heat generation rate in the wall boundary conditions, what this?

serguei · September 10, 2015, 12:14

Hi all,
If anybody may clarify, please: in thermal wall boundary conditions, the “heat generation rate” option relates to the heat generation where? In fluid or in solid domain? Is that heat generation in the fluid volume by the hot solid wall?
Thank you

LuckyTran · September 10, 2015, 13:20

It's the volumetric heat generation rate in the (solid) wall. It only works if you specify a wall thickness. It is part of the thin wall model, which is also used for modelling thermal resistances.

If you do use it, note that the normal wall boundary conditions are applied to the backside. That is, you can specify the backside wall heat flux or backside wall temperature with volumetric heat generation across a thin layer so that the temperature at the solid-fluid boundary may be less than the temperature that you specify as the wall boundary condition.

serguei · September 10, 2015, 16:02

thank you,
but is there any way to generate the heat in the fluid domain, from some external source?
I don't care about the nature that source, what it do - generates the heat with known rate (w/m3)

serguei · September 10, 2015, 16:24

and when you are talking about "backside", do you mean the outer wall surface, which is in contact with fluid?

September 10, 2015, 12:14	heat generation rate in the wall boundary conditions, what this?	#1
serguei Member Serguei Join Date: Mar 2015 Posts: 33 Rep Power: 11	Hi all, If anybody may clarify, please: in thermal wall boundary conditions, the “heat generation rate” option relates to the heat generation where? In fluid or in solid domain? Is that heat generation in the fluid volume by the hot solid wall? Thank you

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September 10, 2015, 13:20		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	It's the volumetric heat generation rate in the (solid) wall. It only works if you specify a wall thickness. It is part of the thin wall model, which is also used for modelling thermal resistances. If you do use it, note that the normal wall boundary conditions are applied to the backside. That is, you can specify the backside wall heat flux or backside wall temperature with volumetric heat generation across a thin layer so that the temperature at the solid-fluid boundary may be less than the temperature that you specify as the wall boundary condition.

September 10, 2015, 16:02		#3
serguei Member Serguei Join Date: Mar 2015 Posts: 33 Rep Power: 11	thank you, but is there any way to generate the heat in the *fluid* domain, from some external source? I don't care about the nature that source, what it do - generates the heat with known rate (w/m3)

September 10, 2015, 16:24		#4
serguei Member Serguei Join Date: Mar 2015 Posts: 33 Rep Power: 11	and when you are talking about "backside", do you mean the outer wall surface, which is in contact with fluid?