How to compute an average slip velocity using DPM
 

Hi, I am trying to compute bubble induced turbulence (BIT) effect using DPM model. For that I have the following relation for the extra turbulmence production term which has to be included in the k-eps turbulence model: (BIT)= Dragforce x alpha * (1-alpha) * Vslip * (Vslip)^2. The alpha represent the particle volume fraction which can be easily computed from the macro DPM_CONCENTRATION. However I have difficulties to compute an average slip velocity. I mean i can easily get the slip velocity for each trajectory. But knowing that the cells are crossed by more than a particle (i have 100 tries per injections), how can I compute a slip velocity averaging over the number of trajectory/particle crossing the cell. Apparently it does not exist a loop macro over the different trajectories -> certainly too demanding in CPU time.

If there is no possibility 'Is there someone who has an exresion of the BIT for Langragian method, i mean an expression not involving alpha !. Thanks in Advance. Thomas