Menu

Discussion Forum

New Discussion
Filtern

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Modelling admittance in Comsol V4

Posted 28.06.2010, 10:13 GMT-4 5 Replies

David Smith
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi,

I have a model which uses conductivity and permittivity as the parameters for a dielectric material. This dielectric is placed between a HV supply (modelled as terminal and ground), using 'electric currents' mode. In the previous version, v3.5a using 'quasi-statics' mode, it was the case of evaluating the admittance (then converting to resistance and capacitance). v4 doesn't seem as simple, I've tried 'derived values, global evaluation' - I can get a resistance, but no capacitance.

Has anyone managed to do something similar in v4?

Regards, David.
5 Replies Last Post 12.07.2011, 07:14 GMT-4
David Smith
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 09.07.2010, 08:27 GMT-4
I've found the problem.

When v3.5a frequency dependent models are brought across into v4 the freqency domain needs to be re-activated in advanced settings. Once this is done the admittance becomes available as a variable.
I've found the problem. When v3.5a frequency dependent models are brought across into v4 the freqency domain needs to be re-activated in advanced settings. Once this is done the admittance becomes available as a variable.
Nidhi Maheshwari
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 03.07.2011, 16:07 GMT-4
Dear David,
I am also trying to simulate impedance for a parallel plate capacitor with water as a dielectric. I do not see a change in the value of impedance/admittance with frequency. Can you shed some light on this. Do we need to define permittivity and conductivity of the solution as a function of frequency. If you can share your model which can give a fair idea about the variables defined and the boundary conditions, it will be of great help. I have tried simulating in both version 4.0 and 3.5, so model in any of the versions would be of help.
Thanks in anticipation
Nidhi
Dear David, I am also trying to simulate impedance for a parallel plate capacitor with water as a dielectric. I do not see a change in the value of impedance/admittance with frequency. Can you shed some light on this. Do we need to define permittivity and conductivity of the solution as a function of frequency. If you can share your model which can give a fair idea about the variables defined and the boundary conditions, it will be of great help. I have tried simulating in both version 4.0 and 3.5, so model in any of the versions would be of help. Thanks in anticipation Nidhi
David Smith
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 06.07.2011, 08:17 GMT-4
Dear Nidhi,

Thanks for your interest in this work.

You should see a change in admittance (capacitive component) with changes in frequency without specifying frequency dependent material properties as Xc=1/(2*pi*f*C), where C=ep*A/d.

The model should be set-up as follows:

- Electric currents application mode
- Frequency domain study

- The energised boundary should be a 'terminal'
- The grounded boundary is of course 'ground'
- The open boundaries are 'electric insulation'

I have attached a basic model for reference.

Meshing is critical and you may need to use the 'adaptive mesh refinement' tools for an accurate solution.

I hope this had been of assistance.

Regards,
David.
Dear Nidhi, Thanks for your interest in this work. You should see a change in admittance (capacitive component) with changes in frequency without specifying frequency dependent material properties as Xc=1/(2*pi*f*C), where C=ep*A/d. The model should be set-up as follows: - Electric currents application mode - Frequency domain study - The energised boundary should be a 'terminal' - The grounded boundary is of course 'ground' - The open boundaries are 'electric insulation' I have attached a basic model for reference. Meshing is critical and you may need to use the 'adaptive mesh refinement' tools for an accurate solution. I hope this had been of assistance. Regards, David.

Attachments:

Nidhi Maheshwari
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 07.07.2011, 05:02 GMT-4
Thanks David for sending the information across. Can you please let me know which version of comsol you have used for the model. I have not been able to open the file in Comsol 4.0, it says that an advanced version has been used to make the model. If possible can you send a 4.0 compatible version of the model?

Regards,
Nidhi
Thanks David for sending the information across. Can you please let me know which version of comsol you have used for the model. I have not been able to open the file in Comsol 4.0, it says that an advanced version has been used to make the model. If possible can you send a 4.0 compatible version of the model? Regards, Nidhi
David Smith
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 12.07.2011, 07:14 GMT-4
Hi Nidhi,

I am using COMSOL 4.1 and do not have any older versions installed on my computer.

Have a read of the example (tunable capacitor) in the COMSOL model library as it will help when setting up your model.

Regards,
David.

Hi Nidhi, I am using COMSOL 4.1 and do not have any older versions installed on my computer. Have a read of the example (tunable capacitor) in the COMSOL model library as it will help when setting up your model. Regards, David.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content