Gates, Ian DonaldLee, Young Hoon2024-03-192024-03-192024-03-15Lee, Y. H. (2024). Viscous fingering instability of complex fluids in a radial Hele-Shaw cell (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/118301https://doi.org/10.11575/PRISM/43144When a less-viscous fluid displaces another fluid of higher viscosity in a porous medium, instability can develop at the interface between the two fluids. The instability manifests itself in the form of finger-like patterns of the displacing fluid propagating through the displaced one. In this work, viscous fingering instabilities involving complex fluids in a radial Hele-Shaw is investigated. Many fluids in our lives such as shaving foams, glues, flour-water dough, mayonnaise, and paints are complex fluids which exhibit multiple non-Newtonian properties simultaneously such as shear-thinning or shear-thickening, yield stress, and viscoelastic effects. First, the effects of normal stress differences of dilute low molecular weight poly(ethylene oxide) (PEO) solutions on viscous fingering instability are studied. Second, we investigate the instabilities associated with air invading foam in Hele-Shaw cell. Third, we examine the effects of water in viscous fingering instabilities of air displacing mineral oil. Fourth, the instability at the interface between two parallel flows of immiscible liquids through a uniform planar pore is studied by using linear stability analysis. We pose important questions: How does normal stresses affect immiscible radial viscous fingering? How does fingering occur into foam? Is it similar to that of a single-phase liquid? The experimental observations reveal nonmonotonic and opposing effects are evident depending on the molecular weight of the PEO and the stage of the radial viscous fingering evolution. We have identified three different flow regimes in the immiscible radial displacement flows of air invading foam in Hele-Shaw cell. The presence of a small volume of water leads to significantly different fingering patterns than that when no water is present. The outcomes are significant because the results demonstrate new behaviors for displacement flow of complex fluids.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.viscous fingeringelastic instability interfacial instabilityHele-Shawpoly(ethylene oxide) solutionelastic fluidsfoam displacementfoam flowair injectionthree phase displacementmineral oilinstabilitystability analysisoil sandssteam-assisted gravity drainagemultiphase flowEngineering--Chemicaldoctoral thesis