dBasisdx over Edges

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gagliar
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Joined: 04 Sep 2009, 16:34
Location: LGGE - Grenoble
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dBasisdx over Edges

Post by gagliar »

Hello,

I'm solving for a variable defined on the element edges (202 type element). For the assembly, I'm doing a loop over Solver % Mesh % NumberOfEdges.
The call to ElementInfo return
Basis(1:2) = [0.21132486540518713 0.78867513459481287]
dBasisdx(1:2,1) = [0.0000000000000000 0.0000000000000000 ]
dBasisdx(1:2,2) = [3.3333333333333335E-005 -3.3333333333333335E-005]

whereas I would expect only dBasisdx(1:2,1) to have non zero value?
Only the local coordinate u is non zero (v and w are zero).

What I'm doing wrong here?

Thanks
Olivier
Juha
Site Admin
Posts: 357
Joined: 21 Aug 2009, 15:11

Re: dBasisdx over Edges

Post by Juha »

Hi,

the derivatives from ElementInfo are with respect to global coordinates.
In your example the edge might be oriented along y-coordinate, for
example? If you need tangential derivatives, take a dot product with
edge direction vector?

Regards, Juha
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