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Integrating within Silce

Posted Feb 20, 2011, 12:52 p.m. EST RF & Microwave Engineering 5 Replies

Ran Califa
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Hi,

I am doing a 3D Comsol simulation for a rectangular Optical waveguide coupler .

In this simulation i need to find the -3db point (in this point the power is spliting equaly betwin the two arms of the Coupler and i need to find the length that it happens in).

To get this doen i need to find the slice in wich the energy flow (integrated enrgy throu the both coupler arms are equal)

I found away to plot an internal slice on Comsol, but how can i make integration on diffrent areas within this slice ?
(the two ares within the slice have rectangular shape with different dialectric constant from it's surrounding ).

Thank you for your help,

Ran
5 Replies Last Post Feb 21, 2011, 5:15 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 20, 2011, 4:25 p.m. EST
Hi

I mostly cut my domains/boundaries such that I can use internal boundaries to integrate over. But in V4 you can make slice data sets and further process these. One way to extract only part of a boundary for an integration is to integrate over the full are, but multiply the integrand with a bolean operator of the type

(xmin < x)*(x < xmax)*(ymin < y)*(y < ymax) * your_operand

hope this can give you some ideas

By the way a slice data set is created "statically" when you define it, I have so far not managed to use a variable to be able to scan the slice data set over a solution domain

--
Good luck
Ivar
Hi I mostly cut my domains/boundaries such that I can use internal boundaries to integrate over. But in V4 you can make slice data sets and further process these. One way to extract only part of a boundary for an integration is to integrate over the full are, but multiply the integrand with a bolean operator of the type (xmin < x)*(x < xmax)*(ymin < y)*(y < ymax) * your_operand hope this can give you some ideas By the way a slice data set is created "statically" when you define it, I have so far not managed to use a variable to be able to scan the slice data set over a solution domain -- Good luck Ivar
Ran Califa
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Posted: 1 decade ago Feb 20, 2011, 6:16 p.m. EST


Hi Ivar

First thank you for the quick answear,

I succed to define on "data set" the cut plane that i wanted as you adviced (it takes some time to find the currect one by iterating manualy but its o.k),

Anyway, after i got this cut on the screen i didnt understand how can i defined the integral of energey flow over it (or part of it).
Should i definde the calculation i want to do on this cut plan before making the compute process or after? is it under probs menu?

Thanks for your help with this matter.

Ran
Hi Ivar First thank you for the quick answear, I succed to define on "data set" the cut plane that i wanted as you adviced (it takes some time to find the currect one by iterating manualy but its o.k), Anyway, after i got this cut on the screen i didnt understand how can i defined the integral of energey flow over it (or part of it). Should i definde the calculation i want to do on this cut plan before making the compute process or after? is it under probs menu? Thanks for your help with this matter. Ran
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 21, 2011, 1:34 a.m. EST
Hi

your original results are in the "Results - Data Set - Solution 1" (or 2...) a cut plane is just copying over part of this solution into a new data base. Then you can in the "Derived Values" section define an operator (integration or other on this Data Set Cut line/plane .... And in there you can write out your "operand" equation.

including multiplying it by some boolean equation giving "0" outside of a predefined region if this meets your need

--
Good luck
Ivar
Hi your original results are in the "Results - Data Set - Solution 1" (or 2...) a cut plane is just copying over part of this solution into a new data base. Then you can in the "Derived Values" section define an operator (integration or other on this Data Set Cut line/plane .... And in there you can write out your "operand" equation. including multiplying it by some boolean equation giving "0" outside of a predefined region if this meets your need -- Good luck Ivar
Ran Califa
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Posted: 1 decade ago Feb 21, 2011, 7:15 a.m. EST
Thank's it was helpful.

BTW - is there somthing i can do if Comsol write me ("out of memory") ? i am using Core2Duo 2G, ? can i define somehow diffrent (Lower) resulotion for the longitudinal axe to make the proccess shorter?
Thank's it was helpful. BTW - is there somthing i can do if Comsol write me ("out of memory") ? i am using Core2Duo 2G, ? can i define somehow diffrent (Lower) resulotion for the longitudinal axe to make the proccess shorter?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 21, 2011, 5:15 p.m. EST
Hi

indeed FEM models need a laaarge quantity of RAM ;) If you have only 2Gb the only way arounf is to reduce the model, either by using symmetry or reducing the mesh density (but your results become also less rpecise like that)

--
Good luck
Ivar
Hi indeed FEM models need a laaarge quantity of RAM ;) If you have only 2Gb the only way arounf is to reduce the model, either by using symmetry or reducing the mesh density (but your results become also less rpecise like that) -- Good luck Ivar

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