[csacska]

Hi Folks!

I am confused with the parameters of the unsteady particle tracking in the case of discrete phase modelling in Fluent. It is clear what is the continuous phase iterations per DPM iteration is about, let us consider a value of 10 here, this is the default. The inject particles at option is chosen (automatically) to "Fluid Flow Time Step". There are to further settings:
Particle Time Step Size (s) (e.g let it be 0.001s)
Number of Time Steps (e.g. let it be 5)

I made some test simulations to figure out how these parameters effect the injections and the basics were found out. In order to perform only one DPM iteration the given amount of continous phase iterations (value of 10 in my case) have to be run. One DPM iteration will inject 5 series of group of particles with 0.001s time delay.

Until this point it is clear, I suppose these aspects are understood well.

My main question is to how to set these values? How these values are related to the calculation of the particle trajectories? I would like to have restrictions that a particle passes a cell with at least 5-10 steps. My grid is broken into 3mm cells, speed of my particles is about 10m/s, thus I want my particles calculated small displacements, i.e. value of 0.0003m.

I am not sure how to achieve this. At the tracking tab there are the tracking parameters which influences these calculation properties, what is clear in the case of steady particle trajectory treatment, but in the case of unsteady particle tracking I could not figure out how all these parameter settings determine calculations.

I would be really thankful if someone could summarize and make its working conditions clear to me. I have read the fluent manual but it is not detailed enough in my opinion.

Best regards,
Balint