Temperature lower than possible in closed domain

Czarulla · January 14, 2015, 06:59

I am working on transient model of natural convection with heat source inside the closed, cylindrical domain and one BC at the wall of cylinder. The BC is contant temperature of 323 K. Initial temperature of air inside this cylinder is equal to 350 K. After a certain time of simulation the temperature inside the lower part of cylinder fall down under 323 even to 293 K. Air is treated as an ideal gas. I have to mention that I also used S2S radiation model.

How is it possible for a closed domain to acquire from calculations a temperature, which lower than BC? Radiation heat transfer is also occuring from higher to lower temp? Could anyone explain it to me?

Best regards,
Czarulla

Czarulla · January 15, 2015, 05:01

I checked that without using S2S radiation model temperature is reasonable.

Could anyone give me some tips how to appropriately set the S2S radiation model? I cannot set the free stream temperature as this is not the case.

January 14, 2015, 06:59	Temperature lower than possible in closed domain	#1
Czarulla New Member Cezary Join Date: Jul 2014 Posts: 5 Rep Power: 11	I am working on transient model of natural convection with heat source inside the closed, cylindrical domain and one BC at the wall of cylinder. The BC is contant temperature of 323 K. Initial temperature of air inside this cylinder is equal to 350 K. After a certain time of simulation the temperature inside the lower part of cylinder fall down under 323 even to 293 K. Air is treated as an ideal gas. I have to mention that I also used S2S radiation model. How is it possible for a closed domain to acquire from calculations a temperature, which lower than BC? Radiation heat transfer is also occuring from higher to lower temp? Could anyone explain it to me? Best regards, Czarulla

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January 15, 2015, 05:01		#2
Czarulla New Member Cezary Join Date: Jul 2014 Posts: 5 Rep Power: 11	I checked that without using S2S radiation model temperature is reasonable. Could anyone give me some tips how to appropriately set the S2S radiation model? I cannot set the free stream temperature as this is not the case.