Head Requirement for Incipient Fluidization of Fine Sands in Unbounded Domains

Abstract

Fluidization systems in the coastal environment can be used to maintain channels and aid in sand bypassing. Induced flow from small holes in a buried source pipe will fluidize the overlying sand for a sufficiently high flow rate. One important design parameter is the required hydraulic head at the incipient fluidization condition to overcome the porous media head loss. The three-dimensional governing equation for head was solved with the finite-difference method using the theoretical critical hydraulic gradient at the incipient fluidization condition. After comparison to two-dimensional solutions and experimental results, the incipient-condition head-loss requirement was simulated for field geometries. The results indicate that 3-D effects are dissipated within 3 cm from the holes, where about 80% of the head loss occurs. The head requirement is higher for the 3-D simulations compared to 2-D due to the rapid decrease of head near a hole.