Simulating free radiation to space
I am trying a thermal simulation for the described problem:
We have a very hot fluid flowing through a pipe. The pipe is wrapped in insulation. The pipe is in Outer Space.
How can i model a domain that simulates conditions for space? I would like to see how the thermal distribution in the pipe.
I have tried modelling space as a fluid volume that holds the "void" material properties. However, this is not working for the radiation equation.
The key goals here are to see the surface temperature on the outer wall of the pipe.
Best Answer
-
The typical approach to this in AcuSolve would be to add Element Boundary Condition with variable = radiation_heat_flux to the outer surface - the surface you want radiating to space. With type = constant, the constant_value to specify would be sigma * T_Infinity. Sigma is the Stefan-Boltzmann constant, T_Infinity would be the temperature to which the body is radiating.
1
Altair EmployeeAnswers
-
The typical approach to this in AcuSolve would be to add Element Boundary Condition with variable = radiation_heat_flux to the outer surface - the surface you want radiating to space. With type = constant, the constant_value to specify would be sigma * T_Infinity. Sigma is the Stefan-Boltzmann constant, T_Infinity would be the temperature to which the body is radiating.
1 -
acupro_21778 said:
The typical approach to this in AcuSolve would be to add Element Boundary Condition with variable = radiation_heat_flux to the outer surface - the surface you want radiating to space. With type = constant, the constant_value to specify would be sigma * T_Infinity. Sigma is the Stefan-Boltzmann constant, T_Infinity would be the temperature to which the body is radiating.
In HyperWorks CFD, that will be under Radiation > External, and constant
1 -
acupro_21778 said:
The typical approach to this in AcuSolve would be to add Element Boundary Condition with variable = radiation_heat_flux to the outer surface - the surface you want radiating to space. With type = constant, the constant_value to specify would be sigma * T_Infinity. Sigma is the Stefan-Boltzmann constant, T_Infinity would be the temperature to which the body is radiating.
Thanks for this!
I found that really helpful - i was struggling to find documentation on this.
So i have set T_inf = 3K (i.e the the external radiation reference temperature. - now the surface select, does this refer to the surface that is radiating the heat?)
I have also set the External radiation flux = sigma*(T_inf^4) - you didnt' say to the power of 4 but i feel that has to be the case for the units to balance.Did i understand correctly?
0 -
Feroz said:
Thanks for this!
I found that really helpful - i was struggling to find documentation on this.
So i have set T_inf = 3K (i.e the the external radiation reference temperature. - now the surface select, does this refer to the surface that is radiating the heat?)
I have also set the External radiation flux = sigma*(T_inf^4) - you didnt' say to the power of 4 but i feel that has to be the case for the units to balance.Did i understand correctly?
Correct - select the outermost surface, that is radiating to space.
Yes - my mistake - the constant value for external radiation flux is sigma * T_inf^4 as you state.
1 -
acupro_21778 said:
Correct - select the outermost surface, that is radiating to space.
Yes - my mistake - the constant value for external radiation flux is sigma * T_inf^4 as you state.
Thank you so much, this is perfect!
Do you know of decent sources and documentation for working with the solar radiation module in HW CFD?
0 -
Feroz said:
Thank you so much, this is perfect!
Do you know of decent sources and documentation for working with the solar radiation module in HW CFD?
The Heat Transfer tutorial ACU-T: 3201 discusses a fair amount about solar radiation. That's probably a good place to start.
There is a little bit in the AcuSolve Help System - AcuSolve Training Material > Theoretical Background > AcuSolve Solver Features > Heat Transfer. Also in the Help System in the Command Reference Manual > Material Model Commands > Solar_Radiation_Model; and in Element Data Commands > Solar_Radiation_Surface.
0