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-   -   opening temperature for the opening BC (http://www.cfd-online.com/Forums/cfx/76663-opening-temperature-opening-bc.html)

sujay June 1, 2010 08:03

opening temperature for the opening BC
 
How to define the opening temperature for opening BC as temperature is unknown at the defined location.

ghorrocks June 1, 2010 18:42

If you are doing a thermal model and don't know the inlet temperature then you can't use an opening (or inlet) boundary. You have to either specify a temperature or move the boundary to somewhere you do know the temperature, or move the boundary somewhere you can use a boundary which does not require temperature to be specified (such as a wall or symmetry).

sujay June 1, 2010 23:58

The domain has reverse flow at the outlet so needs to define as a opening. The inlet tempearure is specified at the inlet, the fluxes are assigned.

At the outlet tempearure is required output....but as it defined as a opening ask for opening or static temperature....guide to guess the temperature or any other choice.

Pocket June 2, 2010 01:34

I remember reading in one of the tutorials that it is suggested to use a CEL expression and take the average temperature of the opening

ave(T)@REGION:Outlet

maybe "areaAve" would be even better.

But keep in mind that this is not the best solution.
A better way to do it would be to put the outlet further downstream, so that no backflow occurs.

sujay June 2, 2010 03:21

Can you quote the reference of the tutorial where CEL is used.

Pocket June 2, 2010 08:04

It's the conjugate heat transfer in a heating coil.
And they use

areaAve(T)@outflow


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