How Do Dolphins Swim So Fast

ImaginaryNumber · Jan 17, 2014

Mystery Solved: How Do Dolphins Swim So Fast | NATIONAL GEOGRAPHIC

…Physics theory states that for something the size of a dolphin—and for the speed with which it travels through the ocean—water flow over the animal should be turbulent rather than smooth, Fish said. That turbulent flow creates a lot more drag that needs to be overcome than smooth flow does. But when Gray input his variables into his equations and assumed a turbulent flow, "he found the animal didn't have enough muscle mass to produce the power it needed to swim at that speed," said Fish. "This became Gray's paradox," Fish said—sparking a decades-long search for an explanation of how dolphins powered through the water…

Wei had devised a bubble curtain to stand in place of the illuminated glass beads so that he could determine forces generated by human swimmers. So Fish and colleagues created a bubble curtain at the University of California, Santa Cruz (UCSC), where they performed experiments with two captive bottlenose dolphins…

The results showed that a dolphin's tail, or fluke, is more than capable of producing enough thrust to speed the mammal through the water…

The flukes are also flexible, which is key to enabling the dolphin to maintain a highly efficient way of swimming over a broad range of speeds. "The dolphin may have the ability to control that flexibility," Fish explained. It could be that the fluke becomes stiffer the faster the dolphin swims, increasing its swimming efficiency at high speeds. Or maybe the dolphins can actively control fluke stiffness by changing the tension of tendons in their tail, he said…
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For reference see Gray's Paradox

daiquiri · Jan 16, 2014

Sometimes I am lead to think that some scientists live in a parallel world of their own, with very few or no touching points with ours.

ImaginaryNumber said: ↑

But when Gray input his variables into his equations and assumed a turbulent flow, "he found the animal didn't have enough muscle mass to produce the power it needed to swim at that speed," said Fish.
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This could be a nice example of ignorance behind the authority brought by an academic title. Lucky for dolphins they can't read, so they couldn't learn about the above findings. Had they read about it, it would have left them so discouraged that perhaps they'd never try to swim again...

ImaginaryNumber said: ↑

The results showed that a dolphin's tail, or fluke, is more than capable of producing enough thrust to speed the mammal through the water…
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Oh, this sounds like an official act of approval. So Dolphins are now officially certified to have enough power and thrust to swim at the speed they always swim. They can feel relieved.

ImaginaryNumber said: ↑

"The flukes are essentially wings," said Fish. "[They] generate a lift force that is directed forward, on both the upstroke and downstroke." This produces the thrust that pushes the dolphin through the water.
...
"The flukes are also flexible, which is key to enabling the dolphin to maintain a highly efficient way of swimming over a broad range of speeds. "The dolphin may have the ability to control that flexibility," Fish explained. It could be that the fluke becomes stiffer the faster the dolphin swims, increasing its swimming efficiency at high speeds. Or maybe the dolphins can actively control fluke stiffness by changing the tension of tendons in their tail", he said…
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As said at the beginning... Welcome to our planet, Mr. Fish.

This one is probably the best:

"Now he has the answer: Bottlenose dolphins can produce the power they need to swim circles around whatever they wish by using their powerful tails, new experiments show"
What, no kidding??!! They push through the water by using their tails? OMG!!!

Ok, I better stop here, guess I'm a bit acid today.. I am looking forward to seeing this one compete for this year's Ig Nobel Prize.

PAR · Jan 16, 2014

So easily cynical of well funded projects?

The Puget Sound Regional Council (Washington state) spent $260,000 building a pedestrian bridge across the North Creek, just 20 paces from an existing sidewalk crossing this river. Part of a larger $1.1297 million stimulus grant to improve Bothell Trail.

The National Science Foundation awarded a $168,766 federal grant to Columbia University researchers to study the sexual behavior of wild blue monkeys by analyzing monkey feces in Africa.

The National Institutes of Health (NIH) spent $55,000 to promote HIV Vaccine Awareness Day, even though no vaccine exists.

Portland, Oregon spent $900,000 in federal stimulus funds on a new bike signage project even though the city already has similar bike signs, which it plans to leave up. The new signs—which include arrows, distance, and travel times to key destinations— have a slightly different design than existing ones.

Yeah, go ahead and just start me up . . .

NavalSArtichoke · Jan 16, 2014

All too often, a 'shovel ready' project is one which involves moving a pile of BS from one spot to another.

jehardiman · Jan 16, 2014

Obviously, Ms Lee and Mr Fish never Googled the topic, or they would have run into this 10 year old thread. Which Mr Fish is referenced in....publish regularly or die.

http://www.boatdesign.net/forums/boat-design/how-fast-can-we-swim-dolphin-like-propeller-8257.html

Squidly-Diddly · Jan 22, 2014

35yrs ago I read their skin was covered with tiny pillars that prevent turbulence, and that was their secret, and the US Navy was trying to copy the concept, but rubber etc kept getting gummed up real fast with debris(and even "hard water scum").

Baltic Bandit · Jan 23, 2014

PAR said: ↑

So easily cynical of well funded projects?

The Puget Sound Regional Council (Washington state) spent $260,000 building a pedestrian bridge across the North Creek, just 20 paces from an existing sidewalk crossing this river. Part of a larger $1.1297 million stimulus grant to improve Bothell Trail.

The National Science Foundation awarded a $168,766 federal grant to Columbia University researchers to study the sexual behavior of wild blue monkeys by analyzing monkey feces in Africa.

The National Institutes of Health (NIH) spent $55,000 to promote HIV Vaccine Awareness Day, even though no vaccine exists.

Portland, Oregon spent $900,000 in federal stimulus funds on a new bike signage project even though the city already has similar bike signs, which it plans to leave up. The new signs—which include arrows, distance, and travel times to key destinations— have a slightly different design than existing ones.

Yeah, go ahead and just start me up . . .
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The first project was actually of decent significance. That path is heavily used by commuter bikers, and the previous approach required making a series of hair pin 90 degree turns, that in the winter would slick up with black ice from the fog from the slew and the creek.

this is like Proxmire being an *** back in the 1980s and awarding his "Golden Fleece" award to the folks who studied how much methane ruminants were producing on a per animal basis. What he of course did not get was the broader context of understanding how the climate works and what was/is driving the explosion of greenhouse gasses.

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How Do Dolphins Swim So Fast

ImaginaryNumber Imaginary Member

daiquiri Engineering and Design

PAR Yacht Designer/Builder

NavalSArtichoke Senior Member

jehardiman Senior Member

Squidly-Diddly Senior Member

Baltic Bandit Previous Member

Swimming Curved Object - powered by the water flow

Would full extension swim platform add speed?