Appropritate solver for stormwater pipe
 

Hi,
I am new to CFD and OpenFoam. Therefore any guidance would be greatly appreciated.

I need to determine the travel time of stormwater from point A to point B, in a gravity-driven stormwater pipe system (where there is the presence of air). Can I use an incompressible fluid solver (e.g., simple/piso/pimpleFoam), or should I opt for a multiphase solver (e.g., interFoam)?