[climshwuling]

Hello all,

I have been trying to write a heat flux UDF around a cylindrical tube to be applied as a boundary condition in Fluent, and I have been running into some issues regarding defining the "circumferential" direction of the cylinder tube for it to properly represent the heat flux around the tube.

The heat flux I have obtained is through the SolTrace software for concentrating solar collectors. SolTrace outputs a plot for the non-uniform heat flux distribution along the circumference (x-axis) with respect to heat flux (y-axis) of a cylindrical receiver tube. My plan was to write a UDF code that plots a polynomial function of the non-uniform heat flux with respect to circumference of the cylindrical receiver tube, however, i've been running into a lot of errors as I am not sure how Fluent defines a circumference in this case. Is it by angle? Is it by Arc Length? It seems like my error occurred due to not having a good understanding on how Fluent measures/defines circumferential geometries for writing UDF.

If anyone has any experience defining a heat flux UDF profile with respect to a circumferential tube, I would appreciate it if you have any insights on how I should write my UDF code to properly represent the non-uniform heat flux distribution around the tube in Fluent. Of if anyone can help with clarifying how Fluent measures/defines circumferential geometries for writing UDF that will be very helpful too!

Thank you,