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HIgher order derivatives of solved variables
Posted Sep 13, 2013, 11:16 a.m. EDT Low-Frequency Electromagnetics, Parameters, Variables, & Functions, Results & Visualization Version 4.3a 2 Replies
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Looking around the forums and the documentation, it appears that comsol by default uses second order shape functions (I am not entirely sure what they are...). This apparently means that I can not evaluate derivatives of order higher that 2. I assume that, since the model solves for the magnetic vector potential (A), if I ask for the second derivative of the flux density (which is itself a derivative of A), I am asking for a 3rd order derivative of A (which fails in 2nd order shape functions).
So to get the result I need, I think I have to increase the order of the shape functions. I just can't find where to do this. I activated the "Discretization" option under the "Show" menu and selected "Cubic" in the "Magnetic Fields (mf)" node of the Model Builder (see attached image) but this doesn't help. The degrees of freedom increase accordingly but I still get all zeroes in the second derivative. I can't find anywhere else to change this in my version of Comsol and I don't know what I am doing wrong...
Thanks in advance for any help.
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Hello yausern
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