[Getdp] Extension and use of waveguide examples in GetDP

[Christophe Geuzaine]

> On 20 Mar 2015, at 09:47, Benjamin Klein <enkleinb.ay at gmail.com> wrote:
> 
> Dear Christophe Geuzaine,
> 
> I am a phd student in the electrical engineering department at Wits university, you gave us a workshop on GetDP at the beginning of March. I have been modifying and playing with the waveguide examples given on the One Lab website (http://onelab.info/wiki/Waveguides) since then. It is going fairly well, and I have managed to complete the TM case that is started but not finished in those examples. I have attached the tar directory (sorry about the extension gmail refused to send a .tar.gz or .tgz file).

Hi Benjamin,

Great! Let's iterate a little bit on the modifications, so I can merge them in our SVN version:

1) waveguide3D_step.geo is wrong: it includes itself:

   ...
   Include "waveguide3D_step.dat" ;
   Mesh.Optimize = 1;
   
   Include "waveguide3d_step.geo";
   ...

2) There's no need to put all the formulations/postprocessing definitions inside the large "If(Excitation == ...)" blocks: you can just define everything, and simply select the formulation in the Resolution. I would this simply

- define a default value for Excitation in a DefineConstant in formulations.pro

- add a single test in the resolution


> Also, attached is the mathematics from the One Lab website expanded out to show where I get the H-Field description, the "complete solution for the TM10 and TE10 modes"  given on the website is, I believe, wrong.
> 

If I remember correctly, my student Axel based it on Jin's book. You could directly make the corrections in the wiki: just create an account and edit the page.


> The main reason I am writing to you is to get some help on the other .pro example given in the tarred directory, waveguide3D_step.pro . It is taken from an example in FEKO and I would like to replicate the S-parameter plot for the TM11 mode. It would be a good demonstration of your code. I can send you the example from FEKO if you want. I think it is currently failing because of the description of the second passive port, which is given in terms of a mode from the active port.

Ok; what should we do on this port?

> 
> I also have some minor issues making the TE/TM mode an option in the GMSH box, it doesn't seem to reload all the files when this is changed.

What do you mean by "reload all the files"? (It seems to work fine over here...)

> I also found that for some reason the StrCat command on my system (Linux Mint 17.1 i686) only accepts two strings, not multiple as in your code, so I had to modify all instances to: StrCat['a', StrCat['b','c']] etc.

This means you are using an older version of GetDP/Gmsh : the new syntax for StrCat was introduced very recently. It's in the latest stable releases (2.9.1 for Gmsh, 2.5.0 for GetDP).

All the best,

Christophe


> I also had to put in offsets to the existing field description, which is where the W0x and W0y variables come from.
> 
> Best Regards,
> 
> Benjamin Klein 
> 
> 
> -- 
> PGP pub key: 8C4A06D8 
> <waveguidesMod.tar.gzip><RectWaveguide.pdf>

-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine