Ivar KJELBERG
                                                                                                                                                    COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
                                                         
                            
                         
                                                
    
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                                                Posted:
                            
                                1 decade ago                            
                            
                                2012/05/24 14:42 GMT-4                            
                        
                        
                                                    Hi
you do not need the CIR physics to apply a sinus modulation on a BC conditions, you can do it directly in ACDC. But if you know your driving circuit and it's impedance, you can model it with the CIR physics to get the overall system behaviour.
For time dependent solvers you apply your voltage or current as a V0*sin(2*pi*freq*t) and you select a correspondingly short stepping time to correctly sample your sinus (set your time stepping to intermediate or strict, but do NOT leave the default "Free" as this si no good for periodic signals). The time stepping will give you all transients and the temporal side of your problem. Main drawback, solving is slow and can be tedious, particularly if you have many slowly damping transients due to non ideal initial conditions.
The other way is to use the harmonic development "Frequency Domain" solvers where you specify the amplitude V0, it's phase (if required) and the frequency or frequency range sweep in the solver settings, and you solve a harmonic developement of your PDE equations. This simulates a steady state sinus regime, concerges mostly much easier and quicer than an equivalent time series, but will NOT give your any transient turn on effects
Check your dc on the two and more, related solvers
--
Good luck
Ivar                                                
                                                
                            Hi
you do not need the CIR physics to apply a sinus modulation on a BC conditions, you can do it directly in ACDC. But if you know your driving circuit and it's impedance, you can model it with the CIR physics to get the overall system behaviour.
For time dependent solvers you apply your voltage or current as a V0*sin(2*pi*freq*t) and you select a correspondingly short stepping time to correctly sample your sinus (set your time stepping to intermediate or strict, but do NOT leave the default "Free" as this si no good for periodic signals). The time stepping will give you all transients and the temporal side of your problem. Main drawback, solving is slow and can be tedious, particularly if you have many slowly damping transients due to non ideal initial conditions.
The other way is to use the harmonic development "Frequency Domain" solvers where you specify the amplitude V0, it's phase (if required) and the frequency or frequency range sweep in the solver settings, and you solve a harmonic developement of your PDE equations. This simulates a steady state sinus regime, concerges mostly much easier and quicer than an equivalent time series, but will NOT give your any transient turn on effects
Check your dc on the two and more, related solvers
--
Good luck
Ivar