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-   -   DPM particle time step (http://www.cfd-online.com/Forums/fluent/70633-dpm-particle-time-step.html)

amos December 1, 2009 04:31

DPM particle time step
 
Hi,
- I noticed that even if I choose a particular timestep for particles, when I look at its value with a fprintf(using udf) of P_DT(p), I never get the right particle time step, even if I use the DEFINE_DPM_TIMESTEP. Anyone encouters that kind of problem ?

- As en exemple, when I choose dt=1e-4, the time step evolves stochastically from 1e-5 to 1e-7 and hence, the particle trajectory is integrated many times and not once in one step of the continuous phase flow for which I fixed dt=1e-4. Is there a solution to fix the same timestep for the discret particle and the continuous phase ? and most of all to integrate only once the particle equation for trajectory for one fluid time step ?

-If it is not possible, I noticed that Fluent integrates the trajectories many times in one time step for the continuous phase before jumping to the integration of the second particle and so on. I would likle to know if there is a Fluent instruction to force it to jump to the next particle after intagrating only once the first particle, even if it comes back to integrate the first particle after looping over all particles in one continous phase time step) ?

For information, I am not doing interaction with continuous phase and I am injecting as group.
I hope that you understood what I mean ?


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