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Plotting an analytical function with the right Unit

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Hey,

I am new to COMSOL and am trying to rebuild a model and the graphics of the attached tutorial. The tutorial is for version 5.2 but I am using 4.2 which was not a problem so far.

I am struggling in reproducing figure 4 (see attached pdf-file). I get an offset between the analytical solution and calculated solutions. I think it is a Unit-problem.

The attached figures 1 to 3 show:
1. How I defined the analytical solution (1.png): V = 1[A]*rho0/(2*pi)*(1/abs(x-x1)-1/abs(x-x2))
Does the error lie here? Do I somehow have to tell COMSOL what the units of the arguments x, x1 and x2 are?
2. How I added the function to the data set (2.png): This should be okay.
3. How I tried to plot it in a 1D Line graph (3.png): Here I cannot choose a Unit. But strangely, if I put the Unit "dV" (as it is in the point
graph 1 for the calculated solution (dots)) and press "Plot" the line is correct but the "dV" is deleted and if I try to do this for both line graphs it doesn't work as the dV always gets deleted as a Unit...

So the question is: How do I get this correct in a way that I can choose the right Unit in step 3?

Thank you very much in advance!
Sina


0 Replies Last Post 11 mag 2016, 13:37 GMT-4
COMSOL Moderator

Hello Sina

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