Theses and Dissertations at Montana State University (MSU)
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Item Experimental characterization of pore-scale capillary pressure and corner film flow in 2D porous micromodels(Montana State University - Bozeman, College of Engineering, 2023) Molla, Razin Sazzad; Chairperson, Graduate Committee: Yaofa LiMultiphase flow in porous media is ubiquitous in natural and engineering processes. A better understanding of the underlying pore-scale physics is crucial to effectively guiding, predicting and improving these applications. Traditional models describe multiphase flows in porous media based on empirical constitutive relations (e.g., capillary pressure vs. saturation), which, however, are known to be hysteretic. It has been theoretically shown that the hysteresis can be mitigated by adding new variables in the functional form. However, experiments are still needed to validate and further develop the theories. In particular, our understanding of capillary pressure characterization and numerous pore-scale mechanisms is still limited. For instance, during capillary pressure measurement, fluid phases become disconnected, making the bulk pressure an inaccurate measure for the actual capillary pressure. In a strongly wetting medium, wetting phase always remains connected by corner films, through which trapped water continues to drain until a capillary equilibrium is reached, but the effects of corner film flow are minimally characterized. In this thesis, two different experiments are presented. In the first experiment, we focused on the capillary pressure characterization and the effect of measurement resolution. Microscopic capillary pressure along with other geometric measures are characterized during drainage and imbibition. By strategically varying the pressure at the boundary, different equilibrium states were achieved and imaged at four different magnifications (i.e., 2, 1.25, 0.5, 0.25 micron/pixel). In the second experiment, we for the first time characterized the corner film flow again during drainage and imbibition condition employing particle image velocimetry. Overall, our results suggest that the calculated macroscale pressure P c and the bulk pressure drop agree reasonably well when only interfaces associated with the connected phases are considered. A spatial resolution of 2 micron/pixel seems to sufficiently resolve the interface, and further increasing the resolution does not have a significant impact on the results. Additionally, corner film flow was found to be an active transport mechanism. During drainage, trapped water is continuously drained over time via thin film, whereas during imbibition snap-off events are enhanced by wetting films. These observations call for future studies to carefully treat corner film flows when developing new predictive models.Item Effects of tax credits on carbon capture and sequestration in a multi-phased model(Montana State University - Bozeman, College of Engineering, 2021) Strahan, Cooper Davis; Chairperson, Graduate Committee: Sean YawStudies have consistently shown that the increase of CO 2 in the atmosphere is correlated to rising temperatures. In order to stop the rise in global temperatures, climate change mitigation strategies will need to be deployed at scale. All of the plans that meet the goal of staying below 2 °C include CO 2 capture and storage (CCS) as one of those strategies. CCS is a climate change mitigation strategy aimed at reducing the amount of CO 2 vented into the atmosphere by capturing CO 2 emissions from industrial sources, transporting the CO 2 via a dedicated pipeline network, and injecting it into geologic reservoirs. Designing CCS infrastructure is a complex problem requiring concurrent optimization of source selection, reservoir selection, and pipeline routing decisions. Current CCS infrastructure design methods assume that project parameters including costs, capacities, and availability, remain constant throughout the project's lifespan. In this research, we introduce a novel, multi-phased, CCS infrastructure design model that allows for analysis of more complex scenarios that allow for variations in project parameters across distinct phases. We also apply this new model to a study exploring the impacts of modifying CCS tax credits on the economic viability of CCS projects.Item Design and fabrication of membrane-based pressure sensor for capillary pressure measurement in micromodels(Montana State University - Bozeman, College of Engineering, 2021) Raventhiran, Nishagar; Chairperson, Graduate Committee: Yaofa LiPressure is a fundamental quantity in virtually all problems in fluid dynamics from macro-scale to micro/nano scale flows. Although technologies are well developed for its measurement at the macro-scale, pressure quantification at the microscale is still not trivial. Yet, precise pressure mapping at microscale such as in microfluidics is imperative in a variety of applications, including porous media flows and biomedical engineering. In particular, pore-scale capillary pressure is a defining variable in multiphase flow in porous media and has rarely been directly measured. To that end, this study aims to design and fabricate an on-chip sensor that enables quantification of capillary pressure in microfluidic porous media, called micromodels. The micromodel is fabricated in polydimethylsiloxane (PDMS) using soft lithography with a thin membrane incorporated that deflects with pressure variations in the fluid flow. Employing a microscope coupled with a high-speed camera and the astigmatism particle tracking principle, precise pressure measurement is achieved with an accuracy of ~ 60Pa. This sensor is then applied to characterize the viscous pressure drop in single phase flows, and the capillary pressure in a water-air multiphase in microchannels, and good agreement is obtained between the sensor measurement, theoretical values and measurements employing a commercial pressure transducer. This thesis provides a novel method for in-situ quantification of local pressure and potentially 2D pressure field in microfluidics and thus opens the door to a renewed understanding of pore-scale physics of multiphase flow in porous media.Item Intrusive uncertainty quantification method for simulations of gas-liquid multiphase flows(Montana State University - Bozeman, College of Engineering, 2020) Turnquist, Brian Robert; Chairperson, Graduate Committee: Mark Owkes; Mark Owkes was a co-author of the article, 'MULTIUQ: an intrusive uncertainty quantification tool for gas-liquid multiphase flows' in the journal 'Journal of computational physics' which is contained within this dissertation.; Mark Owkes was a co-author of the article, 'A fast, density decoupled pressure solver for an intrusive stochastic multiphase flow solver' submitted to the journal 'Journal of computational physics' which is contained within this dissertation.; Mark Owkes was a co-author of the article, 'MULTIUQ: a software package for uncertainty quantification of multiphase flows' submitted to the journal 'Computer physics communications' which is contained within this dissertation.; Mark Owkes was a co-author of the article, 'Exploration of basis functions for projecting a stochastic level set in a multiphase flow solver' submitted to the journal 'Atomization and sprays' which is contained within this dissertation.Simulations of fluid dynamics play an increasingly important role in the development of new technology. For example, engineers may need to simulate an atomizing jet to create a better direct injection system for improving fuel economy in a vehicle, or to more efficiently spray water for building fire mitigation systems. The increased use of computational fluid dynamics requires improvements in methodology to improve simulation efficiency and accuracy. We can extract a great deal from these models, including uncertainty information. Although simulation of gas-liquid multiphase flow scenarios are common, most are deterministic in nature. Model parameters, like fluid density or viscosity, are assumed to be known and fixed. But this is not usually the case, and a research gap exists for uncertainty analysis in these simulations. For efficient performance, an intrusive approach is used to create a multiphase solver capable of uncertainty analysis. Variables of interest, such as velocity and pressure, are converted into stochastic variables which are allowed to vary in an added uncertainty dimension. Variability is then added to fluid parameters or initial/boundary conditions and a simulation is run which produces stochastic results. To verify the solver, several cases are presented which compare the ability of the solver against analytic solutions. Once satisfied with the ability of the solver, we can answer questions about more complex scenarios. For instance, we may question how uncertainty about the surface tension force may affect the atomization of a jet and find that fluids with a lower surface tension coefficient breakup sooner (as expected). We could also consider scenarios that may not have such an obvious outcome, such as imposing uncertainty about the density ratio for an atomizing jet to determine the effect of running simulations at low vs high density ratios. multiUQ is capable of producing accurate results of real world situations. As a tool it can provide additional insight into understanding complicated multiphase flow systems.Item Accurate conservative simulations of multiphase flows applying the height function method to Rudman dual grids(Montana State University - Bozeman, College of Engineering, 2019) Olshefski, Kristopher Thomas; Chairperson, Graduate Committee: Mark OwkesGas-liquid flows can be significantly influenced by the surface tension force, which controls the shape of the interface. The surface tension force is directly proportional to the interface curvature and an accurate calculation of curvature is essential for predictive simulations of these flow types. Furthermore, methods that consistently and conservatively transport momentum, which is discontinuous at the gas-liquid interface, are necessary for robust and accurate simulations. Using a Rudman dual mesh, which discretizes density on a twice as fine mesh, provides consistent and conservative discretization of mass and momentum. The height function method is a common technique to compute an accurate curvature as it is straightforward to implement and provides a second-order calculation. When a dual grid is used, the standard height function method fails to capture fine grid interface perturbations and these perturbations can grow. When these growing perturbations are left uncorrected, they can result in nonphysical dynamics and eventual simulation failure. This work extends the standard height function method to include information from the Rudman dual mesh. The proposed method leverages a fine-grid height function method to compute the fine-gird interface perturbations and uses a fine-grid velocity field to oppose the fine-grid perturbations. This approach maintains consistent mass and momentum transport while also providing accurate interface transport that avoids non-physical dynamics. The method is tested using an oscillating droplet test case and compared to a standard height function. Various iterations of the fine grid method are presented and strengths and shortcomings of each are discussed.