Scientists calculate the optimum speed at which dogs should shake to most efficiently dry their fur

[The Straight Story]

The last time a wet dog looked Andrew Dickerson in the eye, readying a shake, he didn’t flee in terror like most people would. Instead, like any true physicist, he whipped out a slow-motion video camera to see if he could capture the exact frequency at which its body was oscillating.

Dickerson, along with some colleagues from the Georgia Institute of Technology, has written “The Wet-Dog Shake,” published in Fluid Dynamics. They attempt to calculate the optimum speed at which dogs should shake to most efficiently dry their fur.

The team built a mathematical model of the processes involved, reasoning that surface tension between the water and the dog’s hair is what keeps the dog wet. Overcoming that tension requires a centripetal force that exceeds it.


As centripetal force varies with distance from the centre of the creature, its radius is therefore crucial to work out the speed of the oscillations. The team arrived at an equation that calculates the frequency of that oscillation as R0.5.



Read More http://www.wired.com/wiredscience/2010/10/dog-drying-physics/#ixzz13CREyF1O

[iamtechus]

1. Dogs don't have fur, they have hair. Cats have fur.

[KossackRealityCheck]

2. Most dogs have fur, not hair

The difference is that fur reaches a certain length and stops growing, and fur bearing animals shed, while hair has no determinate length and doesn't shed.

Almost all humans have hair, not fur. Almost all cats have fur. Most dogs have fur, but poodles and a few other breeds, like Portuguese Water dogs have hair.

[boston bean]

3. can you point me in the direction of a human with fur?

[KossackRealityCheck]

4. LOL !

There is a joke that whenever hair/fur is in the wrong place it's name changes.

To wit:

My dog has fur. My couch is covered in dog hair.

My head has hair. My back has fur.

I only used "almost all" because of the prevalence of nit picking on message boards. But there were those two Mexican kids who had a genetic disorder that got them labeled the "werewolf" kids.

I guess they had fur.

[canetoad]

5. I wish someone would build a mathematical model

Explaining why, no matter how far away I am when they climb out of the river, my dogs need to be standing next to me when they shake. :shrug:

[Cal33]

6. From a practical point of view, what difference does it make? They'll still do what comes naturally

[Bill McBlueState]

11. well, it's not really for the dogs

It's a way to learn something about fluid dynamics that might find a more important application somewhere unexpected.

[surrealAmerican]

7. If my dogs are shaking at the wrong speed ...

... what am I supposed to do about it?

[KT2000]

8. Cat purrs

are similar frequency across the species except for the jaguar. It just so happens that it is the same frequency used in orthopedic devices used for humans to speed bone healing.

[Iggo]

9. Man!

I gotta get me some study money!

[gulliver]

10. Interesting

Rats, bears, etc., can do it too. Humans can probably do it if our common ancestor with dogs did it. Next time I see a guy with a hairy back getting out of the pool, I'm going to ask him to try it.