9th July 2007 - 10:51 AM
I'm am trying to solve a Poisson equation problem, I need to find out how to apply a ground to a boundary or point in Comsol script, I cannot do this as the all the other points in the geometry are automatically made a 0*u_test (the dependant variable). This does not help me as I need to determine the impulse response of my geometry which I cannot do without some kind of grounding... I desparately need help...
9th July 2007 - 01:44 PM
Thanks to my girlfriend Suzanne for giving me the answer for this one...
In case anyone is interested (doubtful), It was my boundary conditions that were wrong. I had everything defined as Neumann boundaries but I actually needed the ground area to be defined as Dirichlet conditions. That's why it didn't work and now it works! Goodie!
9th July 2007 - 01:46 PM
How do you delete a topic?
11th March 2008 - 07:39 PM
I am a beginner in working with COMSOL.
I want to ask how can I use a function in defining a global expression.
For example I have several functions, depending on the space: fHx, fBx, fQx =f(x), which I take it from a .txt file.
1. first question
I use them to define some other parameters. I write in global expressions like this:
fvx = fQx(x)/(fHx(x)*fBx(x))
fDx = fBx(x)/(fvx*constant)
COMSOL is computing, but I am not sure is k, because in the end when I want to plot fvx and fDx, form Global variables plot it gives an error: 8032 fvx is not a valid globla expression.
This means that there is the possibility also to compute it wrong along x axis.
I want to calculate a parameter in one point (x=103), depending on the functions I implemented. In global expression I write
c_103 = (fQx(103)*c+constant)/(fQx(103)+constant)
c is the dependent variable of the model.
The expression is computed, but I don't trust is k. The same warning when I try to plot it.
Any suggestions would be of great help!