We introduce a simple model for granular flows with hydrodynamic interactio
ns. The hydrodynamic part of the model relies on a coarse grained picture o
f the granular medium, and is described in terms of the pressure by a local
Darcy law. The model thus avoids the large computational cost of solving f
or detailed hydrodynamic how fields between grains. The solid phase is desc
ribed explicitly in terms of gains by event driven molecular dynamics. In t
he first two test cases, the model is employed to simulate a sedimenting an
d a fluidized particle bed. It is shown that the qualitative aspects of bot
h phenomena are correctly captured: The sedimenting particles form a sharp
upper front and move according to the theoretical prediction, which is also
given. When external pressure gradients are applied the bed fluidizes, and
spontaneously produces bubbles of the shape observed experimentally. Moreo
ver, these bubbles are seen to merge, as is experimentally observed.