INVESTIGATION OF MULTI-PHASE FLOW PHENOMENA USING TRANSPARENT SOIL

Multi-phase flow in general is affected by the quantity of the respective fluids present (normally water and air). Numerous multi-phase flow studies including numerical, field-scale as well as laboratory investigations are found in the literature. Numerical simulations may be performed based on Green-Ampt, Richard’s equation, network models, statistical methods and others. Generating laboratory or field data that can be used to calibrate and validate these models (network models in particular) can be a difficult process as the quantity and quality of data is limited by the apparatus, measurement devices or the type of porous media employed. To overcome these limitations the authors have developed a transparent soil that allows tracking of multi-phase fluid movement throughout the experimental profile. The soil is composed of a fused quartz and a mineral oil mixture with matched reflective indices. At 100% fluid saturation the soil is transparent and at 100% air saturation the soil is white. The transparent soil is tested in an apparatus constructed of acrylic and placed in front of a black background. This creates a sharp contrast in color intensity between saturated (black) and dry (white) conditions. Between the two saturation extremes the color intensity of the soil varies with degree of saturation. A relationship has been developed which converts digital pixel intensity to degree of saturation. Digital images are taken of experiments and the images are analyzed to provide degree of saturation data throughout the experimental profile at 1 mm resolution. In this presentation the development of the relationship between digital pixel intensity and degree of saturation is presented. Also the benefits and limitations of employing transparent soil to investigate multi-phase flow behavior are presented. Preliminary results show accurate tracking of the wetting and drying front as well as the degree of saturation within the transmission zone is able to be measured using the transparent soil. Use of transparent soil could allow the effect of air compression and air counterflow through the advancing wetting front to be tracked. Unsaturated transparent soil shows great promise to allow new insights into multi-phase flow phenomenon.