Originally Posted by bozont
there is a link for a video where a physics guy involved with gaming explain the whole problem about computational physics. (lol cant find it).
Search for Brian Beckman & Forza - that is the interview.
The "physics guy" is Dr. Brian Beckman, a Physicist.
fluid/air flow simulation - just a simple cylinder - a P4 took it an hour+ . - intersting for gaming
contact simulation - its even worse than fluid flow simulation. interesting for gaming too.
This (car and tire behaviour, and on top collision physics) is obviously complex.
It is not as terrible as you make it look, though.
BMW stated in 2000 that they used pc's connected together with 200 cpu working together to simulate a car crash of 1:1 detailed model of the 5 series with LS Dyna (which should be the fastest solver of that time) . it took 2 weeks to compute just a head on crash. try this on 36+ cars
so the whole thing must be very very simplyfied to do it realtime-ish.
and dont forget the tires...
Taking your info at face value...
That was in 2000. So, either update the info or the comparison is no longer valid.
On the other hand, you are talking about a different thing than we are.
The goal of iRacing and the racing simulations we like is not to attempt to replace physics crash testing with a simulated one.
The goal here is racing simulation. Collision physics in simracing does not have to be ultra-sophisticated and ultra-complex - there really is no point in doing that. It is, however, rather good, in that it deals with chassis deformation, loss of wheels, loss of steering, loss of car body parts (prominently, aerodynamics apps), all of which are key to racing and how a race ends.
As for tires, Dr. Brian Beckman explained it quite well not only in that interview you allude to, but also in his racing physics series. There are, however, other experts, like Veble, Pacejka/Sharp/Bakker/Besselink, Gent, Assaad and Ebbon, the Millikens, all of which have contributed with their knowledge and in some capacity to the formulation of different tyre models (from Fiala to Swift and MF).
Iirc, most of these people have stated some compromises are necessary between complexity and accuracy.
Computational resources restrictions add up one more element to this, true, but the models used (math based, empirical based, physical based) in current simulations work and provide very good results - albeit not being 100% as accurate or effective as a multi-million dollar simulation developed by the likes of Mercedes.