hi i modeled a straight duct with deformations on the surface.the cad model was first run thru prosurf and repaired for CAD errors and the mesh was generated using proam.But when i refine the mesh and chck for cells it shows around 1300 no volume cells.my model has about 70000 cells.is there any specific way to rectify or correct the no volume cells?pls help

i am sorry that is not no volume error.. itz a negative volume cell error..

use the check tool and check for negative volume. This will put all negative volume cells in the same cset. Then try cflip,cset. Sometimes this works.

Tom

Thanks Tom, it works.but now it shows an error - x number of cracks found in the specified region.how to clear this??

Cracks are the scourge of mankind. CD-adapco makes them happen just to watch mere mortals squirm and cuss. However, try putting them in a cset. Grow the cset and then use the couple tool to join them with couples. Check again for cracks and you should have eliminated them. If not zoom in on them and take a look. You may have to fix them manually by moving vertices. I have found that one of the reasons for cracks is that when you make the subsurface, the tool also makes lines and points. Because of the tolerances on the code, these lines and points do not line up with the ones in the surface. Believe it or not, but all you have to do is to load your subsurface and count cells. Delete all lines and points and save, and then build the mesh from that. Probably more than you wanted to know. Good luck. Tom

Thanks a lot.I'll try.

Tom,Using couple tool works to eliminate cracks,but when checking for couples it gives the error er. no 84 : a master cell face in one couple is defined as slave cell face in another couple.

er.no 61:Couple has partial boundary,but is not assigned to a partial boundary couple type.

any suggestions?? Thanks

Now it is a matter of how many cracks there are. If there are only a few, try fixing them by hand. Put them in a cset and talke a close look. Sometimes you can fix them by moving vertices, etc. If there are a lot, then you may want to just start over. A lot of cracks indicate a problem with your basic surface. You may want to go all the way back to it and try improving it. For example, check where your cracks are and then check that part of the surface. You may want to improve the triangulation there. Make sure you have remove the lines and points from your subsurface before building your custom mesh.

I am at the point of having 250 cracks in my model, so I am going back to the surface as we speak. I have some sharp angles that are giving the mesh problems, so I am going back to my surface to refine that part.

Good luck.

Tom

Hi Tom,so to clear the error in couples we have to know the number of cracks ??could u tell me how to fix them by hand?