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Felipe Matos February 2, 2011 20:39

Startup Additional Variables
 
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

joey2007 February 3, 2011 15:44

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.

Felipe Matos February 3, 2011 19:49

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

ghorrocks February 4, 2011 06:33

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.

armyou March 28, 2011 23:59

Quote:

Originally Posted by ghorrocks (Post 293610)
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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