Heat Transfer Coefficient

AndBra · May 28, 2013, 14:31

Hi!
Might be a stupid question, but I have not been able to find the answer to it.
How does Fluent calculate the convective heat transfer between a fluid and a solid? Usually for convective heat transfer a heat transfer coefficient (HTC) is needed, but this is (as far as I know) not available in Fluent. One can get an approximation of the HTC, but fr that you need to specify a fixed reference temperature and the HTC is calculated based on this temperature, the wall temperature and the heat flux. But how does it get the heat flux to start with?

Sorry if it's a "basic" question, but I would really appreciate if someone has the answer or can point me in a direction where I can find it.

Musa · May 29, 2013, 04:16

Heat transfer coefficient between a solid and particle is calculated using two correlations available in FLUENT i.e. Ranz-Marshall and Gunn correlations. However to access these you must first enable the heat equation in the model tab and specify the thermo physical properties of the phases. There is no input for heat flux because the htc is calculated from the Nusselt correlation as given by Ranz-Marshall and Gunn.

delaneyluke · June 4, 2013, 16:35

If you fluid-solid interface is an interior (conjugate heat transfer) then the heat flux is calculated from the energy transport equation between solid and fluid.
If the interface is a wall (you've not modeled the solid) then you need to define either a temperature or an htc on that wall and heat flux is calculated from them.

Regards
Luke

May 28, 2013, 14:31	Heat Transfer Coefficient	#1
AndBra New Member Join Date: Mar 2010 Posts: 4 Rep Power: 16	Hi! Might be a stupid question, but I have not been able to find the answer to it. How does Fluent calculate the convective heat transfer between a fluid and a solid? Usually for convective heat transfer a heat transfer coefficient (HTC) is needed, but this is (as far as I know) not available in Fluent. One can get an approximation of the HTC, but fr that you need to specify a fixed reference temperature and the HTC is calculated based on this temperature, the wall temperature and the heat flux. But how does it get the heat flux to start with? Sorry if it's a "basic" question, but I would really appreciate if someone has the answer or can point me in a direction where I can find it.

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May 29, 2013, 04:16		#2
Musa Member Musango Lungu Join Date: Dec 2011 Location: China Posts: 73 Rep Power: 14	Heat transfer coefficient between a solid and particle is calculated using two correlations available in FLUENT i.e. Ranz-Marshall and Gunn correlations. However to access these you must first enable the heat equation in the model tab and specify the thermo physical properties of the phases. There is no input for heat flux because the htc is calculated from the Nusselt correlation as given by Ranz-Marshall and Gunn.

June 4, 2013, 16:35		#3
delaneyluke Senior Member Join Date: Mar 2009 Location: Indiana, US Posts: 186 Rep Power: 17	If you fluid-solid interface is an interior (conjugate heat transfer) then the heat flux is calculated from the energy transport equation between solid and fluid. If the interface is a wall (you've not modeled the solid) then you need to define either a temperature or an htc on that wall and heat flux is calculated from them. Regards Luke