Moving solid particles in a laminar flow

Hello,

I want to simulate moving solid particles in a laminar flow with some obstacles (vertical columns) in their way. What I want to see is that how they get trapped in the gaps between the columns (when the diameter of the spheres is larger than the gaps). I have tried the Particle Tracing module, but it doesn't consider the particles as real rigid bodies. I mean even if I set the diameter of the particles higher than the gap space, the particles still pass through. The only thing that changing the diameter would affect is the velocity of the particles. I was wondering if there is any way that I can make these particles as real rigid spheres, so when they are larger than the space between the columns, they will not pass and get trapped there.

Thank you so much,
Yasamin