Learning Forum

[ggardini]

Hello!

I believe this is the correct area to post this question, but please let me know if I am mistaken.

I am working on a class project using ANSYS Fluent 2025, where we are simulating a "Lifted Turbulent Jet Flame in a Vitiated Co-Flow". We are directed to use the Composition PDF Transport model under Species Models, with imported Chemkin mechanisms. We are then told to use the "Particle Tracks" function under "Results" to view the particles after reaching a converged solution. This works perfectly fine for older versions of Fluent (2020 was used in the demonstration), but when this is done in Fluent 2025 R1 or R2, the following error is returned when attempting to display the particle tracks:

"Particle Track object is not valid to display, saving object."

Note that we are never instructed to enable the Discrete Phase Model and, without it enabled, the prompts produced in the console for each iteration indicate that particles are indeed being injected and tracked. I have found that Fluent 2025 will display the particle tracks only after I have done the following:

1.) Enable DPM
2.) Under DPM, check the "Interaction with Continuous Phase" and "Unsteady Particle Tracking" boxes
3.) Define a new injection
4.) In the new injection, set Particle Type to "Massless" and Injection Type to "Single"
5.) Leave all other injection settings as default (in my case X-Position: 0, Y-Position: 0, Start-Time: 0, End Time: 0)
6.) Run the calculation to convergence
7.) Create a particle track object
8.) Under the particle track object, check the "Track PDF Transport Particles" and select the injection object listed under "Release From Injections"

I have also confirmed that the produced particle track plot responds to changes made to the "Particles per Cell" setting within the "Compostion PDF Transport" Species Model. 

I'd like to get some insight on whether newer versions of ansys require DPM to be enabled and an injection to be defined before particle tracking is possible, whereas previous versions did not. I'd also like to confirm that enabling DPM with the steps I listed is not affecting the underlying physics of the solution.

Any insight is greatly appreaciated! Thanks!