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magSf() on boundaries

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Old   March 14, 2012, 10:53
Question magSf() on boundaries
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Lorenzo A. Ricciardi
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Hi FOAMers,

how do I get magSf() on bounday faces?

I noticed that mesh.magSf()[faceI] gives correct results on internal faces, but when faceI is on a face, it gives ~1e-320...

Code:
label startFace = mesh.boundaryMesh()[ib].start();
label nFaces    = mesh.boundaryMesh()[ib].size();
for (label faceI = startFace; faceI < startFace + nFaces; faceI++)
    {
...
vector normal = mesh.Sf()[faceI]/mesh.magSf()[faceI]; \\floating point error
      }
What's wrong ?
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Old   March 15, 2012, 05:22
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Lorenzo A. Ricciardi
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I've solved this problem, simply taking

mag(mesh.Sf()[faceI]);

However, I really can't understand why there isn't a mesh.magSf() method for boundary faces when there is a mesh.Sf() method defined on them...
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Old   March 15, 2012, 05:30
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ngj
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Niels Gjoel Jacobsen
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Hi

You should be able to access the data in any of the following manners:

Code:
const scalarField magnitude0 = Foam::mag( mesh.Sf().boundaryField()[patchi] );
const scalarField & magnitude1 = mesh.magSf().boundaryField()[patchi];
This gives you the magnitude of the normal vectors on a given patch through its index patchi.

Best regards,

Niels
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