A three-dimensional non-steady state shot peening simulation platform for coverage prediction is developed based on commercial Computational Fluid Dynamics (CFD) ANSYS-FLUENT software. To simulate the air-peen flow, the airflow is treated as a continuum phase governed by the Reynolds-averaged Navier-Stokes conservation equations, while the peen is taken as a discrete phase in which the trajectories of the peens are tracked individually. Two-way air-peen interactions are solved by exchanging mutual momentum during the peening process. User Defined Functions (UDFs) for particle loading distribution in the nozzle, particle dispersion, particle rebound, and nozzle movement are developed and incorporated into ANSYS-FLUENT. A numerical procedure based on the Eulerian-Lagrangiah approaches is used in the solution. The air-peen simulation results based on the above model and numerical procedure is found to be in excellent agreement with the literature experimental data. For coverage prediction, both single dimple area and multiple impact coverage models are developed and validated by both experimental data and in-house Finite Element Method (FEM) simulation result. The obtained simulation results for coverage are in good agreement with existing experimental data. In addition, the simulations for two other configurations, that is, round-flat and airfoil NACA0012 specimens, are also performed to demonstrate the capability of the simulation platform. The present work shows that the multiphase shot peening simulation platform developed here can be used to accurately predict air-peen flow and coverage and to further optimize shot peening processes under real operating conditions. (C) 2014 Elsevier B.V. All rights reserved.