Using high-resolution CFD to develop new technologies for underground construction

Support fluids are used to keep excavations open for underground construction. Polymer fluids (suspensions of polymer in water) have significant advantages over more conventional bentonite suspensions. Polymer fluids are non-Newtonian fluids and so the conventional modelling tools used in geotechnical engineering cannot be employed to predict their behaviour. This has hindered their use in UK ground engineering. We have used a multi-scale modelling approach to answer key questions posed about these fluids by the construction industry. To achieve this goal, we first employed a direct numerical simulation (DNS) to investigate the fluid-particle interaction forces in ordered granular materials. Then, A generalised Darcy’s law is formulated for non-Newtonian fluids, validated through pore network modelling (PNM), which can provide valuable insights for scaling up to the field-scale applications. To further investigate how viscoelasticity impacts the polymer conductance in sands, simulations using more advanced viscoelastic constitutive equations are conducted.