[payam_IUST]

In particle tracking in fluent when we choose type of particle as "massless"(Only availabe in ansys-fluent 12) or "inert",the collisions of particles by themselves is considered by fluent or not?is it possible that we track the particles separately??

[Andrej]

You can turn On or turn Off the model for collision. The collision model work only with unsteady particle simulation. You can track particle separately. Did you read the user guild for DPM-Model?

[payam_IUST]

thank you for your reply,
but I track 2000 particle together and write solution variables of a specific particle in a step by step file,Another time I track that
particle lonely and compare two files,they was a little different,Why this problem accur if fluent track particles separately?

[Andrej]

Default you have turn on the Discrete_Random_Walk in the Stochastic Tracking. You must turn off this Model in Particle Injection when you need always the same trajectories.

[payam_IUST]

Originally Posted by Andrej

Default you have turn on the Discrete_Random_Walk in the Stochastic Tracking. You must turn off this Model in Particle Injection when you need always the same trajectories.

thank you again for yout attention,
But in this case the particle type is massless and the solver is "laminar" and tracking is steady and for this reasons turbulent dispersion and Discrete_Random_Walk in the Stochastic Tracking is unavailable

[Andrej]

Probably Start Positions are different. When the some and no more fluid iteration was made - I don't know. Numeric? When collision model is turn off, you do not have collision influence.