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Jack July 16, 2008 21:36

Gridgen database modification
Hi all!

I have a complex model and going to generate grid system in the GRIDGEN.

I'm facing to problem are: The database can not be modified as designed (Devide ...) and Connectors between different database are not smooth curves at the gap of database.

So anybody can suggest for me an idea !

Thanks in advance!

Chris July 17, 2008 09:12

Re: Gridgen database modification
Are you saying your database (geometry), when imported, has gaps/cracks in it? And when you create connectors (grid lines) on this non-watertight geometry, they are unsatisfactory?

Can you clarify your question a little further?

In general, you are not required to repair non-watertight database surfaces in Gridgen. You can use it to "guide" the shape the mesh but you are not forced to create connectors/domains that exactly match database.

The other option is to use quilts and solid modeling. This can repair faulty geometry and make it watertight. See the DLR-F6 tutorial in Gridgen for an overview.

Jack July 17, 2008 20:44

Re: Gridgen database modification
Thanks Chris!

You are right! About my problem and the solution with "Quilt" and "Model" to modify the database in Gridgen and DLR-F6 tutorial also.

I did with Quilt and Model, and got the smooth database.

However, when connectors are created on the batabase (Connectors/ Create/ On DB Entities), connectors are not smooth between two database (a small broken line appears).


John Chawner July 19, 2008 09:24

Re: Gridgen database modification

Allow me to add to Chris' answer. If I understand correctly what you've written above, the "small broken line" sounds like a branch connector. These are automatically inserted when a connector traverses from one db surface to another. (The reason is because the connectors are defined in the parametric space of the surface. In the gap between surfaces there are no parameters so the line must be a straight line. The dashed line is a visual cue that this has occurred.)

However, if the dashed line is big enough to be seen easily then I'm going to assume that the gap between surfaces is large. When the gap is that large it's probably too big relative to your mesh size. Rather than mesh over it, you'll probably need to fill it. You can use one of the surface creation tools like the Coons Patch or a Ruled Surface to do this.

Hope this helps. If not, please contact our Tech Support Team at 800-4PTWISE or

Jack July 20, 2008 21:29

Re: Gridgen database modification
Hi John Chawner!

Thanks so much, you know that problem exactly.

The dashed line is very relative small, I guess that, there is no effect on the final result.

How do you think about that?

Once more, thanks for your reply!

John Chawner July 20, 2008 21:59

Re: Gridgen database modification

The dashed line is OK. All it's telling you is that it's a straight line between curved sections on different database surfaces. Just keep in mind that the dashed line needs to be short relative to your mesh size or you can introduce discontinuities into the mesh.

Good luck.

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