Theory of the Golf Ball Dimples

[freebeard]

Well, it spoils the joke but Okay:

https://en.wikipedia.org/wiki/Ground...(aerodynamics)

If a cars attitude is nose up so there is a positive pressure underneath, it approaches ground effect. It's exploited the most in the Ekranoplan type airframe.

The joke is that it's really https://en.wikipedia.org/wiki/Microscale_meteorology AKA ground turbulence.

Flow over a golf ball. (This can be best understood by considering the golf ball to be stationary, with air flowing over it.) If the golf ball were smooth, the boundary layer flow over the front of the sphere would be laminar at typical conditions. However, the boundary layer would separate early, as the pressure gradient switched from favorable (pressure decreasing in the flow direction) to unfavorable (pressure increasing in the flow direction), creating a large region of low pressure behind the ball that creates high form drag. To prevent this from happening, the surface is dimpled to perturb the boundary layer and promote transition to turbulence. This results in higher skin friction, but moves the point of boundary layer separation further along, resulting in lower form drag and lower overall drag.

https://en.wikipedia.org/wiki/Turbul..._of_turbulence

[LittleBlackDuck]

Originally Posted by freebeard

The golf ball flies out of ground effect. Skateboards and cars don't. QED

LittleBlackDuck -- Does the LX450h have an electric rear axle or a driveshaft? The motor for my someday EV conversion is from the LX400h.

Freebeard, the 450h has the MGR assembly that can deliver up to 60KW. I love the simplicity of no direct mechanical connection between front and rear.

Simon

[freebeard]

Did you know there's a whole thread on that?

[LittleBlackDuck]

Originally Posted by freebeard

Did you know there's a whole thread on that?

Yeah, been reading it. Looks loke a slightly different version of what is in mine.

Simon

[freebeard]

We're going off topic, but I'm curious about the differences. Does it have the optional oil cooler?

[botsapper]

Originally Posted by RandomFact314

I was just watching a video on Youtube where these guys got a hold of a golf ball dimpled skate board that was supposed to flip faster so they could do better tricks...]

If the balance, weight, elasticity & inertial characteristics are comparable to a plywood deck and they want faster roll due to aerodynamics...http://skateandannoy.com/wp-content/...5/12/metal.jpg

[samwichse]

So basically... vortex generators at/on the trailing curved departure surfaces of a car would have the same effect?

[ChazInMT]

Originally Posted by samwichse

So basically... vortex generators at/on the trailing curved departure surfaces of a car would have the same effect?

Yes, they would both be pretty much worthless. Except they would cost you time and money to futz with them, so you'd be in the hole to start with and have next to no chance of getting your investment back. Unless the vortex generators were able to create a calibrated vortex in the space-time continuum allowing you to just teleport yourself instantly to your destination, so you'd save money that way.

[LittleBlackDuck]

Originally Posted by freebeard

We're going off topic, but I'm curious about the differences. Does it have the optional oil cooler?

Next time it is up in the air I will try and get some photos. My CT is in for a service and I will try and grab a few photos of the underside too.

Simon

[freebeard]

Originally Posted by ChazInMT

Unless the vortex generators were able to create a calibrated vortex in the space-time continuum allowing you to just teleport yourself instantly to your destination, so you'd save money that way.

"So you're saying there's a chance?"

Jim Carey