Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted:
1 decade ago
06.02.2012, 01:26 GMT-5
Hi
in EC or electric currrent you solve for "V" the voltage, and find the electric field (Ex,Ey,Ez)=-grad(V) so you are already taking a first derivative of V. now if you want to derivative of the field Ex you are asking for the 2nd derivative of a dependent variable, this is only possible if you are using a 2nd order (or preferrably higher) shape function, and that your mesh is of sufficient quality (symmetric) to allow such high order shape functions
Whn you apply AC currents, you should consider the frquency domain solver, this does a development of the ime derivativeinto the harmonic representation with omega = 2*pi*f, you define the amplitude and the phase ans well as the frequency in latter in the solver section (or frequency range for a scan) and off you go.
Check the doc and the examples in the model library
--
Good luck
Ivar
Hi
in EC or electric currrent you solve for "V" the voltage, and find the electric field (Ex,Ey,Ez)=-grad(V) so you are already taking a first derivative of V. now if you want to derivative of the field Ex you are asking for the 2nd derivative of a dependent variable, this is only possible if you are using a 2nd order (or preferrably higher) shape function, and that your mesh is of sufficient quality (symmetric) to allow such high order shape functions
Whn you apply AC currents, you should consider the frquency domain solver, this does a development of the ime derivativeinto the harmonic representation with omega = 2*pi*f, you define the amplitude and the phase ans well as the frequency in latter in the solver section (or frequency range for a scan) and off you go.
Check the doc and the examples in the model library
--
Good luck
Ivar
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Posted:
1 decade ago
06.02.2012, 01:51 GMT-5
Hi, Ivar,
Thanks for your reply.
I saw the pre-defined expression for electric field, norm: normE_dc; x component: Ex_dc; y component: Ey_dc;
Now I want to get grad(E^2) in the x direction. I write it as d(Ex_dc^2,x) but it still give zero value...
I checked some previous thread but can't figure it out...
www.comsol.com/community/forums/general/thread/4711/
www.comsol.com/community/forums/4-1/thread/17498/
For AC simulations, all I need to do is to change the solver parameter ?
Hi, Ivar,
Thanks for your reply.
I saw the pre-defined expression for electric field, norm: normE_dc; x component: Ex_dc; y component: Ey_dc;
Now I want to get grad(E^2) in the x direction. I write it as d(Ex_dc^2,x) but it still give zero value...
I checked some previous thread but can't figure it out...
http://www.comsol.com/community/forums/general/thread/4711/
http://www.comsol.com/community/forums/4-1/thread/17498/
For AC simulations, all I need to do is to change the solver parameter ?
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Posted:
1 decade ago
06.02.2012, 03:13 GMT-5
I think there should be something wrong with my plots. How could I plot the global expression at each point and give a surface plots ?
I think there should be something wrong with my plots. How could I plot the global expression at each point and give a surface plots ?
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Posted:
1 decade ago
26.11.2012, 03:34 GMT-5
I also want to do same king of simulation but i am not able to get exact solution? can u tell me how can i start to simulate the AC Dielectrophoresis?
I also want to do same king of simulation but i am not able to get exact solution? can u tell me how can i start to simulate the AC Dielectrophoresis?
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Posted:
10 years ago
03.06.2015, 22:36 GMT-4
Dear Sir,
I did my doctorate on dielectrophoresis in 1988 and my master's on magnetic separation.
I am not answering your request directly but I thought it could be useful to note that it's easier to plot magnetic fields using fine iron powder.
Dr. Allen Shalom
Dear Sir,
I did my doctorate on dielectrophoresis in 1988 and my master's on magnetic separation.
I am not answering your request directly but I thought it could be useful to note that it's easier to plot magnetic fields using fine iron powder.
Dr. Allen Shalom