Laminar Flow and swimsuit

[Fairytales]

Hi

 

I’m student at a french university, I have to present a project about swimsuit and I must carry out experiments. I’ve decided to work on the buoyancy of swimsuits, the flow around it and drag. To measure drag, I think I’ll drop a heavy ball wrapped in swimsuit material in the water and take measures. Then I’ll do the same with just the ball and compare the results.

 

But I have a problem concerning the flow. I’ve read from a swimsuit manufacturer website that swimsuits help create laminar flow. And that’s what I don’t understand: Why ? And how can I prove it in an experiment ? I know it’s all about fluid mechanics but I haven’t studied that yet.

 

Thank you so much for your help! ^^

[Newbies_Kid]

Laminar flows occurs when a fluid flows in parallel layers, with no disruption between the layers. In other word, it create smooth motion between swimmer and fluid around it. So less drag created and less force required for swimmer to move. Swimsuit help it user by re-shaping the users body for minimum drag. I heard that michael phelp's swimssuit is custom made by NASA. They made special materials that greatly reducing drag force.

 

Don't think too much on laminar flow because it just simple.

Edited May 30, 2010 by Newbies_Kid

[Fairytales]

But what I don't undersand is how comes that the swimsuit itself helps create laminar flow around the swimmer ?

[mooeypoo]

Water flow is very similar in that aspect to air flow, Fairytales. The swimsuit makes the swimmer's body more airodynamic (or in this case "water-dynamic"). In some cases, the suits also help the swimmers keep their bodies in the proper position for swimming with all kids of pressure points.

 

I actually wrote an article about that when the "LZR" swimsuit came out in the 2008 Olympics.. you can read it here http://www.smarterthanthat.com/physics/olympic-controversy-how-does-the-space-age-swimsuit-work/

[Newbies_Kid]

Wow.. so you are the writer of that article. Good article. I used your article once for my surface engineering assignment during my study (early 2009 if i'm not mistaken). I still remember the title of my assignment.. Surface engineering: This could be something big.... Thank you mooeypoo~~

[mooeypoo]

Oh, wow, I'm glad it helped you

[Bignose]

Mooey, did you read "Will Humans Swim Faster or Slower in Syrup?" by Gettelfinger and Cussler, AIChE Journal, 2004? That article had univeristy swim team members perform laps in water and in a guar gum solution with about 10 times the viscosity of water, and found that times were pretty darn close to the same. The major conclusion was that competitive swimming wasn't really in the laminar flow regime, and that surface drag was only a tiny factor. Of course, the recent Olympics and all the records that fell seems to point differently, but I remember that article. I think that the authors won an Ig Nobel Prize for it, if I am not mistaken.

[J.C.MacSwell]

Mooey, did you read "Will Humans Swim Faster or Slower in Syrup?" by Gettelfinger and Cussler, AIChE Journal, 2004? That article had univeristy swim team members perform laps in water and in a guar gum solution with about 10 times the viscosity of water, and found that times were pretty darn close to the same. The major conclusion was that competitive swimming wasn't really in the laminar flow regime, and that surface drag was only a tiny factor. Of course, the recent Olympics and all the records that fell seems to point differently, but I remember that article. I think that the authors won an Ig Nobel Prize for it, if I am not mistaken.

 

Can't comment on the article, but often in flows the drag will drop when the skin friction increases.

 

Turbulent boundary layers will often delay separation, which can reduce form drag (or increase lift by delaying separation)

 

Not sure exactly how the swimsuits work, but it may be related.

[mooeypoo]

Mooey, did you read "Will Humans Swim Faster or Slower in Syrup?" by Gettelfinger and Cussler, AIChE Journal, 2004? That article had univeristy swim team members perform laps in water and in a guar gum solution with about 10 times the viscosity of water, and found that times were pretty darn close to the same. The major conclusion was that competitive swimming wasn't really in the laminar flow regime, and that surface drag was only a tiny factor. Of course, the recent Olympics and all the records that fell seems to point differently, but I remember that article. I think that the authors won an Ig Nobel Prize for it, if I am not mistaken.

No, I've never heard of it, and in my short research for the article in my blog I didn't come accross it either. I'm definitely going to look it up, though.. it sounds a bit weird, doesn't it? It's movement in a fluid -- the viscocity should affect it. What I suspect, though, is that if the speed wasn't reduced, perhaps the energy wasted by the swimmers was larger? I wonder how they could check against that...

[iNow]

Hs4Q5jZSJbA

[Double K]

The swimsuits that the Australian swim team have been using are nicknamed "sharkskin" suits..

 

"Previous work confirmed the formation of the embedded vortices, and the new grants will focus on mechanisms within the bristled shark skin geometry that lead to separation control, decreased drag and increased maneuverability for the shark."

http://blog.al.com/live/2009/11/alabama_studies_shark_skin_tec.html

[mooeypoo]

Hs4Q5jZSJbA

It seems my suspicion was correct -- even though they managed to get mostly the same times, they had to exert more *WORK* and effort through the goopy stuff. They said that even though the speeds are more or less the same, it was more effort to go through the goop than it was in water.

 

The entire point of the swimsuits is to lower the drag not just for speed, but to make sure the swimming gets tired less and can spend energy BETTER.

 

~moo