Quote:
Originally Posted by AeroMcAeroFace
Well I have been around here for a bit longer than that, not as a member though, and I don't remember anyone saying "Don't use the template in the tools section, it is wrong" Why is it in the tools section if it is the wrong tool?
Imagine a builder turning up at your house, wearing a tool belt with a hammer in it, but then every time he needs a hammer he goes back to the van to get a different hammer, uses it and puts it back in the van. You would question why he doesn't put the hammer that he uses in the tool belt.
It seems like whatever shape that a car maker uses there is a different template that fits.
Which is the one that is supposed to predict separation?
And if there is one that can predict separation (along the centreline), surely you need a correction factor for boundary layer thickening and transition to turbulent flow? Upstream effects are important and not usually considered.
I have seen so many people using the template in the tools section for their "assessment" of how aerodynamic a car is, rarely is there someone "correcting" them and using a different template to "assess" the car.
|
1) boundary layer thickness has nothing to do with passenger car drag.
2) above 20-mph, a passenger car is already at supercritical Reynolds number, with 100% turbulent boundary layer. And that's a 'GOOD' thing.