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Item Magnetic resonance imaging studies of forced and free convective heat transfer in packed beds and fluid columns(Montana State University - Bozeman, College of Engineering, 2021) Skuntz, Matthew Eric; Chairperson, Graduate Committee: Ryan Anderson; This is a manuscript style paper that includes co-authored chapters.Prediction of fluid flow and associated energy transport is an essential component in many engineering applications where analytical solutions are not possible. In these systems experimentation and numerical simulations are a necessary part of the design process. This work focuses on the experimental study of mass and energy transport in packed beds and pure fluids under forced and natural convection using nuclear magnetic resonance (NMR) imaging (MRI) techniques. It further evaluates the efficacy of commercial computational fluid dynamics (CFD) software to simulate these processes. The study of heat transfer via NMR has proven difficult historically, despite sensitivity of NMR parameters to temperature. Here, a novel experimental setup is pioneered, which enables the study of heat transfer in packed beds. The method employs fluorinated pore-filling fluid and hydrogen-rich core-shell packing particles. Hydrogen and fluorine are NMR-active chemicals that can be imaged with the same experimental equipment by adjusting the resonance frequency; providing means to image the two domains separately. Pore- fluid velocities and particle-wax melting are observed in the same packed bed, at sub-millimeter resolutions, presenting a more complete picture of the conditions in these hard-to-measure systems. In the presented studies, this methodology is demonstrated under forced convection and proven capable in identifying and correlating spatial variations in heat transfer to pore-fluid velocity. The technique is then employed to assess the accuracy of a CFD model in the commercial software package, STAR CCM+, using the melt to quantify energy absorbed by the bed. In natural convection studies of a pure fluid and packed bed in the Rayleigh-Bénard configuration, the axial circulation pattern is found to change with axial position in the long narrow cylinder, a result that is rarely discussed in literature. A CFD model is shown to match well with these experimental findings. In porous media convection with sub-, near- and super- critical fluid, the rapidly changing thermal diffusivity was captured by the rate the particles absorb energy. Finally, a correlation is developed allowing particle-wax T 2 relaxation time to be converted into temperature.Item Transient and steady state Rheo-NMR of shear banding wormlike micelles(Montana State University - Bozeman, College of Engineering, 2020) Al Kaby (Al Qayem), Rehab Noor; Chairperson, Graduate Committee: Sarah L. Codd and Jennifer Brown (co-chair); Jayesha S. Jayaratne, Timothy I. Brox, Sarah L. Codd, Joseph D. Seymour and Jennifer R. Brown were co-authors of the article, 'Rheo-NMR of transient and steady state shear banding under shear stratup' in the journal 'Journal of rheology' which is contained within this dissertation.; Sarah L. Codd, Joseph D. Seymour and Jennifer R. Brown were co-authors of the article, 'Characterization of velocity fluctuations and the transition from transient to steady state shear banding with and without pre-shear in a wormlike micelle solution under shear startup by Rheo-NMR' submitted to the journal 'Journal of applied rheology' which is contained within this dissertation.Over many years, the combination of nuclear magnetic resonance (NMR) techniques with rheometry, referred to as Rheo-NMR has been used to study materials under shear noninvasively. Rheo-NMR methods can provide valuable information on the rheological responses of materials or their behavior by temporally and spatially resolved mapping of the flow field. In this thesis, 1D velocity profiles across the fluid gap of a Couette shear cell are recorded using Rheo-NMR velocimetry to investigate the wormlike micelles (WLMs) surfactant system under transient and steady state flow conditions. The WLM system was a solution of 6 wt. % cetylpyridinium chloride (CPCl) and sodium salicylate (NaSal) in 0.5 M NaCl brine which is well-known for its ability to exhibit a mechanical response during flow known as shear banding. The shear banding phenomena is simply defined as the splitting of the flow into two macroscopic layers, a high and low shear band bearing different viscosities and local shear rates. Elastic instabilities are well known to develop in the unstable high shear band and manifest as fluctuations in the 1D measurements. Recently, it has been suggested that 1D velocimetry alone cannot reveal information about those observed fluctuations in terms of a sequence of elastic instabilities and 2D or 3D measurements are required. In this thesis, new Rheo-NMR equipment and quantitative analysis are used to characterize those fluctuations and show that 1D velocity measurements still have the potential to provide valuable information about 3D flows. Transient and steady state shear banding was observed for a range of shear rates across the stress plateau and the impact of several flow protocols were studied. The evolution of the high, low, and true shear rates, as well as interface position with time after shear startup was used to evaluate changes in the kinetics of shear band formation as a function of applied shear rate and flow protocol. Ultimately, these results will help in understanding the correlation between the macroscopic flow field and the microscopic structure and dynamics of WLMs and can also be a way to gain information about the presence and the dynamic of secondary flow without the need of a 3D measurement.Item Thermal energy storage with sensible heat in an air-alumina packed bed using axial flow, axial flow with layers and radial flow(Montana State University - Bozeman, College of Engineering, 2020) Al-Azawii, Mohammad Mahdie Saleh; Chairperson, Graduate Committee: Ryan Anderson; Carter Theade, Megan Danczyk, Erick Johnson and Ryan Anderson were co-authors of the article, 'Experimental study on cyclic behavior of thermal energy storage in an air-alumina packed bed' published in the journal 'Journal of energy storage' which is contained within this dissertation.; Carter Theade, Pablo Bueno and Ryan Anderson were co-authors of the article, 'Experimental study of layered thermal energy storage in an air-alumina packed bed using axial pipe injections' in the journal 'Applied energy' which is contained within this dissertation.; Duncan Jacobsen, Pablo Bueno and Ryan Anderson were co-authors of the article, 'Experimental study of thermal behavior during charging in thermal energy storage packed bed using radial pipe' in the journal 'Applied thermal engineering' which is contained within this dissertation.Thermal behavior in a packed bed thermal energy storage (TES) system is studied experimentally. TES systems are a promising solution to integrate renewable energy sources such as solar energy. The performance of such systems can be affected by different variables such as storage material size/type, pressure, temperature, heat transfer fluid (HTF), storage type (sensible/latent heat), and flow rate. Although these variables have been studied in literature, the resulting thermal dispersion and heat losses to the environment have been considered in few studies. This thesis studies the thermal behavior of an air-alumina TES packed bed focusing on dispersion and heat losses to quantify the thermal performance. Reducing their effects can improve the thermocline and thus thermal efficiency. The research efforts in this work quantify these effects and provide two new methods to reduce thermal dispersion and increase exergetic efficiency. Three configurations were considered in the present study. In the first configuration, a traditional packed bed is used focusing on performance for multiple partial cycles. This configuration quantified the thermal performance and served as a basis to compare the results from the other configurations. Dispersion effects were found to accumulate before a steady state was achieved during cycling. In the second and third configurations, novel pipe injection techniques were used to charge/discharge the bed. First, the normal bed is divided into layers via inserting pipes along the bed's axial length, focusing on a full charge-discharge cycle. Results show that exergy efficiency increases with flow rate and number of layers. The thermocline improved and dispersion losses decreased with number of layers. Second, a perforated pipe to facilitate radial flow was inserted at the center of the bed along the axial length to heat the bed. Radial charging shows higher charging efficiency compared to normal axial charging. Pipe injection is a novel method and a promising technique that improves the thermal performance of a lab scale storage bed, especially the layering method. Radial injection warrants more investigation to quantify its performance in thermal cycles.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.Item Extraction of droplet genealogies from high-fidelity atomization simulations(Montana State University - Bozeman, College of Engineering, 2019) Rubel, Roland Francis Clark, IV; Chairperson, Graduate Committee: Mark OwkesMany research groups are performing high-fidelity simulations of atomizing jets that are taking advantage of the continually increasing computational resources and advances in numerical methods. These high-fidelity simulations produce extremely large data-sets characterizing the flow and giving the ability to gather a better understanding of atomization. One of the main challenges with these data sets is their large size, which requires developing tools to extract relevant physics from them. The main goal of this project is to create a physics extraction technique to compute the genealogy of atomization. This information will characterize the process of the coherent liquid core breaking into droplets and ligaments which may proceed to break up further. This event information will be combined with detailed information such as droplet size, shape, flow field characteristics, etc. The extracted information will be stored in a database, allowing the information to be readily and quickly queried to assist in the development and testing of low-fidelity atomization models that agree with the physics predicted by high-fidelity simulations.Item The interstitial fluid pressure response during stress-relaxation of articular cartilage due to viscosity and porous media effects: a computational study(Montana State University - Bozeman, College of Engineering, 2018) Paschke, Brandon James; Chairperson, Graduate Committee: Erick JohnsonArticular cartilage is a complex material made of several fluid and solid components. A model that fully describes the responses of cartilage is required to accurately create a cartilage replacement that can be used in cases of injury or disease. Modeling of articular cartilage has proven difficult and currently no constitutive law fully describes its solid and fluid responses. Many of the current models describe the interstitial fluid as inviscid, even though it is known that proteoglycan migration within cartilage causes a viscous response within interstitial fluid. The goal of this research was to create a viscous fluid porous media model that better captures the compressive resistance of cartilage created by migration of interstitial fluid during cartilage compression. Through the creation of this model it was possible to capture the experimental magnitudes of fluid pressure within cartilage during unconfined slow compression simulations. As part of this model, a porous media approximation was used, which demonstrates that small variations in the solid matrix, comprised of collagen fibers, can cause large variations in system response. Magnitudes of mean pressure values, after 150 seconds of compression, for the viscous fluid porous media model bound the values found in experimental testing. Limitations of the fluid model are that system relaxation isn't captured and the slope increase of pressures during compression for experiments don't match those of the fluid model. A main conclusion drawn from the model is that viscosity of interstitial fluid plays a large role in creating compressive resistance within articular cartilage. Another takeaway is that the porous media approximation greatly impacts the magnitude of fluid pressurization, which creates a need to accurately represent the solid matrix within cartilage.Item Influence of orifice plate shape on condenser unit effectiveness(Montana State University - Bozeman, College of Engineering, 2018) Kuluris, Stephen Patrick; Chairperson, Graduate Committee: Erick JohnsonIn both residential and commercial buildings, heating, ventilation and air-conditioning (HVAC) is the largest consumer of energy. The HVAC industry works to consistently reduce their energy consumption in order to lower consumer costs and to stay competitive in the field. Therefore, improving fan efficiency of any component in an HVAC system is beneficial. A major part of the industry is to use the vapor-compression refrigeration cycle to cool buildings and an essential component of the cycle is the condenser unit. Axial fans are commonly used to move air through and cool the heated refrigerant coil. Improving axial fan performance by redesigning the casing that surrounds the fan, known as an orifice plate, is suspected to lead to a more productive condenser unit. Changing the geometry can increase performance by reducing turbulence generation both upstream and downstream of the fan, which is thought to be a major contributor to loss in fan fan efficiency. Manufacturing many different geometries in a design process to find an improved orifice plate is time-consuming and expensive. With advances in computer technologies, computational fluid dynamics (CFD) has become a low-cost alternative to iterative, physical prototyping. This work uses CFD in the design process of an orifice plate, to characterize and analyze the effects of different geometries. Fan fan efficiency and volume ow rate characterize the performance of the design, and turbulence, vorticity, and pressure visualization provides further information about the effects of design changes. The orifice geometry upstream and downstream of the fan were changed independently, and then both regions were combined into a single design. Results show that the flow upstream and downstream are affected in different ways, and contribute to overall fan efficiency through different mechanics. An improvement to the inlet region produced an fan efficiency increase of 4.8%, and the addition of an outlet region increases fan efficiency by 9.8%. The combined change in the orifice resulted in an overall increase in fan efficiency by 15.85% over the original design.Item Characterization of the primary instability on atomizing jets using dynamic mode decomposition(Montana State University - Bozeman, College of Engineering, 2018) Krolick, William Christopher; Chairperson, Graduate Committee: Mark OwkesNumerical methods have advanced to the point that many groups can perform detailed numerical simulations of atomizing liquid jets and replicate experimental measurements. However, the simulation results have not lead to a substantial advancement to our understanding of these flows due to the massive amount of data produced. In this work, a tool is developed to extract the physics that destabilize the jets liquid core by leveraging dynamic mode decomposition (DMD). DMD takes ideas from the Arnoldi method as well as the Koopman method to evaluate a non-linear system with a low-rank linear operator. The method reduces the order of the simulation results from all the original data through time to a few key pieces of information. Most important of these are the dynamic modes, their time dynamics, and the DMD spectra. In this case, DMD is applied to the jets liquid core outer radius, which is computed at streamwise and azimuthal locations, i.e., R(theta; x). With the DMD data, we obtain the dominant spatial and temporal modes of the system and their characteristics. The dominant modes provide a useful way to collapse the large data set produced by the simulation into a length and timescale that can be used to initiate reduced-order models and numerically categorize the instabilities on the jets liquid core.Item Evaluation of pitch control techniques for a cross-flow water turbine(Montana State University - Bozeman, College of Engineering, 2017) Gauthier, Timothy Andrew; Chairperson, Graduate Committee: Erick JohnsonCross-flow water turbines are complex devices that have yet to see large-scale implementation relative to conventional horizontal-axis wind turbines. While wind energy was the primary target of past investigations, water energy follows most of the same dynamic principles. However, water currents tend to be much more stable than their wind current counterparts, and many water currents exist in channels that favor the compact shape of the cross-flow turbine. These advantages have rejuvenated interest in cross-flow turbine design for marine energy generation. Computational models give engineers the ability to accurately estimate what designs work best to avoid costly field maintenance and downtime. Specifically, computational fluid dynamics uses the Navier-Stokes equations, a set of differential equations that describe the pressure and velocity fields in a fluid domain. The Reynold-Averaged Navier-Stokes turbulence model described in this work examines how controlling the pitch of water turbine blades can improve system performance and reliability. Pitch means that the blade noses up or down about the chord line which runs from leading edge to trailing edge relative to the inflow. Pitch control was originally developed for helicopter blades and is commonly used by conventional wind turbines, but pitch control for water turbines is a relatively new research area. Initial results suggest significant incremental gain in power output with pitch control up to 149%, as compared to a no-pitch case, based on a to-scale representation of the cross-flow water turbine in the Fluids and Computations Laboratory at Montana State University. Simultaneous reliability gain is observed as the force transmitted by the water to the blades is reduced by 135%; this may allow for lower cost turbine structures and streamlined hydrofoil design. Additionally, turbine wake profile visualization and blade pressure coefficient curves describe the viscous interaction both quantitatively and qualitatively. Cross-flow water turbines have the potential to become a significant worldwide energy source, with performance optimization studies such as these a necessary prerequisite.