Biomimicry News
Recent News |  Archives |  Tags |  About |  Newsletter |  Submit News |  Links |  Subscribe to BiomimicryNews.com RSS Feed Subscribe


More Articles
The story of animal domestication retoldThe story of animal domestication retold

Diffeomorphometry and geodesic positioning systems for human anatomyDiffeomorphometry and geodesic positioning systems for human anatomy

Thermoelectric generator on glass fabric for wearable electronic devicesThermoelectric generator on glass fabric for wearable electronic devices

Scientists grow cartilage to reconstruct noseScientists grow cartilage to reconstruct nose

Simplicity is key to co-operative robotsSimplicity is key to co-operative robots

Researchers develop ErSb nanostructures with applications in infrared and terahertz rangesResearchers develop ErSb nanostructures with applications in infrared and terahertz ranges

Appearance of night-shining clouds has increasedAppearance of night-shining clouds has increased

Ancient shark fossil reveals new insights into jaw evolutionAncient shark fossil reveals new insights into jaw evolution

Deadly human pathogen Cryptococcus fully sequencedDeadly human pathogen Cryptococcus fully sequenced

Vitamin B3 might have been made in space, delivered to Earth by meteoritesVitamin B3 might have been made in space, delivered to Earth by meteorites

Chemists' work with small peptide chains may revolutionize study of enzymes and diseasesChemists' work with small peptide chains may revolutionize study of enzymes and diseases

Satellite shows high productivity from US corn beltSatellite shows high productivity from US corn belt

Sperm meets egg: Protein essential for fertilization discoveredSperm meets egg: Protein essential for fertilization discovered

Researchers determine how mechanical forces affect T-cell recognition and signalingResearchers determine how mechanical forces affect T-cell recognition and signaling

The surprising consequences of banning chocolate milkThe surprising consequences of banning chocolate milk

Running geese give insight into low oxygen toleranceRunning geese give insight into low oxygen tolerance

Galactic serial killerGalactic serial killer

Positive, negative thinkers' brains revealedPositive, negative thinkers' brains revealed

Babies prefer fairness -- but only if it benefits them -- in choosing a playmateBabies prefer fairness -- but only if it benefits them -- in choosing a playmate

A new twist makes for better steel, researchers findA new twist makes for better steel, researchers find

Renewable energy market share climbs despite 2013 dip in investmentsRenewable energy market share climbs despite 2013 dip in investments

Study finds gaming augments players' social livesStudy finds gaming augments players' social lives

A breakthrough in creating invisibility cloaks, stealth technologyA breakthrough in creating invisibility cloaks, stealth technology

Overcoming structural uncertainty in computer modelsOvercoming structural uncertainty in computer models

Monkey caloric restriction study shows big benefit; contradicts earlier studyMonkey caloric restriction study shows big benefit; contradicts earlier study

Researchers developed world's first fluorescent sensor to detect date rape drugResearchers developed world's first fluorescent sensor to detect date rape drug

Copied from nature: Detecting software errors via genetic algorithmsCopied from nature: Detecting software errors via genetic algorithms

Turning back the clock on aging muscles?Turning back the clock on aging muscles?

New study finds differences in concussion risk between football helmetsNew study finds differences in concussion risk between football helmets

Amazing skin gives sharks a push (2/13/2012)

Tags:
swimming, locomotion, sharks, fish

Streamlined sharks are legendary for their effortless swimming. George Lauder from Harvard University, USA, explains that the fish have long inspired human engineers, but more recently attention has focused on how the fish's remarkable skin boosts swimming. Coated in razor sharp tooth-like scales, called denticles, the skin is thought to behave like the dimples on a golf ball, disturbing the flow of water over the surface to reduce the drag. But something didn't quite sit right with Lauder. 'All of the shark skin studies were done on flat shark skin mimics that were held straight and immovable. But shark skin moves', recalls Lauder. So, when Masters student Johannes Oeffner joined his lab, Lauder suggested that they take a look at the fluid dynamics of shark skin and its analogues to find out how the fish's motion affects fluid flowing over the rough surface. The duo publishes its discovery that shark skin actually generates thrust to give the fish an additional boost in The Journal of Experimental Biology at http://jeb.biologists.org/.

But first the scientists had to get hold of some fresh shark skin, so they went to a market in Boston where they found several large makos. Back in the lab, Oeffner carefully removed sections from a mako's skin and attached them to both sides of a rigid aluminium foil. Then he immersed the foil in a flow tank, reproduced the swimming motion of a fish by wiggling it from side to side and measured the rigid 'swimming' foil's speed by matching it with the flow of water moving in the opposite direction.

Having measured the foil's swimming speeds with intact skin - compete with denticles - Oeffner carefully sanded off the denticles and set the foil swimming again. However, instead of slowing down - as the duo had expected - the denticle-free foil speeded up. So the shark skin's denticle surface impeded the rigid swimmer. 'But then we remembered our premise that the sharks aren't rigid', remembers Lauder, so how would the shark skin perform when flexing like a real fish?

Gluing two pieces of shark skin together to produce a flexible foil, Oeffner repeated the swimming experiment, and this time the denticles had a dramatic effect. The intact skin foil swam 12.3% faster than the sanded skin. The shark's rough surface improved the swimming performance spectacularly.

However, when the duo tested the swimming performance of two shark skin mimics - a sharp-edged riblet design and the famous SpeedoŽ FastskinŽ FS II fabric - they were in for a shock. Although the riblet surface improved the flexible foil's swimming speed by 7.2%, the dented surface of the SpeedoŽ fabric had no effect at all. However, Lauder points out that figure-hugging FastskinŽ swimming costumes probably enhance the swimmer's performance in other ways.

After proving that the denticles on shark skin significantly improve the fish's propulsion, Lauder and Oeffner were keen to find out how they affect fluid flows around the body. Returning the flexible shark skin foil to the swim tunnel, Oeffner and Lauder captured the water's swirling motion with laser light and realised that in addition to reducing drag, the skin was actively generating thrust.

'That's the number one surprise. It's not just the drag-reducing properties, but the denticles alter the structure of flow near the shark skin in a way that enhances thrust', explains Lauder. He is now keen to design physical models to see how altered denticle arrangements affect fluid flows over the skin and to build a computational model to tease apart the beneficial effects of the skin's thrust and drag reduction.Note: This story has been adapted from a news release issued by the The Company of Biologists

Post Comments:

Search
New Articles
Gecko-like adhesives now useful for real world surfacesGecko-like adhesives now useful for real world surfaces

Antennae help flies 'cruise' in gusty winds

Inspired by moth eyeballs, chemists develop gold coating that dims glare

Researchers uncover secrets of a mollusk's unique bioceramic armor

Gecko-inspired adhesion: Self-cleaning and reliableGecko-inspired adhesion: Self-cleaning and reliable

Bats inspire 'micro air vehicle' designsBats inspire 'micro air vehicle' designs

How stick insects honed friction to grip without stickingHow stick insects honed friction to grip without sticking

Quest for jellyfish robot leads to discovery of bending rules for animal wing, fin tipsQuest for jellyfish robot leads to discovery of bending rules for animal wing, fin tips

Artificial leaf jumps developmental hurdleArtificial leaf jumps developmental hurdle

Artificial cells and salad dressingArtificial cells and salad dressing

Robotic fish aids understanding of how animals move

New 'pomegranate-inspired' design solves problems for lithium-ion batteriesNew 'pomegranate-inspired' design solves problems for lithium-ion batteries

With their amazing necks, ants don't need 'high hopes' to do heavy liftingWith their amazing necks, ants don't need 'high hopes' to do heavy lifting

Fur and feathers keep animals warm by scattering lightFur and feathers keep animals warm by scattering light

Seashells inspire new way to preserve bones for archeologists, paleontologists



Archives
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
October 2006


Science Friends
Agricultural Science
Astronomy News
Sports Tech
Biology News
Cognitive Research
Chemistry News
Tissue Engineering
Cancer Research
Cybernetics Research
Electonics Research
Forensics Report
Fossil News
Genetic Archaeology
Genetics News
Geology News
Microbiology Research
Nanotech News
Parenting News
Physics News


  Archives |  Submit News |  Advertise With Us |  Contact Us |  Links
Use of this site constitutes acceptance of our Terms of Service and Privacy Policy. All contents © 2000 - 2015 Web Doodle, LLC. All rights reserved.