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FD analysis
Posted 6 ago 2010, 07:27 GMT-4 2 Replies
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Hi,
I have attahced a model, i want to do frequency domain analysis, i have applied a sinosodial input and applied a edge probe where i want to see the potential with respect to frequency changes. But i do not understand what is going wrong with the model that the potential on the edge is coming zero.
Secondly if you could look at the memberane capcitance. i wanted to have a memberane capaciatance of 0.01(micro farad per meter) . as far as i understan to give the memberane capacitance, i need to use relative permitivity and need to calculate relative permitivity for unit area. is it right in context of comsol ? because when i also calculate from the help of comsol the capcitane on the boundry of the membrane that comes about approx 10.12 e-14.
Any idea how can i resolve both issues using the same physics of electric currents and frequency domain solver
I have attahced a model, i want to do frequency domain analysis, i have applied a sinosodial input and applied a edge probe where i want to see the potential with respect to frequency changes. But i do not understand what is going wrong with the model that the potential on the edge is coming zero.
Secondly if you could look at the memberane capcitance. i wanted to have a memberane capaciatance of 0.01(micro farad per meter) . as far as i understan to give the memberane capacitance, i need to use relative permitivity and need to calculate relative permitivity for unit area. is it right in context of comsol ? because when i also calculate from the help of comsol the capcitane on the boundry of the membrane that comes about approx 10.12 e-14.
Any idea how can i resolve both issues using the same physics of electric currents and frequency domain solver
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2 Replies Last Post 6 ago 2010, 10:30 GMT-4
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Posted:
1 decade ago
Hi
I believe you are confused in the terminology here. You do indeed try to apply a time dependent voltage value on your electrode but you have choosen a frequency domain or harmonic solver and not a time dependet solver.
The frequency domain solver means that you are looking at your equations with a harmonic development (similarity a la Fourier) and you are assuming sinus excitation of the approach amplitude + frequency (set in the freq tab) with possibly a phase. Your time variable is by default t=0 in this case (which means that your function sets 0V on your electrode that is also why you see 0 out).
therafter the solver is set for a 100 Hz scan, while the deeper parametric settings is 0-1 Hz scan, which means that you have generated a solver sequence once, and changed deep down in the solver tree without chaning the master parameter. This is slightly tricky in V4 and it took me some times to understand: you can have the same parameter defined at different levels, the deeper you dig into the tree these are overwriting the outer levels (just as for BC (boundary conditions) the lower you are in the sequence at equal branch level, (which is analysed top down) the more you might overwrite previously defined elements.
to get your solution running, set a voltage V0 (i.e. 1V) as a parameter and apply it to your electrode, and remove your sinus function totally.
then go to the Study>SolverConfiguration node do a "delete solutions" (you will loose some of your plot settings, but these are rather quick to set up again). Go to the Study>Frequency domain> Frequencies type 5000 or whatever frequency or range(start,step,stop) for a range and do a Study>solverConfiguration "compute"
--
Good luck
Ivar
I believe you are confused in the terminology here. You do indeed try to apply a time dependent voltage value on your electrode but you have choosen a frequency domain or harmonic solver and not a time dependet solver.
The frequency domain solver means that you are looking at your equations with a harmonic development (similarity a la Fourier) and you are assuming sinus excitation of the approach amplitude + frequency (set in the freq tab) with possibly a phase. Your time variable is by default t=0 in this case (which means that your function sets 0V on your electrode that is also why you see 0 out).
therafter the solver is set for a 100 Hz scan, while the deeper parametric settings is 0-1 Hz scan, which means that you have generated a solver sequence once, and changed deep down in the solver tree without chaning the master parameter. This is slightly tricky in V4 and it took me some times to understand: you can have the same parameter defined at different levels, the deeper you dig into the tree these are overwriting the outer levels (just as for BC (boundary conditions) the lower you are in the sequence at equal branch level, (which is analysed top down) the more you might overwrite previously defined elements.
to get your solution running, set a voltage V0 (i.e. 1V) as a parameter and apply it to your electrode, and remove your sinus function totally.
then go to the Study>SolverConfiguration node do a "delete solutions" (you will loose some of your plot settings, but these are rather quick to set up again). Go to the Study>Frequency domain> Frequencies type 5000 or whatever frequency or range(start,step,stop) for a range and do a Study>solverConfiguration "compute"
--
Good luck
Ivar
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Posted:
1 decade ago
Thank you Ivar for replying.
I think i need to give more in-detail look to the model. and i would like to come back with some more questions very soon.
Regards
Muhammad