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'sigma_dc' on vertices

Posted Jul 9, 2012, 7:29 a.m. EDT Low-Frequency Electromagnetics 2 Replies

Hoda Ayati
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Hi,

I am using Comsol/Matlab interface. I have a model which is solved in 'Conductive Media DC' for voltage over the surface. The inputs are the injected current and the known conductivity of the area and the output is the potential. the model and the solution working properly.

What I want is the value of the conductivity of the vertices of the mesh.

What I used is <<sigmax = postinterp(f,'sigma_dc',vert{n});>> which is working but takes too long as it solves the problem again for each element. but as the conductivity is an input there should be another way to plot it.

the vertices are come from 'pd.p'.

I was wondering if you could help me.

Thanks,
Hoda
2 Replies Last Post Jul 10, 2012, 4:09 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jul 10, 2012, 3:27 a.m. EDT
Hi

try to avoid thinking mesh and nodes for postprocessing in COMSOL, you will get confused, that is the "old" way of FEM. COMSOl uses entities: geoemtric domains, boundaries (and perhaps edges and points if applicable). You shoudl use the properties on domain and boundaries (volumes and surfaces in 3D, surfaces and edges respectively in 2D) and select the boundaries and plot thereafter. COSMOL will then apply the values to these entities. Not that a Boundary heritates its results from the surrounding domains, which means that sometimes you get average values, or undefined derivatives as these cannot be correctly estimated, all depends on your model set up

--
Good luck
Ivar
Hi try to avoid thinking mesh and nodes for postprocessing in COMSOL, you will get confused, that is the "old" way of FEM. COMSOl uses entities: geoemtric domains, boundaries (and perhaps edges and points if applicable). You shoudl use the properties on domain and boundaries (volumes and surfaces in 3D, surfaces and edges respectively in 2D) and select the boundaries and plot thereafter. COSMOL will then apply the values to these entities. Not that a Boundary heritates its results from the surrounding domains, which means that sometimes you get average values, or undefined derivatives as these cannot be correctly estimated, all depends on your model set up -- Good luck Ivar
Hoda Ayati
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Posted: 1 decade ago Jul 10, 2012, 4:09 a.m. EDT

Hi,

Thank you for your response.

Actually I need a coordinate of an area on the surface which I do not have access through the geometry information. but if I have the value of the nodes on that area and their coordinates, I would find coordinate of that area which I could but it takes too long as it solves the problem again over the nodes.

I just wanted to know whether I can have it without solving the problem again.

Thanks,
Hoda
Hi, Thank you for your response. Actually I need a coordinate of an area on the surface which I do not have access through the geometry information. but if I have the value of the nodes on that area and their coordinates, I would find coordinate of that area which I could but it takes too long as it solves the problem again over the nodes. I just wanted to know whether I can have it without solving the problem again. Thanks, Hoda

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