Hi SD,nYes, I tried to debug with all possible values in the UDF. The droplet just stops after hitting the wall.nI used D_RATIO of 1. It did not help. I removed the inert material condition for the particle rebound. Standalone DEFINE_DPM_BC works fine. nWhen I saved the velocity and diameter from the DEFINE_FILM_REGIME with FILM_USER_0, I can see the updated values. However, I also tried to save the values from the DPM scaler update, and the values are not updating there. The path stops after hitting the wall and using the DEFINE_IMPINGEMENT and DEFINE_FILM_REGIME UDFs.nnWere you able to get the particle rebound with the DEFINE_FILM_REGIME(dry_breakup, regime, tp, pp, f, t, f_normal, update) example in the UDF manual?Thanks,nJon