Trouble creating watertight geometry

[APayne723]

Hi,

I have an imported .iges model that I need to create watertight to run CFD on it. I am designing an aerodynamic package for the car. But first I need to get the general model working. It has over 5000 surfaces after importing and has me stumped after 2 days of working on it.

I keep getting a connexity issue when trying to join the surfaces after I have tried to simplify it. Any help or tips would be appreciated.

I would attach the file but the engineering.com upload is working either.

 

[KhimaniMohiki]

Increase your join tolerance?

Khimani Mohiki
Design Engineer - Aston Martin
NX8.5

 

[jackk]

I've never had an IGES file that didn't need some kind of surface clean-up.

First thing is, as Khimani said, use a larger Merging Distance on your Join. (I think the default is .00004in, change it to .001in or the max gap you can work with) This should eliminate most of the issues.

You also could try HEALING, instead of JOIN.

Next, change the display options to see where the edge connexity issues are. (see attachment) Use a bright color.

The highlighted boundaries could indicate several issues. There will probably be many that you will have to fix one at a time; when all the boundaries are no longer highlighted, the Join is probably OK.

MISSING SURFACE - use FILL to add a surface (and add this surface to the Join)

DUPLICATE SURFACE - delete one of the duplicates

GAP BETWEEN EDGES - delete one of the surfaces, and add a new FILL surface using the edges of the adjacent surfaces (add new surface to the Join)

 

[KhimaniMohiki]

If the gaps are small enough cant you just mesh over them in whatever pre-processor your using?

Khimani Mohiki
Design Engineer - Aston Martin
NX8.5

 

[APayne723]

Thank you for the replies.
I eventually got the body to become watertight. Unfortunately that required rebuilding half of the car.

And yes as im using star-ccm+ I couldve used surface wrapper but preferred to have a solid body to make aerodynamic modifications easier in the future

 

[loki3000]

try to get a step file, it's somewhat better.