Effects of immiscible interface and particle channelization on particle dynamics of oblique oily sand jets

Abstract

This paper investigates the evolution of oblique sand jets passing through a thin layer of oil and entering stagnant water known as oily sand jets. The jet evolution parameters include the frontal position, the trajectory of particle clusters, the frontal width, the area of oily sand clusters, cloud velocities, and bursting times. Two scaling parameters, known as aspect ratio and particle to nozzle size ratio, were found to control the evolution of oily sand jets. The results show that the ratio of a nozzle to sand particle size can cause particle channelization, which can significantly alter the motion of particle clusters in stagnant water. Moreover, the aspect ratio indicating the correlation between sand mass and nozzle diameter describes the dispersion of particle clusters during the evolution of oily sand jets. The frontal width of the oily sand jet was measured during the experiment, and the results were compared with the width of vertical sand jets in water. The results show that the width of the oblique oily sand jets increased as oily sand jets descended into water. In addition, the frontal width of oily sand jets was found to be greater than the frontal width of vertical sand jets without an oil layer. Experimental observations indicated that the channelization effect is initiated when the nozzle diameter is more than 36 times of mean particle size. The centroid of oily sand jets in the vertical direction increased by 50% due to the channelization effect. A two-stage cluster bursting was observed due to the excess shear stress between the outer boundary of clusters and the ambient water. The bursting stages were called the primary and secondary bursting, and the onset of cluster bursting was extracted for both stages. It was found that the primary and secondary bursting times were longer in experiments without particle channelization. The mean shear stress acting on the oil layer was calculated based on the forces acting on the control volume. Particle channelization was found as the main factor affecting the magnitude of shear stress at the boundary of sand clusters.