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1
Love, Peter John. "Three dimensional lattice gas models for amphiphilic fluids." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365431.
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Johansson, Ann. "Video Games Fluid Flow Simulations Towards Automation : Smoothed Particle Hydrodynamics." Thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-219951.
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A complete understanding of the cooling process when hot rolling steel is essential to understanding how the quality of the steel is connected to the cooling. This is why it is of great interest to simulate this process. However traditional CFD methods are too expensive in terms of CPU time. Knowing that video games successfully simulate fluids in reasonable time, those methods could be useful for simulating the cooling process in steel manufacturing. This would mean a loss in accuracy that could be acceptable. In this thesis different methods used for fluid simulations have been studied. The Smoothed Particle Hydrodynamics (SPH) method has been chosen. The method has been implemented for simulating the cooling process in MATLAB, which is a matrix operation based programming tool. Convincing results have been achieved for a big scale, but problems still remain for an implementation on a small scale.
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Thornhill, Lindsey Dorough. "Fatigue behavior of flexhoses and bellows due to flow-induced vibrations." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/17624.
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Yurko, James Andrew 1975. "Fluid flow behavior of semi-solid aluminum at high shear rates." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8451.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2001.<br>"June 2001."<br>Includes bibliographical references (leaves 119-127).<br>The rheological behavior and microstructure of semi-solid aluminum alloys were studied using a novel apparatus, the Drop Forge Viscometer (DFV). The viscometer determines force from the curvature of displacement data allowing calculations of viscosities at shear rates in excess of 1000 s-1. Alternatively, the DFV can be operated like a conventional parallel-plate compression viscometer, attaining shear rates as low as 10-5 s-1. Durations of an experiment range between approximately 5 ms and 24 hours. Most rapid compression tests resulted in periods of first rapidly increasing shear rate followed by rapidly decreasing shear rate. Viscosity during the increasing shear rate period decreased by 1-2 orders of magnitude. The viscosity during the decreasing shear rate was an order of magnitude smaller (relative to another experiment) when it achieved a 75% greater maximum shear rate. The DFV was used to calculate viscosity as a function of shear rate for Al-Si and Al-Cu alloys that were rheocast with the commercial SIMA and MHD processes, as well as the recently developed MIT method. Experiments were conducted between fractions solid of 0.44 and 0.67. Viscosity of A357 produced by the three processing routes all had similar viscosities, ranging from 300 Pas at 120 s-1 to 2.2 Pas at 1500 s-1. The final height of compressed Al-Cu was always greater than Al-Si for a given set of experimental conditions. Segregation was not observed in rapid compression experiments shorter than 10 ms, either visually or with EDS characterization. At low compression velocities, segregation was observed and increased with the amount of strain.<br>by James Andrew Yurko.<br>Ph.D.
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Thompson, Willis Hope III. "Numerical Analysis of Thermal Behavior and Fluid Flow in Geothermal Energy Piles." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/24013.
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Geothermal heat exchangers are a growing energy technology that improve the energy efficiency of heating and cooling systems in buildings. Vertical borehole heat exchangers (BHE) coupled with ground source heat pumps have been widely developed and researched in the past century. The major disadvantage of BHEs is the initial capital cost required to drill the boreholes. Geothermal energy piles (GEP) were developed to help offset the high initial cost of these systems. A GEP combines ground source heat pump technology with deep earth structural foundations of buildings. GEPs are relatively new technology and robust standards and guidelines have not yet been developed for the design of these systems. The main operational difference between GEPs and conventional BHEs is the length and diameter of the below ground heat exchangers. The diameter of a GEP is much larger and the length is typically shorter than BHEs. Computational fluid dynamics (CFD) analysis is used in this study to investigate and better understand how structural piles perform as geothermal heat exchangers.
The CFD analysis is used to simulate an existing experimental energy pile test. The experimental test is modeled as built including fluid modeling to provide additional detail into the behavior of the circulation fluid within the pile. Two comparisons of large diameter GEPs are made using CFD analysis to gain knowledge of the effects of varying pile diameter and loop configuration. The thermal response test was successfully modeled using the CFD model. The CFD results closely match the results of the field test. The large diameter comparisons show that the performance of an energy pile will increase as the diameter increases with a constant loop density. Multiple numbers of loops were tested in a constant diameter pile and the results show that with symmetrically placed loops the performance will increase with a greater number of loops in the pile.<br>Master of Science
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Albrecht, Karen A. "Observation scale effects on fluid transport behavior of soil." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/43037.
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<p>Variabilities of hydraulic and solute transport properties of soil are examined at three scales: pore-scale, sample volume-scale, and field-scale. Undisturbed soil cores were taken at 19 subsites spaced logarithmically along a 150 m line transect in a Groseclose mapping unit near Blacksburg; Virginia. Three core sizes were taken at each subsite at the soil surface and 0.5 m depth. 'Small' cores were-40x54 mm; 'medium' cores were 60X100 mm; and 'large' cores were 100x150 mm. Macropore effects on solute transport
were evaluated using monocontinuum and bicontinuum models. Bicontinuum-predicted solute breakthrough curves
(BTC) closely agreed with observed BTC data with mean errors of reduced concentrations </- 0.05 for 97% of the samples, Monocontinuum predicted BTC's had comparable fits with 80% of the samples having mean errors </- 0.07. The simpler monocontinuum model was chosen for estimating dispersion coefficients
for all samples on the basis that seven percent error in concentration is acceptable for the purpose of making
field predictions in light of high spatial variability.
Sample volume did not significantly affect the low variation (coefficients of variation, (CV) of 7-20%) soil properties bulk density or moisture retention characteristics in Ap or Bt horizons. Large cores are recommended for assessing high variation (CV of 60-280%) fluid transport parameters, saturated
hydraulic conductivity (Ks), pore water velocity and
dispersion coefficients (D) since they yielded less variance than the smaller cores. Ranges of about 25 m were determined for log-transformed Ks and D from semivariograms. Monte Carlo simulations were used to predict field-average BTC's.</p><br>Master of Science
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Kwon, Ronald Young. "Mechanical behavior and early molecular signaling during mechanotransduction of fluid flow in bone cells /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Fu, An. "Investigation of Fluid Wicking Behavior in Micro-Channels and Porous Media by Direct Numerical Simulation." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563272437544414.
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Ogbuagu, Too-chukwu C. "Numerical Investigation of the Near FieldZone Flow Behavior of Isothermal CornerImpinging Jet Ventilation Using CFD." Thesis, Högskolan i Gävle, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-35982.
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Abstract The impinging jet ventilation's importance in providing better air distribution and energy-efficient operation, as well as both its heating and cooling flexibility potential cannot be overemphasized. This is because acceptable indoor air quality and its environmental conditions are essential to occupant’s wellbeing, comfort, productivity, and improved cognitive function. Poor air quality conditions could result in sick building symptoms (SBS) and several studies have investigated that the prevalence of sick building symptoms is associated with indoor air quality. Consequently, to the need for high ventilation effectiveness, the impinging jet ventilation system has been developed and applied in different types of buildings as a new ventilation strategy and concept within the last two decades. Therefore, it is important to continuously develop inventive air distribution systems such as IJV with a better location and terminal configuration of the supply device to adequately provide an acceptable indoor environment in an energy-efficient manner. This study aims at reaching a comprehensive understanding of the near field zone of an isothermal turbulent corner impinging jet in a room by using computational fluid dynamics (CFD) simulation tool. Thus, directly investigating the flow field involving the velocity magnitude, velocity decay, and spreading rate along the diagonal of the room.The cases carried out consist of 12 different three-dimensional modeled configurations (room) of the computational domain with the dimension 7.0 (L) x 7.0 (W) x 2.67 (H) m. The cases which comprised different aspects of diffuser geometry (triangle, quadrant, square), diffuser area, discharge height, and flow rates, used the RNG k-ε turbulence model to solve the turbulence flow.The result obtained, from the parametric study in all the cases was detailed to analyze the effect of the different flow rate, discharge heights, diffuser geometry, and its area on the velocity profile development, velocity decay, and spreading rate along the diagonal of the room. This study significantly shows the triangular geometries having greater velocity magnitude and velocity decay along all the line profile positions. Interestingly, a comparison between the quadrant and square geometry illustrates that their characteristics of generating a greater velocity magnitude depend on its discharge height. The result also demonstrated a decrease in jet velocity decay with an increase in jet discharge height. With similar jet spread at higher jet discharge, the square geometry exhibited a higher spreading rate at lower discharge height.
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Freedland, Graham. "Investigation of Jet Dynamics in Cross-Flow: Quantifying Volcanic Plume Behavior." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3314.
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Volcanic eruption columns inject high concentrations of ash into the atmosphere. Some of this ash is carried downwind forming ash clouds in the atmosphere that are hazardous for private and commercial aviation. Current models rely on inputs such as plume height, duration, eruption rate, and meteorological wind fields. Eruption rate is estimated from plume height using relations that depend on the rate of air entrainment into the plume, which is not well quantified. A wind tunnel experiment has been designed to investigate these models by injecting a vertical air jet into a cross-flow. The ratio of the cross-flow and jet velocities is varied to simulate a weak plume, and flow response is measured using particle image velocimetry. The plumes are characterized and flow data relative to the centerline is examined to measure the growth of weak plumes and the entrainment velocity along its trajectory. It was found that cross-flow recirculates behind the jet and entrainment occurs both up and downstream of the jet. Analysis of the generation of turbulence enhanced results by identifying the transition point to bending plume and the growth of the shear layer in a bending plume. This provides information that can be used to improve models of volcanic ash concentration changes in the atmosphere.
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Chibwe, Deside Kudzai. "Flow behavior, mixing and mass transfer in a Peirce-Smith converter using physical model and computational fluid dynamics." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6798.
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Less, David Matthew. "Transient behavior of liquid jets injected normal to a high velocity gas stream." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53887.
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The transient effects of the breakup and atomization of liquid jets in a crossflow on the size of droplets within the spray plume was experimentally determined. Water and water/methanol mixtures were injected normal to a high velocity air stream at Mach numbers of 0.48 and 3.0 with ambient stagnation temperature and respective stagnation pressures of 1.4 and 4.3 atm. The liquids were injected at liquid-to-gas momentum flux ratios ranging from 4 to 12. Droplet size distributions were obtained using a Fraunhofer diffraction technique at sampling rates of up to 9 kHz. Liquid mass flow rates were inferred from measurements of the extinction of a laser beam traversing the plume. The droplet sizes were found to fluctuate with frequencies of the order of 1 to 10 kHz. The fluctuations were characterized by a sudden and relatively brief increase in the mean diameter of the droplets caused by the passage of fractured clumps through the spray plume. Also evident in the droplet size distributions was the very small size of the droplets that had been sheared off the windward surfaces of the jet. The jet fracture frequency was related to the frequency of waves propagating along the initial jet column. The column waves are postulated to have been caused by jet perturbations created by vortices in the air flow around the jet column.<br>Ph. D.
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Park, Chang Shin. "A dynamic behavior of pulp floc and fibers in the papermaking process." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/7044.
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True, Aaron Conway. "Patchiness: zooplankton behavior in finescale vertical shear layers." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42925.
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Regions containing gradients of vertical flow are often associated with sharp changes in hydrographic and biochemical water properties in coastal marine ecosystems. Often these are sites of dense plankton aggregations of critical ecological importance. In this study, a recirculating flume apparatus with a laminar, planar free jet (the Bickley jet) was used to create finescale gradients of fluid velocity (shear) in both upwelling and downwelling configurations for zooplankton behavioral assays. Particle image velocimetry (PIV) was used to fully resolve the velocity fields allowing us to fine-tune experimental parameters to match fluid mechanical conditions commonly measured in the field. Zooplankton behavioral assays with two tropical calanoid copepods, Acartia negligens and Clausocalanus furcatus, an estuarine mysid, Neomysis americana, and the larvae of an estuarine mud crab, Panopeus herbstii, were conducted in control (stagnant), upwelling, and downwelling flow configurations. Statistical analyses (ANOVA) of individual zooplankton trajectories revealed the potential for individual behavioral responses to persistent finescale vertical shear layers to produce population scale aggregations, which is proposed here as a mechanism of patchiness in coastal marine ecosystems. Results from behavioral analyses reveal species-specific threshold shear strain rates that trigger individual behavioral responses. Furthermore, results show statistically significant changes in behavior (relative swimming speed, turn frequency, heading) for all species tested in response to a coherent shear structure in the form of finescale upwelling and downwelling jets. The results show that changes in individual behavior can increase Proportional Residence Time (PRT = percent time spent in the jet structure). On a population scale, the increase in PRT can lead to dense aggregations around persistent flow features, which is consistent with numerous field studies. These dense, patchy aggregations of zooplankton have profound trickle-up ecological consequences in coastal marine ecosystems.
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Frascoli, Federico. "Chaotic and rheological properties of liquids under planar shear and elongational flows." Swinburne Research Bank, 2007. http://hdl.handle.net/1959.3/22416.
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Thesis (PhD) - Swinburne University of Technology, Centre for Molecular Simulation - 2007.<br>Dissertation submitted in fulfilment of requirements for the degree Doctor of Philosophy, Centre for Molecular Simulation, Faculty of Information and Communication Technologies, Swinburne University of Technology, 2007. Typescript. Includes bibliographical references (p. 151-161).
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Russ, Thomas William. "A surface flow visualization study of boundary layer behavior on the blades of a solid-wall compressor cascade at high angles of attack." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/53161.
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The oil-film surface flow visualization technique was applied to circular arc compressor blades in a solid wall, high aspect ratio cascade for the purpose of describing the transition from corner stall to full blade stall, and the blade surface flow under fully stalled conditions. Photos of the visualizations for three stagger angles are presented and analyzed. A map quantitatively describing the observed boundary layer development at midspan is presented.
The most interesting discovery of the work showed the suction surface flow to be essentially two-dimensional, in the geometric sense, preceding and following the transition to a fully separated flow at the leading edge. Corner stall was the observed three-dimensional mechanism prior to full stall. For fully-stalled conditions, the three-dimensional mechanism took the form of recirculating flow regions at the blade ends. Complete separation at the leading edge occurred at lower angles of attack for the higher stagger angles. Special blade oil-flow tests were conducted to evaluate Reynolds number and tip clearance effects on boundary layer development.
The experimental work was done as part of a larger research program aimed at measuring and predicting the stalled performance of a compressor cascade.<br>Master of Science
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Baratta, Daniel Jacob. "EXPERIMENTAL INVESTIGATION INTO UTILIZING SYNTHETIC JET ACTUATORS TO SUPPRESS BI-MODAL WAKE BEHAVIOR BEHIND AN AHMED BODY." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2099.
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Testing done on the flat-back Ahmed Body and other bluff bodies has shown the existence of a bi-stable reflectional symmetry-breaking wake at Reynolds numbers ranging from 340 to 2.41 x 106. Several methods of flow control, both active and passive, have been used to improve the efficiency of the Ahmed body but their effect on the bi-stable nature of the wake has not been investigated. This work details the experimental investigation done to determine if piezoelectrically driven synthetic jet actuators are capable of suppressing the bi-stable wake effects observed behind the Ahmed Body. The synthetic jets were designed and manufactured to have a maximum total coefficient of momentum of 1.0E-3 with a frequency range up to 2000 Hz or F+ = 17.25. The piezoelectric actuators used were bimorph bending disks with no center shim and were driven by a square waveform. Pressure data was collected from 25 pressure ports on the rear of the model at 625 Hz for 600 seconds per run and filtered using a lowpass filter at 35 Hz to remove interference. Center of Pressure probability distributions and Principle Component Analysis were used to identify wake shapes and modes. Results with no jet actuation showed good agreement with previously published work on the Ahmed Body. It was found that the actuation frequency had an effect on the ability of the synthetic jets to affect the wake. Actuating at F+ = 1 (116 Hz) showed a bi-stable wake with an even distribution between wake modes. Higher actuation frequencies showed either a skewed distribution with a weakening of the bi-stable effects (4 < F+ < 8) or a complete removal of the bi-stable distribution (8 < F+ < 12). Frequencies higher than F+ = 12 did not show any effect on the bi-stable distribution. There was a negative correlation between actuation frequency and average wake pressure; it is theorized that the synthetic jets enhance mixing in the shear layer around the recirculation bubble in the wake to decrease average pressure.
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Breitner, Emily Katherine. "Enhanced Physiological Microenvironment for Improved Evaluation of Nanoparticle Behavior." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1438096109.
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Du, Fengshuang. "Investigation of Nanopore Confinement Effects on Convective and Diffusive Multicomponent Multiphase Fluid Transport in Shale using In-House Simulation Models." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100103.
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Extremely small pore size, low porosity, and ultra-low permeability are among the characteristics of shale rocks. In tight shale reservoirs, the nano-confinement effects that include large gas-oil capillary pressure and critical property shifts could alter the phase behaviors, thereby affecting the oil or gas production. In this research, two in-house simulation models, i.e., a compositionally extended black-oil model and a fully composition model are developed to examine the nano-pore confinement effects on convective and diffusive multicomponent multiphase fluid transport. Meanwhile, the effect of nano-confinement and rock intrinsic properties (porosity and tortuosity factor) on predicting effective diffusion coefficient are investigated.
First, a previously developed compositionally extended black-oil simulation approach is modified, and extended, to include the effect of large gas-oil capillary pressure for modeling first contact miscible (FCM), and immiscible gas injection. The simulation methodology is applied to gas flooding in both high and very low permeability reservoirs. For a high permeability conventional reservoir, simulations use a five-spot pattern with different reservoir pressures to mimic both FCM and immiscible displacements. For a tight oil-rich reservoir, primary depletion and huff-n-puff gas injection are simulated including the effect of large gas-oil capillary pressure in flow and in flash calculation on recovery estimations. A dynamic gas-oil relative permeability correlation that accounts for the compositional changes owing to the produced gas injection is introduced and applied to correct for changes in interfacial tension (IFT), and its effect on oil recovery is examined. The results show that the simple modified black-oil approach can model well both immiscible and miscible floods, as long as the minimum miscibility pressure (MMP) is matched. It provides a fast and robust alternative for large-scale reservoir simulation with the purpose of flaring/venting reduction through reinjecting the produced gas into the reservoir for EOR.
Molecular diffusion plays an important role in oil and gas migration in tight shale formations. However, there are insufficient reference data in the literature to specify the diffusion coefficients within porous media. Another objective of this research is to estimate the diffusion coefficients of shale gas, shale condensate, and shale oil at reservoir conditions with CO2 injection for EOR/EGR. The large nano-confinement effects including large gas-oil capillary pressure and critical property shifts could alter the phase behaviors. This study estimates the diffusivities of shale fluids in nanometer-scale shale rock from two perspectives: 1) examining the shift of diffusivity caused by nanopore confinement effects from phase change (phase composition and fluid property) perspective, and 2) calculating the effective diffusion coefficient in porous media by incorporating rock intrinsic properties (porosity and tortuosity factor). The tortuosity is obtained by using tortuosity-porosity relations as well as the measured tortuosity of shale from 3D imaging techniques. The results indicated that nano-confinement effects could affect the diffusion coefficient through altering the phase properties, such as phase compositions and densities. Compared to bulk phase diffusivity, the effective diffusion coefficient in porous shale rock is reduced by 102 to 104 times as porosity decreases from 0.1 to 0.03.
Finally, a fully compositional model is developed, which enables us to process multi-component multi-phase fluid flow in shale nano-porous media. The validation results for primary depletion, water injection, and gas injection show a good match with the results of a commercial software (CMG, GEM). The nano-confinement effects (capillary pressure effect and critical property shifts) are incorporated in the flash calculation and flow equations, and their effects on Bakken oil production and Marcellus shale gas production are examined. The results show that including oil-gas capillary pressure effect could increase the oil production but decrease the gas production. Inclusion of critical property shift could increase the oil production but decrease the gas production very slightly. The effect of molecular diffusion on Bakken oil and Marcellus shale gas production are also examined. The effect of diffusion coefficient calculated by using Sigmund correlation is negligible on the production from both Bakken oil and Marcellus shale gas huff-n-puff. Noticeable increase in oil and gas production happens only after the diffusion coefficient is multiplied by 10 or 100 times.<br>Doctor of Philosophy<br>Shale reservoir is one type of unconventional reservoir and it has extremely small pore size, low porosity, and ultra-low permeability. In tight shale reservoirs, the pore size is in nanometer scale and the oil-gas capillary pressure reaches hundreds of psi. In addition, the critical properties (such as critical pressure and critical temperature) of hydrocarbon components will be altered in those nano-sized pores. In this research, two in-house reservoir simulation models, i.e., a compositionally extended black-oil model and a fully composition model are developed to examine the nano-pore confinement effects on convective and diffusive multicomponent multiphase fluid transport. The large nano-confinement effects (large gas-oil capillary pressure and critical property shifts) on oil or gas production behaviors will be investigated. Meanwhile, the nano-confinement effects and rock intrinsic properties (porosity and tortuosity factor) on predicting effective diffusion coefficient are also studied.
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Sanvicente, Estibaliz. "Experimental investigation of thermal and fluid dynamical behavior of flows in open-ended channels : Application to Building Integrated Photovoltaic (BiPV) Systems." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00961231.
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Among technologies capable to produce electricity locally without contributing to GHG releases, building integrated PV systems (BIPV) could be major contributor. However, when exposed to intense solar radiation, the temperature of PV modules increase significantly, leading to a reduction in efficiency so that only about 14% of the incident radiation is converted into electrical energy. The high temperature also decrease the life of the modules, thereby making passive cooling of the PV components through natural convection a desirable and cost-effective means of overcoming both difficulties. An experimental investigation of heat transfer and fluid flow characteristics of natural convection of air in vertical and inclined open-ended heated channels is therefore undertaken so as provide reliable information for the design of BIPV. Two experimental set ups were developed and used during the present investigations; one located at the CETHIL laboratory in Lyon, the F-device and the other located at the University of New South Wales in Sydney, the R-device. Both channels consisted of two wide parallel plates each of which could be subjected to controlled uniform or non-uniform heat fluxes. The investigation has been conducted by analyzing the mean wall temperatures, measured by thermocouples and mean velocity profiles and turbulent quantity distributions of the flow, measured with a PIV system. Flow patterns close to the heated faces were also investigated. The study is particularly focused on the transition region from laminar to turbulent flow. Three different heating geometric arrangements are examined in the modified Rayleigh number range from 3.86 x 105 to 6.22 x 106. The first is a vertical channel with one wall uniformly heated while the other was unheated, the second was a vertical channel in which both walls were non-uniformly heated and the third is an inclined channel uniformly heated from above. In the vertical configurations the width-to-height channel aspect ratio was fixed at 1:15 and in the inclined ones at 1:16. It is shown that the flow is very sensitivity to disturbances emanating from the ambient conditions. Moreover, the propagation of vortical structures and unsteadiness in the flow channel which are necessary to enhance heat transfer, occurred downstream of the mid-channel section at Ra* = 3.5 x 106 for uniformly and asymmetrically heated channels inclined between 60° and 90° to the horizontal. Indeed, these unsteady flow phenomena appears upstream the location of the inflexion point observed in the temperature excess distribution of the heated wall. In the case of non-uniform heating on both sides of the channel, a stronger 'disruption mechanism' exists, which leads to enhanced mixing and increased Reynolds stresses over most of the width of the channel. Empirical correlations of average Nusselt number as a function of modified Rayleigh number were obtained for each configuration.
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Hasnaoui, Abdennebi el. "Introduction aux methodes de raccordement : application a la modelisation d'ecoulement central de convection naturelle dans une piece d'habitation." Toulouse 3, 1987. http://www.theses.fr/1987TOU30141.
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Presentation de la methode fet (formalisme d'evolution par transfert) permettant d'utiliser dans une meme simulation des modeles varies pour les diverses parties du systeme etudie, et d'autre part, de comparer a l'experience sur modele d'ecoulement pour le coeur d'une piece d'habitation succeptible d'etre raccordee a d'autres modeles par le fet. Analyse quantitative des resultats
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Rigal, Claire. "Comportement de fluides complexes sous écoulement : approche expérimentale par résonance magnétique nucléaire et techniques optiques et simulations numériques." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0091/document.
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Cette thèse est une contribution à la fois expérimentale, théorique et numérique à l'étude des écoulements bidimensionnels de fluides complexes dans une conduite cylindrique présentant des singularités et dans une géométrie annulaire à cylindres excentrés. Le fluide utilisé est une solution de xanthane à différentes concentrations présentant un caractère non newtonien rhéofluidifiant. L'objectif principal de cette thèse est la caractérisation de l'influence des propriétés rhéofluidifiantes sur le comportement des zones de recirculation, en terme de morphologie, de positionnement et d'intensité, par l'utilisation et le développement de techniques de mesures non intrusives et performantes. La première méthode expérimentale utilisée une technique laser classique: la vélocimétrie par images de particules. La seconde technique mise en oeuvre est une méthode originale: la vélocimétrie par imagerie par résonance magnétique. Elle est utilisée pour la première fois au laboratoire pour la mesure de champ de vitesse d'écoulement de fluides complexes en conduite cylindrique, représentant l'intérêt majeur de cette thèse. La première partie de notre travail consiste en une description rhéologique complète de nos fluides modèles avec la détermination de leur loi de comportement et la mise en évidence de leurs propriétés viscoélastiques, par ailleurs négligeables. Par la suite les mesures de champ de vitesse des écoulements bidimensionnels étudiés et la représentation des lignes de courant montrent que les propriétés rhéofluidifiantes influencent très fortement la structure et la morphologie de ces écoulements et le comportement des zones de recirculation. Par une étude fine nous observons qu'il existe une compétition entre les effets d'inertie et les effets rhéofluidifiants induisant un champ de contrainte variable qui modifie le positionnement et la taille de la zone de recirculation. Nous montrons également que l'augmentation du caractère rhéofluidifiant affaiblit son intensité de la zone de recirculation. Enfin, des simulations numériques utilisant la loi de comportement macroscopique déterminée par rhéométrie classique ont été réalisées avec le logiciel Fluent. Une bonne concordance est observée entre les résultats de ces simulations numériques et les expérimentaux. Cette comparaison permet ainsi de valider le code de calcul et la loi de comportement, utilisée pour les simulations numériques au travers de sa modélisation suivant la loi de Cross, pour les écoulements considérés<br>This thesis is an experimental and numerical study of structured fluids bidimensional flows in a cylindrical pipe with singularity and in an annular geometry with eccentric cylinders. The objective of this thesis is to characterize the influence of the shear thinning properties on the recirculation zones by using efficient and non-intrusive techniques: particle image velocimetry and velocimetry by nuclear magnetic resonance imaging. Materials are xanthane solutions at different concentrations. In the first part, we determine the rheological and viscoelastic properties of the fluids used. The second part concerns the measured velocity field. It is shown that the shear thinning behavior have a strongly influence on the structure and the morphology of these flows and the pattern of the recirculation zones. Simultaneously, numerical simulations performed by Fluent and using the rheological behavior. A good concordance is observed between the experimental and numerical results. For the flows considered here, this comparison allows to validate the computational code and the behavior law used in the numerical simulations and modelling by a Cross model
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JENG, TZER-MING, and 鄭澤明. "Fluid Flow and Heat Transfer Behavior in Porous Channels." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/34602967514984489177.
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博士<br>國立清華大學<br>動力機械工程學系<br>90<br>A series of experimental and theoretical investigations on the fluid flow and heat transfer behavior in porous aluminum foam channels have been successfully performed. The parametric studies on the local and average heat transfer characteristics have been explored. The influencing parameters include steady-state air preheating temperature ratio at channel inlet (), Reynolds number (Re) and porosity/pore density of test specimen (/PPI). The ranges of the above-mentioned parameters are: = 1.8-3.0, Re = 2219-7595 and /PPI = 07-0.93/5-40PPI. In hydrodynamic aspect, the porous flow characteristics such as the Darcy number (Da), inertia coefficient (CF) and Darcy friction factor (f) have been investigated. In heat transfer aspect, from the study, it manifests that the erroneous deviation of the results evaluated by the transient liquid crystal method from the measured data become more significant for the cases with lower porosities. The main reasons to cause this discrepancy may be due to the following two effects: (1) the transient energy storage due to the matrix capacity and (2) the conductive heat transfer due to the direct contact between the solid matrix and channel wall. In order to overcome the deficiency of using the transient liquid crystal method to the study in porous channels with low porosities, a new semi-empirical model with an improved single blow method for exploring the heat transfer behavior in aluminum foam channels has been successfully developed. The heat transfer paths and mechanisms in porous channels have also been explored. The relationships among the fluid-solid, fluid-wall, effective solid-wall heat transfer coefficients and solid matrix capacity for porous channels have been presented. In addition, the influencing parameters on local and average heat transfer behavior have also been studied. The heat transfer enhancement of porous channels to hollow channels are, , much greater than unity and generally decrease with increasing Re. Two new correlations of and in terms of , Re, Da, and are proposed. Furthermore, a concept of the amount of enhanced heat transfer is also introduced. A new empirical correlation of j/f in terms of , Da and is presented.
As compared with the results evaluated by the transient liquid crystal method, the channel wall temperatures predicted by the semi-empirical model have a more satisfactory agreement with the experimental data, especially for the cases with smaller porosities. The limitations with relevant error maps of using the transient liquid crystal method in porous aluminum foam channels are finally postulated.
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Chao, Yen-Ting, and 趙晏廷. "An Automation Flow of OP Amplifier Design with Accurate Behavior Model." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/58046970602870390100.
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碩士<br>國立中央大學<br>電機工程研究所<br>95<br>An automation flow of OP Amplifer design is proposed in this thesis. Four common OP Amplifers topologies: telescopic、folded cascade、current mirror and two stage are supported in this flow. It has been implemented by C++ program and HSPICE. Given the required specification and target topology, the tool will offer the circuit with detailed sizes that meets the required specification in the choosed topology. OP Amplifers are the fundamental components in analog circuits that have been used in many kinds of circuits extensively. An automation flow of OP Amplifer design can greatly decrease the design time of the analog circuit.
As CMOS process technology scales, the increasing complexity of VLSI systems also increase the simulation time and verification efforts. In order to reduce the simulation time, the behavioral models of the generated OP circuits are provided simultaneously, which can be used to verify the behavior of the entire system at behavioral level to reduce the system simulation time.
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Tai, Yu-Chih, and 戴詠哲. "Mass-Transfer and Fluid Flow Behavior in the Fuel Cell." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/52404746776851178846.
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Lee, Chien-Hsien, and 李建賢. "Fluid Flow and Heat Transfer Behavior in Glass Melting Furnace." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/57850640273666826599.
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碩士<br>國立成功大學<br>材料科學及工程學系碩博士班<br>93<br>The quantities of bubbles and inclusions that remain in glass substrate strongly depend on the refining ability of the glass melting furnace and have significant effects on the quality of glass substrate. This study, focused merely on the molten glass zone in the glass melting furnace, developed a mathematical model and a physical model to investigate fluid flow and heat transfer behaviors and to evaluate the glass qualities under different bubbling fluxes and heating temperatures.
By using finite difference method and a computational fluid dynamics technique, SOLA-VOF, the mathematical model could be used to analyze the velocity, temperature fields and active volume ratio of glass melting furnace. The physical model which executed in a reduced acrylic mold used silicon oil as a substitute for molten glass. The flow path and minimum residence time was recorded. The glass qualities under different operation conditions are evaluated by minimum residence time and active volume ratio of glass melting furnace in the end.
Three bubbling fluxes and two heating temperatures were investigated. The results showed that as the bubbling flux increases the bubbling circulation, flow path, and the minimum residence time and active volume ratio all increase. Therefore, the glass quality promotes as bubbling flux increases. To heating operating conditions, flow paths and active volume ratios are slightly raised, minimum residence times are significantly decreased, and suspended bubbles in the back zone of glass melting furnace are reduced. Therefore, the glass quality under heating should be evaluated by other appropriate glass quality indexes.
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Bent, J., L. R. Hutchings, R. W. Richards, et al. "Neutron-mapping polymer flow: scattering, flow visualization and molecular theory." 2003. http://hdl.handle.net/10454/3862.
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No<br>Flows of complex fluids need to be understood at both macroscopic and molecular scales, because it is the macroscopic response that controls the fluid behavior, but the molecular scale that ultimately gives rise to rheological and solid-state properties. Here the flow field of an entangled polymer melt through an extended contraction, typical of many polymer processes, is imaged optically and by small-angle neutron scattering. The dual-probe technique samples both the macroscopic stress field in the flow and the microscopic configuration of the polymer molecules at selected points. The results are compared with a recent "tube model" molecular theory of entangled melt flow that is able to calculate both the stress and the single-chain structure factor from first principles. The combined action of the three fundamental entangled processes of reptation, contour length fluctuation, and convective constraint release is essential to account quantitatively for the rich rheological behavior. The multiscale approach unearths a new feature: Orientation at the length scale of the entire chain decays considerably more slowly than at the smaller entanglement length.
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Ou, Shin-Chih, and 歐信志. "System Feedback Behavior and Simulation for Fluid Flow in Unit Operation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/16532747753014666938.
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碩士<br>國立雲林科技大學<br>環境與安全衛生工程系碩士班<br>99<br>System Dynamics with systems analysis, information feedback, control theory and computer simulation of system behavior, decision-making Process and the time delay and so on, in this study for the automatic control unit operations of fluid flow experiments, with VENSIM simulation and LabVIEW control. Information and feedback from the system fluid and time delay in the correction LabVIEW automation control and signal acquisition, the electronic device measuring differences in fluid velocity and temperature will also affect the signal feedback, the temperature increases, the error range increases, the system feedback increased risk of miscarriage of justice.
When the steady-state experimental valve opening is greater than 35%, flow and pressure can be stabilized until the valve is opened to 85%, flow that is not increased. After the dynamic test flow delayed effects about 10 seconds, the pressure is about 5 seconds, to understand the reasons for the delay and time, the operator can provide the use of appropriate control strategies. In steady state experiments such as goals seeking curves behavior of fluid, dynamic experiments are like S-shaped growth curve, or maximum value near the goal behavior when the shock behavior, because part of the interference from the detection of errors caused? the other part of the delay effect the performance of the system behavior. Using VENSIM simulation fluid system, whether it is single-loop or double-loop simulation in steady state and dynamic, temperature changes can also be included, and the fast simulation time and number of adjustable parameters. In the future simulation can be expanded around impact of environment variables, different characteristics of the fluid and the change due to different systems, so as to act as an automatic control system of the reference.
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Rubenstein, Brandon Aaron. "Computational fluid dynamics predictions of volume flow and in-cylinder flow behavior with comparison to experiment." 2000. http://catalog.hathitrust.org/api/volumes/oclc/46320527.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 2000.<br>Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (139-141).
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Lai, Zheng-Wen, and 賴政文. "A Study on the Behavior of a Viscoelastic Fluid Flow pasta Cavity." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/68552116685954411297.
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碩士<br>中原大學<br>機械工程研究所<br>95<br>The behavior of a viscoelastic fluid flow past a cavity was studied. Through changing Reynolds number, elastic coefficient and cavity length separately, the project explores the way that viscoelastic fluid flows behave under various conditions.
The profiles of flow field were studied by a numerical computational method. The finite difference method was used in the vorticity and stream function equations. The Gauss-Seidel method with successive over relaxation (SOR) is implemented in the finite difference method to obtain the solutions. The results suggest that with higher elastic coefficient and the higher Reynolds number, the more obvious the overshoot of the primary recirculation zone. In addition, the steady-state secondary recirculation zone will not exist unless the cavity is longer than 1.5 multiple of the height of the channel at the Reynolds number of 75.
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Chellam, Shankararaman. "Laminar fluid flow, particle transport and permeate flux behavior in crossflow membrane filters." Thesis, 1996. http://hdl.handle.net/1911/16962.
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Similarity solutions for axial and lateral velocity profiles, pressure gradients and wall skin friction are derived for the laminar, isothermal single phase flow of incompressible fluids in channels having porous boundaries. Results from a finite difference solution to the vorticity-stream function formulation of the Navier-Stokes equations are compared with previously reported perturbation, asymptotic, similarity and infinite series solutions. Initial transport of non-interacting particles suspended in laminar flow in the membrane far-field is reported to be accurately predicted by trajectory theory. RTDs obtained in response to pulse inputs in slow axial crossflows and high permeation rates appear to reveal a minimum in back-transport for 7 $\mu$m particles in the range of experimental conditions investigated here. Back-transport of smaller particles is due to Brownian diffusion whereas shear-induced diffusion appears to control the behavior of larger macrocolloids. The effects of suspension concentration, shear rate, Particle Size Distribution (PSD) and initial permeation rate on permeate flux are reported. Existing transient models based on shear-induced diffusion and particle adhesion as well as the steady state inertial lift model are found inadequate in predicting experimental observations of the specific permeate flux during the laminar crossflow filtration of narrow PSD suspensions. Under the range of experimental conditions investigated here, smaller particles deposit preferentially in the cake. Also, under identical experimental conditions higher permeate fluxes are obtained during the filtration of suspensions with a higher average particle size. Hence, pretreatment aimed at coagulating smaller particles could have a beneficial impact on permeate flux production. In all cases, specific resistances of cakes are higher in the crossflow mode compared to the dead-end mode. Also, cake specific resistances increased with shear and decreased with increasing permeation rate. Cumulative resistance to permeation is reported to increase on application of shear even without particle feed. Thus, even though cake mass decreases with increasing shear, it may not result in higher permeate flux. Therefore, pilot scale testing may still be necessary to evaluate the fouling potential of feed waters as well as in optimizing the operation of existing crossflow membrane filters.
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Ravi, Gurunarayana. "Study of Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid." 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2008-12-231.
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The heat transfer behavior of phase change material fluid under laminar flow conditions in circular tubes and internally longitudinal finned tubes are presented in this study. Two types of boundary conditions, including uniform axial heat flux with constant peripheral temperature and uniform axial and peripheral temperature, were considered in the case of circular tubes. An effective specific heat technique was used to model the phase change process assuming a hydrodynamically fully-developed flow at the entrance of the tube. Results were also obtained for the phase change process under hydro dynamically and thermally fully developed conditions. In case of a smooth circular tube with phase change material (PCM) fluid, results of Nusselt number were obtained by varying the bulk Stefan number. The Nusselt number results were found to be strongly dependent on the Stefan number. In the case of a finned tube two types of boundary conditions were studied. The first boundary condition had a uniform axial heat flux along the axis of the tube with a variable temperature on the peripheral surface of the tube. The second boundary condition had a constant temperature on the outer surface of the tube. The effective specific heat technique was again implemented to analyze the phase change process under both the boundary conditions. The Nusselt number was determined for a tube with two fins with different fin height ratios and fin thermal conductivity values. It was determined that the Nusselt number was strongly dependent on the Stefan number, fin thermal conductivity value, and height of the fins. It was also observed that for a constant heat axial flux boundary condition with peripherally varying temperature, the phase change slurry with the internally finned tube performed better than the one without fins. A similar trend was observed during the phase change process with internal fins under the constant wall temperature boundary condition.
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Wang, Teng-Yen, and 王登彥. "A Study of the Characteristic Behavior of Electro-Rheological Fluid Flow Through the Laminar Gap." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/57803266772531229818.
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碩士<br>國立成功大學<br>機械工程學系<br>86<br>This fluid has the property,what is called Electrorheological
fluid,that the viscosity of ER fluid will change reversiblely,
if the electric field strength is applied to ER fluid.Becauseof
dispersing the particles which cause a dielectric
polarization in the insulation oil.ER fluid shows as Newtonian
fluid behavior with no electric effect,when electric
fieldstrength is applied, ER fluid as Bingham plastic behavior.
In this study,the possibility to apply a manufactured fluid
control valve making use of the ER fluids and ER fluids to fluid
power system is considered.The characteristics of the ER valve
among the flowrate,the pressure drop and the electric field
strength are experimentally clarified.Dynamic characteristics of
the ER valve are experimentally clarified with the electric
field strength change stepwise.It is confirmed that the rise
time of the pressure is between 30-40ms.
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Blankenberger, Patricia Lynn. "The effect of fluid properties on the physical behavior of adiabatic annular two-phase flow." 2003. http://catalog.hathitrust.org/api/volumes/oclc/52906772.html.
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Hertel, Tobias. "On the time-analytic behavior of particle trajectories in an ideal and incompressible fluid flow." 2016. https://ul.qucosa.de/id/qucosa%3A17052.
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This (Diplom-) thesis deals with the particle trajectories of an incompressible and ideal fluid flow in 𝑛 ≥ 2 dimensions. It presents a complete and detailed proof of the surprising fact that the trajectories of a smooth solution of the incompressible Euler equations are locally analytic in time. In following the approach of P. Serfati, a complex ordinary differential equation (ODE) is investigated which can be seen as a complex extension of a partial differential equation, which is solved by the trajectories. The right hand side of this ODE is in fact given by a singular integral operator which coincides with the pressure gradient along the trajectories. Eventually, we may apply the Cauchy-Lipschitz existence theorem involving holomorphic maps between complex Banach spaces in order to get a unique solution for the above mentioned ODE. This solution is
real-analytic in time and coincides with the particle trajectories.
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Schneider, Julia 1981. "Compression and permeability behavior of natural mudstones." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4730.
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Mudstones compose nearly 70% of the volume of sedimentary basins, yet they are among the least studied of sedimentary rocks. Their low permeability and high compressibility contribute to overpressure around the world. Despite their fundamental importance in geologic processes and as seals for anthropogenic-related storage, a systematic, process-based understanding of the interactions between porosity, compressibility, permeability, and pore-size distribution in mudstones remains elusive.
I use sediment mixtures composed of varying proportions of natural mudstone such as Boston Blue Clay or Nankai mudstone and silt-sized silica to study the effect of composition on permeability and compressibility during burial. First, to recreate natural conditions yet remove variability and soil disturbance, I resediment all mixtures in the laboratory to a total stress of 100 kPa. Second, in order to describe the systematic variation in permeability and compressibility with clay fraction, I uniaxially consolidate the resedimented samples to an effective stress equivalent to about 2 km of burial under hydrostatic conditions. Scanning electron microscope images provide insights on microstructure.
My experiments illuminate the controls on mudstone permeability and compressibility. At a given porosity, vertical permeability increases by an order of magnitude for clay contents ranging from 59% to 34% by mass whereas compressibility reduces by half at a given vertical effective stress. I show that the pore structure can be described by a dual-porosity system, where one rock fraction is dominated by silt where large pores are present and the majority of flow occurs and the other fraction is dominated by clay where limited flow occurs. I use this concept to develop a coupled compressibility-permeability model in order to predict porosity, permeability, compressibility, and coefficient of consolidation. These results have fundamental implications for a range of problems in mudstones. They can be applied to carbon sequestration, hydrocarbon trapping, basin modeling, overpressure distribution and geometry as well as morphology of thrust belts, and an understanding of gas-shale behavior.<br>text
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Kondle, Satyanarayana. "Laminar Flow Forced Convection Heat Transfer Behavior of Phase Change Material Fluid in Straight and Staggered Pin Microchannels." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8493.
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Microchannels have been studied extensively for electronic cooling applications ever since they were found to be effective in removing high heat flux from small areas. The rate of heat removed using microchannels depends on many factors including the geometry shape, solid and fluid materials used, and surface roughness, among others. Many configurations of microchannels have been studied with various materials and compared for their effectiveness in heat removal. However, there is little research done so far in using Phase Change Material (PCM) fluids and pin fins in microchannels to enhance the heat transfer.
PCM fluids exhibit greater heat transfer when the phase change material undergoes liquid-to-solid transformation. Staggered pins in microchannels have also shown higher heat removal characteristics because of the continuous breaking and formation of the thermal and hydrodynamic boundary layer; they also exhibit higher pressure drop because pins act as flow obstructers.
This paper presents numerical results of circular, square, straight rectangular microchannels with various aspect ratios (1:2, 1:4 and 1:8), and rectangular microchannels with two characteristic staggered pins (square and circular, fixed height with no variation in aspect ratio). The heat transfer performance of a single phase fluid and PCM fluid in all of these microchannels and the corresponding pressure drop characteristics are also presented.
An effective specific heat capacity model was used to account for the phase change process of PCM fluid. Comparison of heat transfer characteristics of single phase fluid and PCM fluid are presented for all the geometries considered. Among the straight microchannels, 1:8 geometry was found to have the highest Nusselt number. The use of PCM fluid in straight microchannels increased the Nusselt number by 3-7 percent compared to the single phase fluids. Among the staggered pin microchannels, circular pins were found to be more effective in terms of heat transfer by exhibiting higher Nusselt number. Circular pin microchannels were also found to have lower pressure drop compared to the square pin microchannels. Overall, for all the geometries considered, it was found that the PCM fluid enhances the heat transfer compared to the SPF fluid.
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Hadisujoto, Budi Sutanto. "Control-oriented modeling of dynamic thermal behavior and two‒phase fluid flow in porous media for PEM fuel cells." Thesis, 2013. http://hdl.handle.net/2152/28727.
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The driving force behind research in alternative clean and renewable energy has been the desire to reduce emissions and dependence on fossil fuels. In the United States, ground vehicles account for 30% of total carbon emission, and significantly contribute to other harmful emissions. This issue causes environmental concerns and threat to human health. On the other hand, the demand on fossil fuel grows with the increasing energy consumption worldwide. Particularly in the United States of America, transportation absorbs 75% of this energy source. There is an urgent need to reduce the transportation dependence on fossil fuel for the purpose of national security. Polymer electrolyte membrane (PEM) fuel cells are strong potential candidates to replace the traditional combustion engines. Even though research effort has transferred the fuel cell technology into real‒world vehicle applications, there are still several challenges hindering the fuel cell technology commercialization, such as hydrogen supply infrastructure, cost of the fuel cell vehicles, on‒board hydrogen storage, public acceptance, and more importantly the performance, durability, and reliability of the PEM fuel cell vehicles themselves. One of the key factors that affect the fuel cell performance and life is the run‒time thermal and water management. The temperature directly affects the humidification of the fuel cell stack and plays a critical role in avoiding liquid water flooding as well as membrane dehydration which affect the performance and long term reliability. There are many models exists in the literature. However, there are still lacks of control‒oriented modeling techniques that describe the coupled heat and mass transfer dynamics, and experimental validation is rarely performed for these models. In order to establish an in‒depth understanding and enable control design to achieve optimal performance in real‒time, this research has explored modeling techniques to describe the coupled heat and mass transfer dynamics inside a PEM fuel cell. This dissertation is to report our findings on modeling the temperature dynamics of the gas and liquid flow in the porous media for the purpose of control development. The developed thermal model captures the temperature dynamics without using much computation power commonly found in CFD models. The model results agree very well with the experimental validation of a 1.5 kW fuel cell stack after calibrations. Relative gain array (RGA) was performed to investigate the coupling between inputs and outputs and to explore the possibility of using a single‒input single‒output (SISO) control scheme for this multi‒input multi‒output (MIMO) system. The RGA analyses showed that SISO control design would be effective for controlling the fuel cell stack alone. Adding auxiliary components to the fuel cell stack, such as compressor to supply the pressurized air, requires a MIMO control framework. The developed model of describing water transport in porous media improves the modeling accuracy by adding catalyst layers and utilizing an empirically derived capillary pressure model. Comparing with other control‒oriented models in the literature, the developed model improves accuracy and provides more insights of the liquid water transport during transient response.<br>text
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李嘉炎. "Fluid Flow Behavior and Thermal Optimization for a Stationary or Rotating Multi-Chip Module Disk with Various Types of Jet Impingement." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/55797296893883147021.
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博士<br>國立清華大學<br>動力機械工程學系<br>96<br>A series of experimental investigations with stringent measurement methods on the studies related to fluid flow and heat transfer characteristics of a stationary or rotating MCM disk with various types of jet impingement have been performed. The total experimental cases for a stationary or rotating MCM disk with various types of jet impingement are statistically designed by the Design of Experiments (DOE) together with Central Composite Design method (CCD). The relevant parameters influencing fluid flow and heat transfer performance for a stationary or rotating MCM disk with various types of single jet and jet array impingement include: steady-state Grashof number (GrH), ratio of jet separation distance to nozzle diameter (H/d), ratio of nozzle diameter to disk diameter (d/D), ratio of nozzle geometric-mean pitch to disk diameter ( /d), jet Reynolds number (Rej) and rotational Reynolds number (Rer).
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Lee, Chen-Chung, and 李臻誠. "Theoretical Analysis and Experiment of Fluid Flow of Slurry and Tribological Behavior in the Chemical Mechanical Polishing of a Silicon Wafer." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/35021057629794129619.
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碩士<br>國立成功大學<br>機械工程學系<br>87<br>Abstract
The theoretical model in Chemical Mechanical Polishing (CMP) is a new area that did not bring much attention until recently. This thesis introduced a theoretical model to study various aspects of this complicated problem. The model takes into account the effects of the friction coefficient, the removal rate of the wafer, the roughness factors and the flow field in the polishing fluid under different operating conditions. The features of this CMP model are the inclusion of the surface roughness and the detail analysis of the flow field. In the current model, the wafer is polished on the pad with roughness that resulted from the powder in the slurry. The flow equation is then derived from the Reynolds equation with roughness effect. The distribution of flow speed and the pressure (stress) in the wafer is the main focus. Based on this calculation, the film thickness, the hydrodynamic load and the drag force in the slurry were readily available. The analysis of the roughness depends on the powder and the friction force on the pad. Furthermore, normal pressure induced elastic-plastic deformation on the wafer as well as the elastic deformation on the pad are also considered. The analytic results are compared with the experimental findings and the agreement is good. Two different models are established : one is concentric model and the other is eccentric model. The former comes with experimental validation while the later is pure numerical parameter study. The chemical effect is neglected in this study.