Relevant bibliographies by topics / Fluid mechanics and thermal engineering not elsewhere classified

Academic literature on the topic 'Fluid mechanics and thermal engineering not elsewhere classified'

Author: Grafiati
Published: 10 December 2022
Last updated: 3 July 2024

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Journal articles on the topic "Fluid mechanics and thermal engineering not elsewhere classified"

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Tanasawa, Ichiro. "Recent Progress of Japanese Research on Condensation Heat Transfer." Applied Mechanics Reviews 43, no. 1 (January 1, 1990): 1–11. http://dx.doi.org/10.1115/1.3119158.

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A state-of-the-art review is presented on the research activities in Japan on condensation heat transfer during these nine years. The papers published on the Trans. JSME (Series B for thermal and fluids engineering) from 1980 until 1988 are chosen as the main target of the review, since it is considered that the majority of principal achievements in condensation research in Japan are contained in these volumes. The papers printed elsewhere on other publications or prior to 1980 are referred to only whenever it is needed. The author classifies the subjects into five items. They are (1) Film condensation of single-component vapor, (2) Film condensation of multi-component vapor, (3) Enhancement of condensation heat transfer, (4) Dropwise condensation, and (5) Direct contact condensation and other forms of condensation. However, the author’s effort is focussed mostly on the item (3) on the techniques of enhancement of condensation heat transfer. Dropwise condensation is another subject that is discussed in some detail. Only the outlines are presented for the remaining items. In the concluding remarks of this article the author’s personal comments on the future trends of the condensation research is presented.
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Bisio, G. "Exergy Analysis of Thermal Energy Storage With Specific Remarks on the Variation of the Environmental Temperature." Journal of Solar Energy Engineering 118, no. 2 (May 1, 1996): 81–88. http://dx.doi.org/10.1115/1.2848020.

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Energy storage is a key technology for many purposes and in particular for air conditioning plants and a successful exploitation of solar energy. Thermal storage devices are usually classified as either variable temperature (“sensible heat”) or constant temperature (“latent heat”) devices. For both models a basic question is to determine the efficiency suitably: Only exergy efficiency appears a proper way. The aim of this paper is to examine exergy efficiency in both variable and constant temperature systems. From a general statement of exergy efficiency by the present author, two types of actual definitions are proposed, depending on the fact that the exergy of the fluid leaving the thermal storage during the charge phase can be either totally lost or utilized elsewhere. In addition, specific remarks are made about the exergy of a system in a periodically varying temperature environment.
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Yan, Jun, Yin Qi Wei, and Hong Cai. "A Mathematical Thermal Hydraulic-Mechanical Coupling Model for Unsaturated Porous Media." Applied Mechanics and Materials 602-605 (August 2014): 365–69. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.365.

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s: Temperature, seepage and deformation are the important parts of the engineering geological mechanics both in water conservancy and hydropower engineering since there are highly nonlinear complex coupling effect between each other. In this paper, the earth and rock mass are classified as continuous porous media. The thermal constitutive relation of porous media and motion regularity of pore fluid are deduced from the basic theory of solid mechanics, hydraulics, and thermodynamics. Based on momentum, mass and energy conservation equations, the multi-field controlling equations of unsaturated porous media are given, in which the unknown variables include displacements, pore liquid pressure, pore gas pressure, temperature, and porosity.
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Al Shdaifat, Mohammad Yacoub, Rozli Zulkifli, Kamaruzzaman Sopian, and Abeer Adel Salih. "Thermal and Hydraulic Performance of CuO/Water Nanofluids: A Review." Micromachines 11, no. 4 (April 14, 2020): 416. http://dx.doi.org/10.3390/mi11040416.

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This paper discusses the behaviour of different thermophysical properties of CuO water-based nanofluids, including the thermal and hydraulic performance and pumping power. Different experimental and theoretical studies that investigated each property of CuO/water in terms of thermal and fluid mechanics are reviewed. Classical theories cannot describe the thermal conductivity and viscosity. The concentration, material, and size of nanoparticles have important roles in the heat transfer coefficient of CuO/water nanofluids. Thermal conductivity increases with large particle size, whereas viscosity increases with small particle size. The Nusselt number depends on the flow rate and volume fraction of nanoparticles. The causes for these behaviour are discussed. The magnitude of heat transfer rate is influenced by the use of CuO/water nanofluids. The use of CuO/water nanofluids has many issues and challenges that need to be classified through additional studies.
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Cabezas-Gómez, Luben, Hélio Aparecido Navarro, and José Maria Saiz-Jabardo. "Thermal Performance of Multipass Parallel and Counter-Cross-Flow Heat Exchangers." Journal of Heat Transfer 129, no. 3 (June 14, 2006): 282–90. http://dx.doi.org/10.1115/1.2430719.

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A thorough study of the thermal performance of multipass parallel cross-flow and counter-cross-flow heat exchangers has been carried out by applying a new numerical procedure. According to this procedure, the heat exchanger is discretized into small elements following the tube-side fluid circuits. Each element is itself a one-pass mixed-unmixed cross-flow heat exchanger. Simulated results have been validated through comparisons to results from analytical solutions for one- to four-pass, parallel cross-flow and counter-cross-flow arrangements. Very accurate results have been obtained over wide ranges of NTU (number of transfer units) and C* (heat capacity rate ratio) values. New effectiveness data for the aforementioned configurations and a higher number of tube passes is presented along with data for a complex flow configuration proposed elsewhere. The proposed procedure constitutes a useful research tool both for theoretical and experimental studies of cross-flow heat exchangers thermal performance.
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Wei, Aibo, Lianyan Yu, Limin Qiu, and Xiaobin Zhang. "Cavitation in cryogenic fluids: A critical research review." Physics of Fluids 34, no. 10 (October 2022): 101303. http://dx.doi.org/10.1063/5.0102876.

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Cavitation occurs as the fluid pressure is lower than the vapor pressure at a local thermodynamic state and may result in huge damage to the hydraulic machinery. Cavitation in cryogenic liquids is widely present in contemporary science, and the characteristics of cryogenic cavitation are quite different from those of water due to thermal effects and strong variations in fluid properties. The present paper reviews recent progress made toward performing experimental measurements and developing modeling strategies to thoroughly investigate cryogenic cavitation. The thermodynamic properties of cryogenic fluids are first analyzed, and different scaling laws for thermal effects estimation are then introduced. As far as cryogenic cavitation experimental research is concerned, the progress made in the cavitation visualization and cavity dynamics and the synchronous measurements of the multi-physical field are mainly introduced. As for the study on numerical simulation of cryogenic cavitation, the commonly used cavitation models and turbulence models are, respectively, classified and presented, and the modifications and improvements of the cavitation model and turbulence model for thermal effect modeling of cryogenic cavitation are examined. Then, several advances of critical issues in cryogenic fluid cavitation research are reviewed, including the influences of thermal effects, unsteady shedding mechanisms, cavitation–vortex interactions, and cavitation-induced vibration/noise. This review offers a clear vision of the state-of-the-art from both experimental and numerical modeling viewpoints, highlights the critical study developments and identifies the research gaps in the literature, and gives an outlook for further research on cryogenic cavitation.
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PARK, JUN SANG, and JAE MIN HYUN. "Transient motion of a confined stratified fluid induced simultaneously by sidewall thermal loading and vertical throughflow." Journal of Fluid Mechanics 451 (January 25, 2002): 295–317. http://dx.doi.org/10.1017/s002211200100653x.

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An analytical study is made of the transient adjustment process of an initially stationary, stably stratified fluid in a square container. The boundary walls are highly conducting. The overall Rayleigh number Ra is large. Flow is initiated by the simultaneous switch-on of a temperature increase (δT) at the vertical wall and a forced vertical throughflow (Ra−1/4δw) at the horizontal walls. The principal characteristics are found by employing the matched asymptotic expansion method. The flow field is divided into the inviscid interior, vertical boundary layers and horizontal boundary layers and analyses are conducted for each region. The horizontal boundary layers are shown to be of double-layered structure, and explicit solutions are secured for these layers. Evolutionary patterns of velocity and temperature in the whole flow domain are illustrated. Both opposing (δw/δT > 0) and cooperating (δw/δT < 0) configurations are considered. The flow character in the opposing configuration can be classified into (a) a forced-convection dominant mode (δw/δT > 1/ √2), (b) a buoyancy-convection-dominant mode (0 < δw/δT < 1/√2), and (c) a static mode (δw/δT ≈ 1/√2). Global evolutionary processes are depicted, and physical rationalizations are provided.
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Nasrin, Rehena, Md Hasanuzzaman, and N. A. Rahim. "Effect of nanofluids on heat transfer and cooling system of the photovoltaic/thermal performance." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 6 (June 3, 2019): 1920–46. http://dx.doi.org/10.1108/hff-04-2018-0174.

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PurposeEffective cooling is one of the challenges for photovoltaic thermal (PVT) systems to maintain the PV operating temperature. One of the best ways to enhance rate of heat transfer of the PVT system is using advanced working fluids such as nanofluids. The purpose of this research is to develop a numerical model for designing different form of thermal collector systems with different materials. It is concluded that PVT system operated by nanofluid is more effective than water-based PVT system.Design/methodology/approachIn this research, a three-dimensional numerical model of PVT with new baffle-based thermal collector system has been developed and solved using finite element method-based COMSOL Multyphysics software. Water-based different nanofluids (Ag, Cu, Al, etc.), various solid volume fractions up to 3 per cent and variation of inlet temperature (20-40°C) have been applied to obtain high thermal efficiency of this system.FindingsThe numerical results show that increasing solid volume fraction increases the thermal performance of PVT system operated by nanofluids, and optimum solid concentration is 2 per cent. The thermal efficiency is enhanced approximately by 7.49, 7.08 and 4.97 per cent for PVT system operated by water/Ag, water/Cu and water/Al nanofluids, respectively, compared to water. The extracted thermal energy from the PVT system decreases by 53.13, 52.69, 42.37 and 38.99 W for water, water/Al, water/Cu and water/Ag nanofluids, respectively, due to each 1°C increase in inlet temperature. The heat transfer rate from heat exchanger to cooling fluid enhances by about 18.43, 27.45 and 31.37 per cent for the PVT system operated by water/Al, water/Cu, water/Ag, respectively, compared to water.Originality/valueThis study is original and is not being considered for publication elsewhere. This is also not currently under review with any other journal.
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Ray, Atul Kumar, and Vasu B. "Influence of chemically radiative nanoparticles on flow of Maxwell electrically conducting fluid over a convectively heated exponential stretching sheet." World Journal of Engineering 16, no. 6 (December 2, 2019): 791–805. http://dx.doi.org/10.1108/wje-04-2019-0100.

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Purpose This paper aims to examine the influence of radiative nanoparticles on incompressible electrically conducting upper convected Maxwell fluid (rate type fluid) flow over a convectively heated exponential stretching sheet with suction/injection in the presence of heat source taking chemical reaction into account. Also, a comparison of the flow behavior of Newtonian and Maxwell fluid containing nanoparticles under the effect of different thermophysical parameters is elaborated. Velocity, temperature and nanoparticle volume fractions are assumed to have exponential distribution at boundary. Buongiorno model is considered for nanofluid transport. Design/methodology/approach The equations, which govern the flow, are reduced to ordinary differential equations using suitable transformation. The transformed equations are solved using a robust homotopy analysis method. The convergence of the homotopy series solution is explicitly discussed. The present results are compared with the results reported in the literature and are found to be in good agreement. Findings It is observed from the present study that larger relaxation time leads to slower recovery, which results in a decrease in velocity, whereas temperature and nanoparticle volume fraction is increased. Maxwell nanofluid has lower velocity with higher temperature and nanoparticle volume fraction when compared with Newtonian counterpart. Also, the presence of magnetic field leads to decrease the velocity of the nanofluid and enhances the skin coefficient friction. The existence of thermal radiation and heat source enhance the temperature. Further, the presence of chemical reaction leads to decrease in nanoparticle volume fraction. Higher value of Deborah number results in lower the rate of heat and mass transfer. Originality/value The novelty of present work lies in understanding the impact of fluid elasticity and radiative nanoparticles on the flow over convectively heated exponentially boundary surface in the presence of a magnetic field using homotopy analysis method. The current results may help in designing electronic and industrial applicants. The present outputs have not been considered elsewhere.
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Alavizadeh, N., R. L. Adams, J. R. Welty, and A. Goshayeshi. "An Instrument for Local Radiative Heat Transfer Measurement Around a Horizontal Tube Immersed in a Fluidized Bed." Journal of Heat Transfer 112, no. 2 (May 1, 1990): 486–91. http://dx.doi.org/10.1115/1.2910404.

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An instrument for the measurement of the radiative component of total heat transfer in a high-temperature gas fluidized bed is described. The main objective of this paper is to emphasize the design, instrumentation, and calibration of this device. The results are presented and discussed elsewhere (Alavizadeh, 1985; Alavizadeh et al., 1985). The design makes use of a silicon window to transmit the radiative heat flux to a thermopile-type heat flow detector located at the base of a cavity. The window material thermal conductivity is sufficiently large to prevent conduction errors due to the convective component of total heat transfer. Also, its transmission and mechanical hardness are well suited for the fluid bed environment. The device has been calibrated using a blackbody source both before and after exposure to a fluidized bed, indicating the effect of the abrasive bed environment on performance. The instrument has been used to measure local radiative heat transfer around a horizontal tube. Typical results for a particle size of 2.14 mm and a bed temperature of 1050 K are presented and discussed to illustrate instrument performance.
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Dissertations / Theses on the topic "Fluid mechanics and thermal engineering not elsewhere classified"

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(9802553), Nur Hassan. "Bubble rise phenomena in various non-Newtonian fluids." Thesis, 2011. https://figshare.com/articles/thesis/Bubble_rise_phenomena_in_various_non-Newtonian_fluids/13459244.

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"The bubble rise characteristic is very important for the design of heat and masss transfer operations in chemical, biochemical, environmental, and food processing industries. The rate of heat and mass transfer is affected by the bubble size, pressure inside the gas phase, interaction between bubbles, rise velocity and rising trajectory. Research on bubble rise phenomena in non-Newtonian fluids is very limited and there is an increased demand for further research in this area since most of the industrial fluids are non-Newtonian in nature. This study investigated the bubble rise phenomena in water (Newtonian fluid) and various non-Newtonian stagnant fluids"--Abstract.
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(13754529), Shaik Mohammed Tayeeb. "Effect of polymer concentration and roughness of pipes on friction in fluid flows." Thesis, 1995. https://figshare.com/articles/thesis/Effect_of_polymer_concentration_and_roughness_of_pipes_on_friction_in_fluid_flows/21049354.

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The phenomenon of drag reduction by addition of polymer to a solvent has been one of the most fascinating subjects of Fluid Mechanics in recent years. Despite many years of intensive research the mechanism is not fully understood. This thesis provides an experimental study of this phenomenon of drag reduction (reduction of friction factor) with effect to the concentration of the fluid, the roughness of straight pipes and the different types of curved pipes. The experimental results reveal that significant reduction can be achieved with higher concentrations of polymer

additives, but the drag reduction is reduced with the increase in pipe roughness and the radius of curvature in curved pipes show considerable effect on the drag reduction.

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(9790778), Prasanjit Das. "Experimental investigation of fluid dynamics effects on scale growth and suppression in the Bayer process." Thesis, 2018. https://figshare.com/articles/thesis/Experimental_investigation_of_fluid_dynamics_effects_on_scale_growth_and_suppression_in_the_Bayer_process/13445966.

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Scale formation on the process equipment is a major problem in the mineral industry because it leads to reduced plant efficiency and additional operational cost. Scale formation in the Bayer process equipment is a natural consequence of supersaturated solutions that are generated throughout the process and the costs involved in the de-scaling process may be as much as one-quarter of operational costs of an alumina refinery. The scale formation in the Bayer process mainly occurs from crystallisation of Bayer liquor which is not well understood yet. A series of systematic experiments were done using laboratory-made potassium nitrate (KNO3) aqueous solutions for safety reasons, since the real Bayer liquor requires high processing temperature and pressure and it has caustic property. The study provides a novel approach to elucidating the fluid dynamics effects on crystallisation scale growth and its suppression mechanism using for the first time a normal soluble salt to generate the crystallisation scale deposition in a newly fabricated lab-scale agitation tank that effectively replicates many industrial processes. Firstly, the impact of impeller agitation rate on the scale growth and its suppression was examined. Tests were conducted with three different size impellers (86, 114 and 160 mm) at varying rotational speeds ranging from 100 to 700 rpm using the KNO3 solutions of various supersaturation levels (4.5, 4.75 and 5.25 mol/dm3) to investigate the hydrodynamic effects on scale growth and suppression in the agitation tank. It was found that higher agitation rates suppressed the scale deposition on the agitation tank wall and lower agitation rates enhanced the scale deposition. The wall scale growth rate decreased asymptotically with time ranging from 58.06% to 6.79% and the corresponding bottom settled scale increased ranging from 4.19% to 80.2% depending on the agitation rate, impeller size, solution concentration and tank conditions. Secondly, the investigation of the impact of scale growth on heat transfer was conducted and observed that there was a significant variation of overall heat transfer coefficients (OHTC) and scaling thermal resistance (TR) coefficients due to crystallisation scale deposition. For a concentration of 4.50 mol/dm3, OHTC decreases asymptotically with time ranging from 75% to 38%, 73% to 23% and 72% to 2.6% for impeller diameters of 86, 114 and 160 mm respectively, due to crystallisation scale deposition on the wall of the tank with inserted baffles. For the unbaffled tank, OHTC decreases asymptotically with time ranging from 70% to 0.6% which depends on agitation rate and impeller size. The TR appreciably decreases with the increase of impeller agitation rate ranging from 159.37 to 0.57 cm2K/W. It is observed that the lesser scale deposition occurs in unbaffled condition compared to the baffled condition, due to the former creating a swirl flow condition that is conducive to augmentation of OHTC and reduction of TR. Finally, the effect of scale growth on different heat exchanger pipes material such as copper, aluminium, stainless steel, mild steel and polycarbonate (Cu, Al, SS316, MS, and Polycarbonate) during the convective heat transfer was investigated. The results show that crystallisation scale deposition increases with time and is augmented with an increase in thermal conductivity in the hierarchical order of copper (Cu) > aluminium (Al) > stainless steel (SS316) > mild steel (MS) > polycarbonate. The potential of a gum arabic additive to mitigate the crystalline deposition of normal soluble salt at convective heat transfer condition in the heat exchanger was also investigated, and a noticeable scale suppression was observed. The outcomes of this study offer a new body of knowledge in elucidating the scale growth characteristics and provide design guidelines for agitation tanks and selection of suitable impeller blades which attract less or no scale deposition under hydrodynamics conditions.
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(9749204), John Lawrence Resa. "Numerical study of solidification and thermal-mechanical behaviors in a continuous caster." Thesis, 2020.

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This work includes the development of computational fluid dynamic (CFD) and finite element analysis (FEA) models to investigate fluid flow , solidification, and stress in the shell within the mold during continuous casting. The flow and solidification simulation is validated using breakout shell measurements provided by an industrial collaborator. The shell can be obtained by the solidification model and used in a FEA stress model. The stress model was validated by former research related to stress within a solidifying body presented by Koric and Thomas. The work also includes the application of these two models with a transient solidification model and a carbon percentage investigation on both solidification and deformation.
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(13114245), Stuart Jonathan Nawrath. "Investigation into the relationship between scale growth rate and flow velocity for a supersaturated caustic - Aluminate solution." Thesis, 2004. https://figshare.com/articles/thesis/Investigation_into_the_relationship_between_scale_growth_rate_and_flow_velocity_for_a_supersaturated_caustic_-_Aluminate_solution/20334891.

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Scale formation in pipe work and process equipment is inherent to the operation of many chemical processing industries. It results in reduced equipment availability; lost

production and is costly to remove. In the Bayer process, where alumina is chemically extracted from bauxite ore, the specific process step used to recover the alumina from

supersaturated caustic-aluminate solution, referred to as Precipitation, results in significant scale formation on tank walls, process piping and process equipment in contact with the fluid. Operational experience has shown that the rate at which the scaling occurs is, in part, a function of the fluid velocity.

This thesis presents and discusses the experimental observations of an investigation into scale growth rate and fluid velocity not previously conducted at the Queensland Alumina Limited (QAL) process plant. The experimental results have identified that gibbsite scale growth is a non-linear function of the flow velocity and viscous sub -layer conditions, and that the rate of deposition, with time, is also exponential.

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(8817533), Hadi Shagerdi Esmaeeli. "MULTISCALE THERMAL AND MECHANICAL ANALYSIS OF DAMAGE DEVELOPMENT IN CEMENTITIOUS COMPOSITES." Thesis, 2020.

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The exceptional long-term performance of concrete is a primary reason that this material represents a significant portion of the construction industry. However, a portion of this construction material is prone to premature deterioration for multi-physical durability issues such as internal frost damage, restrained shrinkage damage, and aggregate susceptibility to fracture. Since each durability issue is associated with a unique damage mechanism, this study aims at investigating the underlying physical mechanisms individually by characterizing the mechanical and thermal properties development and indicating how each unique damage mechanism may compromise the properties development over the design life of the material.

The first contribution of this work is on the characterization of thermal behavior of porous media (e.g., cement-based material) with a complex solid-fluid coupling subject to thermal cycling. By combining Young-Kelvin-Laplace equation with a computational heat transfer approach, we can calculate the contributions of (i) pore pressure development associated with solidification and melting of pore fluid, (ii) pore size distribution, and (iii) equilibrium phase diagram of multiple phase change materials, to the thermal response of porous mortar and concrete during freezing/thawing cycles. Our first finding indicates that the impact of pore size (and curvature) on freezing is relatively insignificant, while the effect of pore size is much more significant during melting. The fluid inside pores smaller than 5 nm (i.e., gel pores) has a relatively small contribution in the macroscopic freeze-thaw behavior of mortar specimens within the temperature range used in this study (i.e., +24 °C to -35 °C). Our second finding shows that porous cementitious composites containing lightweight aggregates (LWAs) impregnated with an organic phase change material (PCM) as thermal energy storage (TES) agents have the significant capability of improving the freeze-thaw performance. We also find that the phase transitions associated with the freezing/melting of PCM occur gradually over a narrow temperature range (rather than an instantaneous event). The pore size effect of LWA on freezing and melting behavior of PCM is found to be relatively small. Through validation of simulation results with lab-scale experimental data, we then employ the model to investigate the effectiveness of PCMs with various transition temperatures on reducing the impact of freeze-thaw cycling within concrete pavements located in different regions of United States.

The second contribution of this work is on quantification of mechanical properties development of cementitious composites across multiple length scales, and two damage mechanisms associated with aggregate fracture and restrained shrinkage cracking that lead to compromising the long-term durability of the material. The former issue is addressed by combining finite element method-based numerical tools, computational homogenization techniques, and analytical methods, where we observe a competing fracture mechanism for early- age cracking at two length scales of mortar (meso-level) and concrete (macro-level). When the tensile strength of the cement paste is lower than the tensile strength of the aggregate phase, the crack propagates across the paste. When the tensile strength of the cement paste exceeds that of the aggregate, the cracks begin to deflect and propagate through the aggregates. As such, a critical degree of hydration (associated with a particular time) exists below which the cement paste phase is weaker than the aggregate phase at the onset of hydration. This has implications on the inference of kinetic based parameters from mechanical testing (e.g., activation energy). Next, we focus on digital fabrication of a cement paste structure with controlled architecture to allow for mitigating the intrinsic damage induced by inherent shrinkage behavior followed by extrinsic damage exerted by external loading. Our findings show that the interfaces between the printed filaments tend to behave as the first layer of protection by enabling the structure to accommodate the damage by deflecting the microcrack propagation into the stable configuration of interfaces fabricated between the filaments of first and second layers. This fracture behavior promotes the damage localization within the first layer (i.e., sacrificial layer), without sacrificing the overall strength of specimen by inhibiting the microcrack advancement into the neighboring layers, promoting a novel damage localization mechanism. This study is undertaken to characterize the shrinkage-induced internal damage in 7-day 3D-printed and cast specimens qualitatively using X-ray microtomography (μCT) technique in conjunction with multiple mechanical testing, and finite element numerical modeling. As the final step, the second layer of protection is introduced by offering an enhanced damage resistance property through employing bioinspired Bouligand architectures, promoting a damage delocalization mechanism throughout the specimen. This novel integration of damage localization-delocalization mechanisms allows the material to enhance its flaw tolerant properties and long-term durability characteristics, where the reduction in the modulus of rupture (MOR) of hardened cement paste (hcp) elements with restrained shrinkage racking has been significantly improved by ~ 25% when compared to their conventionally cast hcp counterparts.

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(9216107), Jordan D. F. Petty. "Modeling a Dynamic System Using Fractional Order Calculus." Thesis, 2020.

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Fractional calculus is the integration and differentiation to an arbitrary or fractional order. The techniques of fractional calculus are not commonly taught in engineering curricula since physical laws are expressed in integer order notation. Dr. Richard Magin (2006) notes how engineers occasionally encounter dynamic systems in which the integer order methods do not properly model the physical characteristics and lead to numerous mathematical operations. In the following study, the application of fractional order calculus to approximate the angular position of the disk oscillating in a Newtonian fluid was experimentally validated. The proposed experimental study was conducted to model the nonlinear response of an oscillating system using fractional order calculus. The integer and fractional order mathematical models solved the differential equation of motion specific to the experiment. The experimental results were compared to the integer order and the fractional order analytical solutions. The fractional order mathematical model in this study approximated the nonlinear response of the designed system by using the Bagley and Torvik fractional derivative. The analytical results of the experiment indicate that either the integer or fractional order methods can be used to approximate the angular position of the disk oscillating in the homogeneous solution. The following research was in collaboration with Dr. Richard Mark French, Dr. Garcia Bravo, and Rajarshi Choudhuri, and the experimental design was derived from the previous experiments conducted in 2018.

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(11198988), Brayden W. Wagoner. "ELECTROHYDRODYNAMICS OF FREE SURFACE FLOWS OF SIMPLE AND COMPLEX FLUIDS." Thesis, 2021.

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For centuries, fluid flows (hydrodynamics) and electromagnetic phenomena have interested scientists and laypeople alike. The earliest recording of the intersection of these two ideas, electro-hydrodynamics, was reported four centuries ago by William Gilbert who observed that static electricity generated from rubbed amber could ``attract" water. Today electrohydrodynamic phenomena are the underlying mechanisms driving the production of nano-fibers through electro-spinning, printing circuitry, and electrospraying, which John Fenn used in his Nobel prize winning work on electrospray ionization mass spectrometry. In all of these applications, a strong electric field is used to deform a liquid-gas interface (free surface) into a sharp conical tip. Unable to sustain these large interfacial stresses, a thin jet of fluid emerges from the tip of the cone and may subsequently break into a stream of smaller droplets. This tip-streaming phenomenon demands fundamental understanding of three canonical problems in fluid mechanics: electrified cones (Taylor cones), jets, and droplets.
In this thesis, the electrohydrodynamics of free surface flows are examined through both analytical and numerical treatment of the Cauchy momentum equations augmented with Maxwell's equations. Linear oscillations and stability of (inviscid) conducting charged droplets are examined in the presence of a solid ring shaped constraint. Here the constraint gives rise to an additional mode of oscillation---absent in the analysis of a free (unconstrained) droplet. Interestingly, the amount of charge necessary for instability, the Rayleigh charge limit, is unaltered by the constraint, but the mode of oscillation associated with instability changes. While all of the aforementioned applications involve electrified liquid-gas interfaces, recent experiments reveal a previously unknown type of streaming can occur for droplets suspended in another fluid. In these experiments, the suspending fluid is more conductive and an external electric field drives the intially spherical drop to adopt an oblate shape. Based on the viscosity ratio between the drop and suspending fluid, two different types of instability were observed: (i) if the drop is more viscous, then the drop forms a dimple at its poles and ruptures though its center, a phenomenon that is now referred to as dimpling, and (ii) if the suspending fluid is more viscous, then the drop adopts a lens-like shape and emits a sheet from its equator that subsequently breaks into a stream of rings and then tiny droplets, a phenomenon that is now called equatorial streaming. The physics of these two instabilities are far beyond the applicability of linear theory, requiring careful numerical analysis. Here steady-state governing equations are solved using the Galerkin finite element method (GFEM) to reveal the exact nature of these two instabilities and their dependence on the viscosity ratio. The fate of these drops once they succumb to instability is then analyzed by fully transient simulations.
Lastly, in a growing number of applications, the working fluid is non-Newtonian, and may even contain suspended solid particles. When non-Newtonian rheology is attributable to the presence of polymer, the dynamics is analyzed by means of a DEVSS-TG/SUPGFEM algorithm that is developed for simulating viscoelastic free surface
flows. When complex fluid rheology is due to the presence of suspended solid spherical particles, both early-time (linear) and asymptotic dynamics are uncovered by coupling the motion of the particles and Newtonian fluid implicitly in a GFEM fluid-structure interaction (FSI) algorithm. These novel algorithms are used to analyze the pinch-off dynamics of liquid jets and drops.
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(5929685), Vishrut Garg. "Dynamics of Thin Films near Singularities under the Influence of non-Newtonian Rheology." Thesis, 2019.

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Free surface flows where the shape of the interface separating two fluids is unknown apriori are an important area of interest in fluid dynamics. The study of free surface flows such as the breakup and coalescence of drops, and thinning and rupture of films lends itself to a diverse range of industrial applications, such as inkjet printing, crop spraying, foam and emulsion stability, and nanolithography, and helps develop an understanding of natural phenomena such as sea spray generation in oceans, or the dynamics of tear films in our eyes. In free surface flows, singularities are commonly observed in nite time, such as when the radius of a thread goes to zero upon pinchoff or when the thickness of a film becomes zero upon rupture. Dynamics in the vicinity of singularities usually lack a length scale and exhibit self-similarity. In such cases, universal scaling laws that govern the temporal behavior of measurable physical quantities such as the thickness of a lm can be determined from asymptotic analysis and veried by high-resolution experiments and numerical simulations. These scaling laws provide deep insight into the underlying physics, and help delineate the regions of parameter space in which certain forces are dominant, while others are negligible. While the majority of previous works on singularities in free-surface flows deal with Newtonian fluids, many fluids in daily use and industry exhibit non-Newtonian rheology, such as polymer-laden, emulsion, foam, and suspension flows.

The primary goal of this thesis is to investigate the thinning and rupture of thin films of non-Newtonian fluids exhibiting deformation-rate-thinning (power-law) rheology due to attractive intermolecular van der Waals forces. This is accomplished by means of intermediate asymptotic analysis and numerical simulations which utilize a robust Arbitrary Eulerian-Lagrangian (ALE) method that employs the Galerkin/Finite-Element Method for spatial discretization. For thinning of sheets of power-law fluids, a signicant finding is the discovery of a previously undiscovered scaling regime where capillary, viscous and van der Waals forces due to attraction between the surfaces of the sheet, are in balance. For thinning of supported thin films, the breakdown of the lubrication approximation used almost exclusively in the past to study such systems, is shown to occur for films of power-law fluids through theory and conrmed by two dimensional simulations. The universality of scaling laws determined for rupture of supported films is shown by studying the impact of a bubble immersed in a power-law fluid with a solid wall.

Emulsions, which are ne dispersions of drops of one liquid in another immiscible liquid, are commonly encountered in a variety of industries such as food, oil and gas, pharmaceuticals, and chemicals. Stability over a specied time frame is desirable in some applications, such as the shelf life of food products, while rapid separation into its constituent phases is required in others, such as when separating out brine from crude oil. The timescale over which coalescence of two drops of the dispersed phase occurs is crucial in determining emulsion stability. The drainage of a thin film of the outer liquid that forms between the two drops is often the rate limiting step in this process. In this thesis, numerical simulations are used to decode the role played by fluid inertia in causing drop rebound, and the subsequent increase in drainage times, when two drops immersed in a second liquid are brought together due to a compressional flow imposed on the outer liquid. Additionally, the influence of the presence of insoluble surfactants at the drop interface is studied. It is shown that insoluble surfactants cause a dramatic increase in drainage times by two means, by causing drop rebound for small surfactant concentrations, and by partially immobilizing the interface for large surfactant concentrations.
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10

(8726829), Vaseem A. Shaik. "The Motion of Drops and Swimming Microorganisms: Mysterious Influences of Surfactants, Hydrodynamic Interactions, and Background Stratification." Thesis, 2020.

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Microorganisms and drops are ubiquitous in nature: while drops can be found in sneezes, ink-jet printers, oceans etc, microorganisms are present in our stomach, intestine, soil, oceans etc. In most situations they are present in complex conditions: drop spreading on a rigid or soft substrate, drop covered with impurities that act as surfactants, marine microbe approaching a surfactant laden drop in density stratified oceanic waters in the event of an oil spill etc. In this thesis, we extract the physics underlying the influence of two such complicated effects (surfactant redistribution and density-stratification) on the motion of drops and swimming microorganisms when they are in isolation or in the vicinity of each other. This thesis is relevant in understanding the bioremediation of oil spill by marine microbes.

We divide this thesis into two themes. In the first theme, we analyze the motion of motile microorganisms near a surfactant-laden interface in homogeneous fluids. We begin by calculating the translational and angular velocities of a swimming microorganism outside a surfactant-laden drop by assuming the surfactant is insoluble, incompressible, and non-diffusing, as such system is relevant in the context of bioremediation of oil spill. We then study the motion of swimming microorganism lying inside a surfactant-laden drop by assuming the surfactant is insoluble, compressible, and has large surface diffusivity. This system is ideal for exploring the nonlinearities associated with the surfactant transport phenomena and is relevant in the context of targeted drug delivery systems wherein one uses synthetic swimmers to transport the drops containing drug. We then analyze the motion of a swimming organism in a liquid film covered with surfactant without making any assumptions about the surfactant and this system is relevant in the case of free-standing films containing swimming organisms as well as in the initial stages of the biofilm formation. In the second theme, we consider a density-stratified background fluid without any surfactants. In this theme, we examine separately a towed drop and a swimming microorganism, and find the drag acting on the drop, drop deformation, and the drift volume induced by the drop as well as the motility of the swimming microorganism.
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Conference papers on the topic "Fluid mechanics and thermal engineering not elsewhere classified"

1

Traum, Matthew J., and Luis Enrique Mendoza Zambrano. "A Fluids Experiment for Remote Learners to Test the Unsteady Bernoulli Equation Using a Burette." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-70018.

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Abstract The COVID-19 pandemic illuminated the critical need for flexible mechanical engineering laboratories simultaneously deployable in multiple modalities: face-to-face, hybrid, and remote. A key element in the lesson portfolio of a forward-looking engineering instructor is economical, hands-on, accessible, “turn-key” lab activities; kits that can be deployed both in brick-and-mortar teaching labs and mailed home to remote learners. The Energy Engineering Laboratory Module (EELM™) pedagogy, described elsewhere, provides an underpinning theoretical framework and examples to achieve these features. In addition, instructional lab kits must demonstrate foundational engineering phenomena while maintaining measurement accuracy and fidelity at reasonable cost. In the energy-thermal-fluid sciences, achieving these conditions presents challenges as kits require energy and matter transport and conversion in real time at scales large enough to reveal measurable phenomena but not so large as to become hazardous to users. This paper presents theoretical underpinning and experimental verification of a fluid mechanics lab experiment appropriate for undergraduate engineering students that 1) meets all the above-described criteria, 2) costs less than $30 in materials, and 3) can be easily mailed to remote learners.
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