James Allison on Wind-Tunnel & CFD ->
"'Everyone's windtunnel is beautifully calibrated,' said Allison. 'They are exquisitely calibrated with very expensive instruments. I think that the word that people maybe should use is correlated. What aero guys are continually searching for is correlation between the tests they do in the windtunnel, on track and in CFD. I'm sure if you went to the teams up at the front end of the grid, one of the reasons is that they are at the front end is that the vast majority of the experiments they do in their testing domain translate into the physical domain. What aero teams strive for in addition to coming up with good aerodynamic ideas is a testing environment where they know the fruits of their labour in the tunnel will translate to laptime on the track.'
"So, that's the idea. The trouble is that this correlation takes a little work to get right. At the level that F1 teams are operating, very tiny discrepancies in correlation can make a big difference and it's only possible to know if a car is going to work properly when you run it in the real world. Teams have a multitude of factors to take into account. In the windtunnel, there's a danger you can come up with a car that works perfectly on the flat but has big airflow separation problems once bumps and yaw are taken into account. Teams try to factor this in, but you can only really be sure how the world works in the real world. With CFD, for example, the further downstream you go in the car, the more calculations the simulation relies upon and the greater margin for error. In the windtunnel, you can only simulate the car in so many transient states so you need to get it onto a real track to see how it works. Ideally, the correlation is good and your car is a goer. If not, as Ferrari found this year, very small differences can put you on the back foot."
I hope Merc have some trick up there sleeve otherwise this could be a disaster. These 5 days of running are like 7-8 race Weekends. Huge changes in set-up & can lead to huge possible gain especially over long run with varying fuel loads.
Keeping my Fingers Crossed. Waiting for 21st & hoping Mercedes deliver a Fantastic Car