Streaming potential dependence on water-content in Fontainebleau sand

摘要: SUMMARY The electrokinetic potential results from the coupling between water flow and electrical current because of presence ions within water. The coefficient is well described in fluid-saturated media, however its behaviour under unsaturated conditions still discussed. We propose here an experimental approach to investigate streaming variations sand at conditions. present for first time continuous records as a function content. Two drainage experiments have been performed column filled with clean sand. Streaming measurements are combined pressure content every 10 cm along column. In order model hydrodymanics during experiments, we solve Richards equation coupled inverse problem estimate hydraulic parameters constitutive relations conductivity, C shows more complex than it was previously reported cannot be fitted by existing models. normalized increases when saturation decreases 100 about 65–80 per cent, then decreases, whereas all previous works monotone decrease decreases. delimited two domains, deduced different empirical laws describing evolution Moreover, introduce concept residual saturation, Sr,ekw, which allows us new derived relative permeability used hydrodynamics.