[Trilinos-Users] Sundance boundary conditions

[Kevin Long]

Hi Andrea,

This is odd. Identifying boundaries by label is the most common use 
case, so it's tested thoroughly.

A few questions/suggestions:

(1) What, precisely, goes wrong? Does it fail to find any labeled cells? 
Crash? Get cells mixed up?

(2) You might use ncdump to write the exodus file to text format so you 
can verify that the cells are labeled correctly.

(3) Could you email me the exodus file so I can test it?

Regards,

Kevin





On 12/22/2011 09:09 AM, Andrea Penza wrote:
> Hi all,
> working on Sundance with a 2D ExodusII mesh I have trouble to let
> identify edges where enforce boundary conditions.
> My mesh is made by Icem Cfd because I have no license to work on Cubit.
> The problems come when I try to use:
>
> CellFilter edges = new DimensionalCellFilter(1);
>
> CellFilter left = edges.labeledSubset(1);
> CellFilter right = edges.labeledSubset(3);
> CellFilter top = edges.labeledSubset(2);
> CellFilter bottom = edges.labeledSubset(4);
>
> where int 1, 2, 3, and 4 are labels made by the mesher.
> This doesn't work if I put labels with Icem and then export in ExodusII
> file format.
> So I've tried the way to use CELL_PREDICATE like these:
>
> CELL_PREDICATE(LeftPointTest, {return fabs(x[0])<  1.0e-10;})
> CELL_PREDICATE(BottomPointTest, {return fabs(x[1])<  1.0e-10;})
> CELL_PREDICATE(RightPointTest, {return fabs(x[0]-1.0)<  1.0e-10;})
> CELL_PREDICATE(TopPointTest, {return fabs(x[1]-1.0)<  1.0e-10;})
>
> CellFilter edges = new DimensionalCellFilter(1);
>
> CellFilter left = edges.subset(new LeftPointTest());
> CellFilter right = edges.subset(new RightPointTest());
> CellFilter top = edges.subset(new TopPointTest());
> CellFilter bottom = edges.subset(new BottomPointTest());
>
> This works, but it is really uncomfortable to use because it depends on
> the tolerance used and it could lose precision with more complex
> geometry, such as curved edges like in my case.
> Has anyone some suggestion about it, or has encountered the same problem
> before?
> Thanks a lot to everyone for your support.
> Best regards,
>
> Andrea
>
>
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-- 
Kevin Long
Associate Professor
Department of Mathematics and Statistics
Texas Tech University

"The end of fear is the beginning of wisdom"
- Bertrand Russell