i use DPM to model particle depostion in a pipe turbulent flow. just set the outlet as 'escape' and the walls as 'trap'. the particles are in range from 0.01 um to 100 um. In principle, it should get a 'V' shape profile of depostion. But, when i reduce the diameter of the particle from 1 um, i cannot trap even one particle. the density ratio is 2000. i already set brownian correction constant from the equation given in user guide. Can anybody give me some clues? thanks in advance.

Did you enable particle-turbulence interaction?

I think the particle which is expected to be traped didn't hit the wall. Have you adjust the maxim iterate step of particle?

no, i'm not sure whether i should enable particle-turbulence interaction. because i just want the influence of flow on the particles. i don't want the exchange of energy, momentum between them. do i have to enable that function in such a case? sorry for the stupid question.

yes. all the particles 'escaped' from the exit. if i increase the particle diameter to 10 um, it's working.

I enabled 'interaction' and increase the cunningham correction to a very large number. but i still cannot get one 0.1 um particle trapped. i realeased 2000 particles of such sizes near the wall. Do i have to enable gravity or something else?

I think the diameters you are working with justify the inclusion of the virtual mass force in the particle force balance. The particle turbulence interaction is imperative in accounting for the random velocity fluctuations in the continous phase.