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Sand jet in non-Newtonian viscoplastic fluid is associated with a number of industrial and engineering applications, including sand capping for the reclamation of oilsands tailings ponds and sediment deposition into soft mud. In this study, several experiments were carried out by depositing circular sand jets vertically into viscoplastic fluids, known as Laponite gel. The deformation regimes of sand jets in the gel were investigated. The yield-gravity parameter of the deformed sand drop in the gel was computed. c ⃝

Withdrawal of water-capped viscoplastic fluid was investigated using laboratory experimentation and numerical modeling. The viscoplastic fluid was modeled using a Laponite suspension, which was withdrawn by a vertical pipe intake. Variations of the Laponite–water interface and intake configurations were investigated in this study. The critical submergence, the depth of the intake in the Laponite layer when the upper water begins to withdraw, was studied under different experimental conditions, and the critical depths were measured for different flow rates. An empirical relationship was found between the withdrawal flow rate and the critical submergence. The averaged Laponite velocity was measured at different withdrawal stages to identify the critical stage. A series of numerical simulations were conducted to study the effect of intake structures so that a maximum amount of the Laponite suspension can be withdrawn before the water layer being withdrawn. It was found that a combination of a collar and a cone with an edge length to the intake diameter of 1.5 can increase the pumping duration by 16.7%. The installation of a collar or collar-cone setup can also decrease the disturbance in Laponite layer.

Experimental and numerical studies were performed to investigate the pumping withdrawal of a Bingham plastic fluid using a vertical circular pipe. A Laponite suspension with 3% mass concentration was used for the experimental study. Results are compared with the theoretical solution of a point sink. A virtual point sink can be identified to exist below the intake along its centerline. With the assumption of an axisymmetric flow condition, radial velocity is found to be the same within a conical zone, but varies with the axial angle outside this zone in spherical polar coordinates. It was found that the flow viscosity and yield stress do not change the location of the virtual sink but they reduce the horizontal velocity of the Laponite suspension. The extent of the sheared flow region was also studied and the deformation radius was found to be proportional to the 1 / 3 power of the pumping rate.

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