Learning Forum

[scabo]

Hi-There is some confusion after reading the theory and user guide. What is the difference between DPM time step and particle time step? Can I inject the particles at every 100 flow time steps into the domain but move them at a different time step integration size? Also for unsteady, does DPM iteration interval make any sense? If DPM iteration interval =10, does it mean particles are injected at every 10 flow iteration or they are tracked at every 10 flow iterations but injected at particle time step? thanks for clearing my query.

[SRP]

Hi,

The DPM time step generally refers to the interval at which the DPM solver updates particle tracking and source terms, often synchronized with the fluid flow solver's time step. The particle time step is the integration step size used to advance individual particles along their trajectories, and can be set independently of the fluid flow time step for finer or coarser particle tracking.

The DPM Iteration Interval does not directly control the injection frequency. Instead, it determines how often particles are tracked and DPM source terms are updated. The injection frequency is set separately, either at the particle time step or fluid flow time step.

 If you inject particles every 100 flow time steps (using the appropriate injection setting) and set DPM Iteration Interval = 10, the DPM solver will update particle tracking and source terms every 10 flow iterations, but the actual injection of new particles will occur at the interval you specified for injection (e.g., every 100 flow time steps

[scabo]

Hi-thanks for reply. Then DPM time step and DPM iteration interval are same? And to inject the particles every 100 flow time step, I have to set the particle time step 100 times more than flow time step and then set particle injection through particle time step. Is this correct?

[scabo]

Hi-Also when Fluent say Particle Variables, does it mean individual particles or parcel? Also when we display Particle tracks does it display the trajectory of the parcel or individual particles? This is because i thought parcel is a collection of particles but when i do Report>Summary then it is showing something confusing where the particles is showing less than parcel numbers. Can someone please clarify? I have attached the picture.

[scabo]

Hi-If someone can answer the above query-many thanks