dear Rwoolhou,

thank you so much for your kind reply.

So you are saying that there is no direct way to get the drag force exerted on each particle, and I should calculate the force for each particle by myself? Actually I was thinking about this method to write the x and y particle velocities (it is a 2D domain)  and the velocity field at the corresponding particle positions into an Excel file to calculate the drag force vector(magnitude and angle), exerted on each particle. However, there are two concerns regarding this suggestion:

1-  I want to depict the drag force vectors on each particle later (like velocity vectors for each particle that is already available in Fluent). Is it possible to import the calculated force vectors back to Fluent and relate them to the corresponding particles? 

2- how to relate the vectors to the correct particle? the information is sorted according to particle residence time when I get the outputs to Excel and I wouldn't know which vector would be for a particular particle.  


about the DEFINE_DPM_DRAG that you mentioned, I have noticed that before. However, as I understood, it is used to define the drag force correlation and I could not find out how I would be able to report the calculated drag based on this UDF. I tried report definitions, the UDF section, but it didn't work out. Could you show me a way to get a report from this UDF, the problem is almost solved.

Regards, Reza