Heat Flux , Convective + Radiant Heat flux

Mandeep · October 24, 2012, 12:33

I have a Pipe which have hot gas(No Domain modeled for this) flowing inside and cooling water outside.
The data available is Bulk temperature of Hot gas varying along the length, film heat transfer coefficient varying along the length and Radiant heat flux varying along the length. I generated three functions to read the profile data for these three parameters and applied heat flux over the inner surface of the pipe using

QTotal = QRadiation+(TempBulk-T)*HTC

This boundary condition is applied as a variable T which is the surface temperature (unknown)
Will this boundary condition work or is there any other method I can apply
Radiant heat flux and HTC&Bulk Temperature on the inner wall of the pipe.

After applying the boundary condition the H-Energy , T-energy is not getting converged . Any Clue

evcelica · October 24, 2012, 16:33

That sounds a little wierd, it may work, but I wouldn't have done it like that.
I would just input a convection boundary condition on the inside with the HTC and Bulk Temperature being functions of the pipe location (say x). Then, I would add a source term for the radation heat flux, which can also vary with pipe location.

ghorrocks · October 25, 2012, 06:10

I have used a similar approach to model combined convective and radiative boundaries. I do not recall having to do anything special to get it to converge, it works fine. Erik's approach woudl work as well.

So if you are having convergence issues I would check you have implemented it correctly.

Mandeep · October 25, 2012, 16:57

Thanks Glenn and Eric, The thing is system has many domains and between them are the interfaces that just is not allowing to get it converged.

October 24, 2012, 12:33	Heat Flux , Convective + Radiant Heat flux	#1
Mandeep New Member Mandeep Singh Join Date: Oct 2012 Posts: 5 Rep Power: 13	I have a Pipe which have hot gas(No Domain modeled for this) flowing inside and cooling water outside. The data available is Bulk temperature of Hot gas varying along the length, film heat transfer coefficient varying along the length and Radiant heat flux varying along the length. I generated three functions to read the profile data for these three parameters and applied heat flux over the inner surface of the pipe using QTotal = QRadiation+(TempBulk-T)*HTC This boundary condition is applied as a variable T which is the surface temperature (unknown) Will this boundary condition work or is there any other method I can apply Radiant heat flux and HTC&Bulk Temperature on the inner wall of the pipe. After applying the boundary condition the H-Energy , T-energy is not getting converged . Any Clue

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October 24, 2012, 16:33		#2
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,167 Rep Power: 23	That sounds a little wierd, it may work, but I wouldn't have done it like that. I would just input a convection boundary condition on the inside with the HTC and Bulk Temperature being functions of the pipe location (say x). Then, I would add a source term for the radation heat flux, which can also vary with pipe location.

October 25, 2012, 06:10		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	I have used a similar approach to model combined convective and radiative boundaries. I do not recall having to do anything special to get it to converge, it works fine. Erik's approach woudl work as well. So if you are having convergence issues I would check you have implemented it correctly.

October 25, 2012, 16:57		#4
Mandeep New Member Mandeep Singh Join Date: Oct 2012 Posts: 5 Rep Power: 13	Thanks Glenn and Eric, The thing is system has many domains and between them are the interfaces that just is not allowing to get it converged.