Separation of oil-sand-water mixtures is vital in oil sands production and processing. The co-existence of sand and oil in oily water systems can cause corrosion problems to the operational facilities and equipment. Immoderate oil and oil-coated sand levels have negative impacts on the environment. This research attempts to provide further understanding and some solutions to this problem by hybridization of two hydrocyclones for solid-liquid and liquid-liquid separation. The hybrid hydrocyclone is hydrodynamically designed to incorporate a transverse aperture for sand rejection, a transformation of which enables concurrent liquid-solid-liquid three-phase separation of the oily sands. Through computer simulation, the hybrid hydrocyclone has demonstrated promising performance in separating oil-sand-water in a single-stage oil sands production operation. For concentration up to 40% by mass of feed there was good stability and accuracy in the model determination. Beyond that, droplet degeneration and break-up and bedding, and bridging of the hybrid spigot by sand characterized poor accuracy. Two distinct phases of behaviour were exhibited in the hybrid model -collinear velocity spectra as the forced vortex flow emanated through a 5-mm radius cylindrical envelope co-axial with the hybrid and parabolic spectra as the flow proceeded beyond this transition envelope towards to its wall liberating the vortex. © 1999 Published by Elsevier Science Ltd. All rights reserved.