Hello! It seems to me that FLUENT is injecting particles every time step. I'd like to define injections less often than every time step, because my time steps need to be very low, otherwise the number of bubbles is too high! Thanks in advance. Marie.

hi,

for an unsteady simulation you probably defined the maximum number of iteration per time step in your unsteady simulation.

Then for example if you set 20 max iterations per time step, you just set it to 30 number of continuous phase iterations per DPM iteration once you ticked the box "interaction with continuous phase".

Try it, let us know if that works and have any effect on your simulation.

I hope this helps.

David

The problem I have concerns the injection time, because it seems that FLUENT injects particles every time step and gives each calculated particle a ponderation number so that the mass flow rate you want is respected. The problem is that my number of calculated particles becomes large very quickly and is much higher than the real number of particles. Regards

There is an unsteady particle tracking option in FLUENT where particle trajectories can also be advanced in time with the flow simulation.

With this option, you will need to set the start and stop time of your injections in the injection properties panel.

Select the unsteady tracking option under unsteady parameter.

have you tried this?

let me know if that answers your question.

i hope this helps

David

[Eng_mech78]

Hi!
I am modeling a Spray injection in a constant volume chamber in Fluent. My problem is that when I inject with smaller injection velocities (40-80 m/s) everything is fine but in higher injection velocities (300-500 m/s) it diverges quickly. I have even tried to reduce the time step, & increase the number of iterations but it`s not working.
Thanks.