  Discrete particle simulations are widely used to study large-scale
particulate flows in complex geometries where particle-particle and
particle-fluid interactions require an adequate representation but the
computational cost has to be kept low. In this work, we present a novel
coupling approach for such simulations. A lattice Boltzmann formulation of the
generalized Navier-Stokes equations is used to describe the fluid motion. This
promises efficient simulations suitable for high performance computing and,
since volume displacement effects by the solid phase are considered, our
approach is also applicable to non-dilute particulate systems. The discrete
element method is combined with an explicit evaluation of interparticle
lubrication forces to simulate the motion of individual submerged particles.
Drag, pressure and added mass forces determine the momentum transfer by
fluid-particle interactions. A stable coupling algorithm is presented and
discussed in detail. We demonstrate the validity of our approach for dilute as
well as dense systems by predicting the settling velocity of spheres over a
broad range of solid volume fractions in good agreement with semi-empirical
correlations. Additionally, the accuracy of particle-wall interactions in a
viscous fluid is thoroughly tested and established. Our approach can thus be
readily used for various particulate systems and can be extended
straightforward to e.g. non-spherical particles.
