Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Space Industry and Business News .




TECH SPACE
CCNY Team Models Sudden Thickening of Complex Fluids
by Staff Writers
New York NY (SPX) Jan 21, 2014


An increase in the rate of shearing of just 50 percent puts the suspension above the transition to DST, as depicted by the dense network of connections.

A new model by a team of researchers with The City College of New York's Benjamin Levich Institute may shed new understanding on the phenomenon known as discontinuous shear thickening (DST), in which the resistance to stirring takes a sudden jump. Easily observed in a 'kitchen experiment' by mixing together equal amounts of cornstarch and water, DST occurs because concentrated suspensions of hard particles in a liquid respond differently than normal fluids to shear forces.

Because many materials are handled in industrial applications as suspensions, engineers need to understand how to predict their flow properties. However, they have been hard-pressed to understand DST and calculate when it will occur during processing. Since concentrated suspensions are found in everything from consumer products to cement, a range of industries stand to find better ways to manage suspensions.

For simple liquids, such as water or glycerin, resistance increases in proportion to the stirring speed. However, in complex fluids such as suspensions, emulsions and polymers the relationship is not proportional. Resistance increases either faster than the stirring speed - shear thickening - or slower - shear thinning. DST occurs when resistance increases suddenly.

Research associates Ryohei Seto and Romain Mari and chemical engineering Professors Jeffrey Morris and Morton Denn set out to develop a model that would predict how resistance changes in relation to stirring speed. Their findings were reported in "Physical Review Letters" in November.

The model modifies the classical fluid mechanics approach to suspension behavior, in which liquid lubrication keeps particles from contact, to permit contact and to include forces resulting from friction as particles move past one another.

As friction increases two or more particles can act like a single entity with regard to the surrounding fluid. When concentrations of particles and the shear rate reach sufficient levels, the particles form temporary chains that can fill space. This causes jamming, which can make flow difficult or even impossible.

Using the model, the team was "able to accurately reproduce experimental observations of the steep viscosity versus shear rate curves and their evolution with packing friction, both of which are first for numerical simulations," Dr. Eric Brown, Yale University assistant professor of mechanical engineering and materials science, wrote in a commentary published in "Physics."

Future investigations will address moving beyond a simulation "that follows the mechanics of a finite number of particles in a cube to predicting the flow of concentrated suspensions in arbitrary geometries," Professor Denn noted. "A long-term goal is to be able to develop a 'continuum' description of concentrated suspensions in which the behavior is averaged over large numbers of particles."

On the Internet - Journal article (PRL 111, 218301 (2013)) - Viewpoint in "Physics" - Physics World" article

.


Related Links
City College of New York
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





TECH SPACE
What makes superalloys super - hierarchical microstructure of a superalloy
Berlin, Germany (SPX) Jan 21, 2014
Researchers have observed for the first time in detail how a hierarchical microstructure develops during heat treatment of a superalloy Materials in high-performance turbines have to withstand not only powerful mechanical forces, they also have to maintain their chemical and mechanical properties almost up to their melting points. For this reason, turbine manufacturers have employed specia ... read more


TECH SPACE
Smooth sailing: Rough surfaces that can reduce drag

CCNY Team Models Sudden Thickening of Complex Fluids

CCNY Team Models Sudden Thickening of Complex Fluids

ESA to develop satellite reentry technology

TECH SPACE
Boeing Transmits Protected Government Signal Through Military Satellite

Boeing Transmits Protected Government Signal Through Military Satellite

Fifth MUOS Completes Assembly, Enters System Test

Northrop Grumman Supports US Marine Corps Command, Control and Communications Facility for Tactical Air Operations

TECH SPACE
Turkish Telecoms Satellite to Launch From Baikonur Feb. 15

Russia's Soyuz Rocket to Get Video Cameras

NASA Commercial Crew Partner SpaceX Tests Dragon Parachute System

NASA's Commercial Crew Partners Aim to Capitalize, Expand on 2013 Successes in 2014

TECH SPACE
India to launch three navigation satellites this year

NGC Wins Contract For GPS-Challenged Navigation and Geo-Registration Solution

20th Anniversary of Initial Operational Capability of the GPS Constellation

Northrop Grumman and Trex Enterprises to Introduce Celestial Navigation to Soldier Precision Targeting Laser Systems

TECH SPACE
Boeing Starts Assembly of Final KC-46A Test Aircraft

Novel technology reveals aerodynamics of birds flying in a V-formation

Indonesia plane crashes after lightning strike, 4 dead

Indonesia closes in on Grumman F-5 Tiger replacement

TECH SPACE
Dutch hi-tech group ASML profits dip despite record sales

2-proton bit controlled by a single copper atom

New Technique for Probing Subsurface Electronic Structure

Fastest organic transistor heralds new generation of see-through electronics

TECH SPACE
Signed, Sealed and Delivered: New NASA Video Shows GPM's Journey to Japan

China's pollution seen from space

Charles River Analytics Develops Satellite Image Processing System for NASA

Earth may be heaver than thought due to invisible belt of dark matter

TECH SPACE
Loss of biodiversity limits toxin degradation

US consumers to blame for some air pollution from China

Waterfowl poisoning halved by lead shot prohibition

Dangerous pollution hits China's capital




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement