ringo wrote:It's good for drag they just setup the thing too stingily for the computing power they have.
I'd also disagree, but primarily with that sentence. The internal flows are likely to be a source of error, but then again I would say the wind tunnel would struggle to get decent correlation with the real thing regarding the internal flows. CFD is getting less processor and memory limited, its storage limited these days, I guess it becomes a compromise of what you want to know, and what you consider more crucial than other aspects.
And when I say CFD is not good for drag, I mean it in every sense, but it depends what you define as acceptable parameters. In aerospace applications 0.1% error in drag is highly unacceptable when you consider that there are numerous wind tunnels with the ability to calculate Cd upto +-0.0001 accuracy with a repeatability error of 0.00005 Cd. (Consider a 0.1% error in Cd in relation to fuel burn, it gets quite costly).
Drag is a difficult subject to understand, let alone calculate. Its far more complex than people initially think. It just so happens the 4 black round things on an F1 car mean drag is the least their worries. So in that respect, maybe CFD calculation of drag is acceptable for F1. But in general terms its far from it.
Even given experimental setup data, WT turbulence, calculating a Cd on a simple aerofoil its hard enough to get within 0.5% in CFD.