy (Sep. 29, 2014) — More and more studies are showing positive benefits to playing video games, but the jury is still out on brain training programs. Video provided by Newsy
Powered by NewsLook.com
CERN Celebrates 60 Years of Science

CERN Celebrates 60 Years of Science

Reuters - Business Video Online (Sep. 29, 2014) — CERN, the European Organisation for Nuclear Research, celebrates 60 years of bringing nations together through science. As Joanna Partridge reports from inside the famous science centre it's also planning to turn the Large Hadron Collider particle accelerator back on after an upgrade. Video provided by Reuters
Powered by NewsLook.com
This 'Invisibility Cloak' Is Simpler Than Most

This 'Invisibility Cloak' Is Simpler Than Most

Newsy (Sep. 28, 2014) — Researchers from the University of Rochester have created a type of invisibility cloak with simple focal lenses. 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