The 'Dimple Effect"

[Djpolly12]

Im 17, year 12 at school in oz.
I'm involved in a different type of racing through school similar to F1 just on a smaller level... eg. using composite materials, machinery skills etc etc.

What I wanted to ask was.... Has anybody heard of the 'dimple effect' used in aerodynamics? basically what it is, is little dimples like on a golf ball that help laminar air flow over the surface of an object. For example, a golf ball with dimples can travel twice as far as one without.

Would this be helpfull in F1 where thousandths of seconds are usefull?? The 'dimple effect' would primarily be used on pieces of the car that are not that aerodynamic and disrupt the air flow.

Interested to hear other peoples thoughts, as I know the dimples are being used in cycling equitment where speeds are only around 60 km/h compared to an F1 cars 200 km/h. I have also hear that the dimples have been outlawed in the rules.

Any help would be greatly appreciated.
Cheers!

[The Thorn]

It was once brought up, a few years ago. If I remember right, McLaren was investigating the benefit of it. Sadly i never heard of it again.

If it can make a golfball travel twice the distance, it must be of some benefit on bigger objects, like vehicles. It might be pretty usefull for the suspension arms, i think, because they always are in a place the designers don't really want them to be (in front of air-inlets etc..).

[Djpolly12]

That's what I was thinking. Bigger objects (bigger frontal area etc) would need more assistance especially like you said with suspension arms and the like in the way.

[mikhak]

The idea of dimples on a golf ball is to initiate turbulent flow earlier. Flow over a sphere will encounter a massive pressure gradient. Laminar boundary layers dont deal with pressure gradients well and will seperate easily. The dimples promote transition to a turbulent boundary layer which deals with a pressure gradient much better and therefore stays attached longer.

I think the use of dimples for major improvements would be limited to high pressure gradient cases. On surfaces like the suspension arms there is not a high pressure gradient so one would want the flow to remain laminar. Many studies have been performed on keeping flow laminar on wings etc. by use of suction of boundary layer and even raised 'dimples'.

But i'm not sure how golf ball like dimples would work on F1 wings. The reason why golf balls are most suitable to dimples is because without dimples laminar flow will extend as far as the pressure gradient and hence detach. With F1 cars, bigger geometries and faster speeds the transition to turbulent flow is quite soon and therefore dimples are not needed to induce turbulence because the boundary layer is already turbulent.

[ISLAMATRON]

It would only work on Piquet's car since he spins more than a golf ball.

[Jersey Tom]

It has potential. On a golf ball it does move the flow separation point and produces a much smaller wake. Bear in mind the flaps, Gurneys, etc on F1 airfoils serve a similar purpose in mitigating flow separation and allowing increased wing camber or AoA.

I'm sure it's been evaluated. Why isn't it used? Who knows.

[Belatti]

It would only work on Piquet's car since he spins more than a golf ball.

Hi DJPolly, these are the two topics where your question has been discussed:

viewtopic.php?f=6&t=5455&hilit=golf+ball

viewtopic.php?f=6&t=3185&hilit=+golf+ball

[Ian P.]

What I wanted to ask was.... Has anybody heard of the 'dimple effect' used in aerodynamics? basically what it is, is little dimples like on a golf ball that help laminar air flow over the surface of an object. For example, a golf ball with dimples can travel twice as far as one without.

There is a similar phenomena with young females of the species. The value of strategically placed dimples (on the surface of certain facial features) has a tremendous benefit in transitioning flow in certain social circles. As with golf balls, it can let them fly much farther than those without dimples.

[jeff8407]

If I recall correctly, Toyota had a few (three I think) inset dimples like a golf ball on their sidepods earlier this year during testing? Anyone else recall that...

[Tim.Wright]

It would only work on Piquet's car since he spins more than a golf ball.

Haha, you beat me to it.

But yes, from what I have heard, the dimpled object needs spin to work properley.

Dimpled tyres?

[Ciro Pabón]

This is a subject that raises its head once a year or so.

I post just to clarify that you do not need an object to spin for the dimples to work.

The dimples do not work because they diminish drag, but because they create turbulent flow. The turbulent flow has more energy, so the flow separation behind the golf ball is smaller. They diminish what's called pressure drag, caused by a relative "void" behind the ball.



So, dimples are not that good for objects that have small flow separation, like wings or F1 cars. They work well in "blunt" objects, like golf ballls. Check this, taken from one of the threads mentioned by Belatti:



For wings and the such, you use vortex generators to diminish drag, like those serrated edges, taken from the same thread:

Serrated Gurney flap (the small vertical plate at the back edge of the wing)


Serrated windscreen (the metallic plate with holes in front of the steering wheel)


Sorry for the repetition, but I'm positive most people don't follow links in threads.

Finally, I think Junior is taking risks and spinning because he must be a little desperate. That's nothing to be ashamed of.

NOTE: if this thread "drags" on, I think it's better to incorporate it into the previous ones.

[snoro]

well it have already been applied to high end bicycle wheel, Zipp wheels have like 90% of their wheel range made with dimple.go check their website for more info on the advantage that it gives for a cyclist.

[pgj]

Even if dimples are not suitable for aerofoil surfaces, could it work on things like side-pods or even the underside of the floor?

[RacingManiac]

IIRC the idea is a turbulent flow reduces boundary layer thickness and makes the flow less stagnant and therefore stays attached longer and reduces drag. The same effect on the underbody is achieved through use of serrated edges off the bargeboard or just plain vortex generator like Ciro's pics above....in effect the principle is in use, just done differently....

[pgj]

@RacingManiac Thank you.