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Rotating Machinery - Identity Pairs and Boundary Conditions

Posted Jun 22, 2017, 3:19 p.m. EDT Low-Frequency Electromagnetics, Fluid & Heat, Computational Fluid Dynamics (CFD), Geometry, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5.2a 0 Replies

Sean McMahon
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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
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