Effects on oily sand jet evolution from impact momentum and channelization of particles through an immiscible interface

Abstract

The evolution of sand jets passing through an immiscible layer and entering water was experimentally investigated to understand the effects of controlling parameters on the formation of particle clusters. In order to increase the impact momentum, sand particles were released from different heights from the surface of the immiscible interface. The channelization of particles through the immiscible layer was found to be correlated with the ratio of the nozzle diameter to the diameter of sand particles. For relatively large nozzle diameters, dry particles directly impinged into the ambient water with minimum contact with the immiscible layer. The channelization of particles significantly reduced the particle momentum transfer and the energy dissipation within the immiscible layer. It was found that the channelization effect begins when the nozzle diameter is approximately forty times larger than the mean particle diameter. The dynamic characteristics of oily sand jets – penetration length, width, and frontal velocity – were measured and results were analyzed in both time and space frames. It was observed that the space domain is suitable for regime classification while the time domain is suitable for developing semi-empirical correlations. A non-dimensional time instance t* was defined for flow visualization and to study the transitional effects of the jets’ evolution where at t*=1 all particles enter into the ambient. The average shear stress in the immiscible layer and in the early stages of evolution (t*<1) was calculated from the measurements: the normalised shear stress between sand particles and the immiscible layer was found to linearly increase with the impact momentum. The average drag coefficient of sand jet front was calculated and results were compared with the classical drag models. The average drag coefficient of oily sand jets was found to be smaller than the drag coefficient of individual sand particles in a steady-state condition.