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-   -   nonuniform temperature boundary condition (http://www.cfd-online.com/Forums/cfx/73578-nonuniform-temperature-boundary-condition.html)

blackbody March 11, 2010 14:34

nonuniform temperature boundary condition
 
hello

when i want to use a nonuniform temperature distribution at inlet as a boundary condition (values from measurement), what do i have to do?

- where can i set this BC?
- what kind of file does it has to be?
- any other things i have to consider?

i checked the user manual and the only thing i found is something about a junction box routine that i don't understand...

how should i approuch to this problem?
thank you very much!!!

puga March 11, 2010 15:36

The first thing you'll want to do is create a user function. Specify whatever input/output units you want, and give it the data points for the function. If you like, you can create a variable (such as the radius in a cylindrical system calculated from cartesian coordinates) that can be used as the input.

Once you have the function specified, open up the boundary conditions for your inlet. Under Heat Transfer, select the type of temperature you are inputting, and in the text box, put:
NAMEOFFUNCTION.OUTPUTVARIABLE(INPUTVARIABLE)

E.g. if your function was called InletT, with the input being "radius" and output being "Tt", you would put

InletT.Tt(radius)

That'll do it. You can also specify the function from a text file if you like (instead of putting the points in manually)

ghorrocks March 12, 2010 00:45

I might rewrite puga's first sentence as "The last thing you'll want to do is create a user function". Avoid user fortran if at all possible is my advice. The first thing you should try is using a simple 1D lookup table as a CEL expression. You can enter your data points as a temperature vs height dataset and use that as the temperature field for your inlet. See, easy and no fortran required.

Only go to fortran if you can't do what you want in CEL - and 95% of the time it can be done in CEL.

puga March 12, 2010 07:42

I wasn't implying user Fortran. You can simply scroll to the bottom of the main menu and click "add user function." No fortran required. I should also put the caveat that I'm using version 11.

blackbody March 15, 2010 16:47

CEL !!! was the answer ;) thank you...


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