Azaiez, JalelDastvareh, Behnam2019-04-082019-04-082019-04-08Dastvareh, B. (2019). Instabilities of nanofluid flow displacements in porous media (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.http://hdl.handle.net/1880/110149The interface of two approaching fluids in porous media becomes unstable at strong enough flow rates when the viscosity of the displacing fluid is less than that of the displaced one. This phenomenon is studied to address the effect of nanoparticles (NPs) dispersed in the displacing fluid assumed fully miscible with the displaced one. The problem is first studied under isothermal conditions. The effects of the NP-induced additional properties such as the viscosity of the nanofluid, the Brownian diffusivity and the NP deposition are addressed on both the flow instability and the flow configuration. It was found that NPs attenuate the instability of an initially unstable flow, but this effect is mitigated in the presence of NP deposition. Moreover, the Brownian diffusivity was found to have a destabilizing effect, but it cannot make an initially stable system unstable. The study is then extended to include the thermal effects. This leads to the emergence of a new NP transport phenomenon known as thermophoresis in which NPs migrate in opposite direction of the temperature gradient. This effect is addressed in connection with other properties. Specifically, depending on whether a hot fluid is displacing a cold one or vice versa, the competition between the two transport mechanics, Brownian motion and thermophoresis, is found to lead to different trends in terms of the flow configuration and instability. Next, the catalytic roles of NPs on the flow and instability are investigated for approaching reactive fluids. The study is conducted under both isothermal and non-isothermal conditions resulting from the heat of the reaction. A new set of conditions is introduced to predict the instability of the isothermal case based on the species mobility ratios, which then leads to six different flow configurations. Finally, the coupled effects of the heat of reaction and thermophoresis on the flow configuration and the amount of chemical products are addressed.University 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.Flow InstabilityFlow in Porous MediaNanofluidsThermophoresisReactive FlowsViscous FingeringEngineering--ChemicalEngineering--EnvironmentalEngineering--Mechanicaldoctoral thesishttp://dx.doi.org/10.11575/PRISM/36347