Elmer Discussion Forum

This is a simplified version of my problem. The actual problem is a Navier Stokes gas flow of 2 gasses mixing with complex shaped boundaries. I have not been successful with setting the boundary condition on the original problem. I would like to be able to break up the problem into separate "zones?" and make the boundaries between them transparent. The finished analysis of the simplified version is shown below.

The .brep and .cif files are attached.
Any help will be sincerely appreciated.

Gary R

You are getting that result because their are coincident nodes at the boundary between the bodies. Body 1 and body 2 need to share the same nodes for the boundary to be transparent. Merge coincident nodes in the mesh and it will work.

Thanks for the reply Kevin. I corrected the node problem in my freecad sketch and re built the Elmer files. The problem persists. In addition, for some reason, the sif file now contains a Helmholtz solver that errors out at the very end of the run. It complains about not being able to find the frequency which makes no sense. I've tried to remove it manually.I've double checked all of my model settings but when I reload the project the the Helmholtz solver is reinserted into the cif file. Is this normal?

I am not at all sure what to use for a boundary condition for the input to the second solver. I used velocity 2 = 0.0 but do not think that is correct.

I've attached the new .brep and cif files.

Gary R

The coincident nodes are still there. The Helmholtz equation would be on if the Helmholtz equation tab was checked active.

Hello,

The following forum post may help you with coincident node removal:

viewtopic.php?p=25772#p25772

It may help if you zip and upload the ElmerGUI project folder.

Rich.