Thermally Coupled Boundary Conditions

ment_87 · July 24, 2013, 03:25

Hello,

I was trying to solve a problem with reaspiration on a simplified train geometry.
Problem: the train has a brake resistor cooling system, which heats the air up. This hot air gets convected towards the next inlet of this cooling system, so this air gets sucked in and heats up the cooling system, which blows out even hotter air and so on and so on...
Now I am trying to couple these two boundaries (brake resistor cooling system inlet and outlet) to know the maximum steady-state temperature of this system.
I am using the steady state, incompressible solver simpleFoam, coupling the energy-equation with a Boussinesq approach -> buoyantBoussinesqSimpleFoam solver
Questions: how to do the coupling of two boundaries with this solver? Is there any option in the pre-processing?
Would this solver be the right choice?

Best regards,
Marc

PS: is this even the right thread? Sorry I am new here... :$

gillimaniac · July 26, 2013, 05:20

Hey,

If i understand you correctly you would like to set the temperature on the blowers outlet to the temperature it sucks in at his inlet - right?

You can do this by defining the boundary on the blowers outlet in 0/T to:

blower_outlet
{
type outletMappedUniformInlet;
outletPatchName blower_inlet;
value uniform 1; //placeholder
}

This will apply the mean temperature from the patch "blower_inlet" to the patch "blower_outlet".

ment_87 · July 31, 2013, 05:35

Hey gillimaniac,

thank you for your response! I am actually looking for a thermally coupled inlet. This means that if the air at the inlet is warmer than the ambient temperature, the air at the outlet will also be warmer. This heating up is dependant on a heating load P.

As to say: T_out = T_in + Qdot/(mdot*cp)

Would this be possible?

Regards!

gillimaniac · August 1, 2013, 01:44

Okay there's the difficulty....

I'm sorry but i think there's no boundary condition like that implemented at the moment and you will have to code it yourself.
At least I don't know about an implemented condition thats doing something like that...

ment_87 · August 1, 2013, 02:16

oh... that's what i thought!

but thanks anyways! i will keep my eyes open and post any new information i get...

vfl · December 2, 2015, 09:46

Hello ment_87,

Interesting problem! Did you manage to fix it ?
I'm currently dealing with the same kind of recirculation problem.

Best regards,

July 24, 2013, 03:25	Thermally Coupled Boundary Conditions	#1
ment_87 New Member Join Date: Jul 2013 Posts: 3 Rep Power: 12	Hello, I was trying to solve a problem with reaspiration on a simplified train geometry. Problem: the train has a brake resistor cooling system, which heats the air up. This hot air gets convected towards the next inlet of this cooling system, so this air gets sucked in and heats up the cooling system, which blows out even hotter air and so on and so on... Now I am trying to couple these two boundaries (brake resistor cooling system inlet and outlet) to know the maximum steady-state temperature of this system. I am using the steady state, incompressible solver simpleFoam, coupling the energy-equation with a Boussinesq approach -> buoyantBoussinesqSimpleFoam solver Questions: how to do the coupling of two boundaries with this solver? Is there any option in the pre-processing? Would this solver be the right choice? Best regards, Marc PS: is this even the right thread? Sorry I am new here... :$

August 1, 2013, 02:16		#5
ment_87 New Member Join Date: Jul 2013 Posts: 3 Rep Power: 12	oh... that's what i thought! but thanks anyways! i will keep my eyes open and post any new information i get... vfl likes this.

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July 26, 2013, 05:20		#2
gillimaniac New Member Stefan Gaerling Join Date: Dec 2012 Posts: 22 Rep Power: 13	Hey, If i understand you correctly you would like to set the temperature on the blowers outlet to the temperature it sucks in at his inlet - right? You can do this by defining the boundary on the blowers outlet in 0/T to: blower_outlet { type outletMappedUniformInlet; outletPatchName blower_inlet; value uniform 1; //placeholder } This will apply the mean temperature from the patch "blower_inlet" to the patch "blower_outlet".

July 31, 2013, 05:35		#3
ment_87 New Member Join Date: Jul 2013 Posts: 3 Rep Power: 12	Hey gillimaniac, thank you for your response! I am actually looking for a thermally coupled inlet. This means that if the air at the inlet is warmer than the ambient temperature, the air at the outlet will also be warmer. This heating up is dependant on a heating load P. As to say: T_out = T_in + Qdot/(mdot*cp) Would this be possible? Regards!

August 1, 2013, 01:44		#4
gillimaniac New Member Stefan Gaerling Join Date: Dec 2012 Posts: 22 Rep Power: 13	Okay there's the difficulty.... I'm sorry but i think there's no boundary condition like that implemented at the moment and you will have to code it yourself. At least I don't know about an implemented condition thats doing something like that...

December 2, 2015, 09:46		#6
vfl New Member vfl Join Date: Oct 2015 Posts: 1 Rep Power: 0	Hello ment_87, Interesting problem! Did you manage to fix it ? I'm currently dealing with the same kind of recirculation problem. Best regards,