Dynamic Nonequilibrium of Water Flow in Porous Media: A Review

摘要: This review provides an overview on various phenomena, hypothesized causes, and modeling approaches that describe “dynamic nonequilibrium” (DNE) of water flow in soils. Dynamic nonequilibrium is characterized from observations the macroscale by apparent flow-rate dependence hydraulic properties or local between content pressure head under monotonic imbibition drainage histories, i.e., not affected traditional hysteresis. The literature indicates key processes causing DNE are pore-scale phenomena such as relaxation air–water-interface distributions, limited air-phase permeability, dynamic contact angles, time-dependent wettability changes. Furthermore, entrapment pore blockage, air-entry effects, temperature effects might be involved. These act at different regions time scales, which makes effective combined challenging. On larger heterogeneity soil can contribute to observations. We conclude there urgent need for precision measurements designed quantify effects.