Need help!:Particle flow through porous zone
 

Hi, Fluent users,

Really appreciate if you can help me in the simulation of Particle-laden air flow through porous zone!
The problem is to simulate low loading particle laden air flow through porous zone, we need to calculate the collection efficiency of the porous zone to filter the particle. It asks one-way coupling of air and particles of different sizes. There is an equation for the flux of particles filtered by the porous material. I have the following questions:
1. Should I use only DPM model or combine with User-defined scalar, I am a little bit confused using scalar? If I just use DPM model, there is no particle tracked. I used user defined scalar, the gravity doesn't work.

2. The "Interaction with continuous phase" should not be checked, since it is one-way coupling. However, the FLUNENT guide says that there is NO need to set the flow rate in the Point Properties, then how can i calculate the concentration?

3. How can I set the porous material as a sink of particles? In boundary condition, the porous zone is only a type of fluid.

Thanks for taking your time!