'Port1' does not have a mesh instance

Altair Forum User

Hello FEKO users,

 

Today I started my first simulation with CADFEKO version 7.

 

I just ...

- created a helmholz coil

- set the frequency

- set loads

- set voltage source

- requested the near field

- meshed all parts

- CEM validated the simulation (all green)

- started the solver

... and then I the error occured as mentioned in the title.

 

What I have done so far:

- I made sure that no other FEKO project is interfering.

- A .pre-file has been created, but no .out-file.  But the .pre-file does not say more to me than the error window.

 

Does anybody know what my problem could be?

Many thanks in advance!

 

 

JIF

Hi Wilson,

 

That error usually happens when you have a port, but have not meshed the model yet. Basically what happens is that CADFEKO has a source or a load that it needs to write to the *.pre file, but there is no mesh instance for the port. Simply meshing and saving should resolve the problem. But, since you stated that you did mesh, maybe something else is causing the problem. Are you able to provide the model so that I can take a look?

 

I would recommend that you upgrade to the latest version of FEKO (version 2018).

Altair Forum User

Hello JIF,

 

thanks for your immediate response!

 

At the moment I do not know if I am allowed to send you my complete project.

But this is what I did since I read your response:

 

- deleted the meshing of all (coils, wires and surrounding box)

- extended the wires, so the source is not touching any material of the encasing box.

- deleted the load (as Port1 has been mentioned in its properties)

- deleted port1 out of the model tree, as I could not see any source in the 3D-view anyway.

- added a fresh port1.

- added a load again with the same parameters as before.

- meshed all again

- unlinked the meshing, so in the model tree I can see port1 and additionally port1_1

 

Now in the .pre-file no error has been mentioned and I get an .out-file.

But now I got another error: 'Error 15: No exitation has been definded'

 

So for the moment I regard my question as solved.

I will come back to this question only if the new error was hiding the old error.

 

PS: Has the step mentioned above really been necessary to extend the wires?

 

 

 

 

 

 

 

JIF

Hello Wilson,

 

Without a model and without pictures, it is quite difficult to follow what you are doing and thus difficult to comment if what you are doing is correct. Are you able to reproduce the problem with a simplified model of send screenshots of the tree.

 

Why do you unlink the mesh? When you mesh, a mesh representation will be associated with the geometry. When you unlink, you create a disconnected mesh instance. The source will still be on the geometry port (not port1_1) as far as I know and that is probably not what you want.

 

The error stating that there is no excitation means exactly that. You somehow created a model and there is not source (voltage source, plane wave, etc.). From the steps you mention, it seems to be correct, since you added load, but no source. Adding a port is not the same as a source. A port is simply a connection point where sources or loads can be connected (or serve as a port for S-parameter calculations).

Altair Forum User

Hello Jif,

 

here you got  actual pictures. I unlinked the mesh just to get a better overview in the tree.

Could there be another reason for unlinking a mesh?

 

Oh! You are right. I added a new port, but now the source missing!

 

 

 

Altair Forum User

Okay. I added the source again. And solving works much longer than before!

No Errors, just a warning (No. 83) counted 40 times.

 

But to me, this seems be be a task for tomorrow.

Thanks Jif,  have a nice evening!

 

JIF

Hi Wilson,

 

I'm glad the problem has been solved. The warning simply states that you have requested a near field calculation on the axis of a segment, but this is not possible (singular field).

 

I do see that you used an assembly for your wires. This might not be a problem if your wires only connect (touch) at the start and end of wires, since the segments will still align correctly. If your wires and your box never touch, all should be find. In general, you should union to ensure correct connectivity. I suspect you know this, I'm just making sure.

Altair Forum User

Altair Forum User said:

Hi Wilson,

 

I'm glad the problem has been solved. The warning simply states that you have requested a near field calculation on the axis of a segment, but this is not possible (singular field).

 

I do see that you used an assembly for your wires. This might not be a problem if your wires only connect (touch) at the start and end of wires, since the segments will still align correctly. If your wires and your box never touch, all should be find. In general, you should union to ensure correct connectivity. I suspect you know this, I'm just making sure.

 

Hello Jef,

 

I deleted the box to find out if the warning still remains. And yes, the warning remains.

I changed the lenght of the coils to make sure that their wires don't touch. This finally leaded to the goal.

Thanks Jef!

 

About the electromagnetically shielding box - which way will be more convenient:

- Should the wires be isolated or should I give the box two holes where the wires go trough?

 

JIF

Hello Wilson,

It depends on what you want to model and thus it is not easy to advise. Most people would simply union, but creating holes could also work.