In an effort to test the extent to which fundamental fluid mechanics can provide a prediction of particle separation in a flowing film concentrator, a study on a simple parallel-sided channel has been carried out using glass beads at various particle concentrations and flow rates. The actual particle separation taking place was compared to predictions made by first describing the slurry flow based on the Prandtl's mixing length approach. Particle concentration distributions were described using Hunt's sediment transport model. Settling velocities of particles in water were calculated using either the Richardson and Zaki or Brauer and Thiele models. The latter takes into account particle size and density distributions and solids volumetric concentration. The resulting predictions of particle separation are remarkably good. (C) 2010 Elsevier B.V. All rights reserved.