Smooth bodywork

[kilcoo316]

I know renault previously looked at vgs (which is really what you are all talking about) on the suction surface of the rear wing, and found a good improvement with them...


For some reason (regulation maybe), they were never used in a race that I am aware of.

[Mystery Steve]

... not to dispute your intuition, but I would argue that the wake from an F1 car is far greater than a passenger car, due the the wake from the rear wings. Of course in F1 we harness that wake to use it to power the diffuser and it creates more downforce, our goal in F1.

Good point... perhaps I should clarify what I meant. The wake due to flow around the general body (not considering wings/diffusers/etc) is lower than say a Ford Taurus, which is where an advantage would be gained using golf ball dimple or shark skin "flow conditioners" on the bodywork. But yes, of course the wings contribute greatly to the big picture.

You mind sharing that picture of the RB5? The wake/vortex effect of aerodynamic bodies is actually larger than some people probably think, such as the wingtip vortices off a small plane:



My family is actually from Cincinnati... always a fun city to visit.

[rjsa]

A straight (is this right, as opposed to delta? sorry, not educated in English), no winglets, about to stall wing is the extreme case of vortex forming.

Nice image!

[BreezyRacer]

Here's the pic I was referring to. Took some time to find it as it wasn't at Spa, but rather Turkey. There's lots of shots like this but just study the heat flows between the rear wings and look at the wake distortion of the painted lines of the track in the background. Check it out full scale.

[BreezyRacer]

One more thing regarding these dimples and shark skin patterns. For a while 3M made a textured aero tape for wings. I guess it didn't sell well so it's history now and I've never seen it but stumbled across mentions of it from time to time.

[riff_raff]

The shark skin analogy is only appropriate for liquid flows. The slight roughness of the shark skin works by trapping a boundary layer of liquid against the skin, which reduces the viscous fluid drag effects. This is a result of fluid-on-fluid flow interaction producing less drag than fluid-on-smooth surface flow. The America's Cup yacht racers figured this out many years ago, and that's why they sand down their boat hulls before each race in order to produce a slightly rough surface.

The same is not necessarily true for compressible fluid flows, like that over an airfoil surface. Drag losses over an aero surface are more a function of local turbulence and compressibility effects within the boundary layer flows. A smooth, clean surface is most important to ensure laminar flows. However, when laminar flows want to become detached, like on an airfoil trailing edge, a little bit of turbulence in the boundary layer flow can encourage that flow to remain attached, thus reducing drag.

Regards,
Terry

[Mystery Steve]

This is what MythBusters should have done with their Taurus:

[youtube]http://www.youtube.com/watch?v=jd71qpfU ... re=related[/youtube]

If you pause around 20 seconds, you can see the boundary layer formation. It's relatively attached over the roof, but then begins separating at the trunk. Theoretically, the golf ball dimple car in the MB episode would not have as much separation over the trunk, and it would have less drag as a result. 1:05 is a really good illustration of the turbulent wake behind a vehicle that is not streamlined. This kind of turbulent wake is minimized (at least to a much greater extent) on an F1 car. The wake they leave is largely due to pressure differences caused by the diffuser and the massive upwash of the rear wing.

[BreezyRacer]

Yeah a wind tunnel would be neat but those guys didn't have access to a wind tunnel and they were really approaching it from angle of dimpled golf balls vs smooth golf balls. I think their methods were sound, and perhaps one could argue that it was more real life than a wind tunnel.

I agree that they sure didn't have to clay up the whole car to take advantage of the dimpling benefit but for the casual watcher this made more sense because of "the whole golf ball was dimpled so the whole car should be dimpled too" argument. Imagine if they had only done the roof and tail and it didn't show a change. Viewers could have reasonably argued that the comparison was compromised even though you and I wouldn't feel so.

With all the focus on fuel economy and efficiency these days I'm sure some car company will step into the fray. A 10% savings in incredible. Who knows, maybe this will become as commonplace as spoilers on cars these days. Think about it .. even garden variety passenger cars these days come with spoilers because customers have positive feeling about them. Certainly not because they do anything. For instance if the spoiler on that Ford Taurus weighs 40 lbs, it's only benefit I can see is 40 lbs of tire loading .. ha ha. Yet everyone wants them on their car and I would go so far as to say that many a buyer would feel that the car was plain without one.

Maybe dimples/sharkskin patterns will become that common someday. If they made a big deal out of it on an upscale hybrid car, for instance, consumers would come to ask for it. Eventually function becomes form.