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-   -   problem in CFX solver about isolated volumes (http://www.cfd-online.com/Forums/cfx/20542-problem-cfx-solver-about-isolated-volumes.html)

Yuan August 9, 2004 10:35

problem in CFX solver about isolated volumes
 
Dear all CFX experts:

When we tried to run CFX solver, it terminated with error about isolated volumes as following. We couldn't sort this out and all the setting in Pre seems fine. Some said that it was nothing to do with isolated volumes but the setting of reference pressure. Since we set the reference pressure to be o pa before. However, same error occourred after we set the reference pressure to be 1 atm.

we appreciate any reply from you.

Best regards,

Yuan

*************************************************

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

Impeller Inblock Outblock

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". ************************************************** ***

Yuan August 9, 2004 10:47

Re: problem in CFX solver about isolated volumes
 
By the way, specifically how can i plot the isolated volumes in POST? I tried to do it but failed.

Thanks,

Yuan

Neale August 16, 2004 22:54

Re: problem in CFX solver about isolated volumes
 
You have probably set the problem up incorrectly.

Are you running CFX-5.6 or 5.7. If 5.7 then make sure you install the service pack, there was a bug which caused writing the isolated volumes results file writing to fail.

Once you get this file into CFX-Post there will be a variable called "Isolated Volumes". You can make plots of this variable like any other (eg: pressure, temperature, etc...). It will show you where the isolated volumes are (they are numbered 1, 2, 3, etc...)

Note that the error message does not specifically refer to whether or not you have generally set the reference pressure. This is set "per domain", but even if you do that it is still possible to have regions within a given domain which are completely disconnected (isolated) from the rest of the domain. The flow solver will fail badly if this is the case and those disconnected regions do not have the pressure level set through say a boundary condition (eg: pressure specified outlet).

Neale



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