Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Rotating Machinery - Identity Pairs and Boundary Conditions

Please login with a confirmed email address before reporting spam

I'm using the Rotating Machinery Physics from the COMSOL CFD package, to model fluid flow around a rotating helix. From what I've read online, it sounds like I should be using "Form Assembly" instead of "Form Union" for my geometry finalization.

However, using "Form Assembly" seems to have introduced an issue in my boundary conditions. I originally had chosen No Slip boundary conditions for the boundaries between the helix the fluid, but since switching from"Form Union" to "Form Assembly", it appears the boundary conditions are no longer applied.

My thought was I could solve the loss of boundary conditions by applying some type of boundary condition to the identity pair produced by "Form Assembly." However there are two problems:

1. An Identity pair was not produced by "Form Assembly."
2. Even if there was an identity pair to select, I'm not sure how I would go about applying No Slip boundary conditions.

I haven't been able to figure out why an identity pair isn't produced. As for the boundary conditions, I don't think "Pair -> Flow Continuity" is the right choice since the helix is not a fluid, it's a solid. Maybe "Pair -> Wall" is the proper choice? Or maybe it's a different option entirely?

Comsol Version: 5.2a

Thanks,
Sean

0 Replies Last Post Jun 22, 2017, 3:19 p.m. EDT
COMSOL Moderator

Hello Sean McMahon

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.