Space Industry and Business News  





.
TECH SPACE
Mixing fluids efficiently in confined spaces: Let the fingers do the working

Follow this link to a movie simulation showing that the formation of "fingers" by a yellow fluid moving through a more viscous fluid causes the two to mix quickly and naturally. Video / Birendra Jha of the Juanes Lab, MIT
by Denise Brehm
Boston MA (SPX) May 17, 2011
Getting two fluids to mix in small or confined spaces is a big problem in many industries where, for instance, the introduction of one fluid can help extract another - like water pumped underground can release oil trapped in porous rock - or where the mixing of liquids is the essential point of the process. A key example of the latter is microfluidics technology, which allows for the controlled manipulation of fluids in miniscule channels often only a few hundred nanometers wide.

Microfluidic devices were first introduced in the 1980s and for many years were best known for their use in ink-jet printers, but have since been introduced in other fields, including the chemical analysis of blood or other sera in lab-on-a-chip technologies. These devices - usually not much larger than a stick of chewing gum - sometimes rely on nano-sized moving components, the geometry of the grooved channels or pulsed injections to induce a mixing of the fluids. But researchers in MIT's Department of Civil and Environmental Engineering suggest that a simpler method might be equally, if not more, effective.

"Getting two fluids to mix in a very tight space is difficult because there's not much room for a disorderly flow," said Professor Ruben Juanes, the ARCO Associate Professor in Energy Studies and principal investigator on the research. "But with two fluids of highly contrasting viscosity, the thinner fluid naturally creates disorder, which proves to be a marvelously efficient means of mixing."

In an analysis published online May 12 in Physical Review Letters (PRL), the researchers show that the injection of a thin or low-viscosity fluid into a much more viscous fluid (think of water spurting into molasses) will cause the two fluids to mix very quickly via a physical process known as viscous fingering. The thinner liquid, say the researchers, will form fingers as it enters the thicker liquid, and those fingers will form other fingers, and so on until the two liquids have mixed uniformly.

They also found that for maximum mixing to occur quickly, the ideal ratio of the viscosity of any two fluids depends on the speed at which the thinner liquid is injected into the thicker one.

The research team of Juanes, postdoctoral associate Luis Cueto-Felgueroso and graduate students Birendra Jha and Michael Szulczewski, made a series of controlled experiments using mixtures of water and glycerol, a colorless liquid generally about a thousand times more viscous than water. By alternating the viscosity of the liquids and the velocity of the injection flows, Jha was able to create a mathematical model of the process and use that to determine the best viscosity ratio for a particular velocity. He is lead author on the PRL paper.

"It's been known for a very long time that a low viscosity fluid will finger through the high viscosity fluid," said Juanes. "What was not known is how this affects the mixing rate of the two fluids. For instance, in the petroleum industry, people have developed increasingly refined models of how quickly the low viscosity fluid will reach the production well, but know little about how it will mix once it makes contact with the oil."

Similarly, Juanes said, in microfluidics technology, the use of fluids of different viscosities has not been seriously proposed as a mixing mechanism, but the new study indicates it could work very efficiently in the miniscule channels.

"We can now say that on average, the viscosity of the fluid injected should be about 10 times lower than that of the fluid into which it is injected," said Juanes. "If the contrast is greater than 10, then the injection should be done more slowly to achieve the fastest maximum mixing. Otherwise, the low viscosity fluid will create a single channel through the thicker fluid, which is not ideal."

Cueto-Felgueroso said a similar process is at work in the engraved channels of a microfluidic device and in subsurface rock containing oil. "Mixing fluids at small scales or velocities is difficult because you can't rely on turbulence: it would be hard to stir milk into your coffee if you were using a microscopic cup," Cueto-Felgueroso said. "With viscous fingering, you let the fluids do the job of stirring."

This work was funded by the Italian energy company, Eni, and the ARCO Chair in Energy Studies.




Share This Article With Planet Earth
del.icio.usdel.icio.us DiggDigg RedditReddit
YahooMyWebYahooMyWeb GoogleGoogle FacebookFacebook



Related Links
-
Space Technology News - Applications and Research



Tempur-Pedic Mattress Comparison

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News
TECH SPACE
Making strong, tough metallic glass cheaply
Pasadena CA (SPX) May 16, 2011
Stronger than steel or titanium - and just as tough - metallic glass is an ideal material for everything from cell-phone cases to aircraft parts. Now, researchers at the California Institute of Technology (Caltech) have developed a new technique that allows them to make metallic-glass parts utilizing the same inexpensive processes used to produce plastic parts. With this new method, they c ... read more

.
Get Our Free Newsletters Via Email
  


TECH SPACE
How to control complex networks

Video gaming teens sleep less: study

Mixing fluids efficiently in confined spaces: Let the fingers do the working

When is it worth the cost of remanufacturing

TECH SPACE
Northrop Grumman Awarded Contract to Develop EHF SatComms Antenna for B-2 Bomber

Lockheed Martin To Produce Equipment For US Army Tactical On-The-Move Network

Emirates lofts satellite to boost military

LockMart Battle Command System Replaces US Army Legacy System

TECH SPACE
ST-2's installation on SYLDA marks the start of final payload integration for Ariane 5's next mission

Arianespace to launch ABS-2 in 2013

GSAT-8 put through its paces

Ariane Ariane 5 enjoys second successful launch for 2011

TECH SPACE
Europe's first EGNOS airport to guide down giant Beluga aircraft

'Green' GPS saves fuel, energy

Apple update fixes iPhone tracking "bugs"

Russia, Sweden to boost space cooperation

TECH SPACE
Solar plane makes 13-hour flight

Swiss solar aircraft makes first international flight

China Southern Airlines unit buys six Boeing 787s

Successful advanced JAXA drop test performed at Esrange Space Center

TECH SPACE
Graphene optical modulators could lead to ultrafast communications

Pentagonal tiles pave the way towards organic electronics

NRL Scientists Achieve High Temperature Milestone in Silicon Spintronics

Intel chip breakthrough a boon for mobile gadgets

TECH SPACE
ESA's water mission keeps tabs on dry spring soils

Aquarius to Illuminate Links Between Salt and Climate

Mississippi Flooding Captured by NASA Satellites

India's new satellite beams high quality images

TECH SPACE
Indian government vows to pursue Bhopal case

India's top court refuses to reopen Bhopal case

The skinny on how shed skin reduces indoor air pollution

Italian soldiers start clearing Naples garbage


The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. 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 SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement