Dear Wouter, Thank you for saving me time and energy. This is an idea I firmly believed that covering the entire exterior of the car with dimples should work. Back to the drawing board. Thank you wholeheartedly
Back in the day, Mythbusters covered an entire car with dimples and they were surprised that it worked. They saved quite a bit of fuel with the dimples. 2 years ago, Bugatti did something similar to improve the aerodynamics of a specific model of theirs. It works!
Do you have a video about VGs? I'm mostly thinking about the ones we see on the back of the roof on some hatchbacks: aren't they pretty much equivalent to dimples?
We do have a video on VGs: ruclips.net/video/MC6woj6tsQY/видео.html Yes, both dimples and VGs serve to energize the boundary layer to delay separation of the boundary layer.
The plastic undertrays that run along each side of my Volkswagen Golf's (lol) underbody are dimpled. These trays lead to a separation area when they get to the 1/3d of the car where the fuel tank, exhaust, and suspension parts reside.
Hi Michael, that's true! We saw it when we ran an article on the Volkswagen Golf 5 / 8: airshaper.com/blog/volkswagen-golf-aerodynamics-analysis-and-improvement They did remove those dimples on later models, so we're not sure if it really had a positive effect in terms of aerodynamics.
I wanted to know if dimples on my cycling clothing would make any sense and remembered having heard a bit about golf balls having dimples to reduce drag. Anyway not only did I learn about golf balls but also my original question I really wanted answered...
Ah I'm glad you found your answer! And you may also like this video, which covers the application of such techniques to cycling clothing :) airshaper.com/videos/aerodynamic-clothing/A0Gx-lBzSFA
Would putting dimples on a car's rear diffuser to allow it to have a slightly more aggressive angle before flow separation occurs? How about dimples to the underside of a car's rear wing for the same purpose? How large/deep should the dimples be?
Hi Sep, good one! Dimples would need to be applied upstream of any separation location, so you'd have to apply them just ahead of the diffuser. Most diffusers have a sharp angle between the flat underfloor and diffuser plane, and I would guess there it's less effective to make the flow turbulent. But if you have a smooth transition between underfloor and diffuser plane, then it could make more sense. I've heard of stories where people have applied rough paint on certain areas of wings to delay or prevent stall. So perhaps there is some potential to it (although slotted wings also do a fantastic job and you may want to consider the drag penalty as well). In terms of size, a very simple first guess could be to have the dimples as deep as the thickness of the boundary layer at that point (but that's just a rough guess)!
But, the OP didn't take into account the Friction of the boundary layer over an aerodynamic car. THIS is where dimples would benefit. Dimples create a minute turbulent layer at the vehicle surface and lower the direct laminar air flow friction. Thus, less drag even on an aerodynamic vehicle. Less friction is less drag and more mpg???
Do you have any references indicating turbulent boundary layers have a lower drag? Usually it is the opposite, and companies like AIRBUS try hard to maintain a laminar flow to reduce the friction drag. See our interview videos with AIRBUS.
In general, it can work on cylinders too. But it depends on the Reynolds number: you need to check for your building and for your wind speed if you're in the right Reynolds regime, i.e. that you are not already in the drag dip for example (then dimples will not have much effect)
For an inch+ circle , few mm dents hardly matters.... Main purpose , multiple hard hit, less contact ,more life. Inner hard core , outerwear semihard layer....
Short and very clear; thank you.
Thank you very much!
Very good. Short and straight to the point. Also, nice anticipation of the question that I had which was why don't we use dimples on cars or planes.
Thanks David!!
Dear Wouter,
Thank you for saving me time and energy. This is an idea I firmly believed that covering the entire exterior of the car with dimples should work. Back to the drawing board.
Thank you wholeheartedly
Back in the day, Mythbusters covered an entire car with dimples and they were surprised that it worked. They saved quite a bit of fuel with the dimples. 2 years ago, Bugatti did something similar to improve the aerodynamics of a specific model of theirs. It works!
Very informative and helpful. Thanks
Thank you, I'm glad the video was helpful!
Explained really well!!
very well explained!!! god bless you
Thank you Shruti! Have a wonderful day
Simple and clear - thanks a lot
Wow. Very succinct. Thank you!
Thank you very much Mario!
Do you have a video about VGs? I'm mostly thinking about the ones we see on the back of the roof on some hatchbacks: aren't they pretty much equivalent to dimples?
We do have a video on VGs:
ruclips.net/video/MC6woj6tsQY/видео.html
Yes, both dimples and VGs serve to energize the boundary layer to delay separation of the boundary layer.
The plastic undertrays that run along each side of my Volkswagen Golf's (lol) underbody are dimpled. These trays lead to a separation area when they get to the 1/3d of the car where the fuel tank, exhaust, and suspension parts reside.
Hi Michael, that's true! We saw it when we ran an article on the Volkswagen Golf 5 / 8:
airshaper.com/blog/volkswagen-golf-aerodynamics-analysis-and-improvement
They did remove those dimples on later models, so we're not sure if it really had a positive effect in terms of aerodynamics.
@@AirShaper oh wow, great article. It’s always good to see any new analysis of the mk5/6 generation Golfs.
I wanted to know if dimples on my cycling clothing would make any sense and remembered having heard a bit about golf balls having dimples to reduce drag. Anyway not only did I learn about golf balls but also my original question I really wanted answered...
Ah I'm glad you found your answer! And you may also like this video, which covers the application of such techniques to cycling clothing :)
airshaper.com/videos/aerodynamic-clothing/A0Gx-lBzSFA
You've got a new subscriber 👍
Superb, thanks Mejestic!
wow my man thank you!!!
You're welcome!
Would putting dimples on a car's rear diffuser to allow it to have a slightly more aggressive angle before flow separation occurs? How about dimples to the underside of a car's rear wing for the same purpose? How large/deep should the dimples be?
Hi Sep,
good one!
Dimples would need to be applied upstream of any separation location, so you'd have to apply them just ahead of the diffuser. Most diffusers have a sharp angle between the flat underfloor and diffuser plane, and I would guess there it's less effective to make the flow turbulent. But if you have a smooth transition between underfloor and diffuser plane, then it could make more sense.
I've heard of stories where people have applied rough paint on certain areas of wings to delay or prevent stall. So perhaps there is some potential to it (although slotted wings also do a fantastic job and you may want to consider the drag penalty as well).
In terms of size, a very simple first guess could be to have the dimples as deep as the thickness of the boundary layer at that point (but that's just a rough guess)!
Hey, do you if they use this in Formula 1 ? Curious about this because they use so many differents tricks there.
Would the same effect apply to a smaller projectile? .685" (17.4mm) in size being launched at 400 fps? Dimples verses smooth sphere?
That would depend on the Reynolds number!
@@AirShaperHow would one test an object of that size to get that number?
@@dwptechduco ruclips.net/video/sV8l8xd4MEQ/видео.html
But, the OP didn't take into account the Friction of the boundary layer over an aerodynamic car. THIS is where dimples would benefit. Dimples create a minute turbulent layer at the vehicle surface and lower the direct laminar air flow friction. Thus, less drag even on an aerodynamic vehicle. Less friction is less drag and more mpg???
Do you have any references indicating turbulent boundary layers have a lower drag? Usually it is the opposite, and companies like AIRBUS try hard to maintain a laminar flow to reduce the friction drag. See our interview videos with AIRBUS.
would this work on a cylinder shaped building?
In general, it can work on cylinders too. But it depends on the Reynolds number: you need to check for your building and for your wind speed if you're in the right Reynolds regime, i.e. that you are not already in the drag dip for example (then dimples will not have much effect)
dimple 있는 figure 는 laminar boundary layer 가 아니고 turbulent boundary layer 라고 correct 해야.
I'm not sure what the special characters in your post mean, but indeed, we added a correction in the comments!
For an inch+ circle , few mm dents hardly matters....
Main purpose , multiple hard hit, less contact ,more life.
Inner hard core , outerwear semihard layer....
apruebame raquel