[t_money662]

I need to simulate the amount of downforce generated by an aerodynamic undertray, and was referred to Star-CCM+. I havde never used this software, but am familiar with IDEAS, SolidWorks, Pro-E. I have the CAD model of the car (IGS file), and am trying to mesh it in star-ccm, inside of a box to simulate a wind tunnel. I have a few tutorials, but in all of those the CAD models are perfect. The one I am using, apparently there are open or manifold surfaces, as the error I get states whe I try and subtract the car region from that of the box (I use half a car and use symmetry)..In the tutorial it works perfectly, but I am not so lucky..
So I am trying another approach, to put the whole car in the box, and mexh the volume between them...Is this correct? I am having a heck of a time, errors galore, and it is driving my crazy!

What is a good workflow for this type of simulation, I need something to wprk from, but all tutorials I have are just different enought to confuse me and lead me to get errors on nearly every other step...Its hard to learn this software by yourself, any insight would be greatly appreciated!
Thanks