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Old   February 2, 2011, 20:39
Post Startup Additional Variables
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Hi

I'm trying to simulate a problem which requires an Additional Variable "av". The domain's DENSITY is a function of this av: DENSITY = f (av). This av is a function of TEMPERATURE: av = f (TEMPERATURE).

I give the initial temperature, but at the initialization of the run, appears an error:
"Error processing expression 'Density'.
The expression is invalid because: Dano is not available for use in this term"

I think this is because I didn't find anywhere to put an inital value of the av. Where can I initialize the av? If I can't, what can I do?

Thanks
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Old   February 3, 2011, 15:44
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To be honest: i do not fully understand what you intend to do.

There are different kinds of av. If you chose the option transport equation it is possible to initialize. The type algebraic equation should depend on other variables, so it is not required to initialize.
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Old   February 3, 2011, 19:49
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My av is an Algebraic Expression. Like I said: Density = f (av) and av = f (T).
I think the problem is because the CFX initializes first its own variables (like Temperature, COndutivity, Density...); but my Density is a function of the av created, that is initialized olny after this primitive variables.

I don't know if the problem is this... Can anyone help?

Thanks
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Old   February 4, 2011, 06:33
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I can't check this but I suspect you cannot made density a function of a additional variable. There are only limited variables you can make density a function of. You will have to specify density as a direct function of temperature.
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Old   March 28, 2011, 22:59
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Quote:
Originally Posted by ghorrocks View Post
I can't check this but I suspect you cannot made density a function of a additional variable. There are only limited variables you can make density a function of. You will have to specify density as a direct function of temperature.
Yeah, CFX11 Pre would show error information if additional variable is applied in density. In CFX12, although there is no any error or warning information in CFX pre, slover would be stopped because of the additional variable dependent density.

Glenn, do you think it is possible to solve this problem by using subroutine in CFX?

Actually I donot understand why CFX has such a limitation, is it because CFX can not initialize the density if additional variable is included?
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