Insight into Hysteresis of Soil Water Retention from Pore-Scale CFD Analyses

Abstract Predicting the degree of saturation in soil is important to evaluate and improve the resilience of geotechnical structures including embankments. This study focuses on the hysteresis in soil water retention curves (WRCs) caused by the ink-bottle effect. The hysteretic WRCs of a tube-bulb system were simulated with computational fluid dynamics (CFD) and the ink-bottle effect mechanisms were captured. To simulate the WRCs of granular materials, numerical models of face-centered-cubic packing of spheres with tetrahedron and hexahedron meshes were developed. The simulation results showed that the fluid surface was more accurately captured when a hexahedral mesh was used and that the accuracy of the two models was comparable in steady-state saturated flow analysis.