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Applying AC signal in COMSOL 3.5

Posted 9 set 2014, 10:12 GMT-4 5 Replies

Pratik Shah
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Am I applying the correct signal?

I want to apply AC (sine wave) voltage with 1 MHz frequency and 3V peak-to-peak amplitude on an electrode.

I am applying potential in the following form;
sin(2*pi*t*1E6[1/s])*3[V])

Also, If I ant to apply another signal on next electrode with 180 degree out of phase, shall I reqrite the above equation in following form?
sin(1*pi*t*1E6[1/s])*3[V])

Thank you for the help.
5 Replies Last Post 1 feb 2015, 19:44 GMT-5
Robert Koslover Certified Consultant
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Posted: 1 decade ago 9 set 2014, 10:32 GMT-4
Four quick thoughts:
1. Both of your expressions have an extra parenthesis at the end.
2. The amplitude (0 to peak) that would result from your expressions (after you fix the syntax errors) will be 3V. If you want 3V to be the peak-to-peak value, then you need to replace the 3 with a 1.5.
3. Your second expression is incorrect, if you are trying to change the phase. You changed the frequency, not the phase. Instead, the easiest way is to just write the negative of the first expression (i.e., just put a minus sign in front of it).
4. Finally, you appear to be employing a time domain model, but doing a frequency-domain calculation. If all you are going to use is sinusoidal waves, then you should probably build a frequency-domain model instead.

There may be other issues, but that should be enough to give you something to work on for now...

Good luck.

Four quick thoughts: 1. Both of your expressions have an extra parenthesis at the end. 2. The amplitude (0 to peak) that would result from your expressions (after you fix the syntax errors) will be 3V. If you want 3V to be the peak-to-peak value, then you need to replace the 3 with a 1.5. 3. Your second expression is incorrect, if you are trying to change the phase. You changed the frequency, not the phase. Instead, the easiest way is to just write the negative of the first expression (i.e., just put a minus sign in front of it). 4. Finally, you appear to be employing a time domain model, but doing a frequency-domain calculation. If all you are going to use is sinusoidal waves, then you should probably build a frequency-domain model instead. There may be other issues, but that should be enough to give you something to work on for now... Good luck.
Pratik Shah
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Posted: 1 decade ago 9 set 2014, 11:36 GMT-4
Dear Robert,

Thanks for pointing out errors.

Regarding suggestion 4;

When I have selected In plane electric current physics in AC/DC module, I only get to selects options from

Static
Time-harmonic
Transient
Time-harmonic electric current
Transient, electric current

Can you please suggest, how can I select frequency domain when analyzing the field strength?

Thanks a lot!
Dear Robert, Thanks for pointing out errors. Regarding suggestion 4; When I have selected In plane electric current physics in AC/DC module, I only get to selects options from Static Time-harmonic Transient Time-harmonic electric current Transient, electric current Can you please suggest, how can I select frequency domain when analyzing the field strength? Thanks a lot!
Robert Koslover Certified Consultant
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Posted: 1 decade ago 9 set 2014, 15:41 GMT-4
"Time-harmonic" means frequency-domain.
"Time-harmonic" means frequency-domain.
Pratik Shah
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Posted: 1 decade ago 9 set 2014, 19:25 GMT-4
Robert,

Thanks a lot !!
Robert, Thanks a lot !!
Malik Saparov
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Posted: 10 years ago 1 feb 2015, 19:44 GMT-5
HI
i am trying to simulate piezo-acoustic interaction,
and my signal is ac which is V0sin(2*pi*f0*t) and secon is V0cos()2*pi*f0*t
and im usin frequency domain, but when i am solvin there is problem appering, like undefined value "t",
can u help??
HI i am trying to simulate piezo-acoustic interaction, and my signal is ac which is V0sin(2*pi*f0*t) and secon is V0cos()2*pi*f0*t and im usin frequency domain, but when i am solvin there is problem appering, like undefined value "t", can u help??

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