• Instantaneous puff releases require use of relative
dispersion but update frequency of flow field is too low
to resolve turbulent eddies not covered by relative
dispersion concept
• PPM uses a full stochastic Lagrangian particle
dispersion model to determine the puff trajectory
• Kinematic turbulent energy associated with eddies
smaller than the puff size are removed since they are
already accounted for the in relative dispersion
• Every puff carries along it position along with the
position and turbulent velocity components of the
stochastic particle to which it belongs