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How different are these?

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Hi, i am a student in republic of korea.

My model is to observe how E-field enhancement is made by constructing nano gold patterns on a slica galss, applying incident laser from z-axis. However, I have a question which is that why the results are different between applying a big base silica galss and a small one during my modeling. I think if I do same pattern models, base size is unrelated to the result. but in my model, e-field enhancement to which a big slica glass is applied is bigger than e-field enhancement to which a small one is done.
so, my question is
" why are they different? "
" If they are naturally different, what is the reason? "
" or my modeling is wrong, how can i modify? "

thanks.

p.s. two model images is added ,


3 Replies Last Post 22.02.2013, 06:03 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 22.02.2013, 01:37 GMT-5
Hi

I wonder if it could be linked to your mesh (looks slightly coarse in the high gradient region and perhaps some modulation artefact from the graphics rendering.

Have you checked that your results are mesh insensitive ?

--
Good luck
Ivar
Hi I wonder if it could be linked to your mesh (looks slightly coarse in the high gradient region and perhaps some modulation artefact from the graphics rendering. Have you checked that your results are mesh insensitive ? -- Good luck Ivar

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Posted: 1 decade ago 22.02.2013, 02:52 GMT-5
Hi,
First of all, thanks to your reply, but I applied simple mesh because finer mesh, longer simulation time.

I used 785 nm laser, what should i do mesh setting?

Hi, First of all, thanks to your reply, but I applied simple mesh because finer mesh, longer simulation time. I used 785 nm laser, what should i do mesh setting?

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 22.02.2013, 06:03 GMT-5
Hi

clear finer mesh take far longer ;) But check the RF doc about mesh density and wavelength resolution, + model size aspects, then you could try to double the mesh density and see if the results change a lot or not (>10-20%) in which case you should use a finer mesh. Now it could be that you can concentrate the mesh only where the dependent variable gradients are strongest

--
Good luck
Ivar
Hi clear finer mesh take far longer ;) But check the RF doc about mesh density and wavelength resolution, + model size aspects, then you could try to double the mesh density and see if the results change a lot or not (>10-20%) in which case you should use a finer mesh. Now it could be that you can concentrate the mesh only where the dependent variable gradients are strongest -- Good luck Ivar

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