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-   -   constant temperature heat source in subdomain (https://www.cfd-online.com/Forums/cfx/80842-constant-temperature-heat-source-subdomain.html)

 Sanyo October 8, 2010 07:22

constant temperature heat source in subdomain

Dear All,

I want to specify the fixed value of temperature to a specific volume/zone in CFX. I searched on net & I knew that it can be done in fluent but I was not able to find anything for CFX. I can specify the heat source for a subdomain but then how would I keep the temperature constant? :confused:

Regards,

Sanyo

 joey2007 October 8, 2010 16:09

What do you intend to model?

 Sanyo October 9, 2010 02:14

Dear Joey,

Thank you for your reply. I want to model fluidized bed combustion. However, combustion is not in our scope as well necessary data for combustion is not available. We know the temperature of the gas leaving the fluidized bed. So we thought that we might be able to model fluidized bed as subdomain with appropriate momentum loss & defining the fixed temperature to subdomain.

Is it possible to define fixed temperature or should I use energy source? With energy source, we doubt that we wont be able to achieve exact temperature of gases.

Regards,

Sanyo

 ghorrocks October 9, 2010 06:00

Yes, you can fix a regions temperature with an energy source. I think there is an example of how to do it in the documentation. It has been ages since I did it but it is something like:
Set the source term to -C(t-tSET) where tSET is your specified temperature. You then set the source term coefficient to -C (or is it +C, can't remember). C is a constant chosen to be large relative to any possible t, 1e6 should do the trick. This is from my flaky memory so I might have got some signs wrong but that is the basic idea. It is something like that.

 michael_owen October 12, 2010 15:13

Quote:
 Originally Posted by ghorrocks (Post 278523) Yes, you can fix a regions temperature with an energy source. I think there is an example of how to do it in the documentation. It has been ages since I did it but it is something like: Set the source term to -C(t-tSET) where tSET is your specified temperature. You then set the source term coefficient to -C (or is it +C, can't remember). C is a constant chosen to be large relative to any possible t, 1e6 should do the trick. This is from my flaky memory so I might have got some signs wrong but that is the basic idea. It is something like that.
Glenn, the source coefficient should be negative. However, no worries, if you forget and make it positive CFX will multiply it by -1.

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