A particle-wall collision model accounting for the wall roughness in the framework of second-order moment two-phase turbulence models is proposed, combining the advantages of the collision approach in the particle trajectory model and the PDF approach in the two-fluid model. The proposed model is incorporated into the second-order moment two-phase turbulence model to simulate axisymmetric swirling and mixing-layer gas-particle flows. The simulation of swirling gas-particle flows and its comparison with the measurements show that the proposed model gives much better results than the widely used zero-gradient condition does, and is suggested to be used as wall boundary condition for particle phase instead of the widely used one. The simulation of mixing-layer gas-particle flows shows that the model accounting for the wall roughness gives smaller longitudinal mean velocities and greater longitudinal fluctuation velocities for particles, which are in better agreement with the experiment results, than those obtained using the model not accounting for the wall roughness. The results are qualitatively consistent with the simulation results using the particle trajectory model. (c) 2005 Elsevier B.V. All rights reserved.