vall wrote:The CFD code doesn't really care what you plug into it.
Unfortunately, no, it really, really, really cares what you put into it.
vall wrote:Should someone with the knowledge comment on the differences to run CFD now and previous years?
Its all in the boundary conditions you use.
As I said earlier, I'm suspecting the tyres, as they are the biggest change from last year to this - modelling how the tyre deforms under load/unload is critical to good aerodynamics - and it is also far more complex than modelling a deforming wing.
Look how Renault went horribly wrong in 2007 - there is history for it - and I *believe* it is where McLaren's problems lie.
Note also - incorrectly modelling the tyre deformations will affect the wind tunnel* as well as CFD - which is why the tunnel didn't pick up on the problem until the car was on track.
* the tyres in a tunnel are independent of the chassis aero loading - so the teams control how they react through the stings.
This is exactly where my thoughts were heading, albeit in a slightly less technical, more ignorant way.
There is previous with regard to changes in tyres bringing massive benefits/problems on several occasions before.
There is the McLaren and Renault situation in 2007.
McLaren bolt the Bridgestones on the 2006 car and instantly go quicker, Renault do the same and go the same chunk slower.
Also thinking back to BAR/Honda in 2004, their switch from Bridgestone to Michelin yielded positive results whereas the switch back
in 2007, well, we all know about Honda in 2007.
Might it have been that their rear end instability (the same problem now afflicting McLaren I would suggest) was caused by the different aerodynamic properties of the Bridgestone tyre?
I would surely go as far as suggesting that it is obvious that the problems they are encountering are based on the different properties of the new slicks, which they have thus far failed to understand.