CFD Online Discussion Forums - Basic question: UDF for wall heat flux

Thanks for reading. I'm a new FLUENT user. Here's a general description of my problem:

This is a 3d geometry in which a particular wall boundary has an externally-imposed heat flux (from absorption of a proton beam in reality) that varies spatially across the boundary. This heat flux can be described by some simple algebraic function of the "x" coordinate, say.

So the question's simple: How do I specify this heat flux in the wall boundary condition in FLUENT? My preliminary understanding is that this should be done with a user-defined function, written in C. The UDF Manual seems to indicate that an algebraic function cannot be used with the DEFINE_PROFILE macro to describe heat flux, that only a "single value" can be set this way. Alternatively, nothing is noted about such a condition on the "heat generation rate," which perhaps would be a better parameter to use anyway even though the volume in which the heat is deposited is so thin as to be effectively of zero thickness. I should point out that I have no background in C programming.

If you're able to help answer my question, that's awesome...I really appreciate it! Pointers are great, examples are the best! However, I should note that the following responses will NOT be useful to me:

"You need to read the manual / take a remedial FLUENT 101 class, etc." (If the manual solves my problem, tell me where, very specifically.)

"This problem gets brought up on this forum every week by ignorant dunces, learn to do a search." (I apologize in advance for the spam-rated topic. Please point out an applicable response if you can be bothered for a nanosecond.)

"You are an utter n00b." (I already know that you know that I am a n00b.)