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-   -   Particle/Injection Questions (http://www.cfd-online.com/Forums/fluent/96513-particle-injection-questions.html)

Mr. CFD January 24, 2012 22:31

Particle/Injection Questions
 
Hey all, I've got some questions about the dpm model in Fluent. First, how can I get the particle ID number when using the macro DEFINE_DPM_INJECTION_INIT? I want to base the particle velocity on the ID number, but apparently p->part_id is not included in this macro (returns a value of -1 when I tried it). I also tried putting Tracked_Particle *tp along with Particle *p and this didn't work either.

Next, I have set up a group injection in which I am injecting a specific amount of particles all at once. I set the start and stop time to 0, make the amount of streams equal to the total number of particles, and set different values for the first and last point z position, based on some experimental data. The question is, how do I specify the flow rate? I believe it is particle mass / particle time step. Is this correct?

Lastly, I have been having some convergence issues. I suspect it is related to the fact that I set the drag force equal to 0 (through DEFINE_DPM_DRAG) in the beginning until a specified time, and the discrete phase and continuous phase are coupled. I don't remember having any problems before, when I was simply calculating the drag with this macro and returning it to Fluent. Any thoughts on this?

Any help is greatly appreciated!


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