Measurements were made of the concentration of particles in a horizontal transport pipe using an optical probe. The distribution of particles over the pipe cross-section was measured. Particle transport in a horizontal two-dimensional (2-D) channel was simulated using an Eulerian two-fluid model. A model is proposed for the turbulent dispersion of particles and implemented in the two-fluid model. The turbulence in the gas phase is modeled using a modified k - epsilon model that accounts for the influence of the particles on the gas-phase turbulence. Comparisons with measurements of air-particle flow in a horizontal pipe show qualitative agreement between measurements and calculations. (c) 2005 American Institute of Chemical Engineers.