Writing a UDF for heat loss from a composite wall
Hello,
I want to write a UDF file to calculate heat loss from the system to the atmosphere. The wall is insulated. The outside temperature is ambient. The heat loss equation would be: q = U(overall) * (Twall - Tambient); I know the ambient temperature and overall heat transfer coefficient. q (heat flux through the wall) and Twall will be calculated by Fluent I presume. :confused: Thank you. |
Hi! Can you describe the system a bit more? It's not really clear, if the wall is thermally insulated (heat flux=0=adiabatic), why you are specifying a heat transfer coefficient.
Do you mean you have a composite wall with a very low thermal conductivity? If so, Fluent has a built-in functionality to calculate the fluxes through surfaces(find it in Plots). ComputerGuy Quote:
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The wall is thermally insulated but there are some heat losses through the wall. Fluent does not have the functionality to add composite wall. I first have a layer of deposit at the inside of the geometry, then I have the metal wall, then I have a thick layer of insulation. The heat will e lost from inside to outside (ambient). I can only specify one wall with one set of thermal properties and thickness. So I have to write a UDF, through which I calculate the heat flux. Thank you. |
Unless I understand your problem incorrectly, a 3 material wall is absolutely possible in Fluent. Simply construct your mesh such that the layers of the walls share nodes/faces at their interfaces, and Fluent will calculate heat conduction through them. You'll need to name each wall volume individually, but I guarantee multi-layered walls are perfectly acceptable and easily solved in Fluent.
ComputerGuy Quote:
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OK. Just wanted to make sure you understand that I think Fluent can do what you want without having to write a single line of UDF code.
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If you can only specify "one wall," you haven't constructed the wall in such a way that Fluent understands that there are three distinct layers. Ensure you have created a named selected for each of the three wall volumes (Fluent 12+).
You might want to revisit some of the geometry creation and meshing tutorials for more help. If you think you've solved your problem, however, great. ComputerGuy Quote:
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