Particle tracking is not done simultaneously. The particle tracking is a separate algorithm to the flow solver and you can control how frequently it runs. Please see the CFX Solver Modelling Guide for Particle Transport Modelling->Particle Solver Control. If you expect the feedback to be weak you can do the particle update less frequently than the default. But it may still be worth doing more than one particle update. It is probably better to let the solver discover that the feedback is weak and so it will automatically stop once both the flow and particle solvers have converged (and they will do that quite independently if there is no strong feedback) rather than trying to force the issue by running only the flow solver followed by a single instance of the particle solver, although you can do that if you want by adjusting the particle control parameters.
You are navigating away from the AIS Discovery experience