A significant variation in particle size distribution (PSD) is generally encountered in slurry transportation. The goal of this work is to establish the effect of variation in PSD on the centrifugal slurry pump (CSP) performance and particle kinetics. Computational fluid dynamics (CFD) modeling of a CSP with multi size particulate slurry has been performed with a sliding mesh approach using the granular EulerianEulerian model. The numerical model is validated with the experimental data of the pump performance for multi-size particulate fly ash slurry. The maximum deviations in the predicted head and efficiency compared to the measured values are of the order of +/- 2% and +/- 3.5%, respectively. Simulations with a single representative particle size for multi-size particulate slurry using median and weighted mean diameter approach are also carried out to understand the difference in performance prediction with equi-size and multi-size slurry. The predicted trend of pump performance variation with PSD is linear and nonlinear with equi-size and multi-size slurries, respectively. The median and weighted mean approaches showed error in capturing the effect of variation in PSD on pump performance. The variation in PSD significantly affects the flow of particles inside the impeller and casing flow passages due to particle kinetics. Reduction in the intensity of granular pressure, maximum granular viscosity, and the head loss due to friction in impeller and casing flow passages are found with the increase in the fine size particles. (c) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.