Learning Forum

[Jad Kans]

Hello. I am beginner in Ansys Fluent and I need your help. I need to simulate the radiation heat transfer from a 3D emitter (3D model) to a 3D part with a 8 mm distance apart from eachother. I assigned the materials for the emitter and the part, and I constructed an enclosure with incompressible air as a fluid material. I set the radiation model to be DO, laminar viscousity, and energy equation is on. I set the cell zone conditions for the emitter and the part to participate in radiation. I set the temperature of the emitter to be 813K, and I set the boundary conditions of the part for all the walls to be mixed, with a free stream and external temperature of 300K, and convection heat rate of 20W/m.K. However, after initialization and running the calculations, the part temperature is 300K, as there is no radiation. What is the key point that I did not do to have a radiation heat transfer for the part? Thank you in advance.

[Rohan Gulavani]

Hi Mr. Jad Kans, 

I am not sure if you have considered wall thickness. Matertial assignment to part only will be in effect if you defined some thickness.  Also check for radiation BC applied on parts. I believe it could be Opeque, this allows no radiation to pass through.. So if you want to see radiation effect on part, then either to define part thickness or model as solid part and then select that solid as participating media and define internal surface of sink part model as semi transparent. 

For this problem statement, S2S will work well without much confusion. Please try this model too.

Thanks 

[Jad Kans]

Hello Mr. Rohan Gulavani. 

Thank you for your answer. I constructed the emitter and the part as 3D solid parts. I defined the emitter as a whole being one wall (from named selections). However, for the part, I defined each side as a wall (top,bottom,left,right,front,back), without defining wall thicknesses. I also put the two models inside an enclosure, where I defined the top of the enclosure as outlet-vent, and the sides as pressure inlet. I got new results, using S2S model, for radiation heat transfer from the emitter to the part thrpugh temeprature. A picture is attached for more illustration. However, if you can see from teh picture, the dimensions of the emitter are higher the the dimensions of the side (bottom side) of the part facing the emitter. However, if we have greater dimensions of the mitter, shouldn't the temperature at the edges of the facing side (bottom side) be higher than at the center? I am getting a reuslts where temperature is higher at the center of the face not at the edges. Thank you again for you help.