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> It's long been accepted that the smoother the surface, the lower the aerodynamic drag. That turns out not always to be the case. Huh... I'd always heard that
by mlmonkey 4mo ago
> It's long been accepted that the smoother the surface, the lower the aerodynamic drag. That turns out not always to be the case.
Huh... I'd always heard that a golf ball's dimples help reduce drag?
- dathinab 4mo agoyep and a lot of "smooth" aerodynamic surfaces have "microscopic"/"very small" surface patterns to make the surface less perfect smooth as if it is too perfect smooth the air kinda "sticks" to it increasing drag (to say it in a very unscientific way)
- pfdietz 4mo ago[dead]
- beering 4mo agoTFA makes it clear that this is a very different phenomenon than golf ball dimples, and even goes as far as to say they are opposing.
- coldtea 4mo agoHowever the TFA doesn't make clear that this: "It's long been accepted that the smoother the surface, the lower the aerodynamic drag. That turns out not always to be the case" was already known to NOT always be the case (e.g. in golf balls).
- Swizec 4mo ago> Huh... I'd always heard that a golf ball's dimples help reduce drag? Yep also vortex generators in cars have become common. So common that they've filtered down to after market parts you can put on a honda civic Vortexes break up large air pockets and reduce drag.
- SilverElfin 4mo agoIs that what those things are on random civics? Do they make any difference for regular street cars?
- ungreased0675 4mo agoI put some (actual, as in from an airplane parts catalog) vortex generators on my hybrid. It slightly increased gas mileage and slightly reduced noise. The less aerodynamic the vehicle, the more noticeable the result will probably be.
- coldtea 4mo ago>It slightly increased gas mileage and slightly reduced noise. Between the day to day road conditions and different routes noise and the modest effect, I'd say this would be impossible to tell.
- deleted 4mo ago[deleted]
- cpncrunch 4mo agoRead the article….this is a completely different effect.
- NetMageSCW 4mo agoTough behind a paywall.
- deleted 4mo ago[deleted]
- djeastm 4mo agoFrom the article: >This principle is fundamentally different from the effect of dimples on golf balls. Dimples reduce pressure resistance by intentionally turbulizing the airflow and suppressing backward separation. DMR, on the other hand, delays the transition, thereby suppressing not pressure resistance but the wall friction itself. They are opposite mechanisms.
- degamad 4mo agomlmonkey did not say that this new observation was the same phenomenon as golf ball dimples, just golf ball dimples already disproved the "long accepted" belief that "smoother the surface, the lower the aerodynamic drag".
- kazinator 4mo agoExactly; golf balls are one example of it not being accepted that smooth surfaces are always best for drag, regardless of how the new result works.
- kjkjadksj 4mo agoThey don’t though. Hit your golf ball into the cart path and see what happens after. Pro or competitive golfer will toss it and use a new ball.
- aaron695 4mo ago[dead]
- nmstoker 4mo agoAnd the Mig-29 too but according to the reply that's different
- Ekaros 4mo agoI read somewhere that it depends... Different shaped objects benefit from different surface effects. A rounded surface like ball benefits from dimples where as more straight surface like arrow would not. I have no idea but I could also guess that speed affects things.
- stasomatic 4mo agoMe too. Is it known by how much though in relatives percentage terms? Sometime things are just worth the effort. If larger than 20%… okay, but then if everyone uses dimpled balls (I understand they do), it’s just a thought experiment, then what’s the point. Why aren’t ping pong balls dimpled?