To see the other types of publications on this topic, follow the link: Flow effect.
Dissertations / Theses on the topic 'Flow effect'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Flow effect.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Shaglouf, Mukhtar Mohamed A. "Effect of flow on electrochemical noise generation." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/effect-of-flow-on-electrochemical-noise-generation(580f04c4-74a1-4b8d-8662-0ebce9166818).html.
Full textAbstract:
It is known that, in addition to corrosion processes, the electrochemical noise (EN) can be generated by some other disturbances such as mass transfer and flow turbulence. In this study the influence of both laminar and turbulent flow on the characteristics of electrochemical noise (EN) has been studied using a carbon steel rotating cylinder electrode (RCE) in aerated neutral (pH=7) 0.1 M NaCl and 0.1 M NaCl+0.1 M NaNO2 solutions. The RCE has a set of four graphite brushes for electrical connection. The supplied cathodic current was applied through the top two graphite brushes and measured the specimen potential through the bottom two to eliminate any expected cyclic variations in the measured potential.Prior to the measurement of EN, calibration of the mass transport properties of the electrode was performed by measuring the limiting current density for oxygen reduction as a function of rotation speed in order to estimate the transition from laminar to turbulent flow regime. EN experiments have been performed in free corrosion conditions (uninhibited and inhibited solutions), and with applied cathodic polarisation in the regions of hydrogen evolution and oxygen reduction processes. In the case of oxygen reduction and hydrogen evolution cathodic reactions it has been found that laminar flow had a negligible effect on the noise produced but a significant increase in the amplitude of the noise was observed in turbulent flow. On the other hand in free corrosion conditions in uninhibited solution the influence of flow was relatively insignificant and that was attributed to the low impedance of the corroding electrode. It is claimed that flow has a negligible effect in inhibited solutions due to the passivity of the system, which is responsible for the low rate of both anodic and cathodic reactions. Finally spectral analysis showed that the noise produced by turbulent flow had power at significantly higher frequencies than is normal for corrosion-related noise.
2
Akaiwa, Michiro. "The electrorheological effect in static squeeze-flow." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367103.
Full text
3
Hughes, Christopher William. "The effect of topography on ocean flow." Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:37b3f6b2-ce5f-45b3-b2ed-3325518b06bb.
Full textAbstract:
The rôle which topography plays in constraining ocean flow is investigated in several ways, mostly aimed at application to the Southern Ocean where topography is known to be important. The physics of topographic Rossby waves is discussed in some depth and a description of ocean flow in terms of a sum of topographic normal modes is developed. It is shown that the apparent incompleteness of topographic modes can often be circumvented by including a function which absorbs the nett input of potential vorticity. Some subtle problems with this description are dealt with, and a calculation of topographic modes for the Southern Ocean is presented, which shows that the modes are very localised, making the use of them to describe basin-wide flows difficult. The effect of interactions between stratification and topography is investigated in terms of a quasi-two-dimensional model which deals only with the depth-integrated flow, and the assumptions which go into the model are examined in detail both analytically and by calculating terms of interest from a data set produced by the Fine Resolution Antarctic Model. It is shown that advection of density in the Southern Ocean can be described to a first approximation as being due to a barotropic current with no vertical velocity, the horizontal component of the baroclinic flow producing very little effect. The balance of terms reveals interesting features in the modelled flow in the Southern Ocean, showing the value of this type of analysis. Finally, insight developed in the course of the investigation allows a simple model to be constructed representing the feedback between density advection and forcing due to density gradients. This model is used to provide an explanation for the fact that the FRAM model spins up linearly, where most simple models would predict a component of quadratic behaviour in the spin-up.
4
Rigby, Simon Geoffrey. "The electrorheological effect in oscillatory squeeze-flow." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284149.
Full text
5
Sopko, James J. "Modeling fluid flow by exploring different flow geometries and effect of weak compressibility." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FSopko.pdf.
Full text
6
Vanyaza, Sydwell Luvo. "Non-newtonian open-channel flow : effect of shape on laminar and transitional flow." Thesis, Cape Technikon, 2004. http://hdl.handle.net/20.500.11838/874.
Full textAbstract:
Thesis (MTech (Chemical Engineering))--Cape Technikon, 2004When designing the open channels to transport the homogenous non-Newtonian slurries, the effect of channel shape is one of the parameters that should be checked and very little research has been conducted to address this matter. Open channels are commonly applied in the mining industry where mine tailings have to be transported to the disposal dams at high concentrations to save water consumption. This thesis addresses the effect of the cross-sectional shape of the channel with emphasis on laminar and transitional flow of non-Newtonian fluids. The literature review on the flow of Newtonian and non-Newtonian fluids has been presented. The most relevant one to this topic is the work done by Straub et al (1958) for Newtonian fluids and the analytical work presented by Kozicki and Tiu (1967) for non-Newtonian fluids. Authors like Coussot (1994) and Haldenwang (2003) referred to their work but did not comprehensively verified it experimentally. Three flume shapes were designed to investigate this problem namely, rectangular, semi circular, and trapezoidal flume shape. The test rig consisted of a 10 m long by 300mm wide tilting flume that can be partitioned into two sections to form a 150 mm wide channel. All three flume shapes were tested in both the 150 mm and 300 mm wide flumes. This flume is linked to the in-line tube viscometer with three tube diameters namely, 13 mm; 28 mm; and 80 mm. The experimental investigation covered a wide range of flow rates (0.1-45l/s), and flume slopes (1-5 degrees). The fluids tested were kaolin suspension (5.4 - 9% v/v), CMC solution (1 - 4% m/m), and bentonite suspension (4.6 and 6.2% mlm). The models found in the literature were evaluated with the large database compiled from the test results to predict the laminar and transitional flow of these fluids with the aim of checking the effect of the cross-sectional shape of these channels selected in these flow regimes. For all the flume shapes and non-Newtonian fluids selected in this thesis it was found that in predicting the laminar flow, the effect of shape is adequately accounted for by the use of hydraulic radius. In predicting the transitional flow, it was found that the effect of shape does not have to be included.
7
Crossley, Kent Westerberg. "Effect of Cuff Pressure on Blood Flow DuringBlood Flow-Restricted Rest and Exercise." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8259.
Full textAbstract:
Purpose: The purpose of this study was to investigate the blood flow/pressure relationship (linear or nonlinear) in the superficial femoral artery when seated, as well as to investigate blood flow changes with exercise using varying cuff pressures and a preexercise (PE) condition. The presence of venous outflow with occlusion at rest and exercise was also investigated.Methods: Twenty-three subjects visited the lab on 3 occasions. First to determine linearity of blood flow using 0% to 90% arterial occlusion pressure (AOP), and venous outflow at rest and during exercise with cuff inflated to 40% AOP. Subsequent visits compared blood flow between rest and PE conditions to determine average blood flow, heart rate, systolic and diastolic blood pressure changes in response to a blood flow-restricted (BFR) exercise protocol. Results: Blood flow/pressure relationship is nonlinear at the superficial femoral artery (p < 0.01). No significant differences in average blood flow, conductance or mean arterial pressure (MAP) were found between 30% to 80% AOP (p = 1.0 to .08). Blood flow is not significantly different between rest and PE groups (p = 0.49) although initial 40% AOP and 40% exercise arterial occlusion pressure (EAOP) values were different between rest and PE groups. (p < 0.01). Conclusion: The nonlinear relationship at the superficial femoral artery demonstrates higher cuff pressures are not necessary to reduce blood flow in BFR exercise of the lower extremity. Furthermore, PE or warm-up is not necessary prior to determining EAOP as it does not alter blood flow responses during BFR exercise. We found evidence of venous outflow above the cuff both at rest and during exercise at 40% AOP.
8
Paraschiv, Ioana. "Shear flow stabilization of Z-pinches." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3264527.
Full text
9
Golingo, Raymond Peter. "Formation of a sheared flow Z-pinch /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/9960.
Full text
10
Stainer, Michael John. "Numerical prediction of propeller scale effect." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395944.
Full text
11
Tzou, Chung-te. "Effect of canal flow variability on irrigation performance." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/187033.
Full textAbstract:
Flows in an irrigation canal were analyzed to evaluate the effects of lateral flow fluctuations on tailend spill losses and on-farm application losses. The flow variabilities at the farm turnouts due to lateral heading inflow variabilities were examined through CanalCAD modeling simulations of the Palm Lateral in the Imperial Irrigation District. The magnitude of flow fluctuations at the turnouts were dependent primarily on the localized flow conditions (i.e. flow depths) and types of structures at the bifurcations. Simulations of fluctuating lateral heading inflows with coefficients of variations (CV) ranging from 0.0 to 0.15 were evaluated to quantify the effect of inflow variability on tailend spillage. A positive relationship between lateral inflow fluctuations and tailend spill was obtained. The increased spill as inflow variability increased was also related to the localized flow conditions at the bifurcation structures. Significantly higher spill ratios were evident only when inflow CV's were greater than 0.10 and the head differences at the turnouts were relatively large. On the farm, 104 recorded irrigation events from the District were randomly selected. Multiple linear regression analyses were performed on the field data with the tailwater quantities (tailwater volume and fraction) as the dependent variables and the inflow variability (CV) and some other field parameters (e.g. inflow volume, date of irrigation, and crop type, etc.) as independent variables. The best-fit regressor variables were CV, delivery volume, month, and crop for the regression equation to predict tailwater volume. It had an R-squared value of 0.393 which indicated a weak correlation. Two on-farm management conditions were simulated and analyzed for border irrigation using the SRFR model. One set of inflow hydrographs had equal flow volume and duration and were used in simulations with "irrigation by the clock" (i.e. fixed application duration) management method. The results showed that the inflow variability did not affect the irrigation performance (i.e. tailwater ratio, distribution uniformity, application efficiency, etc.). For the other set of hydrographs, the flow volumes were varied. But, the hydrographs were applied with an irrigation method where the application time was determined by the advance of the wetting front. This "irrigation by the advance" method yielded similar performance among the different ranges of inflow variability.
12
Zarifi-Rad, Farrokh. "Effect of model cooling in periodic transonic flow." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334688.
Full text
13
Hodgkinson, Richard. "The effect of extensional flow on shear viscosity." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18327/.
Full textAbstract:
Shear rheology is conventionally studied under pure shearing flows, rather than more realistic mixed flows. Moving parallel surfaces and capillary rheometery are examples of the former, whilst the latter occurs whenever a flow accelerates or decelerates creating an additional component of extension, e.g. on passing through an industrial extrusion die. We postulate and gather supporting evidence that shear rheology is a function of not only shear, but both shear and extension rate, a factor with important consequences for fibre spinning and extrusion operations. The direction, as well as rate, of extensional deformation is important. A novel two-phase flow, planar extension experiment is developed and the surface coatings necessary to control the interface structure identified. Shear viscosity evolution is monitored, in-situ, under extensional flow, by optically measuring shear rates either side of a test fluid – reference fluid interface; issues due to optical refraction are critically addressed. Preliminary evidence is shown for a 1.2wt% 4x10^6 MW PEO solution that parallel (+ve) extensional flow, on the order of 11.5s-1 , causes a reduction in shear viscosity, and perpendicular (-ve) causes an increase in shear viscosity, supporting the hypothesis. A framework for a comparison experiment, with the same shear history but without extension, is presented. As part of this work, design criteria for planar hyperbolic extensional channels are critically assessed. In particular, expanding a hyperbola entrance region would maximise total Hencky strain, yet this region is almost never given rationalised consideration in literature. In this region the basis for the hyperbolic profile breaks down, and a new profiling strategy and channel form are presented, which is found to only differ significantly in this inlet region. A useful design limit of 130 degrees on channel inlet angle is identified. The new profile is compared to a hyperbolic profile through the use of CFD for wall slip flow, and a slight improvement in extension rate uniformity along the centreline found. Deviations are contrasted against assumptions made in the profiling strategy: comments are made with regards the possibility for “internal” shear to occur, and non-uniform extension rates are accordingly found to exist between streamlines in these channels despite the use of full wall slip in the simulations.
14
Hine, C. J. "Effect of liquid flow patterns on distillation trays." Thesis, Aston University, 1990. http://publications.aston.ac.uk/9795/.
Full textAbstract:
The thesis describes experimental work on sieve trays in an air-water simulator, 2.44 m in diameter. The liquid flow pattern, for flowrates similar to those used in commercial scale distillation, was observed experimentally by water cooling experiments, in which the temperature of the water is measured at over 100 positions over the tray area. The water is cooled by the rising air which is forced through the tray. A heat and mass transfer analogy is drawn whereby the water temperature is mapped to liquid concentration in mass transfer, and the water temperature profiles reveal how liquid channelling may reduce the tray efficiency. The first experiment was to observe the flow of water only over an unperforated tray. With the exception of very low weir loads, the flow separated at the ends of the inlet downcomer. This caused liquid to flow straight across the tray between the downcomers and large circulating regions to be formed in the side regions of the tray. The effect of the air crossflow on the flow pattern was then observed on a sieve tray of 10% free area with 1 mm diameter holes (such as is used in cryogenic distillation). The flow patterns developed on the tray were similar to those produced with water only on the unperforated tray, but at low weir loads the air crossflow prevented separation of the water flow and the associated circulating regions. At higher weir loads, liquid channelling down the centre of the tray and circulation in the side regions occurred. The percentage of the tray occupied by circulating liquid depended upon the velocity of the liquid entering the tray, which was set by the weir load and size of the gap under the inlet downcomer. The water cooling experiments showed that the temperature of the water in a circulating region is much lower than in other parts of the tray, indicating that the driving force for heat transfer is reduced. In a column section where trays (and circulating areas) are mounted on top of each other, the circulating regions will cause air (or vapour) passing through them to have a reduced change in temperature or concentration leading a loss in tray efficiency.
15
He, Kui. "Effect of body force on turbulent pipe flow." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11845/.
Full textAbstract:
Two non-equilibrium flows, namely, a transient turbulent pipe flow following a sudden change of flow rate and a turbulent pipe flow subjected to a non-uniform body force are systematically studied using direct numerical simulation (DNS). It is revealed that the transient response of a turbulent pipe flow to a sudden increase of flow rate is a laminar-turbulent transition. The response of the flow is not a progressive evolution from the initial turbulence to a new one, but shows a three-stage development, i.e., a pre-transitional stage, a transitional stage and a fully developed stage. This is similar to a typical boundary layer bypass transition with three characteristical regions, i.e., pre-transitional region, transitional region and fully developed region. The results are carefully compared with those of a channel flow of He & Seddighi, J. Fluid Mech. (2013). The statistical and instantaneous behaviours of the two flows are similar in the near-wall region, but there are distinctive differences in the centre of the flow. The transitional critical Reynolds numbers for the transient pipe and channel flow are predicted with the same correlation. The possibility of predicting such transient flow using transitional turbulence modelling, such as γ-Reθ SST, is discussed. The effect of the rate of the change of the flow is also examined. In a fast ramp-up case, the flow is similar to that of a step-change flow, also showing a three-stage development. In a slow ramp-up case, the flow response is not as clear as that in a fast ramp-up case but the main features of the response are similar. A series prescribed body forces are used to emulate flows, which contain features similar to those of real buoyancy-aiding flows. It has been shown that the body force with various amplitudes, coverages and distribution profiles can systematically influence the base flow. The body force influenced flows are classified into four groups, namely, partially laminarized flow, 'completely' laminarized flow, partially recovery flow and strongly recovery flow. A new perspective has been proposed for the partially laminarized flow and 'completely' laminarized flow. In contrast to the conventional view, which views the flow to be re-laminarized, the new theory proves that the turbulence of the flow remains largely unchanged following the imposition of the body force. The body force induces a perturbation flow, which lowers the pressure gradient required to maintain the same Reynolds number. This is the mechanism of turbulence relaminarization. The recovery flows show two-layer turbulence. The outer turbulence is generated by a shear layer in the core of the flow caused by the body force. The inner turbulence is generated in the wall layer, increasing with the outer turbulence. The two layers of turbulence increase hand in hand. The stronger the outer generation, the stronger the inner recovery is. The inner turbulence structure is very similar to an equilibrium turbulent flow. In the region very close to the wall (y+0 < 10), it shows similar budget patterns and flow structures (sweeps and ejections) to those of the base flow. In the region between y+0=10 and the new shear layer, the turbulence structure is complicated, where the turbulence is a mixture of the inner turbulence and the outer turbulence. The transient response of the turbulence to the imposition of a non-uniform body force has been examined. The turbulence decay and recovery features of the flows with non-uniform body forces are studied in detail. It is found that the transient features are mainly determined by the total amplitude of the body force. The higher the amplitude, the stronger the turbulence decay is. In some flows, the near wall turbulence is recovered toward the later stage of the transient process. Under such condition, the inner self-sustaining regeneration interacts strongly with the turbulence from the outer shear layer.
16
Van, der Westhuizen Ina. "Trickle flow multiple hydrodynamic states the effect of flow history, surface tension and transient upsets /." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-05052008-095050/.
Full text
17
Bohner, John David. "The effect of countercurrent flow limitation in small passages." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/19003.
Full text
18
SoÌlyom, PeÌter. "The effect of flow path geometry on landscape evolution." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422439.
Full text
19
McDarby, John Michael. "Modelling of turbulent rotor-blade flow and ground effect." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1444821/.
Full textAbstract:
Rotor blade flows occur in numerous physical systems from helicopters to fans, and from propellers to food mixers. Many previous studies have concentrated on the laminar flow generated by a set of rotors but in many practical cases the flow is turbulent, a setting in which previous research appears to be mainly experimental or purely numerical. The thesis examines turbulent rotor flow as its prime feature, before moving on to the impact of the ground and side structures on the flow. Whilst there exists a wide variety of rotor blade flows in industry, the present research is motivated by the application to helicopters. Using asymptotic analysis and computational methods the thesis first examines the turbulent boundary layer on a flat plate with a moving surface and, second, a rotating disc. Analytical and numerical predictions are then derived and compared with previous results. Asymmetry about the axis of rotation is introduced next and the problem of a rotating cut-disc is studied as an approximation to a set of rotors. A numerical solution is obtained and is supported by analytical results. Blade inclination and thickness are then incorporated into the three-dimensional case, with asymmetric blade shape being analyzed as if in two dimensions only. The influence of ground effect is examined firstly through the use of an image potential in the two-dimensional asymmetric blade shape problem and secondly in the axisymmetric case of flow between a stationary and a rotating disc. A numerical solution is determined and compared with existing research, whilst an analytical solution is produced for large radii. The flow between a stationary disc and a rotating cut disc is then briefly discussed before, finally, the possible extension of this thesis to the problem of turbulent jets is examined.
20
Welsh, Alexandra Jane Lawson. "Effect of hand-transmitted vibration on finger blood flow." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439368.
Full text
21
Hernández, de Müller Gabriela. "The effect of flow on the crystallisation of polyethylene." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612379.
Full text
22
Burger, Johannes Hendrik. "Non-Newtonian open channel flow: the effect of shape." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1296.
Full textAbstract:
Thesis submitted in fulfilment of the requirements for the degree
Doctor of Technology: Mechanical Engineering
in the
Faculty of Engineering
at the
Cape Peninsula University of Technology
2014Open channels, flumes or launders are used in the mining industry to transport slurries during processing and to disposal sites. Water plays a major part in the makeup of these slurries, its usage and availability is critical in countries where there are strict water usage management programs. The optimisation of flume design involves the maximisation of solids transport efficiency whilst, at the same time reduces water usage. The design of open channels is complex as it is dependent on both the slurry rheology and the channel shape. Very little has been reported in the literature for predicting non-Newtonian laminar flow in open channels of arbitrary cross-section. The only method available was that proposed by Kozicki and Tiu (1967, 1986). The shape factors they used were those evaluated from analytical solutions for flow of Newtonian fluids in open channels of the same cross-section. However, they carried out no experimental work to validate their model. Few experimental studies have been made on the effect of shape on non-Newtonian flow in open channels. Naik (1983) tested kaolin in water suspensions in a rectangular channel. Coussot (1994) provided some data for the flow of a Herschel-Bulkley fluid in rectangular and trapezoidal channels. Fitton (2007; 2008) obtained data for flow of three different non-Newtonian fluids (carboxymethylcellulose, carbopol and thickened tailings) in a semi-circular channel. A large experimental database for non-Newtonian flow in rectangular open channels was published by Haldenwang (2003) at the Flow Process Research Centre, Cape Peninsula University of Technology. Guang et al. (2011) performed Direct Numerical Simulations of turbulent flow of a yield- pseudoplastic fluid in a semi-circular channel. They compared their simulations with actual field measurements and found them to over-predict the flow velocity by approximately 40%. The source for this discrepancy was difficult to ascertain. A comprehensive database was compiled during this research of the flow of three non–Newtonian fluids in rectangular, trapezoidal, semi-circular and triangular channels. The flow of carboxymethylcellulose solutions and aqueous kaolin and bentonite suspensions was investigated in a 10 meter long flume at angles ranging from 1° to 5° from the horizontal plane. The effect of channel shape on the friction factor-Reynolds number relationship for laminar and turbulent open channel flow of these three fluids was investigated. New models for the prediction of laminar and turbulent flow of non-Newtonian fluids in open channels of different cross-sectional shapes are proposed. The new laminar and turbulent velocity models are compared with three previously-published velocity models for laminar flow and five previously-published velocity models for turbulent flow using average velocity as comparison criteria. For each channel shape, the laminar flow data can be described by a general relationship, f = K/Re where f is the Fanning friction factor and Re is the appropriate Haldenwang et al. (2002) Reynolds number. The K values were found to be 14.6 for triangular channels with a vertex angle of 90°, 16.2 for semi-circular channels, 16.4 for rectangular channels and 17.6 for trapezoidal channels with 60 degree sides. These K values were found to be in line with those reported by Straub et al. (1958) and Chow (1969) for open channel laminar flow of Newtonian fluids as opposed to the assumption made by Haldenwang et al. (2002; 2004) of using a constant value of 16 based on the pipe flow paradigm for all channel shapes. This new laminar model gave a closer fit to the laminar flow data than those from the three previously-published models. However, the presence of the yield stress still presents a problem, which makes the flow prediction in laminar flow for such fluids not very accurate. The investigation on non-Newtonian turbulent flow of the three fluids in the four different shaped open channels revealed that the data was described by the modified Blasius equation f = a Re b where a and b are constant values determined for each channel shape and Re is the Haldenwang et al. (2002) Reynolds number. Values of a and b for a rectangular channel were found to be 0.12 and -0.330, for a semi- circular channel 0.048 and -0.205, for a trapezoidal channel with 60° sides, 0.085 and -0.266 and for a triangular channel with vertex angle of 90°, 0.042 and -0.202. New laminar and turbulent velocity models were derived from using the new laminar f = K/Re and turbulent f = a Re b, friction factor-Reynolds number relationship. The laminar velocity model did not always give the best result, but the majority of the time it did, compared to the three previously published models. The new turbulent velocity model yielded the best results when compared to the five previously published models using average velocity as comparison criteria. The composite power law modelling procedure of Garcia et al. (2003) used for pipe flow predictions was extended to the present work on non-Newtonian flow in open channels of various cross-sections. The results show that the modelling technique used by Garcia et al. (2003) for pipe flow can be used to adequately predict flow in an open channel of a given cross-sectional shape provided that an appropriate Reynolds number is used to take into account the non-Newtonian behaviour of the test fluid. It was found that the results using the Haldenwang et al. (2002) Reynolds number yielded better results than those based on the adapted Metzner-Reed Reynolds number. The correlations and models developed and experimentally validated during this research can be used to further improve the design of rectangular, semi-circular, trapezoidal and triangular open channels to transport non-Newtonian fluids.
23
Rapolu, Prakash. "Capillarity Effect on Two-phase Flow Resistance in Microchannels." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204082574.
Full text
24
Brown, Nicholas J. "The effect of wall waviness on shear flow instabilities." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/1275.
Full textAbstract:
This thesis is concerned with the effect of wall waviness on shear flow instability, specifically for the incomprehensiblc flow in a channel. We investigate the stability of the flow in a channel with fixed wavy boundaries using two methods. Firstly the disturbance evolution is calculated using the parabolised stability equations (PSE), which apply to the flow stability at finite Reynolds number, and are solved using a finite-difference marching scheme, marching in the downstream direction. Secondly we employ the triple-deck formulation for channel flow which is valid at asymptotically high Reynolds number and the problem is solved using Floquet theory, making use of the periodic coefficients appearing in the disturbance equations. The mean flow for the PSE analysis is obtained by linearising the Navier-Stokes equations using a perturbation method, valid for small amplitude boundary waviness, Δ. We solve the linear PSE using this periodic mean flow, and it is found that increasing Δ stabilises plane Poiseuille flow near the nose of the neutral curve but has a destabilising effect on the lower branch for higher Reynolds numbers. The nonlinear PSE are used to study thc stability of 2-D finite amplitude waves, and are able to demonstrate the existence of suporcritical equilibrium amplitude solutions, as well as threshold amplitudes separating growing and decaying solutions in the subcritical regime. Wall waviness is found to have a stabilising effect on subcritical disturbances, raising the amplitude needed for instability to occur. Using Floquet theory and decomposing the disturbance equations into Fourier modes enables the high Reynolds number problem to be formulated as an eigenvalue problem. The waviness is found to be able to produce a destabilising effect in agreement with the results for the linear PSE near the lower branch. The method of multiple scales is used to study the wavy channel flow stability at high Reynolds number in the limit of small Δ, which gives an O(Δ 2) correction to the flat boundary eigenvalue, λ. When λ = ±i μ, for boundary wavenumber, μ, we find a degeneracy in the intermediate O(Δ) system of equations due to a resonance ktween a neutrally stable flat-boundary T-S wave and the boundary wave of equal wave-length. New asymptotic scalings are derived in this case to obtain a valid solution.
25
Joober, Khaled. "The effect of flow geometry on critical heat flux." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6544.
Full textAbstract:
An extensive and systematic literature review on the effect of flow geometry on the Critical Heat Flux (CHF) has been performed. This review covers most of the flow geometries such as tubes, concentric and eccentric annuli, rectangular channels, irregular-shaped channels and bundles. The following geometric parameters have been found to strongly influence the CHF: (i) hydraulic-equivalent diameter, (ii) heated-equivalent diameter, (iii) gap size, (iv) unheated adjacent surface, (v) heated adjacent surface, (vi) curvature, (vii) eccentricity (including bowing), and (viii) channel shape. It is found that some of the geometric effects on CHF depend on the flow conditions and the CHF type. For each geometry the parametric trends have been described, whenever sufficient experimental results are available. A review and assessment of the available prediction methods is conducted. The following trends have been identified in this study: (i) in general the CHF in annuli (concentric and eccentric) is lower than that in tubes, especially for high quality and narrow gaps; (ii) for rectangular channels and irregular-shaped channels, corners can cause a large CHF reduction; (iii) the CHF for concave surface is significantly higher than the CHF for a convex surface; (iv) the effect of gap size in concentric annuli is different for a departure from nucleate boiling (DNB) type CHF and CHF type for the annular flow regime. For the first CHF type reduction in gap size results in a CHF decrease, while for the second CHF type it results in CHF enhancement; and (v) heating the adjacent surface results in a CHF increase. Based on the observed trends, CHF correction factors have been derived for each geometry. Finally, an interim CHF prediction method for subchannels and flow conditions of interest to CANDU$\sp*$ reactors has been proposed. ftn$\sp*$CANDU--CANada Deuterium Uranium, a registered trademark.
26
Jane, James Daniel Trevarton. "The effect of the Ricci flow on geodesic and magnetic flows, and other related topics." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612252.
Full text
27
Grundy, Ian H. "Air flow near a water surface /." Title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phg889.pdf.
Full text
28
Jackson, Stuart L. "Density characteristics of a sheared-flow Z-pinch /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/9992.
Full text
29
Debray, Alexis. "Contribution to the study of dissipative silencers : effect of structural vibrations, effect of flow." Le Mans, 2000. http://cyberdoc.univ-lemans.fr/theses/2000/2000LEMA1021.pdf.
Full textAbstract:
Cette thèse s’inscrit dans le cadre du projet européen FLODAC (FLOw Duct ACoustic) et s’intéresse à deux aspects des silencieux dissipatifs. La chambre d’expansion traitée est couramment utilisée pour atténuer des sons en conduit. On propose ici un modèle approché pour un tel système dans lequel les variations radiales de la pression et de la vitesse dans l’air et dans le matériau poreux sont décrites par des polynômes. Ces approximations permettent le calcul des coefficients de transmission et de réflexion qui caractérisent tout à fait les propriétés acoustiques du système à basse fréquence. Des résultats de mesures montrent la validité d’une telle approche. La présence d’un écoulement uniforme dans le conduit d’air est introduite dans le modèle. L’accord de celui-ci avec des résultats expérimentaux est satisfaisant pour les coefficients de transmission. L’étude montre que pour des nombres de Mach inférieurs à 0. 15, l’effet de l’écoulement est déjà important. On note en particulier une diminution du pouvoir atténuant de la chambre dans le sens de l’écoulement. Le second aspect du travail s’intéresse à l’effet des vibrations de la structure du matériau poreux sur l’atténuation d’un conduit traité de longueur infinie. Ces travaux s’appuient en partie sur ceux de E. Lesquins (SNECMA) et de B. Brouard (LAUM). Le matériaux poreux est décrit par la désormais classique théorie de Biot. Différents modèles sont proposés. La géométrie du conduit peut être bidimensionnelle ou circulaire et deux méthodes sont utilisées pour résoudre le problème, i. E. Trouver les constantes de propagation des différents modes. Des simulations numériques montrent que sous certaines conditions les vibrations de structure peuvent provoquer une atténuation importante en basse fréquence. Sous d’autres conditions elles peuvent entraîner une diminution de cette dernière. Une première étude expérimentale montre la validité de ces travauxThis thesis is a part of the European project FLODAC (FLOw Duct ACoustic) and is dealing with two aspects of dissipative silencers. The expansion chamber is commonly used as a dissipative silencer. Here we propose an approximate model for such a system, in which the radial variations of the pressure and velocity in the air and in the porous lining are described by polynomials. These approximations allow the calculation of the reflexion and transmission coefficients which completely descibe the acoustic properties of the chamber at low frequency. Experimental results show the validity of such an approach. The presence of uniform flow in the air duct is introduced in the model. Agreement with experimental results is satisfying for the transmission coefficients. The study shows that for Mach numbers lower than 0. 15, the effect of flow is already important. In particular, we note that the attenuation is lower in the sense of flow. The second aspect of the work is dealing with the effect of the vibration of the structure of the porous lining on the attenuation of a duet of infinite length. This part is partly using the work of E. Lesquins (SNECMA) and B. Brouard (LAUM). The porous material is described by the classical Biot theory. Several models are proposed. The geometry of the duct can be two-dimensional or circula rand two methods are investigated in order to solve the problem, i. E. Determining the propagation constant for the different modes. Numerical simulations show that under certain circumstances structural vibrations can produce an important low frequency attenuation whereas under other circumstances the latter is lower. A first experimental study shows the validity of this work
30
Desta, B. "Modulation of uterine contractility and blood flow by calcium channel antagonists." Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380583.
Full text
31
Selomulya, Cordelia Chemical Engineering & Industrial Chemistry UNSW. "The Effect of Shear on Flocculation and Floc Size/Structure." Awarded by:University of New South Wales. Chemical Engineering and Industrial Chemistry, 2002. http://handle.unsw.edu.au/1959.4/18226.
Full textAbstract:
The effect of shear on the evolution of floc properties was investigated to analyse the flocculation mechanisms. Little fundamental attention has been given to the shear influence that often creates compact aggregates, while the floc characteristics might differ in other aggregating conditions. It is thus crucial to understand how flocs evolve to steady state, if their properties are to be 'tailored' to suit subsequent solids-liquid separation processes. In this work, flocculation of monodisperse latex particles of various sizes (60, 380, and 810 nm diameter) via electrolyte addition was carried out in a couette-flow and also in shear fields generated by an axial-flow impeller (Fluid foil A310) and a radial-flow impeller (Rushton R100) in standard mixing tanks. A small-angle light scattering technique was used to acquire information regarding the time variation of floc properties in a non-intrusive manner. The structure was quantified by a measure of fractal dimension, signifying the degree of floc compactness. Estimates of the average floc mass were also obtained from the aggregate scattering patterns. By monitoring the changes in floc structure and mass, corresponding to the size evolution; mechanisms of floc formation, fragmentation, and restructuring were identified. Aggregates of 60 and 380 nm particles were observed to grew larger initially, before decreasing to their equilibrium sizes at moderate shear rates (32 - 100 s-1) in a homogeneous shear environment. Floc restructuring at large length scales occurred extensively, and was responsible for the drop in size, particularly at the early stage of the process. Aggregates of 810 nm particles did not, however, display this behaviour. Flocs of larger primary particles were presumably susceptible to breakage rather than deformation, as they were weaker under comparable conditions. Denser aggregates were found when restructuring transpired, while comparatively tenuous flocs were observed when formation and breakage kinetics were the governing mechanisms. The disparity in floc behaviour at higher shear rates (246 s-1 - 330 s-1) was less apparent. The intense hydrodynamic stresses in those instances inevitably caused fragmentation, regardless of the intrinsic particle properties; hence the observed floc compaction was the product of break-up and re-aggregation. A population balance model, incorporating variation in floc structure, displayed comparable trends in size evolution; verifying that restructuring indeed took an important role under certain flocculation conditions. Similar phenomena were likewise observed with the flocculation in stirred tanks. The results reinforced findings in literature; that while circulation time controlled the process kinetics; the floc size was determined by the turbulent stresses. In addition, the maximum shear levels also influenced the floc structures, with denser aggregates produced in a shear field generated using the radial-flow impeller at equivalent energy dissipation per-unit mass. A correlation between non-dimensional floc factor that embodied the aggregate size and structure, and aggregation factor comprising the significant parameters from flocculation conditions, was proposed. The proposed relationship takes into account aspects such as the aggregate structure, interparticle forces, and particle concentration that are often overlooked in existing relationships, which usually only relate the maximum floc size to the applied energy dissipation rate. It thus provides an improved manner of presenting general flocculation data, as well as a means to predict floc properties produced under a specific aggregation condition. Future studies with increasingly complex systems that resemble real conditions are recommended in order to establish a practical understanding of the flocculation mechanisms, for the purpose of optimising the aggregate properties.
32
Hadinata, Chitiur, and chitiurh@yahoo com au. "Flow-induced crystallization of polybutene-1 and effect of molecular parameters." RMIT University. Civil, Environmental and Chemical Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080212.163803.
Full textAbstract:
There are two main goals of this thesis: to investigate the flow-induced crystallization behaviour of Polybutene-1 (PB-1 samples, and to study the effects of molecular parameters on the crystallization behaviour While flow-induced crystallization is not a new area in polymer research, well-defined experimental methods that allow access to high flow rate range comparable to that encountered in real processing are still lacking. Two types of flow are considered: shear and uniaxial elongational. Regarding the second aim, several molecular parameters considered are: molecular weight, molecular weight distribution, isotacticity, presence of nucleating agents, and copolymer content. For this purpose an array of PB-1 samples were used. It is found that each of these parameters can have significant effect on the crystallization behaviour. Mainly rheological methods were utilized to conduct the flow-induced crystallization experiments. Crystallization onset time is define d from the change in viscosity or other related parameters. The experiments begin with low shear rate range, to ensure that the results are comparable with literature data. In this range we encounter the quasi-quiescent onset time at very small. shear rates, which draws an interesting comparison with another physical parameter, the gel time. Beyond a critical flow rate a decrease in the onset time is seen, and a plateau-and-slope trend is evident for a curve of onset time vs. shear rate. Using a combination of three experimental methods, shear rates ranging from Q0001 - 500 s-1 are successfully achieved, and a good agreement between these methods is observed. Furthermore, a normalization procedure is introduced, which yields temperature-invariant curves for the mentioned range of shear rate. For the uniaxial elongation flow, the Elongational Viscosity Fixture (EVF) is employed, with the strain rate ranging from 0.0001 - 10 s'. A greater reduction in onset time as compared to shear (at the same shear/strain r ate) is observed, and the difference in the onset times for shear and elongation already reaches more than one decade for a flow rate of 10 5. This quantitative comparison is particularly important; since not so many data on elongation-induced crystallization are available in the literature. Finally, the thesis compares several flow induced crystallization models that can be useful as prediction tools and selects one of these models to be compared with the experimental data. A qualitative agreement is found, however, for better quantitative prediction the model still needs to be.
33
Nolan, Sean Patrick Rock. "Effect of radial transport on compressor tip clearance flow structures and enhancement of stable flow range." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32435.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (p. 66-67).
The relation between tip clearance flow structure and axial compressor stall is interrogated via numerical simulations, to determine how casing treatment can result in improved flow range. Both geometry changes and flow field body forces are used as diagnostics to assess the hypothesis that the radial transport of momentum out of the tip region, and the consequent decrease in streamwise momentum in this region, is a key aspect of the flow. The radial velocity responsible for this transport is a result of the flow field set up by the tip clearance vortex. Altering the position of the tip clearance vortex can alter the amount of streamwise momentum lost due to radial transport and hence increase the compressor flow range. Circumferential grooves improve the flow range in the manner described above. In the presence of such a groove the radial velocity profile along the passage can be altered so that that the radial transport of streamwise momentum is decreased. The flow fields associated with grooves at different axial positions, and of different depths, are also examined, along with previous research on circumferential grooves, and it is shown that these are in accord with the hypothesis.
by Sean Nolan
S.M.
34
Peelukhana, Srikara Vishwanath. "Effect of coronary collateral flow on diagnostic parameters: An In vitro study." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258473630.
Full text
35
Newton, Bradley Scot. "Blood flow evaluation using an intracoronary doppler catheter." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/16404.
Full text
36
Gonzales, Joaquin U. "Effect of exercise-induced blood flow patterns on endothelial function /." Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1208977525.
Full textAbstract:
Dissertation (Ph.D.)--University of Toledo, 2008.Typescript. "Submitted as partial fulfillment of the requirements for The Doctor of Philosophy degree in Exercise Science." Bibliography: leaves 6-9, 39-46, 66-68, 90-94 and 111-115.
37
Momeni, Parham. "Modelling the Effect of Pulsation on Flow and Heat Transfer in Turbulent Separated and Reattaching Flows." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492875.
Full textAbstract:
The focus of this thesis is on the response of separated turbulent flows to imposed unsteadiness in the form of pulsation. There are substantial modelling challenges in imputing flows exhibiting even steady separation and reattachment. Furthermore, to minimise computing times - particularly important in unsteady flows, given the requirement to perform a large number of time steps - there is a desire to use relatively simple RANS models of turbulence. However, simple linear eddy-viscosity models are known to perform badly in separated flows, hi this study refinements are introduced to both a non-linear eddy-viscosity (Craft et al; 2005) scheme and a DSM model (lacovides and Raisee; 1999) and these are shown to perform quite successfully in predicting the steady state flow and heat transfer through a sudden pipe-expansion. The main aim of current study is to then asses the performance of these models in computing three types of forced unsteady separated flows.
38
Wang, Huan, and Huan Wang. "Flow Field Penetration in Thin Nanoporous Polymer Films under Laminar Flow by Förster Resonance Energy Transfer Coupled with Total Internal Reflectance Fluorescence Microscopy." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/565916.
Full textAbstract:
Tethered polymer layers at solid-fluid interfaces are used widely in a variety of surface science applications. Although many of these applications require exposure to dynamic flow conditions, flow field penetration into densely grafted polymer brushes, is still a question open to debate despite the fact that it is a fundamental process crucial to mass transport through these polymer films. Although most theoretical work has indicated flow field penetration into polymer films, with varying predicted penetration depths predicted, the limited experimental attempts to investigate this phenomenon have resulted in inconsistent conclusions due to lack of a proper analytical method. To help resolve this controversy, in this Dissertation, a new spectroscopic method, FRET-TIRFM, based on a combination of Förster resonance energy transfer (FRET) and total internal reflectance fluorescence microscopy (TIRFM), is developed to provide the first direct, quantitative measurements on flow field penetration by measuring linear diffusion coefficients of small molecules through densely grafted, thin poly(N-isopropylacryl-amide) (pNIPAM) films. Decay curves from FRET of the acceptor with a donor covalently attached at the substrate surface were fit to a combined Taylor-Aris-Fickian diffusion model to obtain apparent linear diffusion coefficients of the acceptor molecules for different flow rates. These values can then be used to obtain quantitative estimates of flow field penetration depths. For a pNIPAM surface of 110 nm dry thickness, with a 0.6 chain/nm² grafting density, apparent diffusion coefficients ranging from 1.9-9.1 × 10-12 cm²/s were observed for flow rates ranging from 100 to 3000 μL/min. This increase in apparent diffusion coefficient with applied fluid flow rate is indicative of flow field penetration of the polymer film. The depth of penetration of the flow field is estimated to range from ~6% of the polymer film thickness to ~57% of the film thickness in going from 100 to 3000 μL/min flow rate of a good solvent. Factors other than flow rate that may impact flow field penetration were also investigated using this new FRET-TIRFM method. Solvent quality and polymer brush grafting density are the two most important parameters due to the fact that they influence changes in tethered polymer chain conformation. This work demonstrates that polymer films are most penetrable in a good solvent and least penetrable in a poor solvent under identical flow conditions. These findings are consistent with polymer chain conformational changes going from extended brushes to compact globules. For flow rates ranging from 100 to 3000 μL/min, flow field penetration depth ranges from ~6% of the film thickness to ~57% of film thickness for a good solvent compared to ~4% to ~19% for a poor solvent. Thus, by simply changing solvent quality from good to poor, flow field penetration decreases by about 38%. Grafting density has a less pronounced effect than solvent quality on penetration depth, probably due to the small range of grafting densities chosen for study. However, a roughly 10-20% difference in penetration depth was observed between high density (0.60 chain/nm²) and low density (0.27 chain/nm²) pNIPAM surfaces in the same solvent. Changes in grafting density have a less significant impact in a good solvent compared to a poor solvent. This is most likely caused by the fact that grafting density impacts polymer chain conformation mainly through polymer-polymer repulsion, which becomes less significant in a solvent that better solvates the polymer. For the two extreme cases studied here at flow rates ranging from 100 to 3000 μL/min, the penetration depth is estimated to range from ~4-19% of the original solvent-swollen film thickness for high density pNIPAM films in a poor solvent and from ~7-67% for low density films in a good solvent. One important assumption that underlies all of this work is that the dominant mass transport mechanism for small molecules in dense polymer brushes is diffusion. This assumption was further validated through the use of two different small molecule quenchers, RhB and 2-nitrobenzylalcohol. These molecules are significantly different in size, charge, and structure, and operate by different quenching mechanisms. Despite these differences, the results for flow field penetration are statistically the same for both. These observations validate the assumption of diffusive mass transport in these films.
39
Thomas, Nicholas. "On the application of the Doppler effect in pulsed Doppler flowmeters and the effect of certain propagation and scattering artifacts." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297092.
Full text
40
柳田, 則之, 務. 中島, 麻子 伊藤, NORIYUKI YANAGITA, TSUTOMU NAKASHIMA, and ASAKO ITO. "Effect of Topical Application of Nitroglycerin on Cochlear Blood Flow." Thesis, Elsevier, 1995. http://hdl.handle.net/2237/17092.
Full text
41
Holzinger, Tobias [Verfasser]. "Aspects of the Thermoacoustic Effect Considering Mean Flow / Tobias Holzinger." München : Verlag Dr. Hut, 2013. http://d-nb.info/1042878315/34.
Full text
42
Shahin, Gus A. "The effect of pulsating flow on forced convective heat transfer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ39881.pdf.
Full text
43
Hinkel, Timothy. "The Effect of Cash Flow Forecasts on Cost of Debt." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293406.
Full textAbstract:
I examine the impact of the presence and characteristics of equity analysts' cash flow forecasts on cost of debt. I find the presence of cash flow forecasts is associated with a lower cost of debt relative to firm-years with only earnings estimates or neither estimate. I also find cash flow forecast characteristics are associated with cost of debt after controlling for other known determinants of yield spreads. Additional analyses decomposing earnings forecast characteristics into cash flow and accruals components find the cash flow component is associated with cost of debt, but the accruals component is not. Overall, the results indicate that debt market participants find cash flow forecasts useful in reducing information asymmetry and/or providing monitoring, as well as being useful in providing information regarding expected default risk in determining expected returns.
44
Koliandris, Anne-Laure. "Flow behaviour of biopolymer solutions and effect on saltiness perception." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11703/.
Full textAbstract:
In order to improve public health, active measures are taken to lower the salt (sodium chloride) consumption of the population. However, significant effort is required to reduce salt content in processed foods without adversely affecting taste, flavour and consumer preference. This research aimed at investigating how the saltiness efficiency of sodium chloride could be improved. The first approach investigated the relationship between rheology and taste perception to evaluate whether it is possible to enhance saltiness perception through careful design of product rheology. The objective was to identify the flow parameters correlating to saltiness perception. The shear rate relevant to saltiness perception was investigated using a range of typical solution flow behaviour (Newtonian, shear-thinning, yield behaviour). It was found that saltiness perception is related to viscosity measured at low shear (1-10 s-1) and not to zero shear or high shear viscosity. An enhancement of saltiness perception was found for very high polymer concentrations, which could be explained by the increased osmolality of these solutions. Subsequently, food grade Boger fluids (Newtonian fluids of high elasticity) were formulated and characterised to investigate whether extensional viscosity impacts saltiness perception. As no clear effect was reported, hypothesised to be due to the unfavourable mouthfeel of the relatively thick fluids, an alternative approach using low viscosity polysaccharide solutions of identical shear behaviour but of different extensional behaviour was taken. Extensional behaviour of polysaccharide solutions in large deformation flow has received very little attention compared to shear flow behaviour and was characterised here using the techniques of filament break-up and microfluidics as preliminary work for future sensory studies. Large differences in elasticity among polysaccharides and singularities of polysaccharides compared to synthetic polymers were found. As a second approach it was investigated whether duplex emulsions could be stabilised by chemical cross-linking of proteins adsorbed at the oil-water interface. The interest in duplex emulsions is based on the hypothesis that increase in the salt concentration in the continuous product phase of an emulsion-based food may increase saltiness perception. Formulation of stable food duplex emulsions is challenging and here it was shown that chemical cross-linking of Bovine Serum Albumin (BSA) adsorbed at the oil-water interface improved stability towards coalescence and emptying out of the internal water phase. The interface of single oil-in-water emulsions was also successfully cross-linked. Both the industrial impact and fundamental interest of this research were discussed.
45
Sparrow, Kathryn. "The effect of bed permeability on oscillatory boundary layer flow." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201986.
Full textAbstract:
Oscillatory boundary layer flow is found under waves in the near shore region. This region is responsible for large volumes of sediment transport and whilst a large number of studies have investigated the broader problem only a handful of studies have investigated the boundary layer flow in detail. Most of these studies have also only considered boundary layer flow over rough impermeable beds and therefore do not take into account the potential effect of the flow interaction with a permeable bed. Similar studies in other felds of environmental fluid mechanics have concluded that the presence of a permeable bed can lead to significant diff erence in the boundary layer hydrodynamics when compared to the equivalent flow over an impermeable bed. This thesis presents a series of laboratory experiments that have been conducted over an impermeable gravel bed and a permeable gravel bed to identify the differences in the boundary layer hydrodynamics with a particular reference to the differences in the horizontal velocity profile, the shear stress, turbulence and the bed friction factor. The results indicate that a difference exists in the near-bed flow between the two bed cases. The results also demonstrate that the magnitude of the differences vary with flow Reynolds number, so the more energetic the wave the larger the impact of the permeable bed. The bed shear stress and resulting friction factor was found to be 40% greater for the flows over the permeable bed for the most energetic test case whilst the friction factor for the two bed cases for the least energetic test case are similar. The results also indicate that the permeable bed introduces an unexpected asymmetry in the flow cycle. This is attributed to the high vertical velocities that have been observed. A second series of experiments have been conducted to shed light on the interaction between the flow above the bed and within the bed to help explain the results from the initial gravel-bed experiments. The second series of experiments have been conducted over a regular permeable bed that allows for velocity measurements within the pores. The results indicate that the horizontal velocity, shear stress and turbulence all display signs of being effected by the exchange of flow, or ventilation, that naturally occurs.
46
Lau, Anna. "Effect of pulsatile flow on liquid phase packed bed adsorption." Thesis, University of Bath, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362237.
Full text
47
Ghoma, Mohamed Ibrahem. "The effect of wall jet flow on local scour hole." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5501.
Full textAbstract:
This thesis reports on investigations carried out to study of the effect of horizontal wall jets on rough, fixed and mobile beds in open channel flow. Experimental tests were carried out, using fixed and mobile sediment beds. Computer simulation models for the flow within the jet and resulting sediment transport were developed and their results analysed in this study. In the experimental phase, tests were carried out with both fixed and mobile sediment beds. The shape of the water surface, numerous point velocity measurements and measurements of the evolving scour hole shape were made. Detailed descriptions of the turbulent flow field over a fixed rough bed and for scour holes at equilibrium were obtained for a range of initial jet conditions. Fully turbulent, multiphase flow was modelled using the Fluent Computational Fluid Dynamics software. This was used to analyze the flow caused by a jet in a rectangle open-channel with a rough bed, and also the flow pattern in a channel with a local scour hole. The volume of fluid (VOF) multiphase method and K- model was used to model the fluid flow in both cases. The model predictions of velocity and shear stress were compared against experimental observations. The experimental data was used to develop new empirical relationships to describe the pattern of boundary shear stress caused by a wall jet over fixed beds and in equilibrium scour holes. These relationships were linked with existing bed-load transport rate models in order to predict the temporal evolution of scour holes. An analytical model describing the relationship between the wall jet flow and the development of a local scour hole shape was reported and its predictions compared with experimental data.
48
Van, Sittert Fritz Peter. "The effect of pipe roughness on non-Newtonian turbulent flow." Thesis, Cape Technikon, 1999. http://hdl.handle.net/20.500.11838/1035.
Full textAbstract:
Thesis (MTech (Civil Engineering))--Cape Technikon, Cape Town, 1999Pipe roughness is known to greatly increase the turbulent flow friction factor for Newtonian fluids. The well-known Moody diagram shows that an order of magnitude increase in the friction is possible due to the effect of pipe roughness. However, since the classical work of Nikuradse (1926 -1933), very little has been done in this area. In particular, the effects that pipe roughness might have on non-Newtonian turbulent flow head loss, has been all but totally ignored. This thesis is directed at helping to alleviate this problem. An experimental investigation has been implemented in order to quantify the effect that pipe roughness has on non-Newtonian turbulent flow head loss predictions. The Balanced Beam Tube Viscometer (BBTV), developed at the University of Cape Town, has been rebuilt and refined at the Cape Technikon and is being used for research in this field. The BBTV has been fitted with pipes of varying roughness. The roughness of smooth P\'C pipes was artificially altered using methods similar to those of Nikuradse. This has enabled the accumulation of flow data in laminar and turbulent flow in pipes that are both hydraulically smooth and rough Newtonian and non-Newtonian fluids have been used for the tests. The data have been subjected to analysis using various theories and scaling laws. The strengths and problems associated with each approach are discussed and It is concluded that roughness does have a significant effect on Newtonian as well as non-Newtonlan flow.
49
Al-Sayed, Mohd S. A. "Effect of flow and pH on CO2 corrosion and inhibition." Thesis, University of Manchester, 1989. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488183.
Full text
50
YANG, WEN-BIN, and 楊文賓. "The effect of flow straighteners to wind tunnel flow gualities." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/60725033969663813270.
Full text