A new method for determining the maximum value of the van der Waals force, F-v,F-max, has been developed to analyze the dispersion and aggregation behavior of primary particles in a suspension. The simulation method considered the van der Waals force, the electrical double-layer force and the lubrication force as remote inter-primary-particle interaction forces. Distinct Element Method (DEM) was applied to tracking the motion of primary particles, and DEM was coupled with Computational Fluid Dynamics (CFD) by DEM-CFD coupling model to represent the motion in liquid. Aggregate size distributions (ASDs) were measured and simulated at different pHs and shear rates in order to determine the F-v,F-max and to validate the proposed method. The simulated ASDs qualitatively agreed with the experimental values in general. The result, therefore, indicates that the dispersion and aggregation behavior of primary particles could be analyzed by using the F-v,F-max determined by the proposed method. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V.