  A comparative study on mesh-based and mesh-less Computational Fluid Dynamics
(CFD) approaches coupled with the Discrete Element Method (DEM) is presented.
As the mesh-based CFD approach a Finite Volume Method (FVM) is used. A Smoothed
Particle Hydrodynamics (SPH) method represents mesh-less CFD. The unresolved
fluid model is governed by the locally averaged Navier-Stokes equations. A
newly developed model for applying boundary conditions in the SPH is described
and validation tests are performed. With the help of the presented comparative
tests, the similarities and differences of DEM-FVM and DEM-SPH methods are
discussed. Three test cases, comprised of a single solid particle sedimentation
test, flow through a porous block and sedimentation of a porous block, are
performed using both methods. Drag forces acting on solid particles highly
depend on local fluid fractions. For comparative reasons, the size of a cell in
FVM is chosen such that fluid fractions match those computed in SPH. In
general, DEM-FVM and DEM-SPH methods exhibit good agreement with analytic
reference results. Differences between DEM-SPH and DEM-FVM approaches were
found mostly due to differences in computed local fluid fractions.
