Liquid imbibition in porous media investigated by pore network models and pore-scale experiments

Imbibition is a process in which a wetting liquid is drawn into a porous medium by capillary action. This process is widely encountered in various engineering applications, such as paper coating. Undesired imbibition rate or liquid phase distribution are the two major problems in reality, and a profound study is required to understand the fundamental reasons of these problems, to analyze them and eventually to prevent them. One way to study the imbibition process is to use the pore network modeling approach, which is known to be an effective tool to investigate the pore-scale transport phenomena in porous media. In this thesis, a general pore network model that accounts for liquid properties as well as solid structural properties is developed. This model considers the capillarity, viscous drag and gravity as main mechanisms controlling the liquid flow. Three discrete events of liquid transport, i. e. invasion, retraction and breakage, are introduced based on the experimental observations to create new menisci.