Dissertations / Theses on the topic 'Hydrodynamic studies'
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1
Garcia, Antonio Diego Molina. "Hydrodynamic studies on microorganisms." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303987.
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Gandhi, Bimal C. "Hydrodynamic studies in a slurry bubble column." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq28573.pdf.
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Ang, Shirley. "Hydrodynamic studies on polysaccharides and their interactions." Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508221.
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Dhami, Rajesh. "Hydrodynamic studies of xanthan and xylan systems." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321379.
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Walters, Chris. "Hydrodynamic studies on chaperonins and related molecular assemblies." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368342.
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Johnson, Lowell Morgan. "Hydrodynamic flowfield visualization studies of a Mach 6 waverider." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283445.
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Thesis (M.S. in Aeronautical Engineering) Naval Postgraduate School, March 1994.Thesis advisor(s): Conrad F. Newberry ; J.V. Bowles. "March 1994." Includes bibliographical references. Also available online.
7
Edington, David W. N. "Spectroscopic studies of anomalous hydrodynamic behaviour in complex fluids." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/2789.
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Brillouin spectroscopy probes the thermally generated pressure fluctuations (sound waves) which propagate in a material. The resulting information on sound velocity and absorption provides a fast and efficient method of monitoring high frequency (GHz) dynamics in the system being studied. In certain cases, structural information may also be inferred from changes in the Brillouin spectrum as a function of temperature, pressure or composition (in the case of multi-component systems). The aim of the work presented in this thesis was to integrate Brillouin spectroscopy into current soft condensed matter research projects at Edinburgh, namely (i) hydration in methanol-water mixtures and (ii) the behaviour of hard-sphere colloidal dispersions. A Brillouin spectrometer based on a Fabry-Perot interferometer was developed and tested, resulting in a high-resolution instrument operating at variable scattering vector (exchanged momentum), temperature and pressure. The technical aspects of this work were carried out in collaboration with a colleague. Data analysis routines were designed and implemented, enabling calibrated Brillouin spectra to be produced automatically from raw experimental data. Excellent agreement with results on several materials studied in the literature confirmed the accuracy and sensitivity of the spectrometer. The molecular details of hydration in methanol-water mixtures are of great interest due to the prototypical amphiphilic nature of the methanol molecule. The effect of deep cooling on the Brillouin spectrum across a wide range of methanol concentrations was studied in detail, resulting in the first observation of an anomalous increase in sound velocity and maximum in sound absorption at intermediate compositions. A similar effect was then found at higher temperature in aqueous tertiary butanol, and was identified in a brief survey of several other aqueous solutions. High pressure Brillouin spectra indicate that this anomalous behaviour may also be present in pure water. It is suggested that these novel effects may be due to the presence of a relatively unperturbed water structure in the aqueous solutions studied, even at quite high solute concentration. Preliminary results from a neutron diffraction experiment performed on a 40% by mass methanol-water mixture were consistent with this hypothesis. Brillouin spectroscopy was also used to study the propagation of high frequency sound in monodisperse colloidal suspensions of sub-micron hard spheres. A second longitudinal sound mode was observed for scattering vectors of magnitude greater than pi/d where d is the diameter of the spheres. These results are the first reproduction and extension of the pioneering work in the field, which identified the additional mode with a surface acoustic excitation, propagating between adjacent spheres via an evanescent wave in the solvent. The new results show that the second mode is extinguished at a particular scattering vector - an effect not reported previously. It is suggested that this extinction is due to the minimum in the form factor for elastic scattering from a single sphere.
8
Luttrell, Gerald H. "Hydrodynamic studies and mathematical modeling of fine coal flotation." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49828.
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Liang, Shu-Chien. "Studies on hydrodynamic interactions between particles in liquid-solid systems /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487930304685987.
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Lin, Chia-Po. "Experimental studies of the hydrodynamic characteristics of a sloped wave energy device." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/7521.
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Many wave energy convertors are designed to use either vertical (heave) or horizontal (surge) movements of waves. But the frequency response of small heaving buoys and oscillating water column devices shows that they are too stiff and so their resonance is at too short a period. A device moving in the horizontal (surge) direction has less restoring spring and so its resonance is at too long a period. It follows that a device that moved at some intermediate slope angle could have an intermediate value of hydrodynamic stiffness and so be resonant at a variable and desirable part of the wave spectrum. There have been two series of model tests in this work. The first used a simple free-floating model with no power take-off apparatus and with constraint achieved by means of a large inertia plate lying in the slope plane. The second used a rig that constrained the slope movement of the buoy head by means of hydrostatic bearings running on a guide rod set to the chosen slope angle. An external power take-off system was used to simulate a linear damper for absorbing the incident wave energy and control the motion of the model. This thesis firstly studies the potential of varying the slope angle as a way of tuning the natural period of the device to suit useful wave periods. Secondly, it studies the experimental and theoretical power capture ability of models with different slope angles in regular waves in the frequency domain. The hydrodynamic coefficients of the model were determined both experimentally and numerically based on linear hydrodynamic concepts. The power absorption of the models was calculated using the experimental data of the hydrodynamic coefficients and also measured directly. Some control of power take-off was also investigated. Some irregular wave tests were carried out for the 45 degrees slope angle case. The results show that it is feasible to alter the slope angle of the device as a way of tuning its natural period. However, in further studies of the power capture ability for different slope angles, the device shows a very wide bandwidth and high efficiency performance when it is set to 45 degrees slope angle. This suggests that to constrain the device to a 45 degrees slope angle is suitable for most of the sea states.
11
Chia-Po, L. "Experimental studies of the hydrodynamic characteristics of a sloped wave power device." Thesis, University of Edinburgh, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.642804.
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Many wave energy convertors are designed to utilise either vertical (heave) or horizontal (surge) movements of waves. But the frequency response of small heaving buoys and oscillating water column devices shows that they are too stiff and so their resonance is at too short a period. A device moving in the horizontal (surge) direction has less restoring spring and so its resonance is at too long a period. It follows that a device that moved at some intermediate slope angle could have an intermediate value of hydrodynamic stiffness and so be resonant at a variable and desirable part of the wave spectrum. There have been two series of model tests in this work. The first used a simple free-floating model with no power take-off apparatus and with constraint achieved by means of a large inertia plate lying in the slope plane. The second used a rig that constrained the slope movement of the buoy head by means of hydrostatic bearings running on a guide rod set to the chosen slope angle. An external power take-off system was used to simulate a linear damper for absorbing the incident wave energy and control the motion of the model. The thesis firstly studies of the potentiality of varying the slope angle as a way of tuning the natural period of the device to suit wave conditions. Secondly, it studies of the experimental and theoretic at power capture ability of models with different slope angles in regular waves in the frequency domain. The hydrodynamic coefficients of the model were determined both experimentally and numerically based on linear hydrodynamic concepts. The power absorptions of the models were calculated using the experimental data of the hydrodynamic coefficients and also measured directly. Some control of power take-off were also investigated. Some irregular wave tests were carried out for the 45 degrees slope angle case.
12
Mohan, Aruna 1981. "Studies on the hydrodynamic equations based on the theory of diffusive volume transport." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29377.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, June 2004.Includes bibliographical references (leaves 41-42).
A recently formulated continuum theory has postulated that the momentum per unit volume of fluid differs from the mass flux whenever there are density gradients in the fluid resulting from the molecular transport of heat or mass. In such cases, the Navier-Stokes equations are unable to correctly predict the continuum fields and observed flow phenomena. A new set of continuum equations has been postulated to take into account density inhomogeneities in the fluid, and the consequent difference between the fluid's momentum per unit mass and mass velocity. In this thesis, the modified set of continuum equations is used to solve problems related to fluid flow in the presence of heat and mass transport. Additionally, this thesis includes a comparison between the momentum per unit volume and the mass flux of a fluid calculated from the generalized kinetic equation of Klimontovich.
by Aruna Mohan.
S.M.
13
White, Darren Mark. "Lattice Bhatnagar-Gross-Krook studies of hydrodynamic and thermohydrodynamic internal pressure-driven flows." Thesis, Sheffield Hallam University, 1999. http://shura.shu.ac.uk/20525/.
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In this thesis we develop applications of Lattice-Bhatnagar-Krook (LBGK) models to incompressible flow problems. We show that in geometries where flow is forced via application of a pressure difference, a modified Exactly Incompressible LBGK (EILBGK) scheme must be applied if significant pressure variations occur. We analyse the model's representation of the no-slip wall boundary condition for flow in a straight duct and recover a friction factor in excellent agreement with theory. Simulation of flow over a backward-facing step produces good agreement with other numerical techniques. We propose two new LBGK schemes, one directed towards the calculation of depth-averaged flow quantities and the other which focusses on thermal flows in the Boussinesq-Oberbeck limit. Depth-averaged flow facilitates the two-dimensional simulation of three-dimensional ducts of constant depth. The effect of the unmodelled dimension is accounted for by including momentum sinks in the momentum equations. We apply the scheme to flow in a bifurcating duct and results are again in good agreement with other numerical methods. We develop a thermal model in which energy is treated efficiently as a passively advected scalar quantity. This approach results in a model which is more simpleand robust than other previously reported LBGK thermal models. Our scheme is then validated by application to flow in a straight duct with constant heat flux applied at the walls. Excellent agreement with theoretical predictions is obtained for the calculated Nusselt number.
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Garcia-Briones, Miguel Angel. "Studies on the characterization of the hydrodynamic environment in sparged animal cell cultures /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859313346956.
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Tedjakusuma, Teddy. "Hydrodynamic and dispersion studies in an estuary physical model incorporated with an idealized groundwater." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/110465/.
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A study on hydrodynamic and dispersion has been undertaken in an estuary physical model. The model represented the Severn Estuary in the UK which has the second largest tidal range in the world. The scale of the model was 1:125 vertically and 1:25,000 horizontally. Experiments in nine sample points showed that water level was different in those points. Velocity measurements showed that the velocity in the physical model coild be analysed using the wave resonance theory. The velocity profile measurements showed that the balance between ebb and flood tide, and this balance were different in different sampling points. The experiments were then compared to the computer modelling results. The water level model showed accordance with the experimental results. The velocity model results were then calibrated using several parameters, namely n-Manning, COED, and momentum correctioncoefficient (β). The calibration was then continued by the refinement of boundary condition and bathymetry. Studies on dispersion in the estuary physical model revealed that longitudinal dispersion coefficient affected the dispersion significantly, while the lateral turbulent diffusion affected the dispersion less significantly. Constant dispersion coefficient was compared with the variable dispersion coefficient, and the results showed that the constant dispersion coefficient gave a better representation of the dispersion process. Studies were also undertaken in an idealized groundwater which was linked to the estuary physical model. The static and dynamic conditions of the groundwater were studied. For static condition which was also undertaken to calibrate the water level probes, the change of water level in the groundwater clearly followed the changes in the estuary water levels, with a delay of water level according to the distance between the borehole and the estuary boundary. Dynamic condition of the groundwater as a results of tide in the estuary clearly shows the phase difference and the tide range at each borehole according to their distance to the estuary boundary. The effect between pump and tide was studied, and this showed clearly the effects of each component on groundwater level. Through Darcy’s analysis it was proved that the groundwater hydrodynamics follow the Darcy’s principle. Finally the dispersion in the groundwater were studied using two scenarios, namely open-open boundary and close-open boundary. Analysis results showed that open-open boundary gave lower dispersion coefficient than the close-open boundary.
16
Borren, Bojana [Verfasser]. "Studies on hydrodynamic strategies for intensification of mass transfer in trickle-bed reactors / Bojana Borren." München : Verlag Dr. Hut, 2012. http://d-nb.info/1028783752/34.
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Rinderknecht, Hans G. "Studies of non-hydrodynamic processes in ICF implosions on OMEGA and the National Ignition Facility." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99291.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
Ion kinetic effects are expected to modify plasma dynamics when ion mean-free-paths and collision times become comparable to the scale sizes of the plasma. Such conditions arise during the shock convergence phase of inertial confinement fusion (ICF) implosions, when they may modify the compression and ignition of the fuel from the evolution predicted by main-line hydrodynamic simulations. Kinetic plasma dynamics relevant to ICF implosions have been studied experimentally using strongly-shocked ICF implosions containing multiple ion species, and diagnosed using both new and established nuclear diagnostics and techniques. Implosions of deuterated plastic shells filled with equivalent-mass-density mixtures of deuterium and 3He gas have demonstrated for the first time ion diffusive mixing of the fuel and shell material through observations of the D3He-proton and DD-neutron yields. Implosions with initially separated populations of D in the shell and 3He in the gas produced D3He-fusion from the mixed region on par with implosions filled with equimolar D3 He fuel and an order of magnitude larger than is produced by hydrodynamic models of fuel/shell mix. An extensive survey of kinetic mix- and yield-generation mechanisms and their signatures in nuclear diagnostics establishes ion diffusion as the best candidate to explain these observations. A series of shock-driven implosions of D3He-gas filled glass shells has demonstrated two signatures of significant ion kinetic plasma effects for the first time: ion thermal decoupling and ion species separation. In low-initial gas density implosions, for which the thermal equilibration times were much longer than the burn duration, the burn-averaged ion temperatures were observed to be anomalously invariant with ion species fraction. This behavior has been shown to signify thermal decoupling of the D and 3He ion species between the shock- and fusion-phases. Comprehensive nuclear diagnostic information has been used to infer the burn-averaged deuterium fraction, which was reduced from the expectations of hydrodynamic simulations, the first direct measurement of species separation in an ICF implosion. When corrected for these effects, simulations agreed better with the observed anomalously low nuclear yields. These results have demonstrated the significant modification of ICF-relevant shocked plasmas by kinetic plasma dynamics, motivating further experimental and theoretical investigation of these highly dynamic and poorly understood regimes.
by Hans G. Rinderknecht.
Ph. D.
18
Shojaei, Nasim. "Automatic Calibration of Water Quality and Hydrodynamic Model (CE-QUAL-W2)." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1942.
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One of the most important purposes of surface water resource management is to develop predictive models to assist in identifying and evaluating operational and structural measures for improving water quality. To better understand the effects of external and internal nutrient and organic loading and the effects of reservoir operation, a model is often developed, calibrated, and used for sensitivity and management simulations. The importance of modeling and simulation in the scientific community has drawn interest towards methods for automated calibration. This study addresses using an automatic technique to calibrate the water quality model CE-QUAL-W2 (Cole and Wells, 2013). CE-QUAL-W2 is a two-dimensional (2D) longitudinal/vertical hydrodynamic and water quality model for surface water bodies, modeling eutrophication processes such as temperature-nutrient-algae-dissolved oxygen-organic matter and sediment relationships. The numerical method used for calibration in this study is the particle swarm optimization method developed by Kennedy and Eberhart (1995) and inspired by the paradigm of birds flocking. The objective of this calibration procedure is to choose model parameters and coefficients affecting temperature, chlorophyll a, dissolved oxygen, and nutrients (such as NH4, NO3, and PO4). A case study is presented for the Karkheh Reservoir in Iran with a capacity of more than 5 billion cubic meters that is the largest dam in Iran with both agricultural and drinking water usages. This algorithm is shown to perform very well for determining model parameters for the reservoir water quality and hydrodynamic model. Implications of the use of this procedure for other water quality models are also shown.
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Hamid, Adnan. "Direct Numerical Simulation Studies of Sedimentation of Spherical Particles." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188621.
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Driscoll, Mark D. "Effects of hydrodynamic regime on photosynthesis in the green alga Caulerpa." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000598.
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Kuutmann, Andrej. "Photo-evaporation of Globulettes : Numerical hydrodynamic studies of photo-evaporating low-mass globules in the Rosette Nebula." Thesis, Stockholm University, Department of Astronomy, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8354.
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In this work, the long-term evolution of globulettes, low-mass globules found in H II regions, is studied through numerical hydrodynamic simulations. It has been proposed by Gahm et al. (2007) that these clouds may form free-floating planetary mass objects due to shock compression, caused by heating from the intense UV radiation of the central OB star cluster. To address this possibility, lifetimes are calculated for three different 3D simulated cases, similar to globulettes found in the Rosette Nebula. A plane-parallel approximation of the radiation field is used, as well as an inhomogeneous initial density distribution. The ionizing radiation will cause the globulettes to photo-evaporate, creating a rocket acceleration effect from the mass ejected on the heated side of the cloud. For a typical globulette with an initial mass of 29.5 Jupiter masses a lifetime of 50 000 yrs is estimated. This estimate is compared to the analytical models of Mellema et al. (1998) and Bertoldi and McKee (1990) which suggest longer lifetimes; the discrepancy is attributed to fragmentation of the clouds in the numerical simulation, which is not adequately described by the models. Synthesized H-alpha images and lightcurves are presented, indicating that the bright rims of small clouds are only likely to be visible in dim parts of the Rosette Nebula. The morphology of simulated clouds generally agrees with observations. While the code does not include self-gravity, the gravitational stability of the clouds is studied indirectly. It is concluded that clouds in the planetary mass range are stable against gravitational collapse, from supporting thermal pressure alone, when in pressure equilibrium with the heated ionization front. However, gravity may play a significant role during the initial shock compression.
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Ma, Ningning. "Quantitative studies of the bubble-cell interactions and the mechanisms of mammalian cell damage from hydrodynamic forces /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486459267518873.
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Al-Zubaidi, Hussein Ali Mahdi. "3D Hydrodynamic, Temperature, and Water Quality Numerical Model for Surface Waterbodies: Development, Verification, and Field Case Studies." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4500.
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Numerical modeling has become a major tool for managing water quality in surface waterbodies such as rivers, lakes, reservoirs, and estuaries. Since the two-dimensional longitudinal/vertical model CE-QUAL-W2 is a well-known model and it has been applied to thousands of waterbodies around the world successfully, its numerical scheme was adapted to develop a new three-dimensional numerical model for simulating hydrodynamics, temperature, and water quality in surface waterbodies. Finite difference approximations were used to solve the fluid dynamic governing equations of continuity, free water surface, momentums, and mass transport. No coordinate transformations were performed and the z-coordinate system has been used. Higher-order schemes (QUICK, QUICKEST, and ULTIMATE QUICKEST) in addition to the UPWIND scheme were used for the advective temperature and mass transport. A novel numerical approach was used for the numerical formulation of the three-dimensional scheme. This approach forced the numerical solution of the free surface equation to be a tri-diagonal matrix form rather than a more computationally intensive penta-diagonal matrix solution. This new approach was done by linking a method called line-by-line with the free water surface numerical solution. Another new approach was that the three-dimensional numerical scheme involved a simultaneous solution of hydrodynamics, temperature, and water quality at every model time level instead of saving the hydrodynamic results to be used later for water quality simulation. Hence, this scheme allowed feedback between the hydrodynamics and water quality every time step. In addition, various unique numerical algorithms were employed from CE-QUAL-W2 such as the W2 turbulence model, selective withdrawal theory, surface heat fluxes, and water quality sources and sinks, making the three-dimensional model built on well-tested algorithms.
To test the model structure and assumptions, an analytical verification was performed by comparing model predictions to known analytical exact solutions test cases. Good agreement was showed by the model for all of these tests. A computation of the volume balance over the simulation period was also incorporated within the model to assess how well the code performed. Sensitivity tests were also made varying bed and wind shear.
The model was also applied to three reservoirs in the USA as field case studies: Lake Chaplain in WA, Laurance Lake in OR, and Cooper Creek Reservoir in OR. The model was validated by comparing the model predictions of water levels, velocities, vertical temperature profiles, and dissolved oxygen with field data. Through these real applications, the numerical predictions of the 3D model showed good agreement with field data based on error statistics. The model results of each field case study were discussed separately. In the Lake Chaplain model application, the study was focused on the importance of the higher-order schemes compared to the first-order UPWIND scheme. The model predictions of temperature were determined by using the UPWIND, QUICK, and QUICKEST scheme and compared with field data. The Error statistics of the model predictions compared to field data were an absolute mean error (AME) of 0.065 m for the water level predictions and an overall AME of 1.62 °C, 1.09 °C, and 1.23 °C for the temperature predictions by using the UPWIND, QUICK, and QUICKEST scheme, respectively. In the Laurance Lake model application, a comparison was performed between the present 3D model and the 2D CE-QUAL-W2. Since the 3D model was build based on CE-QUAL-W2, differences between the two models were evaluated. Error statistics between the model predictions of water level and temperature compared to field data showed that both models were in good agreement with field data. However, the 3D model AME (0.30 m for the water level predictions and 0.48 °C for the temperature predictions) was higher than the 2D model (0.03 m for the water level predictions and 0.42 °C for the temperature predictions). Finally, the Cooper Creek Reservoir case study was done to show the model predictions of temperature and dissolved oxygen. In this application, vertical temperature profiles were covered the entire simulation period in order to show how the model transfer heat between stratification and non- stratification conditions. The model showed good agreement with field data (0.12 m AME for the water level predictions, 1.00 °C overall AME for the temperature predictions, and 1.32 g/m3 overall AME for the dissolved oxygen predictions).
Finally, comparisons were made between CE-QUAL-W2 and the 3D model. The 2D model generally performed better in the tests cases if the model user is unconcerned about lateral impacts. The 3D model is important to use when lateral currents and variation in the lateral dimension are important.
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Van, Glubt Sarah. "Hydrodynamic and Water Quality Modeling of the Chehalis River Using CE-QUAL-W2." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3486.
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The Chehalis River Basin is located in the southwest region of Washington State, originating in the Olympic Mountains and flowing to Grays Harbor and the Pacific Ocean. The Chehalis River is over 125 miles, exists within five counties, and flows through agricultural, residential, industrial, and forest land areas. Four major rivers discharge to the Chehalis River, as well as many smaller creeks, five wastewater treatment plants, and groundwater flows.
Flooding is a major problem in the relatively flat areas surrounding the cities of Chehalis and Centralia, with severe consequences for property, safety and transportation. As a result, construction of a flood-control dam in the upper basin has been proposed. One major concern of constructing a dam is the potentially severe impacts to fish health and habitat. The Chehalis River has routinely violated water quality standards for primarily temperature and dissolved oxygen, and has had multiple water quality and Total Maximum Daily Load studies beginning in 1990.
CE-QUAL-W2, a two-dimensional (longitudinal and vertical) hydrodynamic and water quality model, was used to simulate the Chehalis River, including free flowing river stretches and stratified (in summer) lake-like stretches. The goals of this research were to assess the flood retention structure's impacts to water quality, as well as river responses to potential climate change scenarios.
In order to use the model to achieve these goals, calibration to field data for flow, temperature, and water quality constituents was performed. This involved developing meteorological data, riparian shading data, and flow, temperature, water quality records for all tributaries during the calibration period of January 1, 2013 to December 31, 2014. System cross-sectional geometry data were also required for the model grid. Because of the short travel time in the river, the model was sensitive to boundary condition data, wind speed, bathymetry, nutrient kinetics, and algae, epiphyton, and zooplankton kinetics.
Future conditions showed predictions of warmer water temperatures and slight changes to water quality conditions on the river. As fish in the area prefer cooler water temperatures, this could pose a threat to fish health and habitat. Flood retention structures also showed impacts to river temperature and water quality. Structures with the purpose of flood retention only (only operating during times of flooding) gave model predictions for daily maximum temperature higher than structures that employed flood retention and flow augmentation (operating during all times of the year). This suggested the management of flow passage or retention by the dam is important for water quality on the river.
As this research continues improvements will be made, particularly to temperature and water quality constituents. Additional data for the system would be beneficial to this process. Model predictions of temperature were sensitive to meteorological data, including cloud cover, which were largely estimated based on solar radiation. Additional meteorological data throughout the basin would be useful to temperature results. Temperature results were also sensitive to the model bathymetry, and additional investigations into segments widths and water depths may improve temperature predictions.
Water quality constituent data were largely lacking for the system. Many estimation techniques and approximations were used for input water quality constituents for the model upstream boundary and tributaries when little or no data were available, introducing uncertainty to the model. It was not possible to calibrate pH to field data because alkalinity data were essentially unavailable. However, other constituents had good agreement between model predictions and field data, including dissolved oxygen, nitrates, total phosphorus, and total suspended solids.
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Inga, Juan Ricardo. "Hydrodynamic studies and reactor modelling of a three phase slurry reactor in Fischer Tropsch application / Juan Ricardo Inga." Thesis, Potchefstroom University for Christian Higher Education, 1992. http://hdl.handle.net/10394/9611.
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In this .study the hydrodynamic characteristics of the slurry bed
reactor was investigated. This study was aimed to the under"
standing of the important parameters that describe the
hydrodynamic regime and their quantification.
In order to determine the relevant parameters the use of a
theoretical model was necessary. This model should include all
the hydrodynamic parameters in form of correlations. A sensitivity
study was done and the parameters which have great impact were
determined.
An extensive literature review was done in order to gather the
experience of previous investigations. Unfortunately all the
experience was obtained in a different hydrodynamic regime and
therefore the published results could not be used directly in
our study.
Hydrodynamic test were performed in the works pilot plant at the
operating conditions. Unlike a laboratory, the instrumentation
used was the one use in commercial reactors with the commercially
acceptable range of accuracy. A mass balance was done around the
reactor to ensure that the data was sound.
Heat balance was also performed and the study of the heat transfer
coefficient was performed. Although this was beyond the scope
of this study was here included due to its importance in the
design of slurry bed reactors.
An existing computer model was adapted for the churn-turbulent
regime and the hydrodynamic parameters were implemented. This
reactor model was coupled with flashes subroutines in order to
have a complete reactor train. This computer model was used
for the design of the Slurry Bed Commercial Reactor to be commissioned
on 1993 at Sasol One.Thesis (MIng (Chemies))--PU for CHE, 1993
26
Pan, Guangdong. "Electromagnetic Backscattering Studies of Nonlinear Ocean Surfaces." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1204559229.
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Xu, Wenwei. "Development of a Steady-State River Hydrodynamic and Temperature Model Based on CE-QUAL-W2." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1619.
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CE-QUAL-W2 is a 2-D hydrodynamic and water quality model that has been applied to reservoirs, lakes, river systems, and estuaries throughout the world. However, when this model is applied for shallow systems, this model requires a long calculation time to maintain numerical stability, compared to applications of reservoirs or deeper river systems.
To solve this problem, a new hydrodynamic and temperature model was built based on the framework of CE-QUAL-W2 but that allows for steady-state hydrodynamic computations. By calculating the hydrodynamics at steady-state, the time step for stability is relaxed and simulations can proceed at much higher time steps. The rest of the model framework is still used for water quality state variables, in this case, temperature. The algorithm used for computing the water surface elevation is Manning's equation.
This thesis study is one part of the Willamette Water 2100 project (Santelmann et al., 2012), which examines hydrological, ecological, and human factors affecting water scarcity in the Willamette River Basin. This study included three stages: (1) Convert six existing CE-QUAL-W2 V3.1 models into a newer version: CE-QUAL-W2 V3.7. (2) Develop the steady-state model code in FORTRAN. (3) Test the steady-state model on three river systems in the Willamette River Basin at Year 2001 and 2002.
The result proved that the steady-state model could reduce the computing time by 90% for river applications, while predicting dynamic river temperature with high accuracy at a two-minute time scale. This new model will be employed to simulate the future of the Willamette River System at a decadal or centennial timescales, addressing river temperature concerns and fish habitat issues.
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Shendruk, Tyler. "Theoretical and Computational Studies of Hydrodynamics-based Separation of Particles and Polymers in Microfluidic Channels." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30423.
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The advent of microfluidic technology presents many difficulties but also many opportunities for separation science. Leveraging the potential of micro- and nanofluidic geometries is not only a matter of shrinking systems. Miniaturization can shift the relative importance of physical phenomena leading to separation. Theoretical and computational studies into the consequences of miniaturization are vital. Mesoscopic, multi-particle collision dynamics simulations are performed on polyelectrolytes and hard, colloidal solutes. Multiple variations of this simulation algorithm are implemented to achieve versatility for simulating non-equilibrium flows and dispersed solutes. The algorithm is extended to simulate the effects of finite Debye layers on the electro-hydrodynamics of electrophoresing macromolecules and used to study the electrophoresis of charged oligomers, polyelectrolytes and polyampholytes in both free-solution and confined geometries. Multi-particle collision dynamics simulations of hydrodynamic chromatography and field-flow fractionation are also performed to test the predictions of the derived unified, ideal retention theory. This unified, ideal retention predicts the transitions between multiple operational modes, including Faxén-mode FFF. Simulations and the theory show that increases in drag due to hydrodynamic interactions with microfluidic channel walls perturb the retention curves from the ideal predictions at large particle sizes. Further complications to field-flow fractionation including undesirable forces perpendicular to the flow direction, slip at channel walls and rectangular channel geometries are investigated. These theoretical studies lead to the proposal of several novel fractionation techniques, namely adverse-mode FFF, slip-mode FFF and polymer/depletant HC.
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Bidwe, Ajay Ramesh [Verfasser], and Günter [Akademischer Betreuer] Scheffknecht. "Hydrodynamic studies of the dual fluidized bed reactor systems for high temperature solid looping cycles / Ajay Ramesh Bidwe ; Betreuer: Günter Scheffknecht." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2017. http://d-nb.info/1150705086/34.
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Meyers, Alison Cheryl. "Depositional Dynamics in Seagrass Systems of Tampa Bay, FL: Influence of Hydrodynamic Regime and Vegetation Density on Ecosystem Function." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1714.
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Many coastal ecosystems around the world are dominated by submerged aquatic vegetation (SAV) habitats. These SAV habitats are known to provide many highly valuable ecosystem services such as habitat for commercial important species and increased water clarity. Water flow is an environmental variable which can have measurable effects on the ecosystem services provided by SAV, but is often not considered in studies assessing these services. This dissertation sought to investigate the links between SAV, primarily seagrasses, and hydrodynamics, paying special attention to the effects on sediments and fauna. Three main areas are discussed: (1) the effects of SAV on flow, (2) the effects of SAV and flow on deposition in SAV beds, and (3) the effects of SAV and flow on faunal communities in SAV beds. Seagrasses and other SAV reduce currents, attenuate waves, and dampen turbulence within their vegetative canopies, which in turn can enhance deposition and reduce the resuspension of sediment, organic matter, and passively settling larvae. The ability of SAV to retard flow may be further enhanced by increases in vegetated structure, such as shoot density, biomass, or canopy height, which can promote increased abundance and diversity of in- and epifauna within SAV beds. Ultimately, it is clear that hydrodynamics is an important factor that shapes SAV communities both physically (e.g. deposition, sediment structure, etc.) and biologically (e.g. faunal community composition, predation pressure, food availability, etc.).
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Scheck, Leonhard [Verfasser], Hans-Thomas Akademischer Betreuer] Janka, and Andrzej [Akademischer Betreuer] [Buras. "Parametric Studies of Hydrodynamic Instabilities in the Supernova Core by Two- and Three-Dimensional Simulations / Leonhard Scheck. Gutachter: Andrzej Jerzy Buras. Betreuer: Hans-Thomas Janka." München : Universitätsbibliothek der TU München, 2006. http://d-nb.info/105886596X/34.
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Cornelisen, Christopher David. "Nutrient Uptake by Seagrass Communities and Associated Organisms: Impact of Hydrodynamic Regime Quantified through Field Measurements and use of an Isotope Label." [Tampa, Fla. : s.n.], 2003. http://purl.fcla.edu/fcla/etd/SFE0000079.
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Dobrovolný, Martin. "Konstrukční studie axiálních bezucpávkových čerpadel." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378388.
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Review of axial hydraulic machines and elementary procedures of design hydraulic machines are listed in the first part of thesis. Second part is dedicated axial pump with annular motor and measurement its characteristic curve. In the third part of thesis, procedure of design axial pump with tube motor is described, also there are listed CFD results and characteristic curve of axial pump with tube motor is predicted.
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Baran, Oleh. "Numerical studies of thermal hydrodynamics." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36873.
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We introduce and study new lattice gas models of hydrodynamics to simulate thermal fluids in non-equilibrium. The new approach consists in modifying the conventional Lattice Gas Cellular Automata method for fluids by removing the constraints of the Fermi exclusion principle and by introducing internal potential energy levels for the particles. These modifications allow the effective employment of Monte-Carlo dynamics for the evolution of the models, so that the temperature is defined in a natural way, and the introduction of interactions becomes straightforward.Because the transport properties of fluids determine their behavior in non-equilibrium, we study in detail the effect of our modifications on transport coefficients. We derive expressions for these coefficients in two ways: from Chapman-Enskog expansions and from linear response theory. Because of the potential energy, the transport properties are more similar to those of real fluids than are conventional LGCA models with kinetic energy only: the bulk viscosity is non-zero and thermal diffusion is well defined over a range of densities and temperatures.
We construct several models to illustrate the advantages and implications of our approach. One model is used to study the local temperature distribution in a simulation of Rayleigh Benard convection. Another is used to introduce interactions between particles and to simulate the 1st order phase separation of a fluid into the regions of low and high density. This latter model is also used to study the dynamics of interfaces between the phases. We observe the effects of inertia at the interface and demonstrate that the mean square width of an initially flat interface scales as t3/2 for late times t.
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Brynjell-Rahkola, Mattias. "Studies on instability and optimal forcing of incompressible flows." Doctoral thesis, KTH, Stabilitet, Transition, Kontroll, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-218172.
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This thesis considers the hydrodynamic instability and optimal forcing of a number of incompressible flow cases. In the first part, the instabilities of three problems that are of great interest in energy and aerospace applications are studied, namely a Blasius boundary layer subject to localized wall-suction, a Falkner–Skan–Cooke boundary layer with a localized surface roughness, and a pair of helical vortices. The two boundary layer flows are studied through spectral element simulations and eigenvalue computations, which enable their long-term behavior as well as the mechanisms causing transition to be determined. The emergence of transition in these cases is found to originate from a linear flow instability, but whereas the onset of this instability in the Blasius flow can be associated with a localized region in the vicinity of the suction orifice, the instability in the Falkner–Skan–Cooke flow involves the entire flow field. Due to this difference, the results of the eigenvalue analysis in the former case are found to be robust with respect to numerical parameters and domain size, whereas the results in the latter case exhibit an extreme sensitivity that prevents domain independent critical parameters from being determined. The instability of the two helices is primarily addressed through experiments and analytic theory. It is shown that the well known pairing instability of neighboring vortex filaments is responsible for transition, and careful measurements enable growth rates of the instabilities to be obtained that are in close agreement with theoretical predictions. Using the experimental baseflow data, a successful attempt is subsequently also made to reproduce this experiment numerically. In the second part of the thesis, a novel method for computing the optimal forcing of a dynamical system is developed. The method is based on an application of the inverse power method preconditioned by the Laplace preconditioner to the direct and adjoint resolvent operators. The method is analyzed for the Ginzburg–Landau equation and afterwards the Navier–Stokes equations, where it is implemented in the spectral element method and validated on the two-dimensional lid-driven cavity flow and the flow around a cylinder.QC 20171124
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Parameswaran, Gopalkrishnan. "Smoothed Particle Hydrodynamics studies of heap leaching hydrodynamics and thermal transport." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/39879.
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This thesis is concerned with the development and application of Smoothed Particle Hydrodynamics (SPH) models for studying multiphase flows such as those relevant to the analysis of the hydrodynamics and thermal transport involved in heap leaching. The improvements made here to the modelling aspects of multiphase SPH are seen to bring about measurable improvements to solution quality. A relative density formulation and a 'compressibility-matching' method for handling interfaces eliminate what would otherwise be significant obstacles to obtaining stable and smooth pressure fields. The convergence properties of the formulation are seen to approach the theoretically expected value in SPH. Convergence is also seen to strongly depend on the smoothing length factor used. A factor found to influence error magnitudes that nevertheless does not affect convergence rates is the extent of initial particle disorder. The simplified cases representative of heap leaching hydrodynamics studied through 2D simulations allow an understanding of flow at the particle scale. The significant dependence of mean flow rates in these systems on particle sizes, saturation and contact angle is shown. In 3D, saturated flows through packed beds of spherical particles are presented. Steady-state superficial velocities obtained through simulations, compared with analytical relationships given by Cozeny-Karman and Ergun relations are illustrative of the ability of SPH to reproduce packed bed flows satisfactorily. Subsequently unsaturated regimes encountered at the channel scale are studied qualitatively for saturation values typical of real heaps. A heat transfer model based on a formulation for single-phase SPH developed by Szewc et al. is implemented. The model's performance (in terms of Rayleigh numbers indicative of transition to unsteady convection in differentially heated cavities (DHCs)) is satisfactory when compared with the established single-phase results of Le Quere. Its application to an idealised unsaturated scenario demonstrates its useability for multiphase studies. Finally, an extension is made to the model to account for turbulent regime heat transport. This extension, deriving from one used for finite elements by Chatelain et al. is novel in the SPH context and lets the loss of stratification seen in DHCs at high Rayleigh numbers be predicted with reasonable accuracy.
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Hyde, Robert Harry. "Growth and Characterization of Thermoelectric Ba8Ga16Ge30 Type-I Clathrate Thin-Films Deposited by Pulsed Dual-Laser Ablation." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3162.
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The on-going interest in thermoelectric (TE) materials, in the form of bulk and films, motivates investigation of materials that exhibit low thermal conductivity and good electrical conductivity. Such materials are phonon-glass electron-crystals (PGEC), and the multi-component type-I clathrate Ba8Ga16Ge30 is in this category. This work reports the first investigation of Ba8Ga16Ge30 films grown by pulsed laser deposition (PLD).
This dissertation details the in-situ growth of polycrystalline type-I clathrate Ba8Ga16Ge30 thin-films by pulsed laser ablation. Films deposited using conventional laser ablation produced films that contained a high density of particulates and exhibited weak crystallinity. In order to produce high quality, polycrystalline, particulate-free films, a dual-laser ablation process was used that combines the pulses of (UV) KrF excimer and (IR) CO2 lasers that are temporally synchronized and spatially overlapped on the target surface. The effect of the laser energy on stoichiometric removal of material and morphology of the target has been investigated. In addition, in-situ time-gated emission spectroscopy and imaging techniques were used to monitor expansion of components in the ablated plumes. Through these investigations, the growth parameters were optimized not only to significantly reduce the particulate density but also to produce large area stoichiometric films. Structure and electrical transport properties of the resultant films were also evaluated. This work provides new insight toward the in-situ growth of complex multi-component structures in thin-film form for potential TE applications.
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Kochanek, C. S. Blandford Roger D. Blandford Roger D. "Studies in gravitational lensing and numerical hydrodynamics /." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechETD:etd-05222007-073908.
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Yang, Hsun-min. "Studies of distillation tray hydrodynamics and mass transfer." Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/11960.
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Urzay, Javier. "Theoretical studies in spiral edge-flame propagation and particle hydrodynamics." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3398270.
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Thesis (Ph. D.)--University of California, San Diego, 2010.Title from first page of PDF file (viewed May 6, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Wang, Zhiguo. "Experimental studies and CFD simulations of conical spouted bed hydrodynamics." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/61.
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Conical spouted beds have been commonly used for drying suspensions, solutions and pasty materials. They can also be utilized in many other processes, such as catalytic partial oxidation of methane to synthesis gas, coating of tablets, coal gasification and liquefaction, pyrolysis of sawdust or mixtures of wood residues.
The main objectives of this work include both the experimental research and mathematical modelling of the conical spouted bed hydrodynamics.
For experimental research, pressure transducers and static pressure probes were applied to investigate the evolution of the internal spout and the local static pressure distribution; optical fibre probes were utilized to measure axial particle velocity profiles and voidage profiles; the step tracer injection technique using helium as the tracer and thermal conductivity cells as detectors was used to investigate the gas mixing behaviour inside a conical spouted bed. It was found that many factors might affect calibration of the effective distance of an optical fibre probe. Therefore, a new calibration setup was designed and assembled, and a comprehensive sensitivity analysis was conducted to calibrate the optical probes used in this study.
For mathematical modelling, a stream-tube model based on the bed structure inside a conical spouted bed was proposed to simulate partial spouting states. By introducing an adjustable parameter, this model is capable of predicting the total pressure drop under different operating conditions, and estimating axial superficial gas velocity profiles and gauge pressure profiles.
A mathematical model based on characteristics of conical spouted beds and the commercial software FLUENT was also developed and validated using measured experimental data. The proposed new CFD model can simulate both stable spouting and partial spouting states, with an adjustable solids-phase source term. At stable spouting states, simulation results agree very well with almost all experimental data, such as static pressure profiles, axial particle velocity profiles, voidage profiles etc. A comprehensive sensitivity analysis was also conducted to investigate the effect of all possible factors on simulation results, including the fluid inlet profile, solid bulk viscosity, frictional viscosity, restitution coefficient, exchange coefficient, and solid phase source term.
The proposed new CFD model was also used successfully to simulate gas mixing behaviours inside a conical spouted bed, and simulate cylindrical packed beds as well as cylindrical fluidized beds in one code package.
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Al-Ghoul, Mazen. "Studies in generalized hydrodynamics for chemical reactions and shock waves." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0028/NQ29872.pdf.
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Low, Kueng-Chang. "Hydrodynamics and mass transfer studies of a confined plunging jet." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/35026.
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A confined plunging jet may be used as an energy efficient means of entraining a gas into a liquid for mass transfer. The application of such a jet as a wastewater oxygenator has been described. A literature survey of both the theoretical and experimental reports relevant to the hydrodynamics and mass transfer characteristics of both unconfined and confined plunging liquid jets systems, has been presented. The objective of the present study is to develop a better understanding of the confined plunging liquid jets, as a contribution towards establishing its future use as an oxygenator, especially in wastewater treatment. The effects of the three main operating variables investigated are the jet Reynolds number ReN, jet length to nozzle inside diameter ratio Lj/DN and the nozzle inside diameter DN. The effect of the downcomer size Dc on the hydrodynamics properties include the gas entrainment rates was also examined. Desirable effects on the hydrodynamics, with increasing operating variables have been obtained.
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Qu, Xiaocao. "Bench-scale two-dimensional fluidized bed hydrodynamics and struvite growth studies." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/382.
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A bench-scale, two-dimensional multi-compartmentalized fluidized reactor was designed and studies of hydrodynamic behavior of fluidization of struvite pellets were performed. Also size growth distribution tests were analyzed qualitatively.
The study validated a previously-proposed theory, concerning the relationship between dynamic pressure drop and upflow velocity as well the experimental protocol to determine the minimum fluidization velocity. Findings indicated that the mixture of two-sized particles would behave rather independently of each other, before the bed expansion. It was suggested that bed height measurement could be another promising method to pinpoint minimum fluidization velocity as there is a sharp bed surface "waking episode" during the process of a packed bed being gradually fluidized.
Bed expansion equations for the prediction of void fraction as a function of superficial upflow velocity or vice versa, have been established for 4 groups of monosize particles, as well as two mixtures of two-sized particles. The equation constants did not agree well with previously established ones. The two layers of segregated mixture bed had congruent linear relationships between the logarithmic void fraction and logarithmic upflow velocity. It was found that a mixture does not always go through segregation, but only when the size difference is large enough.
Size growth distribution tests were performed under different hydrodynamic configurations as well as seeding conditions. Conclusions can be made that a bed with uniformly- distributed particle void fractions and higher mixing energy input (upflow velocity), normally has better performance of struvite growth in size.
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Reay, William G. "Subsurface Hydrodynamics and Nutrient Exchange within an Extensive Tidal Freshwater Wetland." W&M ScholarWorks, 1989. https://scholarworks.wm.edu/etd/1539617595.
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Located between upland and riverine systems, extensive tidal freshwater wetlands are influenced by a variety of recharging water sources and their respective nutrient contents. Conversely, tidal wetlands discharge interstitial waters and solutes to surface waters during periods of aerial exposure. Geohydrologic and model simulation methodology were utilized in order to aid in the understanding of wetland subsurface flow dynamics, its influence upon pore water nutrient chemistry, and its role in nutrient exchange with adjacent surface waters. Interstitial water nutrient chemistry was monitored along three transects extending from the uplands to the creekbank edge. Surface waters were also monitored throughout the 13 month study period.
Measurements of soil dry bulk density, percent organic matter, fiber content, and horizontal hydraulic conductivity were conducted along a 118 meter transect from the creekbank edge to the high marsh/upland interface. Results indicate vertical and lateral heterogeneity of these physical and hydraulic soil properties within the upper one meter soil profile. Multivariate statistical techniques best described the transect as four separate soil types. General regions of soil types followed wetland elevational regions, these include: the creekbank, levee, low marsh flat, and high marsh regions. Fiber content was identified as the measured parameter which best explained variations in wetland soil permeability. Vertical and horizontal hydraulic head fluctuations were monitored utilizing piezometer/well arrays along the 118 meter transect. Direct measurement of interstitial water seepage flow from the subaquaeous portion of the creekbank to adjacent surface water was determined. Model simulation of subsurface hydrodynamics were made in order to provide water table fluctuations, estimates of horizontal seepage, and pore water budgets along the transect. Field measurements of marsh surface elevations and hydraulic soil properties were incorporated into the model to allow for comparison between simulated and observed results.
Spatial variations in soil properties, and subsurface hydrodynamics indicate that an extensive tidal freshwater wetland cannot be considered as a homogeneous unit. It may be described more accurately as three distinct, yet interactive regions (creekbank, low marsh flat,and high marsh), with varying potentials for surface and interstitial water exchange. The creekbank, experiencing large water table oscillations and hydraulic gradients, was the most dynamic and tidally influenced region. These hydrodynamic characteristics resulted in substantial subsurface water transport and dilution of interstitial waters by recharging surface waters within the creekbank region. Due to extremely low hydraulic gradients and ponding of water, horizontal seepage was minimal within the low marsh flat. Moderate hydraulic gradients in conjunction with highly permeable soils were conducive for significant horizontal seepage within the high marsh. Hydrologic evidence indicates a potential for nutrient rich shallow groundwater recharge within the high marsh region. Sensitivity analysis within the creekbank region indicates that aquifer depth exhibits the largest influence on interstitial water discharge followed by soil permeability and specific yield properties of the aquifer respectively. Inverted results, as those found within the creekbank region, were obtained for the high marsh region.
Interstitial water nitrogen and total phosphorus levels were variable and a function of depth, location, and time. However, several generalities and patterns appeared relatively consistant. Creekbank pore waters were relatively enriched with oxidized inorganic forms of nitrogen relative to low and high marsh regions. Creekbank ammonium, total nitrogen and phosphorus interstitial pools were intermediate, whereas, dissolved organic nitrogen levels was the lowest of the three regions sampled. The low marsh flat was inorganic nitrogen poor, and intermediate with respect to dissolved organic nitrogen, relative to creekbank and high marsh regions. Pore waters within the low marsh were significantly enriched with dissolved total phosphorus as compared to the creekbank and high marsh regions. High marsh interstitial waters displayed reduced levels of nitrate and nitrite, while levels of ammonium, dissolved organic and total nitrogen were elevated in relation to the creekbank and low marsh flat. Interstitial total phosphorus levels within the high marsh were significantly lower than the low marsh and approximately equal to the creekbank region. The role and influence of subsurface hydrodynamics upon pore water nutrient concentrations and spatial variations are discussed.
Spatial and temporal potential patterns of nutrient exchange between surface water and pore waters of various wetland regions are identified. Dissolved oxidized inorganic forms of nitrogen were imported throughout the sampling period by the creekbank, low marsh flat, and high marsh regions. Ammonium flux, due to seepage , was predominantly from the wetland to surface waters; the high marsh exhibited a greatest potential for ammonium export. The high marsh was a source of dissolved organic nitrogen throughout the study, while the low marsh flat and creekbank regions may best be characterized as sources during winter, spring, and summer months, and potential sinks during the fall. The high marsh exhibited the potential to export dissolved total nitrogen throughout the year, whereas, the low marsh flat and creekbank exhibit export potential during spring and summer months. Patterns of total phosphorus exchange were from high marsh, and low marsh regions throughout the year, while exchange between creekbank and surface waters was minimal and temporally variable. Hydrodynamics within each wetland region must be considered in conjunction with pore water chemistry, in order to fully understand nutrient and solute transport potentials.
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Briant, Marc. "On the Boltzmann equation, quantitative studies and hydrodynamical limits." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/246471.
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The present thesis deals with the mathematical treatment of kinetic theory and focuses more precisely on the Boltzmann equation. We investigate several properties of the solutions to the latter equation: their positivity and their hydrodynamical limits for instance. We also study the local Cauchy problem for a quantic version of the Boltzmann equation.
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Chun, Ho Hwan. "Theoretical and experimental studies on the resistance of SWATH ships." Thesis, University of Glasgow, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237814.
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Hornemann, Jennifer Ann. "Magnetic resonance microscopy studies of biofilms diffusion, hydrodynamics and porous media /." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/hornemann/HornemannJ0809.pdf.
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Due to the complicated nature of studying living bacterial communities, Magnetic Resonance Microscopy (MRM) is a necessary tool providing unique data that is complementary to other techniques such as confocal microscopy and microelectrodes. MRM has the ability to probe an opaque system non-invasively and collect velocity measurements, imaging data, diffusion, and relaxation values and is an asset in the quest to learn how biofilms establish, grow, and die. The goal of these studies was to extend current biofilm research using MRM to enhance our understanding of transport phenomena over a hierarchy of scales, from the microscopic diffusion level to the macroscopic bulk flow. Staphylococcus epidermidis was the bacteria chosen for the biopolymer diffusion and the secondary flow studies due to its common identification in opportunistic biofilm infections. This diffusion study was the first Pulse Gradient Spin Echo (PGSE) MRM measurements of the impact of environmental and chemical challenges on the biomacromolecular dynamics in medically relevant S. epidermidis biofilm material demonstrating the ability to characterize molecular dynamics in biofilms, providing a basis for sensors which can indicate the state of the biofilm after thermal or chemical treatment and provide information to further understand the molecular level mechanisms of such treatments. The secondary flow data clearly support the conclusion that reactor size impacts studies of spatially distributed biological activity, and the idea that, scaling of transport models in biofilm impacted devices is possible but requires more study. Additionally, due to the increasing amount of CO2 in the earth's atmosphere and the need to understand the options of sequestering this CO2 to combat the impacts of global warming, studies were conducted to understand how biofilms grow in porous media. The resilience of Bacillus mojavensis biofilms to super critical CO2 is documented, and thus, this bacteria was chosen. Results indicate that by varying exchange times, T2-T2 experiments can determine the extent of biofilm growth in an opaque porous media as demonstrated in multiple glass bead pack configurations. Using MRM as a tool to study these biofilm systems over a wide range of environmental conditions is the focus of the research presented in this dissertation.
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Shah, Lynn. "Hydrodynamics, mixing and mass transfer studies in three external loop airlift reactors." Thesis, Teesside University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411180.
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Barbouche, Naziha. "Réponse biologique de cellules animales à des contraintes hydrodynamiques : simulation numérique, expérimentation et modélisation en bioréacteurs de laboratoire." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL075N/document.
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La réponse globale de cellules animales à des contraintes hydrodynamiques lors de leur culture en suspension dans des réacteurs agités a été étudiée grâce à une approche intégrative couplant les outils du génie biochimique à ceux de la mécanique des fluides numérique. En premier lieu, la description de l’hydrodynamique moyenne et locale de deux systèmes de culture agités de laboratoire, spinner et bioréacteur, a été réalisée. Puis, l'étude des cinétiques macroscopiques de cellules CHO cultivées en suspension, en milieu sans sérum et sans protéine, a été réalisée avec différentes vitesses d’agitation, pour évaluer l'impact de l'agitation sur les vitesses de croissance et de mort cellulaires, ainsi que de consommation des substrats et de production des métabolites et de l'interféron-gamma recombinant. Des caractérisations supplémentaires des cellules (apoptose, protéines intracellulaires) et de l'interféron ont également été réalisées. Les effets de l'intensification de l'agitation ont été représentés avec plusieurs corrélations globales reliant : (i) en milieu contenant du pluronic, l'intégrale des cellules viables au nombre de Reynolds, et la proportion de cellules lysées à la valeur moyenne de l'énergie de dissipation, <[epsilon]? (ii) en milieu sans pluronic, les vitesses spécifiques de croissance et de mort cellulaires à <[epsilon]. De plus, l'analyse par CFD de la distribution spatio-temporelle des contraintes indique que la lyse cellulaire, observée dans le réacteur aux conditions extrêmes d'agitation, serait plutôt liée à des valeurs locales très élevées de [epsilon], ainsi qu’à la fréquence d'exposition des cellules dans ces zones énergétiques. Un modèle hydro-cinétique original, couplant l’hydrodynamique locale aux cinétiques cellulaires de croissance et de mort, et basé sur l’intermittence de la turbulence permet la prédiction de la lyse massive observée en réacteur sous certaines conditions. Pour confirmer le fait que les effets liés à l'intensification de l'agitation sont bien le résultat d'une augmentation des contraintes hydrodynamiques, et non d'une amélioration du transfert d'oxygène, ce dernier a été mesuré et modélisé par couplage avec une simulation numérique de type Volume Of Fluid , concluant en une absence de limitation d'oxygène. Enfin, la conception, le dimensionnement et la caractérisation hydrodynamique d'un réacteur innovant de type Couette-Taylor, sont proposées pour la mise en œuvre de cultures perfusées dans un environnement hydrodynamique mieux contrôléThe global response of animal cells to hydrodynamic stress when cultivated in suspension in stirred tank reactors was studied. To do this, an integrative approach coupling biochemical engineering and fluid mechanics tools were used. First, the description of the global and local hydrodynamics of two bench-scale agitated reactors, a spinner flask and a bioreactor, was carried out. Then, macroscopic kinetics of CHO cells cultivated in a serum and protein-free medium were obtained at various agitation rates, in order to evaluate the impact of agitation on cellular growth and death, as well as substrates consumption and metabolites and recombining IFN-[gamma] production. IFN-[gamma] and cells physiological state were more precisely characterised by glycosylation, apoptosis state and intracellular proteins measurements. The effects of the agitation increase were represented by several global correlations that related: (i) in a medium containing Pluronic F68, the Integral of the Viable Cells Density to the Reynolds number, and the proportion of lysed cells with the average value of energy dissipation rate <[epsilon]? (ii) in a medium without pluronic, specific cell growth and death rates to <[epsilon]. Moreover, CFD analysis of the stress distribution indicated that the cellular lysis observed in the bioreactor at the highest agitation rate, would be related to very high local values of [epsilon], and to the exposure frequency of the cells in these energetic zones. An original hydro-kinetic model based on the intermittency of turbulence and coupling the local hydrodynamics with cell growth and death kinetics, allowed the prediction of the massive cell lysis observed in the bioreactor under some mixing conditions. To decouple shear stress effects from oxygen transfer improvement, the oxygen transfer coefficient was experimentally measured and modelled using a Volume Of Fluid numerical simulation. Our results indicated the absence of an oxygen limitation, which confirmed that this cell response resulted from the hydrodynamic stress increase alone. Lastly, an innovative continuous and perfused Couette-Taylor reactor, allowing a better-controlled hydrodynamic environment was designed and sized. Its hydrodynamic description was carried out using CFD calculations