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22.10.2012 20:43:55
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2.2. The paradox of "Greja".

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In 1936, the British zoologist professor James Gray made the calculation of power, developed by the dolphin muscles at a speed of V=10 m/s (36 km/h) and found out a fantastic paradox: dolphin can not swim with such speed, so as there is the lack of the developing capacity, it is 7 times less than it is needed [2]. This nonsense became called in science as "the Gray's paradox". But the author of the calculation has based on the fact that the boundary layer of liquid, flowing a body of a swimming dolphin, takes turbulent (screw) character, and this increases the friction between the body and the water. Such an assumption would be quite legitimate if we were talking about the flowing the rigid body the same size and shape like a dolphin. But in this case, the body is alive, flexible, and J. Gray suggested that the explanation of the paradox is possible if the flowing has a laminar (inkjet, calm) character, in this case the friction reduces essentially. In other words, a swimming dolphin has a kind of mechanism for laminarization boundary layer of the liquid.

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