Hi Rob, going through the Ansys material I have found a case file devised to include a DEFINE_DPM_SOURCE. I have made some minor rearrangements over this file, and at least, I am getting the message in the console. Now, I have to figure out what the difference is between both cases...

I have a conceptual question regarding the DEFINE_DPM_SOURCE UDF. I have read in the manual that S is the "pointer to the source structure dpms_t, which contains the source terms for the cell", so I am expecting S->species[0] to cause changes only on the fluid of those cells that the particle goes through (surroundings affected by diffusion etc). Am I right?