windtunnel correlation,Williams claiming 30%improvements

[marcush.]

just read in autosport :Andrea Terzi claims correlation improvements of 30% over their previous tunnel results with their new Tunnel now online...
What the heck are all these doing if you could seriously get improvements of 30% in an area where all seems to be scientific....and CFD around making us believe you could draw up a car and predict the real downforce /drag figures reliably?Looks like boffins want to make us believe the stuff they do is scientific ,but looks like all this stuff is empiric,try one thing and compare to what you tried before...
Now that has to bring all the Aero guys jumping at my throat...

[ReubenG]

If it's a correlation improvement that means the error between the tunnel results and the predicted CFD results has decreased by 30 % - i.e. if there was previously a 3 % error between the numerical and experimental result the error is now only 2%.

Remember that CFD, like FEA, is just another numerical/computational tool to an engineer - like all computational tools the results can only be of lesser quality than the inputs.

[Irvingthien]

Surprised to hear that their wind tunnel is the most advanced in the business...that means better than Sauber's.I think that's highly unlikely because Sauber has spent millions and years building their wind tunnel and considering that the Swiss are good at making presicion tools.

[Guest]

good point ,if the difference was 3% before...but would someone really shout that loud about that sort of improvements?Especially when you could state Williams aero is not really advanced apart from THAT nose treatment..marcush.

[dumrick]

...but would someone really shout that loud about that sort of improvements?

Yes, 30% improvement IS a lot, nowadays. To give an idea, I've heard about correlations in the main figures (lift, drag) in fixed floor windtunnels, for closed cars, quite above 90%, in the 80's.

Of course, in open-wheelers, the importance of rolling floors is quite high, but I would assume that the latest rolling-floor windtunnels, for an F1, should have correlations above 95%. For this kind of values, 30% is huge, because it's a lot harder to improve.

[Guest]

the original statement related the two williams tunnels ...which is a mystery to me ...if the new tunnel is giving 30 %better (more accurate )results ,the old tunnel seems pretty useless...
on the other hand Toyotas Brunner states :Rene hilhorst is a very good in analysing the Aero and is a nice bloke,but his work was in all directions ,whereas Gascoyne has his own method to improve the cars aero and he adheres strictly to that(Detail improvement)
Sadly enough the Windtunnelmodel had not enough precision and stiffness to show these tiny improvements securely.So you think you have made an improvement but in reality the Model itself changed a bit and all measurements are invalid....Its as always...chnge change change and forgot to make your baseline verification at the end of the day....leads to a car slowly on the decline...that is pretty basic stuff ,isn´t it?
On the other hand ..if Iám so seriously in the back position aerowise as williams or toyota is ,why should I look intothose tiny percentagesto make that forward leap?
At least Mclaren understood and hey they seem to improve now!