Originally Posted by pakk (Post 496733)

Fluent UDF manual 2.5.1:

"For the return status PATH_ACTIVE, the particle continues to track. For the return status PATH_ABORT, the particle will be stopped and considered to be aborted. For the return status PATH_END, the particle will be stopped as well, but considered to have escaped from the domain."

If you want a particle to be "trapped", use PATH_ABORT; if you want a particle to be "escaped", use PATH_END.
Honestly, I don't know if there is any aspect in which Fluent treats "trapped" particles differently from "escaped" particles, but if I used this I try to choose the most logical condition in my situation.

As of Fluent 15.0, there are seven different statuses (see dpm_types.h, somewhere in your Fluent folder):

PATH_END
PATH_ACTIVE
PATH_BREAK
PATH_ABORT
PATH_STOP
PATH_NON_LOCAL_PERIODIC
PATH_NON_LOCAL

They are listed without explanation, and I don't know more. I would guess that PATH_BREAK indicated a break-up of a particle, and that PATH_NON_LOCAL_PERIODIC and PATH_NON_LOCAL might have to do with parallel issues. I don't know when PATH_STOP should be used, nor what it does.