The hydrodynamics of binary particles in bubbling fluidized beds are of significance to a wide range of industries, and acceptable agreement has been found between experimental measurement and numerical calculation of the vertical velocity distribution of binary particles. Calculations using different drag models and restitution coefficients have been used to model a variety of superficial gas velocities, particle components, and particle diameters. Fluctuation of the void fraction is regular, but its periodicity is complex. Small and large particles are segregated in the bed, and the segregation is more obvious when the restitution coefficient is increased. This demonstrates the complex nature of gas-solid and solid-solid interactions, and the behaviour of binary solids; these results should aid further study of multi-solid behavioural mechanisms. (C) 2019 Published by Elsevier B.V.