Elmer Discussion Forum

raback wrote: ↑28 Feb 2021, 21:14 Hi

Yes, the internal boundary without a BC is not used for anything in ElmerSolver.

ElmerGUI seems to use it to highlight objects. That's certainly a deficiency.

What is your original mesh format? Do you have "mesh.names" in your mesh directory?

-Peter

I have it in various formats right now I am using .mesh.* Elmer mesh format. Yes it has a mesh.name file

OK! by setting the Parent 2 parameter to 0 for plunger and coil boundaries in the Boundary file I am able to select the various bodies separately! THANK YOU!. Now I can move on to generating current in a closed loop in the coil using coilSolver.
Mesh File: https://www.transfernow.net/JDwRMg022021

Hi

If you have the names present it may be convient to use them in your sif file rather than require ElmerGUI to do the numbering. See viewtopic.php?t=4106

-Peter

raback wrote: ↑01 Mar 2021, 01:47 Hi

If you have the names present it may be convient to use them in your sif file rather than require ElmerGUI to do the numbering. See viewtopic.php?t=4106

-Peter

Hello Mr.Peter,
Thank you for the additional input. So here is my understanding as of now:
1) I can set the Parent 2 parameter of internal bodies to zero, making the internal boundries useless. Doing this doesn't break the connections of the internal bodies to its external domain as they are connected at boundary nodes and so boundary surface elements doesn't matter. But setting parent 2 to 0 also makes it impossible to set boundaries conditions on the surfaces of internal bodies.(Also ElmerGUI uses the Boundaries for displaying the selected components and so having Parent 2 set to someting confuses the GUI and so it doesn't show the selected internal body even though the body is actually selected.)
2) I can use the names that I set in the mesh generating software. It's only the code hasn't been implemented in ElmerGUI to use it yet, but the sif file does recognise the names.

If I cannot set BC at internal surfaces then how do I simulate something like wing in a windtunnel...with wing having heated surface BC?

Best regards,
Mandeep

I believe you can assign boundary conditions to internal body boundary surfaces. The statement was that you do not need boundary surfaces to transfer conditions from one body to another if they share nodes. However if you want to introduce conditions at an internal BC than you can use BCs to do that. If you want the wing to have a set temperature than an internal BC can do that. If you want the wing to be heated by the airflow than you only need shared nodes between the air and the wing.

kevinarden wrote: ↑01 Mar 2021, 13:36 I believe you can assign boundary conditions to internal body boundary surfaces. The statement was that you do not need boundary surfaces to transfer conditions from one body to another if they share nodes. However if you want to introduce conditions at an internal BC than you can use BCs to do that. If you want the wing to have a set temperature than an internal BC can do that. If you want the wing to be heated by the airflow than you only need shared nodes between the air and the wing.

Oh, that's great! That should also take care of the no-slip boundary conditions too then(Now that I think of it, no slip BC would have been a better example )! Thank you so much for all the help.

The elmer tutorial in the gui tutorial manual demonstrates fluid flow internal boundary against an elastic object.
Tutorial 23
Interaction between fluid flow and elastic obstacle