Constant temperature in a domain

Sad · October 20, 2014, 04:53

Hi
I want to constrain a region in my domain by fixed temperature in CFX as we can do it in Fluent.
a sub-domain in CFX is defined by a heat flux. Also if we use the isothermal through the heat transfer options in a domain, interface heat flux will not be available between interfaces.

Your suggestions would be highly appreciated.

ghorrocks · October 20, 2014, 06:26

If it is a boundary then just use the specified temperature boundary condition. If you want to constrain a volume then use a energy source term.

I do not understand your second sentence. The isothermal model means constant temperature so no heat transfer takes place - so no thermal model is required. That is why the interface heat flux option is not available.

Sad · October 20, 2014, 08:23

Quote:

Originally Posted by ghorrocks

If it is a boundary then just use the specified temperature boundary condition. If you want to constrain a volume then use a energy source term.

I do not understand your second sentence. The isothermal model means constant temperature so no heat transfer takes place - so no thermal model is required. That is why the interface heat flux option is not available.

Thank you for your comments. I want to constarin a volume by fixed temperature. I defined a energy source via subdomain but only heat flux source option is available and not temperature.
I would like to know whether is there any option for fixed temperature in CFX like what is availabe in fluent through (Cell Zone Conditions>Fixed Values> Temperature).
Thank you in advance

ghorrocks · October 20, 2014, 18:18

Yes, using a source term. Source terms do not have to add/subtract a constant flux, they can be more devious than that so they can be set to force the local temperature to a fixed value.

Set the CFX documentation section 1.3.2.2.2 on "General Momentum Source" for how to specify a fixed value in a region. This discusses the momentum equation, but can be applied to any equation.

October 20, 2014, 04:53	Constant temperature in a domain	#1
Sad New Member Join Date: Oct 2014 Posts: 2 Rep Power: 0	Hi I want to constrain a region in my domain by fixed temperature in CFX as we can do it in Fluent. a sub-domain in CFX is defined by a heat flux. Also if we use the isothermal through the heat transfer options in a domain, interface heat flux will not be available between interfaces. Your suggestions would be highly appreciated.

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October 20, 2014, 06:26		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	If it is a boundary then just use the specified temperature boundary condition. If you want to constrain a volume then use a energy source term. I do not understand your second sentence. The isothermal model means constant temperature so no heat transfer takes place - so no thermal model is required. That is why the interface heat flux option is not available.

October 20, 2014, 18:18		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	Yes, using a source term. Source terms do not have to add/subtract a constant flux, they can be more devious than that so they can be set to force the local temperature to a fixed value. Set the CFX documentation section 1.3.2.2.2 on "General Momentum Source" for how to specify a fixed value in a region. This discusses the momentum equation, but can be applied to any equation.