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error in the model of a coax

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Hi,

I'm a newbie on comsol, trying to model in ac/dc module and electromagnetics.
I started to work with a simple coax cable structure, examined the capacitance wrt radius of insulator as well as different different types of insulators in electrostatics physics. Then studied the tutorial on the empedance of a coax cable.
Now, what I want to is to apply an ac voltage to its conductors and see how it behaves.
However I couldn't do it. First, I solved the problem in time domain of electrostatics and electric currents separately, as seting the terminal voltage a function depended on time, i.e. Vo*sin(2*pi*f*t).

When those did not work, I switched to the freq.domain in electric currents. However, that did not work, either.

This is the error I'm getting,

"
Problem encountered during results while solving.
Evaluation of result expression failed.
Failed to evaluate variable.
- Variable: es.nD
- Geometry: 1
- Boundary: 6 7 8 9 10 11 26 27 28 42 43 44
Failed to evaluate expression.
- Expression: real(es.nD)
Failed to evaluate expression.
- Expression: real(es.nD)
"

What might be the problem?

thanks a lot
CBD

1 Reply Last Post 12.07.2012, 15:39 GMT-4

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Posted: 1 decade ago 12.07.2012, 15:39 GMT-4
Hi again,

I managed my problem, solved it. However now I have a different problem.

I designed a model with a semi-conductor sphere and studied the currents flown on the surface with ec physics. When I add an air around the sphere, that did not work simply. The program couldn't calculate.
What might be the problem?



thanks,
Ceren
Hi again, I managed my problem, solved it. However now I have a different problem. I designed a model with a semi-conductor sphere and studied the currents flown on the surface with ec physics. When I add an air around the sphere, that did not work simply. The program couldn't calculate. What might be the problem? thanks, Ceren

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