Golf ball dimples for cars

[KENAT]

Anyway, when driving several hundred miles the difference between 55 & 75 is very noticeable.

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(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[FeX32]

105 all the way


Fe

 

[robinfryer]

Id be highly suspicious of the results, those guys arnt really experienced in aero testing or anything (i doubt) which is incredibly tricky.

Carbon rod is completely accurate. The Reynolds number is the important factor here. The reynolds number of the ball is much smaller, and in a region of values where flow is mostly laminar. At about Rex10^6 flow typically transitions from laminar to turbulent. The turbulent flow has a higher turbulent kinetic energy and reduces momentum loss to keep the Boundary layer attached.

This brings an increase in skin friction, but the reduction in pressure drag is more signifficant. For a car, flow is mostly already turbulent. Aerodynamicists already use tricks like tripping the boundary layer, on the bonnet to avoid laminar separation.

This sort of thing has been tried on bike wheels and not yielded any improvement. I think the problem is you will still definetly get turbulent separation over most of the parts where it was separating before.

The FACT is that if this were true you would get it on some race cars and streamlined racers (even though i know someone will say racers only want downforce, not true, they still want low drag and high downforce, or high L/D ratios).

Dimples basically arnt the only way, the new world cup football uses seems to trip the boundary layer to create a more predictable separation point (laminar bl separation points are notouriously hard to predict and very unstable).