The effect of meso-scale structures on the hydrodynamic behaviors of particle-fluid systems is considered in an Eulerian-Lagrangian model utilizing the detailed particle distribution information provided by such models. The fluid flow is distributed within each computational cell from pressure balance considerations according to weighted local porosities, rather than by using traditional linear interpolations. The drag on each particle is then calculated with its local porosity and slip velocity, which shows significant difference to traditional methods. Simulations in this model have reproduced multi-scale flow behaviors in better agreement with experimental results, suggesting the validity of the model. (c) 2007 Elsevier Ltd. All rights reserved.