Uneven surfaces reduces drag

[Genie47]

http://www.physorg.com/news11095.html

 

This is the same reason why the swimmers use that "sharkskin" full suit and golf balls got all these dimples on them.

 

Sure is going to be hard to detail a car full of dimples...... WAIT A MINUTE! I will now encourage anybody to open your car door really hard and make dings on my car doors. More the merrier!

[Shull]

Laminar flow, Turbulent Flow..damn familiar..

[Southpark2000]

Hmmmmm......u wan some dings on yr ride? I can do it for u

[Vblaster_w211]

Small eddy current flows...

[Jamesgetz]

drag comprises of 2 kinds: skin and form. the dimpled skin of a golf actually creates turbulent flow to delay flow separation so as to reduce form drag. interesting to see how this will be implemented on a car where people are used to seeing shiny, polished surfaces...

 

http://sln.fi.edu/wright/again/wings.avkid...or/golf-01.html

 

http://science.howstuffworks.com/question37.htm

 

no prob, tell us where you park your car. i'm sure many of us will be glad to help you dimple your car to make it move faster and save fuel

Edited February 26, 2006 by Jamesgetz

[Gadgeter]

you are evil... but I would like to join in too...

[Helix]

eh bro, the surface of the doors is rather flat, no large curvature, so no need to induce turbulent flow (boundary layers). Highly unlikely flow will separate, thus, skin friction is the main contributor here. Instead must keep it smooth and shinny so that laminar flow persist to reduce skin friction...

 

Aircraft wings are curved on the top and at moderate angle of attack, the flow will most likely seperate at the rear end as the boundary layers loses 'steam' hahaha.

 

Instead, you should start whacking your car roof so that flow becomes turbulent to negotiate the sudden curvature at the area connecting the roof anf the back windscreen. Turbulent flows are more 'energized' and can neogotiate complex surface curvatures without separating easier, thus, reducing pressure drag. That's why the new Evo and the Lancer turbo got these vortex generator at the rear roof of the car. Should be known as turbulent generator instead...haha

 

Having said that, cars with low lying spoiler are not useful at all in generating downforce because the flow at rear region of the car is slow and recirculating. No use at all...oh the only downward force that these spoilers are contributing are their own weight...Spoilers should be sufficiently high enough to make use of the undistrubed flow of the air (freestream). GT wings are effective in that sense. However, things are not that simple, installing spoilers (inverted wings) also induces another form of drag known as wave drag which is present in all finite lift generating devices.

 

Thus, now your car faces three components of drag = skin friction + form (pressure) + wave. But nothing will beat that cosmetic enhancement your car will have even if it burn a huge hole in your pocket as a result of burning more fuel...

Edited February 27, 2006 by Helix

[Genie47]

So a dimpled bonnet and a roof might help, huh? No I don't lump in GT wings or whatever on my car. I hardly see 200kph speeds.

[Helix]

oohhhh...yes...golf balls have dimples don't they. Need our help...huhuhuh?? No need to whack your car, just place a large piece of sandpaper over your roof can liao..

[Genie47]

Let me buy a 10yards of sharkskin fabric from Arena. That should do the trick.