Particle-Scale Simulation of Polymer Fluid Permeation in Sand

Support fluids are widely used to provide temporary support to open excavations. Polymer support fluids have advantages over conventional bentonite slurries in many situations; they are cheaper and can have a lower environmental impact. This work employs direct numerical simulations to investigate the flow of a shear-thinning polymer support fluid whose rheology can be described by the Carreau model in an idealized granular material comprising spheres on a lattice packing. We show that particle radii can be calibrated to simulate a permeation behavior similar to that observed in physical permeability tests on sand specimens. The numerical results indicate that the seepage force induced by polymer flow is up to four orders of magnitude higher than that by water at a low seepage rate, providing a physical explanation of how polymer fluids support excavation in civil engineering.