# Discussion Forum

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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## 3D simulation: Extract 2D integrated solution values along a path

I have solved a 3D problem with the RF module, electromagnetic waves (emw), which gives me a nice 3-dimensional electric field distribution.

Now I have a problem with the evaluation, maybe someone of you can help me.
The geometry is sth. extruded from a 2D geometry. In 2D there is a rectangle (R), centered to x,y=0, which in 3D into the z dimension becomes extruded to a long (prolate) rectangular block. It is kind of a waveguide.

What I need: The power flow into z direction (P), integrated in a plane, which is the rectangle (R) over the z coordinate.
I now already tried, defining me a Results-> Datasets->CutLine 3D.
Is this the right approach? Is it possible to define there a 2D integration which I can extract as a scalar along the z (1D) extension?
I have also already included a "line" object in my geometry, central (x,y=0), as I hoped, maybe, I could at least get scalar values along this line. But in principle I want to do this aforementioned 2D integration before going along the line.

To be honest, at this point I am now a bit at a loss.

Has anyone of you already done this?
I guess, if it is then in this discussion forum as an answer, maybe it could be also a good help for others ;-)

Best regards!

Arian

6 Replies Last Post Jun 28, 2011, 4:04 PM EDT
Posted: 7 years ago
Hi

in 4.1 you can define a cut plane ("artificial" interpolated boundary in the results data set) and then integrate over this plane. Often I cut my geometry to have an interiour boundary that I can select and define some probe or integration operator thereon and use them in the postprocessing

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Good luck
Ivar

Posted: 6 years ago
Hi Ivar,

I'm using Comsol 4.1 to solve liquid flow and heat transfer problem in channels. What I need is to evaluate integration or average value on a cross-section plane. I know I can define a "cut plane" to do this. But is there any method to define the boundary of the plane, since on the same plane I've other structures which are not of interest.

I wonder if "parameterized surface" would be a possible solution. But I could not find sufficient instruction information concerning that topic in the help file.

Thank you.
Cheng

Posted: 6 years ago
Hi

but cannt you cut then your geoemtry such that you have a boundary you can integrate over ?

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Good luck
Ivar

Posted: 6 years ago
Hi,

I used to cut my geometry in the drawing step and it works. But is it possible to cut it in the postprocessing step? I don't want to reconstruct the model and solve it again and again for postprocessing purpose.

Thank you.
Cheng

Posted: 6 years ago
You could use a cut plane dataset combined with an integration expression that involves a boolean. Something like T*(dom==1) if you want to integrate T and only integrate on the intersection of your cutplane with domain 1.

Posted: 6 years ago
Hello, Cheng.
Have you managed to solve this issue? Could you help me, please? I am in the same situation now.
Thank you

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