#physicsflow

[nakedfluiddynamics-blog]

Can Michael Phelps swim faster than a shark? Iosilevskii and Weihs have found the physical limits on swimming speed of lunate tail propelled aquatic swimmers: Dolphins, tunas, sharks and Michael Phelps! Well the study does not actually mention MP but with his monofin the results should apply. They found that large swimmers (not humans) were limited by cavitation! They have enough power to swim so fast that the water literally boils around their tail. The cavitation will induce pain to the swimmer due to the violent shocks generated during the collapse (see previous posts). Cavitation happens when the speed of the swimmer exceeds 10-15 m/s referring to the paper. For dolphin this is pretty much the top speed observed. Some fish like tunas don’t have sensors on their tails and thus can exceed this speed but not by much due to the drastic reduction of lift induced by the cavitation. The top speed of monofin swimmer is of the order of 3-4 m/s... We stand no chance... We are still limited by the available power in the human body... Let’s evaluate the top speed of MP: A professional athlete can produce about 20 W/kg (for fish it is in between 10 to 160!). MP is about 80 kg so P = 1.6 kW. Using the paper data we find a top speed due to power limitation of the order of 3 m/s! In good agreement with the actual top speed of finswimmers and the results of the race (38.1 sec on a 100m) Source: Iosilevskii and Weihs, Speed limits on swimming of fishes and cetaceans, J. R. Soc Interface, 2008, 5, 329–338 #nakedfluiddynamics #nakedfluid #fluidmechanics #cavitation #physicsflow #physics #swimming @m_phelps00 #shark #racing #physicsisfun #scienceisfun #scienceisawesome