[Peter023]

Hello FLUENT users,

I'm currently solving a problem about an injection of particles into domain at an arbitrary time during a steady flow simulation with unsteady particle tracking.

A well known way to inject particles is via the particle injection where the start and stop times are defined. The particles are then injected every time step within the defined time interval. If both times are 0, particles are injected only once.

However, I need to be able to inject particles at any time of the simulation at positions and velocities defined by my UDF. One way to do this I found on CDF forum is to inject more particles than I actually need and keep a part of them dormant (inactive, OFF) and activate them when needed. This is, however, a bit inefficient, since FLUENT will still include these particles into the simulation and slow it down.

Is there a better way how to force FLUENT to inject particles (defined by an injection) into simulation at any time I need from a UDF? Or is there a reasonably simple general way how to append or delete particles from an injection I* via a UDF?

Any suggestions will be highly appreciated.

Thank you.

Cheers,
Peter

[TimW]

Hello Peter,

I have a similar problem. Did you find a solution? And could you share it with me? (Even if it was quite a while ago.)

Thank you.

Cheers,
Tim

[obscureed]

Hi TimW,


Have a look at "MARK_TP(tp,P_FL_REMOVED);" or possibly "MARK_PARTICLE(p,P_FL_REMOVED);" or both -- for example here:
Stop particle trajectory in DPM
Assuming you're using an up-to-date version of Fluent (and, really, this is strongly recommended), the first one that I mentioned (involving tp) is more likely to be current.


You can kill particles before they really exist, in DEFINE_DPM_INJECTION_INIT, for example.



Good luck!
Ed

[TimW]

Hello Ed,

thank you for your help!

My current solution is to export a txt-file of particles for every timestep and then define a new injection with execute commands.

Do you know which of these approaches is faster?

Regards,
Tim