Calculate the energy of a capacitor charged

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activ25
Posts: 18
Joined: 31 Oct 2018, 21:04
Antispam: Yes

Calculate the energy of a capacitor charged

Hi,

I would like to calculate the energy the voltage source need to give with a capacitance charged at start. What is the function to set the voltage AND the charge at start. I mean, the capacitance could be charged with 5V before start, but at start I set on a voltage source at 10 V. I would like to calculate the energy I need to charge under 5V and after under 10V when it was charged under 5V before.

Regards
Ludo

mzenker
Posts: 1903
Joined: 07 Dec 2009, 11:49
Location: Germany

Re: Calculate the energy of a capacitor charged

Hi,

that sounds like an electric circuit problem which does not need FEM. Or do you have geometrical issues in your case?
Else I would tend to recommend LTSpice, a freeware electric circuit simulator by Linear technologies (now part of Analog Devices).

HTH,
Matthias

activ25
Posts: 18
Joined: 31 Oct 2018, 21:04
Antispam: Yes

Re: Calculate the energy of a capacitor charged

Hi Mathias,

No, I have a special shape for the plate, I need a 3d simulation.

Thanks
Ludo

mzenker
Posts: 1903
Joined: 07 Dec 2009, 11:49
Location: Germany

Re: Calculate the energy of a capacitor charged

Hi,

you can use the StaticCurrent solver and set potentials as boundary condition for the voltage source and as initial condition for the capacitor. Then you will have to integrate the current between voltage source and capacitor over time, either in Elmer using the SaveScalars solver with some operator, or in the postprocessing (e.g. using ParaView). The energy is the current integral multiplied by the voltage (10 V in this case).

HTH,
Matthias