Experimental Investigation and Modelling of Sand Jets Passing through an Immiscible Layer

Abstract

Sand jets passing through two immiscible liquids, water and oil have many applications in the field of civil and environmental engineering such as tailings transport, dredging and discharge of industrial and urban wastewater. Understanding the dynamic interactions of the sand particles and its ambient are important for proper design and optimizing the engineering systems. Mass, momentum and energy of the system can be influenced by interactions of the suspended particles within the jet. The conducted experimental studies and numerical and nominal modeling in this thesis are new in terms of the fundamental understanding of jet characteristics. Part of this thesis focused on the experimental parameters and characteristics of oily sand jets such as frontal width and velocity. Effects of the controlling parameters of the oily sand jets such as nozzle diameter, oil layer thickness and mass were investigated and it was found that the effect of nozzle diameter on evolution of oily sand jets was more significant than the other parameters. Study in water phase, it was observed that the bursting of a group of particles covered with a thin oil layer can be classified into three different forms. Evolution of trailing waves of the oily sand jets and their characteristics such as wave length and wave amplitude were also investigated. Part of this thesis focused on Data mining and boundary visualization techniques to study the effects of experimental parameters on the shapes of oily sand jets. Model trees were developed to classify and predict the growth of oily sand jets at different conditions. It was found that the model tree can predict the growth of sand jets with an uncertainty of ±8.2%, ±6.8% and ±8.7% for width, velocity and distance from the nozzle, respectively. The main aim of this thesis is to explore and find correlations between the dynamics of sand particles through passing oil-water interface and controlling parameters such as nozzle diameter, oil layer thickness and mass of sand particles. Therefore, it was found that the nozzle size has significant effect on characteristics of evolution of oily sand jets such as frontal velocity, development of bursting, formation of trailing wave section and shear stress in comparison with other controlling parameters such as oil layer thickness and mass of sand particles. Investigation of formation of frontal shapes of oily sand jets in water indicates the fate of sand jets after passing an immiscible interface and sedimentation of sand particles. The main controlling parameter for evolution of various shapes of oily sand jets front is the nozzle diameter. Mass of sand particles and oil layer thickness are the secondary and tertiary important parameters. Evolution of different frontal shapes of oily sand jets can also change specific characteristics of oily sand jets such as frontal velocity and width. In terms of environmental analysing formation of various shapes of oily sand jets can explain variations of velocity of sediments and under which conditions these sediments spread or deposit without dispersion in oceans.