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Driven, Damped Harmonic Oscillator
Posted Jun 24, 2015, 3:11 p.m. EDT 1 Reply
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Hi, I am very new to Cosmol.
I'd like to use the program to solve the damped, driven harmonic oscillator equation (no physical model or anything) and get its frequency response. Basically, I'd like to use Cosmol to give me the resonance curve.
My approach has been to use the Global ODE and DAE module, with a frequency domain study. I define my global equation as utt + gamma*ut + u + sin(2 *pi*t*freq). When I try to run the study, I get the error that the jacobian for t cannot be evaluated, which I guess makes sense since time is not well defined in a frequency study.
So, is there a good way of getting the frequency response of a diff eq in time (like the damped, driven harmonic oscillator) in comsol?
Thanks in advance for your suggestions.
I'd like to use the program to solve the damped, driven harmonic oscillator equation (no physical model or anything) and get its frequency response. Basically, I'd like to use Cosmol to give me the resonance curve.
My approach has been to use the Global ODE and DAE module, with a frequency domain study. I define my global equation as utt + gamma*ut + u + sin(2 *pi*t*freq). When I try to run the study, I get the error that the jacobian for t cannot be evaluated, which I guess makes sense since time is not well defined in a frequency study.
So, is there a good way of getting the frequency response of a diff eq in time (like the damped, driven harmonic oscillator) in comsol?
Thanks in advance for your suggestions.
1 Reply Last Post Jun 25, 2015, 3:25 p.m. EDT
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Posted:
9 years ago
Hi,
You have to express the equation in frequency instead of time. The variable name is 'freq' .
Something like
(-(2*pi*freq)^2+2*damp*i*(2*pi*freq)*omega0+omega0^2)*u-loading
Parameters:
damp is relative damping
omega0 is the natural (angular) frequency
loading is the amplitude of the harmonic load
Regards,
Henrik
You have to express the equation in frequency instead of time. The variable name is 'freq' .
Something like
(-(2*pi*freq)^2+2*damp*i*(2*pi*freq)*omega0+omega0^2)*u-loading
Parameters:
damp is relative damping
omega0 is the natural (angular) frequency
loading is the amplitude of the harmonic load
Regards,
Henrik