Simcenter STAR-CCM+ How can I calculate the spray penetration using a passive scalar?

A passive scalar together with a passive scalar source can be used to monitor the spray penetration (distance travelled by particles from the injector until the current position). 

Note that several definitions of spray penetration exist in the literature. If you are comparing Simcenter STAR-CCM+ results with experimental data, double check that the same definition is used. 

Here is one result from the attached simulation. You can see how the Spray Penetration as a passive scalar matches closely the scene grid and the special Parcel Penetration Report.

How To Steps: First create a passive scalar in the Lagrangian phase which needs to be monitored. Under "Continuum > Lagrangian Multiphase > Phase 1 > Models > Passive Scalar" enable the source option: "Scalar with inferred density". Set the "Particle Velocity: Magnitude" function as the Passive Scalar Source Density Inferred. Check that initial passive scalar is set as 0 in the injector values.

The methodology explained in this article is used in the attached simulation and can be used either in steady or unsteady simulations. In steady state you might have to use track files to look at the scalar.

Simcenter STAR-CCM+ User Guide Section: 
Simulating Physics > Multiphase Flow > Using the Lagrangian Multiphase Model > Lagrangian Phase Models > Lagrangian Passive Scalars