Ansys Employee

One of the requirements of the DPM model is that the particles are smaller than the cells. The solvers also track a point mass, so a 1mm particle can fit through a 0.1mm gap, and will only contact the walls if the centre point enters the near wall cell.  In your case you may be finding the mesh to be too fine, so the particles are striking slightly down stream. 

I'll also move this into the Fluids section so hopefully more of the community will see it.