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 Deevyendu July 2, 2010 01:24

Algorithm for finding surface normals

hi to all ....
As I have done unstructured meshing on symmetric aircraft using ICEM-CFD. Now i required to know how to fine positions of surface normals. Can anybody help me finding so. or any algorithm is there for finding surface normals using euler method ?

 meb July 2, 2010 20:34

Mesh normals

If you need the normal of a surface element it can be easily computed using the cross product (http://en.wikipedia.org/wiki/Cross_product).
For a triangular element (with nodes at p1 p2 p3):
n = vers ( (p2-p1) x (p3-p1) )
where vers(v)=v / |v| is used to have a versor. If you use the half of the cross product only you get the oriented Area, very useful if you need nodal normal that can be calculated summing all the contributions of connected elements.
For a 4 nodes element the normal is usually defined by the cross product of the diagonals...

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