Workflow for F-1 Underbody aero simulation?

t_money662 · April 14, 2009, 17:32

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

guillaumejolly · April 14, 2009, 23:52

Hi
Just get a couple of days of training with CD adapco if you're company is short of finance (a week if else). That will solve your problems.
If you can't do that, send your problem to CD adapco support and they will advise you on what kind of wrapper settings you need for your mesh.

f-w · April 20, 2009, 18:04

Ahh ... welcome to the world of non-ideal geometry. Without confusing you any further, here's my advice:

1) The easiest way to model your car is in a box, with the symmetry on one of the sides. Create that in your CAD package and export.
2) Not everything always imports perfectly, so try importing various formats, Parasolid and IGES usually do the job
3) Import with the high tessellation setting to preserve most of the features (keep increasing tessellation at import until everything looks good). Also, use a large sewing tolerance if using an IGES
4) What version are you using? If v4.02, use "Create new region" at import, this will make things less confusing. Else, ignore this previous comment. For any version, select "one boundary per face," which will split all faces up into different entities for you (will make meshing easier later).
5) All surfaces/boundaries (representing the car and boundary) should be in 1 region (if not change settings at import to create a single region). Combine and name them accordingly, and assign types.
6) Under each boundary, you can select to have a custom surface size, play around with that.
7) Select wrapper, remesher for your surface meshers. For volume, I usually use prism.
8) Try meshing, and see what happens ...

Otherwise, as guillaumejolly pointed out, try to get some training at your local office or through their web classes.

f-w

LiveandLetDrive · June 24, 2009, 05:17

A step-0 to add to the above. If you're using CAD geometry as received that was created for manufacturing purposes it will undoubtedly be messy. Remove any bolt holes and other unnecessary features that will otherwise require excessive mesh density and complicate the import process. It's up to you to decide what's "important."

April 14, 2009, 17:32	Workflow for F-1 Underbody aero simulation?	#1
t_money662 New Member Travis Join Date: Apr 2009 Posts: 1 Rep Power: 0	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

April 14, 2009, 23:52	Workflow for F-1 Underbody aero simulation?	#2
guillaumejolly New Member Guillaume Jolly Join Date: Mar 2009 Posts: 3 Rep Power: 17	Hi Just get a couple of days of training with CD adapco if you're company is short of finance (a week if else). That will solve your problems. If you can't do that, send your problem to CD adapco support and they will advise you on what kind of wrapper settings you need for your mesh.

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April 20, 2009, 18:04		#3
f-w Senior Member Join Date: Apr 2009 Posts: 154 Rep Power: 17	Ahh ... welcome to the world of non-ideal geometry. Without confusing you any further, here's my advice: 1) The easiest way to model your car is in a box, with the symmetry on one of the sides. Create that in your CAD package and export. 2) Not everything always imports perfectly, so try importing various formats, Parasolid and IGES usually do the job 3) Import with the high tessellation setting to preserve most of the features (keep increasing tessellation at import until everything looks good). Also, use a large sewing tolerance if using an IGES 4) What version are you using? If v4.02, use "Create new region" at import, this will make things less confusing. Else, ignore this previous comment. For any version, select "one boundary per face," which will split all faces up into different entities for you (will make meshing easier later). 5) All surfaces/boundaries (representing the car and boundary) should be in 1 region (if not change settings at import to create a single region). Combine and name them accordingly, and assign types. 6) Under each boundary, you can select to have a custom surface size, play around with that. 7) Select wrapper, remesher for your surface meshers. For volume, I usually use prism. 8) Try meshing, and see what happens ... Otherwise, as guillaumejolly pointed out, try to get some training at your local office or through their web classes. f-w

June 24, 2009, 05:17		#4
LiveandLetDrive New Member CSN Join Date: Apr 2009 Posts: 10 Rep Power: 17	A step-0 to add to the above. If you're using CAD geometry as received that was created for manufacturing purposes it will undoubtedly be messy. Remove any bolt holes and other unnecessary features that will otherwise require excessive mesh density and complicate the import process. It's up to you to decide what's "important."