Learning Forum

[peter496]

Hello, is there anywhere that I can find documentation for the BOUNDARY_HEAT_FLUX macro? I have seen this discussed on forums, but I cannot find any Ansys documentation in the UDF manual.

Thanks!

[DrAmine]

Is not officially documented and supported. It provides for boundaries the total heat rate associated with each facet on that boundary.

[peter496]

Hello DrAmine, thanks for your response. What are the units of the output of the macro? And what would this correspond to in the Fluent Results (I assume Total Surface Heat Flux in w/m2, but I just want to confirm)?

[Rob]

All UDFs work on SI, so W, m, K etc. Thankfully the original Fluent team spent a lot of time in the UK so we were spared US Imperial.

[peter496]

Hi Rob, thanks for your response. DrAmine mentioned that the macro returns total heat rate for each face on a boundary (heat rate suggests W). The name "BOUNDARY_HEAT_FLUX" suggests W/m2. Does this macro return a value in W or W/m2?

[Rob]

It should return W/m2 as per the panel you hook it into. Fluent will extract area, temperature etc from your model in m2, K etc. for use in the calculations. 's referring to the report which you'll see for the surface when you check which is W.

[peter496]

Thanks DrAmine and Rob for the help!

[DrAmine]

As far as I tested It returns in W. The name is misleading. You might test and compare to flux report

[peter496]

Hello DrAmine, I tested the BOUNDARY_HEAT_FLUX macro and found that it returns only W (confirming your result). I can match the heat flux (i.e. Total Surface Heat Flux) after dividing by the area of the face:
heat = BOUNDARY_HEAT_FLUX(f,t);
F_AREA(A,f,t);
a_face = NV_MAG(A);
flux = heat/a_face;