- Abstract The effect of a bend on the distribution of particles in a pipe cross section and segregation in pneumatic conveying systems has been investigated numerically. The numerical model solved the finite-volume equations for the conservation of mass and momentum for two phases. The predictions of the numerical model were compared qualitatively with various published experimental data. It was evident that the cross-sectional concentration of the particles a few metres after a bend is not uniform and that the particles tend to concentrate around the pipe wall. Various cross-sectional concentrations of particles were found for different pipe-to-bend radius ratios, particle sizes and direction of gravity (i.e., horizontal-to-vertical flow, and horizontal-to-horizontal flow). Based on the different cross-sectional concentrations for different particle sizes, it was concluded that the paths taken by the particles after the bend were strongly dependent upon their sizes. Since a real particulate phase (i.e., powder, granular material, etc.) is composed of particles with a range of sizes, this would lead to segregation of the particles in the pipe section following a bend. Hence, a better understanding of the segregation process in a pneumatic conveying system was obtained.