Elmer Discussion Forum

Hi,
I am working through the tutorial of the bent waveguide that uses the VectorHelholtz solver and am a little confused by the boundary condition values given to the boundaries,
Why is the Electric Robin Coeffcient im for the output equal to $beta0? Because isn't the outport suppose to be assigned an absorbing boundary condition and by consulting the Models manual it says that it should be omega*sqrt(e_0*mu_0).

Does anyone know why it is like this? Any information will be helpful as I am still confused!

Hi,

I suppose that the model that the tutorial uses implicitly is the total-field/scattered-field formalism and it assumes that scattered field and primary field are some waveguide modes (probably TE_01).

Hi thanks for your answer,
but how does equating the Electric robin coefficient yeild the primary and scattered fields to be waveguide modes?

You are making better progress than me. I just installed Elmer on Windows using nightlybuild from github. I cannot find the waveguide_bend.step file...... What folder is that? I fear that I have a mal-installation.

Duh.... Found it. The folder was not where I was expecting

D:\Program Files (x86)\Elmer 8.3-c30fff2\share\ElmerGUI\samples\step

and the file name was

bent_waveguide.step

Ok. That was the easy bit. Now I just need to get it to converge. I've attached the SIF file. I get the error that

WARNING:: LoadInputFile: > Equation 1 < not used in any Body!

Duh^2... I saw this note online.

After making changes in the GUI, you must always generate the SIF and save the project before re-running the solver with these changes (in this order!)

Now it runs