Measurement and modeling of effective gasliquid interface in unsaturated soil.

点击翻译按钮获取中文摘要

The objectives of this study is to measure the gas-liquid interfacial area in unsaturated soil by gaseous tracers, to distinguish the interface formed on flowing gaseous phase and stagnant gaseous phase, and to construct a network model to simulate the relationship between gas-liquid displacement and change in interfacial area. We used heptane, which was reported to be good tracer for water-air interfacial area measurement. However, in turned out that, with heptane, we hardly are able to measure the interfacial area below 1×10^<-5>m^<-1>, the range we were interested in. Thus, at this moment we are yet to measure the precise gas-liquid interfacial area with gaseous tracers. Now we are improving the gas tracer method, for example we now investigating if addition of surfactant into the liquid enhance the tracer gas adsorption to the gas-liquid interfacial area. For distinguishing the flowing and stagnant part of gaseous phase, we proposed a method to measure the volume of flowing and stagnant gaseous phase, by analyzing the response curve. As for the modeling, we constructed a network model, based on capillary force and incorporating gaseous entapment in a water-wet medium, and simulated the change in interfacial area and compared the results with reported gas-liquid interfacial area measured by liquid tracer methods. The model results agree with the reported experimental ones in drainage processes.