Homely Scientist

Every wonder why swimmers shave off all their body hair?  No, it’s not to look extra sexy in their suits (though … no I’m not going to go there).  It’s all about laminar flow.  While runners, bikers, and other athletes have to consider wind resistance, swimmers have to have a totally different side of physics to consider.  Scott Goldblatt (an Olympic gold medalist and b5 blogger)  talks about the new developments in swimsuits in competitive swimming over on Timed Finals.  All the developments, and shaving, all do one thing … make bodies as smooth as possible so water not only passes over them smoothly, but also help them push through the water with more power.

So, what is laminar flow?  Basically it’s how a fluid (in this case water) passes over and around an object.  Anything that resists the flow slows things done, it’s like friction, but a little different.  The key thing with water is that interruptions in the flow causes ripples and eddies that sap power as well.  I dated some swimmer in the past and they actually let their body hair grow in practice time, making them work harder for their times, then for meets shave.  Even the feeling, they said, of being that smooth and the difference in the way the water flowed over their bodies made them feel faster.  Of course it actually does.

Now for the new high-tech suits the idea isn’t just to make you as smooth as a dolphin, but also harness and re-apply the energy expended to ensure all the power in a stroke goes to pushing the swimmer forward, not having to cut through the water.

Other great examples of laminar flow are submarines.  Submarines need to be smooth not only to go faster, but also to stay silent.  Those little ripples and eddies as water swirls over extruding parts makes sound underwater.  And to a submarine, generating sound is a very bad thing.

Tags: swimming, shaving, laminar flow, submarines

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