Experimental and Numerical Investigations on Withdrawal of Water-Capped Viscoplastic Fluid

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 The viscoplastic fluid was modeled using a Laponite suspension, which was withdrawn by a vertical pipe intake.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were conducted to study the effect of intake structures so that a maximum amount of the Laponite suspension can be withdrawn before the water layer being withdrawn.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.