Another Dicrete phase problem

Newbie

Hi all,

I am trying to model the trajectory of small particles (8 micras) in a dense slow moving diluted fluid. The particles eventually will impact a sphere and I would like to know how many of them will reach the sphere surface when the particles are under the effect of several forces.

In the simulations I've made so far, without any force involved, the particles behave strangely; those close to the center have almost random trajectories and some get trapped in the liquid lowest velocity zone.

I think its a numerical artifact as the brownian option is not used and the flow is laminar but very slow (0.001 m/s or less).

Can anybody, please, tell me if there exists a certain set of conditions or fluent definitions, for these conditions?, or maybe I'm missing some physics.

Thanks

Newbie.