Openfoam vs Ansys
 

Hello everyone,
I am somehow new in CFD and I am going to model a two phase, turbulent flow in a cyclonic separator.
I have been asked to investigate that which software I should choose between the commercial CFD package Ansys Fluent and Openfoam. and I should also report why I have chosen this software for my master.
so generally I wanted to ask you guys that is it any specific physically reason for me to switch to openfoam software(especially in multiphase flows and related complexities) or not?
I will be very glad if you guys help me in this case.
Thanks a lot in advance,
regards