Critical Role of the Immobile Zone in Non-Fickian Two-Phase Transport: A New Paradigm
Journal: Environmental Science and Technology
Publication Date: 26 March, 2016
Department of: Chemical Engineering and Analytical Science
New insights into how solutions disperse in the natural world
An advanced micro-scale visualisation setup developed at The University of Manchester has provided valuable new insight into the complex problem of transporting solutes in multiphase fluid porous materials.
The findings suggest that at present, understanding of this problem is in its infancy and identified some major flaws in the models currently used for these conditions. An experiment was conducted using micromodels with varying rates of ink and water saturation. Processed images from the experiment showed pockets of water in the higher saturated models that did not appear to contribute significantly to the flow of transport and formed ‘dead-end’ clusters with virtually no adjective transport flux. Immobile areas in the model with low saturation are small compared to those with intermediate-to-high levels of saturation.
When it comes to the analysis of major applications – such as the transport of fertilisers in the vadose zone of soil, chemicals in oil reservoirs (for enhanced oil recovery) and the mixing of contaminants in tidal coastal aquifers – simple parameterisation of single-fluid phase conditions is currently used. However, the results of this research indicate that transport coefficients derived under single phase conditions underestimate the multiphase conditions by at least one order of magnitude.