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Open boundary condition for time-dependent EM simulations

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Well, as the title indicates, I would like to know how to model in COMSOL an open boundary condition for EM simulations, using the transient solver.

An open boundary condition is the one which absorbs all EM radiation, with very little reflections going back to the analysis domain. What I am looking for is a boundary condition that performs the same as the PML, but in time domain simulations.

I am asking this because I am working on GPR (Ground Penetrating Radar). For that application I need to model the soil as infinite (so radiation that gets into the soil is not reflected back, as it happens in practice), and this could be accomplished by adding an open boundary condition underneath the soil.


Any help is highly appreciated.

Best Regards,
Ramon Araujo

3 Replies Last Post Jan 27, 2015, 8:30 a.m. EST
Sergei Yushanov Certified Consultant

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Posted: 10 years ago Jan 27, 2015, 8:03 a.m. EST
Ramon,

Use Scattering Boundary Condition to minimize back reflection in time domain analysis.

Regards,
Sergei
Ramon, Use Scattering Boundary Condition to minimize back reflection in time domain analysis. Regards, Sergei

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Posted: 10 years ago Jan 27, 2015, 8:16 a.m. EST
Hello Sergei, thanks for the quick reply.

So the scattering BC is sufficient for my purpose or does it make sense to place a PEC boundary after the scattering BC? People do that for the FDTD method, for example.

Thank you.
Hello Sergei, thanks for the quick reply. So the scattering BC is sufficient for my purpose or does it make sense to place a PEC boundary after the scattering BC? People do that for the FDTD method, for example. Thank you.

Sergei Yushanov Certified Consultant

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Posted: 10 years ago Jan 27, 2015, 8:30 a.m. EST
Ramon,

No, you don't need PEC after SBC.
Make sure you use appropriate Scattered wave type - I guess it would be Spherical wave in your case.

Regards,
Sergei
Ramon, No, you don't need PEC after SBC. Make sure you use appropriate Scattered wave type - I guess it would be Spherical wave in your case. Regards, Sergei

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