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integration coupling variable (unit problem)
Posted Feb 2, 2012, 2:34 p.m. EST Version 4.2, Version 4.2a 5 Replies
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I just have a quick question about evaluating a scalar integral over an area. In the 3D RF simulation, I have:
1) integration operator: intop1, integrating over an 2D boundary;
2) global variable: power_z = intop1(emw.Poavz), which integrates the power density 'emw.Poavz' over that area to give me the total power in the z-direction 'power_z'.
The expression shows up as orange, so I am guessing that there is an issue with the unit. But I don't understand what is wrong. The power density has a unit of 'W/m^2', so if the integration is over an area, it should give me a value in Watts.
I also would like to plot this power_z over a parametrized variable to show the power_z fluctuation with respect to the variable, but unable to find a way to do it. In a 1D plot, I used a 'Global' plot. In the y-axis, I select "power_z" in the expression. In the x-axis, I used "Expression" under the Parameter choice, and entered name of the parametrized variable. But I got an error saying "unknown function. Name: intop1. Plot: glob1(Global)".
Any help would be greatly appreciated. thanks.
Yan Wang
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COMSOl always calulcates in 3D, enven if you are in 1D or 2D, for the latter itassumes you have defined a depth [m] or respectively cross section [m^2] so in 1D integrating along a domain = edge multiplies by "m" so you still need to multiply by the section in m^2 to get a net value, else you remain in per m^2.
The same applies in 2D, COMSOl mostly assumes 1m depth so integrating a force density N/m^2 over a domain in 2D =surface m^2) gives you a result per meter depth N/m. If you know the depth you nedd to multiply by this depth to get the absolute force value in Newtons.
hope it tis clear ;)
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Good luck
Ivar
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if you define an intop1() or any operatir AFTER you have solved, you need to "Update the solver" to be able to use it, or resolve again. Could this be your issue ?
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Good luck
Ivar
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Sorry for disturbing you, but I am not completely understand where should I introduce a depth while integrating e.g. over circular boundary. Should I do it while defining intop function or in derived values section?
Thank you in advance.
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Can you please explain this point more for circular geometry. I obtained perfectly fine modal confinement in the inner core and there is no leaking inside the cladding. The problem is that the power flow time average z-component that is obtained has no order. It should be in the order of 10^12. Since the geometry is in [um], what do you suggest to handle this problem? The core_dia is 0.625*p where p = 3[um].
Regards,
Waqas.