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201 April 23, 2010 13:42

Mixing model with rotating impeller problem
hi erveryone,
i have some problem my project. Mixing model with rotating impeller. the some problem i dont understand and how to repair that:

2 isolated fluid regions were found in the following set of
coupled domains:


If the isolated regions do not have the pressure level set either
by the boundary conditions or using a reference pressure equation,
you may encounter severe robustness problems.

This situation may have arisen because a domain interface was not
properly defined during problem setup. Please carefully check
the setup.

The solver will stop now and write a results file. The isolated
regions can be visualised in CFX Post by making plots of the
variable "Isolated Volumes".

If you are sure that the pressure level is set in each isolated
fluid region then you can force the solver to turn off this check
by setting the expert parameter "check isolated regions = f".

Attesz April 26, 2010 08:10

I think you should check your fluid interfaces.

201 April 27, 2010 09:55

please help me

ghorrocks April 27, 2010 18:32

Attesz has said what the problem is - your interfaces are not correctly connecting the two domains so they end up being isolated.

Jade M May 12, 2010 16:59


Attesz May 12, 2010 17:15

No! I recommend you to do the tutorials and read the basics in CFD. You should set the interface as a Fluid-Fluid Interface. This is a connection between the domains, opening and outlet are boundaries, they BOUND the domains, not connect.

Jade M May 12, 2010 17:18

Yes! Thanks for your quick reply! LOL. I have read the tutorials and manuals but thank you for the suggestion. Fluid-fluid interface is not an option. Perhaps the interface does not need to be explicitly defined?

Can anyone explain this more clearly?

Thank you.

Attesz May 12, 2010 17:49

I can't understand you. You should define an interface, not a boundary condition. In the interface definition, you should set your fluid domains(you should have at least 2 pieces), and the regions, where they connect. It is very simple, and clearly discussed in the help.

Jade M May 13, 2010 08:48


Attesz May 13, 2010 10:19

Please send some picture about your geom, with the interfaces marked, and a screenshot from your setting tree in CFX pre. Did you do the solver's message:

Otherwise, I wrote "I can't understand you" because I really can't understand what the problem is. If it would bother me, I really wouldn't reply :)


How do you define an interface? The interface is already there due to multiple volumes. Is there something more that needs to be done?
If the interface connection isn't automatically generated, you should click on the Interface icon on the top, and set what do you need. Here Interface means a defined connection betweed fluid domains, which need to be automatically or manually adjust.

Jade M May 14, 2010 11:59

Thanks Attesz. I found it in the menu. I was looking for the mechanics of using the software, as this is the first time that I've set up a multizone model. Take care.

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