CFD-DEM approach if particle size lies between the minimum and maximum of mesh size ?

Hello everyone,

I want to simulate particle settling in liquid and have doubt on which approach (resolved or unresolved) to use for following case ?

Particle diameter = d
Mesh height near to wall = h_w
Mesh height far from the wall = h_b

These parameters has following relation: h_w < d < h_b (i.e. Mesh height near the wall is smaller than particle diameter and Mesh height far from the wall is larger than particle diameter).

As per the above conditions, resolved approach would be applicable near the wall and unresolved approach far from the wall. So, Is it possible to simulate this kind of system ? If yes, than which approach (resolved or unresolved or both(?) ) would handle this kind of situation ?

Any comments/suggestions would be appreciated.

Thanks,
Aashish Goyal