Dissertations / Theses: 'Liquid bridges'

1

Harrison, Matthew Robert. "Liquid bridges in printing and coating." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434213.

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Patel, Neha Mehul. "Electrooptic Studies of Liquid Crystalline Phases and Magnetically Levitated Liquid Bridges." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1080932723.

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Crean, Barry. "Novel studies of liquid bridges in high shear wet granulation." Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517771.

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Gopalkrishnan, Prasad. "INTER-PARTICLE LIQUID BRIDGES: A BUILDING BLOCK TO MODEL COMPLEX MIXING PHENOMENA." online version, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1085169849.

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5

Sumner, Loren Bryan Stout. "Energy stability of thermocapillary convection in liquid bridges with a deformed free surface." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17140.

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Brulin, Sebastian [Verfasser], Ilia V. [Akademischer Betreuer] Roisman, Jeanette [Akademischer Betreuer] Hussong, and Edgar [Akademischer Betreuer] Dörsam. "Hydrodynamic Investigations of Rapidly Stretched Liquid Bridges / Sebastian Brulin ; Ilia V. Roisman, Jeanette Hussong, Edgar Dörsam." Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/123006253X/34.

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7

Du, Rand Marlene. "The influence of powder liquid ratio on the flexural strength of fibre reinforced acrylic resin material." Thesis, Cape Peninsula University of Technology, 2007. http://hdl.handle.net/20.500.11838/1535.

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Thesis (MTech (Dental Technology Discipline))--Cape Peninsula University of Technology, 2007
Practitioners often modify the powder:liquid ratio of polymethyl methacrylate resins (PMMA) to improve the handling properties of the material for certain procedures or because of personal preferences. While it is known that this influences the mechanical properties of unreinforced resin materials, little is known about its effect on glass fibre reinforced PMMA resin.

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Rynhart, Patrick Reuben. "Mathematical modelling of granulation processes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Mathematical Physics at Massey University, Palmerston North, New Zealand." Massey University. Institute of Fundamental Sciences, 2004. http://hdl.handle.net/10179/242.

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Granulation is an industrial process where fine particles are bound together into larger granules. The process has numerous applications including the manufacture of pharmaceuticals and the production of cosmetics, chemicals, detergents and fertilisers. This thesis studies aspects of wet granulation which involves the application of a viscous binder, usually in the form of a spray, to an agitated bed of powder particles. Individual powder particles may adhere together, joined by small quantities of binder fluid called liquid bridges. By a process of collision and adherence additional particles may join the newly formed agglomerates. Agglomerates may also coalesce together which is a process that leads to granule formation. On the completion of this process, granules are typically dried.This thesis studies wet granulation on three different levels. First, micro-level investigations of liquid bridges between two and three particles are performed. For the two-particle case, the fluid profile of static (stationary) and dynamic (moving) liquid bridges is investigated. For the static case, a numerical solution to the Young-Laplace equation is obtained; this relates the volume of binder fluid to liquid bridge properties such as the inter-particle force. An analytic solution is also obtained, providing the liquid bridge profile in terms of known mathematical functions. For both solutions, the radii of the (spherical) primary particles may be different. The dynamic case is then studied using the Navier-Stokes equations with the low Reynolds number approximation. The motion of the approaching particles is shown to be damped by the viscosity of the liquid bridge. Static liquid bridges between three equally sized primary particles are then studied. Symmetry of the problem is used to obtain a numerical solution to the Young-Laplace equation. Liquid bridge properties are calculated in terms of the binder fluid volume. Experimental agreement is provided.Secondly, a model to estimate the stickiness (fractional wet surface area) of agglomerates is proposed. Primary particles are approximated as spheres and are added one at a time in a closely packed arrangement. The model includes parameters to control the inter-particle separation distance and the fluid saturation state. Computational geometry is used to obtain results which relate the number of particles and the volume of binder fluid to the stickiness of the agglomerates.Finally, a population balance model for wet granulation is developed by extending an earlier model to incorporate the effects of binder fluid. Functions for the inter-particle collision rate and drying rate are proposed, including functions which are derived from the geometric model, described above, for the case of maximum particle consolidation. The model is solved numerically for a range of coalescence kernels and results are presented which show the effect of binder volume and the drying rate.

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9

Leboi, Jérémy. "Dégivrage des pompes à chaleur sur l’air : influence de la mouillabilité des ailettes d’échangeurs extérieurs et contrôle des flux hydriques lors du givrage et du dégivrage." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14531/document.

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Dans un contexte de limitation de la consommation en énergie fossile et de développement durable, les pompes à chaleur présentent un intérêt majeur. Les obstacles rencontrés, notamment le givrage compact, freinent leur utilisation. La mise en place de nouveaux matériaux, par exemple par des propriétés de mouillage particulières, est une voie innovante. L’étude des déplacements de gouttes et de ponts entre ailettes, par résolution des équations de Navier-Stokes, permet de comprendre localement les écoulements et de caractériser l'effet du mouillage (modèle numérique d'angle de contact) et du confinement. Plusieurs études ont été menées sur des gouttes et des ponts liquides, soumis à des écoulements sur parois inclinées, lors desquelles des comportements significatifs ont été mis au jour et permettent de mettre en place des solutions efficaces pour les enjeux industriels. Une approche des phénomènes de mouillage extrêmes (superhydrophobie) a été réalisée et montre leur intérêt d’un point de vue performance. En revanche, le coût nécessaire pour réaliser les simulations reste très important, et des pistes ont été abordées pour palier à cette difficulté. En parallèle, une méthode de changement d’état a été développée dans le code de calculs scientifiques Thétis pour prédire l'évacuation de la glace lors du dégivrage sur des géométries simples ou réelles. Cette approche originale basée sur la méthode Volume Of Fluid, dérivée de méthodes existantes en Front-Tracking, montre une faisabilité et une efficacité intéressante
In a context of limiting the consumption of fossil energy and of sustainable development, heat pumps are of major interest. Some issues, including icing compaction, reduce its use. The introduction of new materials, including special wetting properties, is an innovative way. The study of displacement of drops and liquid bridges between fins, by solving the Navier-Stokes equations, allows us to understand local flows and to characterize the effect of wetting (numerical model of contact angle which depends on controlling the smoothing of Volume Of Fluid function) and of containment. Several studies have been conducted on the drops and liquid bridges submitted to flow on sloping walls, driving to significant behaviors. These studies can implement effective solutions to industrial difficulties. An approach to extreme wetting phenomena (superhydrophobicity) was performed and showed their interest to a good evacuation efficiency but also the cost to achieve the simulations. Several possibilities were discussed to overcome this difficulty. In parallel, a method of phase change was developed in the code of scientific computing Thetis to simulate the evacuation of ice during defrosting periods on simple geometries or more complex ones. An innovative approach based on Volume Of Fluid method, derived from methods available in Front-Tracking shows its feasibility and efficiency

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10

Lu, Yanfeng. "A Study on Liquid Bridge Based Microstereolithography (LBMSL) System." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468252608.

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11

Tourtit, Youness. "Effect of the Boundary Conditions Applied to the Liquid Bridge on the Liquid Transfer between Two Solid Surfaces." Doctoral thesis, Universite Libre de Bruxelles, 2021. https://dipot.ulb.ac.be/dspace/bitstream/2013/321652/5/contratYT.pdf.

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The trend towards miniaturization requires to handle even smaller micro-components: they must be picked, placed with high accuracy, and then released. This highly challenging process should take into account two aspects: the yield of successful placements and the minimized risk of damaging the manipulated micrometer-sized objects due to contact forces. Despite the advantages of the latest gripping technologies, including low complexity, high accuracy, and high reliability, the component is subjected to high contact forces that could damage it. As a consequence, there is a need of developing new and innovative ways to manipulate micro-sized components with respect to the requirements mentioned above. Gripping based on capillary bridges is a promising technique to handle components at the micrometric scale. This technique offers many advantages: flexibility and reliability, self-centering effect, the capability of grasping small and delicate components in a wide range of shapes and materials thanks to the “bumper” effect of the mediated liquid bridge. Nevertheless, the liquid residue on the component after breaking up the bridge is undesirable. As a consequence, there is a need to design a capillary gripping system that can retain all the liquid after the breakup of the bridge. Understanding the formation, the stretching, and the liquid distribution after the breakup of the liquid bridge is mandatory. In this thesis and in the first place, we studied the rupture of a liquid bridge confined between different geometries of the gripper and the substrate: plane/plane, cone/plane, and cavity/plane. We developed, based on the resolution of the Young-Laplace equation, an operational quasi-static criterion to predict the rupture gap of the bridge. We also investigated the effect of the geometry on the liquid distribution after the breakup. Optimal geometries are found to retain up to 90$%$ of the liquid after the breakup of the bridge. In the second place, we investigated the secretion dispensing in green dock beetles ( extit{Gastrophysa viridula}). Their ability to walk upside-down on any kind of surfaces rely on mediated secretion between their hairy pad and the surface they walk on. We studied the mechanism of the secretion dispensing from the source where it is produced to the contact zone. Experimental setups have been designed, with advancing 3D printing and micro-fabrication techniques. Models have been developed, discussed, and compared to experimental data.
Doctorat en Sciences de l'ingénieur et technologie
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12

Vincent, Lionel. "Dynamique de ponts liquides et ligaments étirés." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4787.

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Dernière étape avant l'atomisation d'un volume de liquide, les ligaments sont présents dans de nombreuses applications industrielles, de même que dans le monde qui nous entoure ; leur dynamique demeure mal comprise. L'étirement, qui permet de leur donner naissance, affecte leur évolution et la manière dont ils se fragmentent (ou non). Pour quantifier l'effet de ce dernier, nous avons choisi d'étudier des configurations modèles dans lesquelles plusieurs paramètres peuvent être bien contrôlés. Une configuration de type pont liquide permet notamment de contrôler l'étirement via le déplacement de l'un des supports solides (mors). Lorsque l'étirement imposé est modéré, il est possible de prévoir analytiquement la déviation entre la forme dynamique et la forme d'équilibre correspondante, quelle que soit la loi de déplacement du mors. Cette prédiction montre en particulier qu'un pont liquide étiré peut s'épaissir appréciablement en son centre, suggérant un retardement de la rupture. Elle montre également que l'étirement axial est réparti de manière très inhomogène. Lorsque l'étirement est suffisamment vigoureux, les résultats expérimentaux montrent que le détachement capillaire du ligament peut être significativement hâté. Le temps de rupture est relié à la masse emportée par le mors en mouvement et dépend du protocole d'étirement. Les résultats suggèrent également la possibilité d'obtenir des ligaments démesurément longs et fins sans l'intervention d'effets visqueux
Liquid ligaments represent the last step before atomization of a liquid volume, and are encountered in a variety of industrial applications, as well as the world around us; yet, there is much to learn about their dynamics and breakup. Stretching is an essential ingredient of ligaments formation, and affect their subsequent dynamics as well as the way they break (or not). In order to quantify its action, we choose model configurations where parameters can be controlled. Liquid bridges, in particular, provide a way to impose stretching by moving one of the solid rod supporting the bridge. When stretching is not too strong, it is possible to predict analytically the shift between the dynamical shape of the bridge and the corresponding static shape, for any given rod displacement. Particularly, this prediction show that the central section of a stretched liquid bridge tend to be thicker, which could delay breakup. It also show that the axial elongation rate is far from being uniform. When stretching is vigorous, experimental results show that the ligament initial breakup can be considerably sped up. Breakup time shows to be linked to the mass taken away by the moving rod and depend on stretching protocol. Finally, results suggest that it is possible to generate infinitely long ligaments without the mediation of viscous effects

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13

Shibata, Manabu. "Accurate Determination of pH by Use of Ionic Liquid Salt Bridge." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157605.

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Valsamis, Jean-Baptiste. "A study of liquid bridge dynamics: an application to micro-assembly." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210117.

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Micro-assembly processes suffer from some breaches due to the continuing trend towards an increase in the production capabilities as well as in the size reduction of the components manipulated. Usual manipulating schemes have reached their limit and capillary forces constitute a valuable alternative strategy.

The goal of this work is to describe the dynamics of liquid bridges in the application of micro-assembly processes. The description is obtained using the Kelvin-Voigt model, with a spring, a damper, and a mass connected in parallel, supported by numerical simulations, analytical approximations and experiments.

The works is divided into three parts. First we present important aspects of microfluidics, as well as the constitutive equations and an overview of numerical approaches used to describe fluid flow problems with moving interfaces.

The second part is devoted to the capillary rise case, intended to validate and to compare the numerical approaches to analytical laws and experimental results. The implementation of the slipping and the dynamic contact angles is discussed.

The last part focuses on the dynamics of the liquid bridge. The liquid bridge is confined between two circular and parallel plates and presents an axial symmetry. The description reveals that the stiffness depends on the surface tension and on the shape of the air/liquid interface, the damping coefficient depends on the viscosity and the volume of liquid and the equivalent mass depends on the density and the volume.

Doctorat en Sciences de l'ingénieur
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15

Decker, Gifford Zach. "Modeling the Mechanical Effects of Liquid Mediated Adhesion Between the Human Vocal Folds." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/501.

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The vocal folds are a complex self-oscillating biological system. In the current research, an equation was developed to model viscous adhesion forces that occur when the collision of the vocal folds results in the formation of a liquid bridge. The adhesion equation was validated using experimental data, and simplified to a one-dimensional approximation with an included correction factor that adjusted the predicted pressure in situations where the one-dimensional approximation was invalid. A non-oscillating vocal fold model with a modeled liquid bridge was used to study stress resulting from viscous adhesion. The vertical normal stress magnitude ranged from about 80 to 1700 Pa. This was shown to be of the same order of magnitude as the stress due to collision of the vocal folds. Also the stress resulted in large normal strains that occurred at small distances below the surface of the vocal folds consistent with lesion development. Therefore, it was determined that the viscous adhesion may be a contributor to damage of the vocal folds that leads to the development of benign lesions, such as vocal nodules. This conclusion was further validated by adding the adhesion equation in a self-oscillating vocal fold model. The influence of adhesion on the dynamics of the model was significant. The frequency of vibration was reduced by nearly 2.5% for the case of adhesion with a mucus viscosity of 0.01 Pa-s. Also adhesion induced positive tensile stress that resulted in normal strain distributions similar to those seen in the non-oscillating cases. These results also indicated that liquid mediated viscous adhesion may be a contributor to the development of benign lesions (nodules). However, further research is needed to validate these conclusions.

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Chandra, Santanu. "A NUMERICAL STUDY FOR LIQUID BRIDGE BASED MICROGRIPPING AND CONTACT ANGLE MANIPULATION BY ELECTROWETTING METHOD." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1197299987.

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17

WANG, AIHUA. "EFFECTS OF FREE SURFACE HEAT TRANSFER AND SHAPE ON THERMOCAPILLARY FLOW OF HIGH PANDTL NUMBER FLUIDS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1094682055.

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18

Sarayloo, Mehdi. "A Sensor for Measuring Liquid Water Content of Wet Snow on Superstructures." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1574893940427478.

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19

Ek, Patrik. "Mass Spectrometry with Electrospray Ionization from an Adjustable Gap." Licentiate thesis, KTH, Chemistry, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4747.

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In this thesis the fabrication and analytical evaluation of two new electrospray emitters utilized for mass spectrometry analysis is presented. The emitters are based on a new concept, where the spray orifice can be varied in size. The thesis is based on two papers.

All present-day nanoelectrospray emitters have fixed dimensions. The range of the applicable flow rate for such an emitter is therefore rather limited and exchange of emitters may be necessary from one experiment to another. Optimization of the signal of the analyte ions is also limited to adjustments of the applied voltage or the distance between the emitter and the mass spectrometer inlet. Furthermore, clogging can occur in emitters with fixed dimensions of narrow orifice sizes. In this thesis, electrospray emitters with a variable size of the spray orifice are proposed. An open gap between two thin substrates is filled with sample solution via a liquid bridge from a capillary. Electrospray is generated at the end point of the gap, which can be varied in width.

In Paper I, electrospray emitters fabricated in polyethylene terephthalate have been evaluated. Triangular tips are manually cut from the polymer film. The tips are mounted to form a gap between the edges of the tips. The gap wall surfaces are subjected to a hydrophilic surface treatment to increase the wetting of the gap walls.

In Paper II, silicon electrospray chips with high precision are fabricated and evaluated. A thin beam, elevated from the bulk silicon chip is fabricated by means of deep reactive ion etching. The top surfaces of the beams of two chips act as a sample conduit when mounted in the electrospray setup. An anisotropic etching step with KOH of the intersecting <100> crystal planes results in a very sharp spray point. The emitters were given a hydrophobic surface treatment except for the hydrophilic gap walls.

For both emitter designs, the gap width has been adjusted during the experiments without any interruption of the electrospray. For a continuously applied peptide mixture, a shift towards higher charge states and increased signal to noise ratios could be observed when decreasing the gap width. The limit of detection has been investigated and the silicon chips have been interfaced with capillary electrophoresis.

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20

Ding, Linfang Verfasser], Liqiu [Akademischer Betreuer] [Gutachter] [Meng, Gerd [Gutachter] Buziek, and Gennady [Gutachter] Andrienko. "Visual Analysis of Large Floating Car Data – A Bridge-Maker between Thematic Mapping and Scientific Visualization / Linfang Ding. Betreuer: Liqiu Meng. Gutachter: Liqiu Meng ; Gerd Buziek ; Gennady Andrienko." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/110169517X/34.

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21

Almeida, Alexandre Barros de. "Análise e modelagem termodinâmica de um modelo de gás de rede para pontes líquidas." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-14032013-153056/.

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Nesta dissertação, estudou-se um modelo tipo gás de rede em três dimensões para simular sistemas líquidos macroscópicos. Aplicou-se o modelo para o estudo das energias e forças envolvidas durante o processo de formação e ruptura de pontes líquidas entre duas placas planas. Esse estudo foi motivado por processos fisiológicos que acontecem no interior dos pulmões dos mamíferos. Além disso, foi feito um estudo das propriedades termodinâmicas do modelo. Com relação a aplicação fisiológica, observou-se que, no processo da formação da ponte líquida, a energia livre da ponte líquida é menor que a energia livre da gota, para diferentes sistemas líquidos. Com este resultado, fez a hipótese de que parte dessa energia é dissipada na forma de energia acústica. A emissão do som também deve ocorrer na ruptura da ponte líquida. Comparando a energia livre no processo de formação e ruptura da ponte líquida observou-se uma curva de histerese. Também foi verificado que para sistemas pequenos, a ponte líquida no modelo computacional se forma antes da previsão analítica. Para a análise termodinâmica, o modelo foi simplificado removendo as placas planas. Foi estudado o caso mais simples desse modelo que continha apenas duas partículas de líquido. Neste caso, calculou-se o calor específico e a energia interna numericamente, e esses resultados foram comparados com cálculos analíticos, validando o modelo numérico. Posteriormente, realizou-se um estudo da transição de fase desse sistema. Em seguida, a energia livre e a força da ponte líquida sobre as placas foram estudadas para diferentes temperaturas utilizando duas metodologias. Na primeira metodologia a entropia foi desprezada, na segunda metodologia, foi utilizando o método ``Overlapping Distribution\'\' que considera a entropia do sistema. Foi concluído que a entropia tem um efeito muito pequeno nas condições estudadas. O modelo é viável para a modelagem de fluidos a nível macroscópico e que portanto pode ser utilizado para quantificar não só as forças internas de estruturas pulmonares como também avaliar as energias liberadas após o processo de ruptura ou formação dessas pontes.
This work studied a three dimension lattice gas model to simulate macroscopic liquid systems. We used the model to study the energy and the forces involved during the process of liquid bridge formation and rupture between two parallel planes. The motivarion of this study was a physiological processes which occur inside the mammals lungs. Furthermore, a study was made to elucidate thermodynamic properties of the model. Concerning to physiological application, it was observed that the free energy of liquid bridge is smaller than the free energy of the droplet, for different liquid systems. With this observation, was proposed that this energy is dissipated as an acoustic energy. This sound should also exist in the rupture of liquid bridge. Comparing the free energy of liquid bridge in the formation and rupture process was observed a hysteresis curve. It was also found an effect of finite size in the formation of small size of the liquid bridge. In the numerical model, the liquid bridge is always formed earlier than expected from the analytical model. In the thermodynamic study, the model was simplified removing both parallel planes. First, the simplest case of this model was studied, only two liquid particles in a large gas lattice. In this case, the specific heat and internal energy was numerically studied and the results was compared with analytical calculation. Subsequently, we carried out a study of the phase transition of this system. Then, the free energy and the force generated between two parallel planes due the presence of the liquid bridge. This studied was performed using two different temperatures and two distinct methods. In the first method the entropy was neglected, and in the second method not. The second method was the ``Overlapping Distribution\'\'. It was concluded that the entropy has a very small effect in the studied conditions. The model is viable for modeling fluids at macroscopic level and therefore can be used to quantify not only the internal forces of the lung structures, but evaluate the energies released after the rupture process of the formation of these bridges.

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Zheng, Jie. "Effects of capillarity on the mechanical stability of small-scale interfaces." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-11212004-180952/unrestricted/zheng%5Fjie%5F200412%5Fphd.pdf.

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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2005.
J. Carson Meredith, Committee Member ; J. Carlos Santamarina, Committee Member ; G. Paul Neitzel, Committee Member ; Richard F. Salant, Committee Member ; Jeffrey L. Streator, Committee Chair. Includes bibliographical references.

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Yasnou, Viktar. "Development and improvement of the experimental techniques for fluid examination." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209175.

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The aim of the thesis is the development and improvement of the experimental techniques for fluid examination. The thesis consists of two parts and both examine heat and mass transfer in liquids using the optical methods and thermal analysis. The first part deals with the measurement techniques for studying flow patterns and their stability in systems with gas/liquid interface, in particular, in a liquid bridge system. The second part is aimed at the improvement of the existing experimental techniques to study the heat/mass transfer in the mixtures with Soret effect, enclosed in a container.

Part A is motivated by preparation of the experiment JEREMI (The Japanese-European Research Experiment on Marangoni Instability) to be performed on the International Space Station (ISS). One of the objectives of the experiment is the control of the threshold of an oscillatory flow in the liquid zone by the temperature and velocity of the ambient gas. The developed set-up for a liquid bridge allows to blow gas parallel to the interface at different temperatures and investigate the effects of viscous and thermal stresses on the stability of the flow. The present study reports on isothermal experiments with moving gas and non-isothermal experiments with motionless gas when the cooling of the interface occurs due to evaporation. The discussion concerning the experimental observations is based on two sources: an interface shape measured optically and the records on thermocouples giving an indication of how temperature and frequency evolve over time.

Part B is related to ground-based studies in course of preparation and realization of the microgravity experiment DCMIX (Diffusion Coefficient in MIXtures). DCMIX project is a series of experiments aimed at measuring of the Soret coefficients in liquid mixtures on the ISS which involves a wide international group of scientists. Two experiments have been recently completed and the third one is under preparation In the course of this thesis all the aspects of the previously existing set-up for measurements of the Soret (thermal diffusion) and diffusion coefficients in binary mixtures were studied, uncertainties were identified and improvements were done to obtain reliable results. The final design has been validated by measuring coefficients in three binary benchmark mixtures and water-isopropanol. The obtained results agree well with literature data.
Doctorat en Sciences de l'ingénieur
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Incerti, Véronique. "Coalescence de gouttes dans l'air : du millimètre au nanomètre." Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19664/7/ChireuxIncerti_19664.pdf.

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La coalescence intervient dans de nombreuses situations physiques, naturelles ou industrielles, de la microphysique des nuages à la stabilité des émulsions ou l’assèchement des pétroles. Dans toutes ces situations, il est crucial de comprendre les mécanismes physiques en jeu, de manière pouvoir influencer la coalescence, la favoriser ou au contraire l’inhiber, selon les besoins. Dans cette thèse, nous étudions la coalescence dans l’air entre deux gouttes attachées et décomposons le processus global en quatre étapes : l’approche avec drainage du film d’air entre les gouttes, le perçage des interfaces, l’ouverture du pont résultant de ce perçage, les oscillations amorties conduisant à l’équilibre de la goutte résultante. Les théories décrivant les étapes 1, 2 et 4 font intervenir des modèles hydrodynamiques continus, se plaçant à une échelle macroscopique. Cependant, à l’articulation entre les deux premières étapes, intervient le perçage des interfaces, processus gouverné par des forces dont la portée correspond à une échelle de quelques dizaines de nanomètres. Une des difficultés les plus importantes dans l’étude de la coalescence est celle de l’intégration des processus ayant lieu à un niveau moléculaire, dans une théorie du continuum dont l’échelle caractéristique est bien supérieure. L’objectif est de faire le lien entre les différentes échelles : y a-t-il des interactions entre les processus se produisant à ces différentes échelles ? Pour répondre à cette question, nous développons trois axes de travail, engageant chacun une échelle caractéristique. L’un est l’étude, au niveau macroscopique du micromètre, de l’ouverture du pont liquide. Grâce à une caméra rapide, plusieurs régimes d’écoulement sont mis en évidence. Les modèles théoriques existants concernent essentiellement le régime visqueux, et aucun modèle complet ne décrit le régime purement inertiel. Nous explorons expérimentalement ce régime et décrivons la forme et la longueur du pont, à l’aide d’ondes capillaires. Nous mettons en évidence l’existence de deux lignes de très forte courbure, que nous appelons singularités, qui naissent sur le lieu de perçage des interfaces et se propagent presque sans déformation de part et d’autre. Ces singularités, conditionnées par la tension superficielle, moteur de la coalescence, façonnent la forme du pont liquide et donc l’écoulement dans ce dernier. Nous proposons un modèle simple d’écoulement inertiel, basé sur la forme du pont liée à ces singularités. Ce modèle permet de mieux comprendre les rôles des forces hydrodynamiques et de la courbure dans l’évolution temporelle de la largeur du pont. Un autre axe est une étude expérimentale par Microscope à Force Atomique, qui permet de décrire les forces responsables de la coalescence à l’échelle nanométrique, les déformations des gouttes intervenant à cette échelle et leur rôle dans la rupture des interfaces. Les mesures de forces entre goutte et flaque, puis entre deux gouttes sont effectuées avec un AFM principalement en mode dynamique de Modulation de Fréquence. Elles permettent de mettre en évidence une distance seuil de déclenchement de l’instabilité hydrodynamique responsable de la coalescence et de mesurer cette distance en fonction des propriétés physiques du liquide et du rayon des gouttes. Un diagramme de coalescence est proposé, qui permet de prévoir la valeur de la distance de déclenchement de la coalescence et le rôle des déformations d’interfaces à l’échelle nanométrique. Enfin, les oscillations du pont liquide, générées par la coalescence, sont étudiées, les modes et fréquences propres sont calculés numériquement par la méthode des éléments finis, puis comparés aux valeurs expérimentales mesurées à partir des films acquis par caméra rapide.

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25

Brulin, Sebastian. "Hydrodynamic Investigations of Rapidly Stretched Liquid Bridges." Phd thesis, 2021. https://tuprints.ulb.tu-darmstadt.de/17537/1/Dissertation_1.0.pdf.

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Liquid bridges have become an integral part of many industrial processes relevant to consumer production. For example, the coating technology often includes dip-coating, printing, or spraying of liquid materials. Liquid bridge or liquid jet fast stretching is an essential element of such processes. Bridge stretching determines the outcome of liquid atomization and the agglomeration of wet particles. Moreover, liquid bridge stretching is used for the rheological characterization of complex liquids. This thesis deals with the investigation of fast stretched Newtonian fluid bridges. The unique feature of this study is the investigation of particularly high stretching rates for very small liquid bridge heights. A system consisting of two parallel substrates was developed. One substrate can be moved with a constant, controllable acceleration while the other substrate remains stationary. It allows performing parameter studies with accelerations of up to 180 m/s2 and initial bridge heights starting from 50 μm. Extensive experimental and theoretical studies were carried out to identify the most influencing parameters and, therefore, to understand the physical mechanisms of the observed phenomena better. The characterization includes a description of the kinematics of the liquid bridge stretching and different outcomes like liquid cavitation, finger formation during stretching, and bridge pinch-off. The evolution of the main geometrical properties of the stretching liquid bridge is characterized. These properties include the curvature and shape of the meniscus, length, and diameter of the liquid bridge. Two main regimes of a fast stretching are identified: viscous regime, determined by the Reynolds number, and capillary regime for low viscosity liquids, governed by the Weber number. The knowledge of the kinematics of the bridge allows us to determine the appropriate scales for a description of the stretching outcomes. The cavitation phenomena are described using the estimation of the distribution of the viscous pressure in the gap. This pressure determines the evolution of the cavity radius. A bubble growth model has been developed, which allows the prediction of the instant of the maximum bubble diameter as a function of the cavitation inception rather well. Next, the stability analysis of the bridge free interface is performed, which accounts for the viscous effects and inertia. The predicted condition for the appearance of the fingers and the number of these fingers agree well with the experimental data. Finally, the model for the pinch-off time of the stretching bridge is developed. The scales for the pinch-off time have been determined for viscous and for the capillary stretching regimes. The experimental and theoretical results can be potentially useful for optimizing the operational conditions during printing and modeling atomization, accretion, and agglomeration phenomena.

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Shu, Po-Sen, and 許博森. "Wind-induced Vibration Control of Long-Span Bridges using Tuned Liquid Column Dampers." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/54484179171306155722.

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碩士
淡江大學
土木工程學系
91
For long-span bridges the aerodynamic stability and buffeting response become more significant due to their large flexibilities and relatively low structural dampings. Since the type of bridge is highly susceptible to wind excitations, it needs some devices to control the aerodynamic vibrations. The passive dampers that have been used in the engineering structures include tuned mass dampers (TMD), tuned liquid dampers (TLD), tuned liquid column dampers (TLCD), and so on. A numerical analysis is used to study the performance of tuned liquid column dampers (TLCD) on wind-induced vibrations of long-span bridges. The governing equations of the bridge-damper system in lift, drag, and torsional directions are formulated and both structural coupling and aerodynamic coupling effects are taken into account. The reduction of dynamic torsional response through the attachment of the damper to the bridge deck are investigated. The effects of torsional mass ratio, head loss, ratio of liquid horizontal length to its total length(B/L), and frequency of TLCD on the performance are also studied. Comparison between the numerical results and the experimental results indicate that they are in good agreement. The results also show that tuned liquid column dampers can effectively suppress torsional buffeting responses of bridges.

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27

Giddings, Eric. "Effect of Helium Circulation on the Onset of Oscillatory Marangoni Convection in Liquid Bridges." Thesis, 2013. http://hdl.handle.net/1807/42847.

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A half-zone experimental set-up was used to study the effects of various liquid bridge and helium flow parameters on the onset of thermocapillary convection in silicone oil liquid bridges. Experiments confirmed that helium flow has a stabilizing effect, with the effect increasing with helium velocity. Furthermore, helium flow in the same direction as surface flow due to Marangoni convection had a more stabilizing effect than countercurrent flow. It was established that increasing helium temperature has a mixed effect, producing a less stable bridge at low helium flow rates, but a more stable flow pattern at higher helium flow rates. Finally, it was confirmed that decreasing the cold disk temperature results in a decrease in critical temperature difference.

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Liao, Che-Shu, and 廖哲樞. "Wind Tunnel Investigation on Wind Induced Vibration Control of Large Span Bridges Using Tuned Liquid Column Damper." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/11825880685482719513.

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碩士
淡江大學
土木工程學系
89
In modern time, the aerodynamics of long-span and light mass bridges becomes a serious problem. This thesis uses a vibration-reduction devices to decrease displacement response of structure. A new vibration-reduction device called tuned liquid column damper (TLCD) were proposed, which is an U shape tube-like damper exploiting the sloshing of liquid to absorb the energy resulting from structures vibration. This thesis studied several important parameters of TLCD, such as tuning frequency, orifice opening ratio and the mass of moment inertia. Wind tunnel experiment was used to measure the effect on flutter and buffeting response of bridges. The efficiency of TLCD on increasing the flutter critical wind speed and the reduction of buffeting vibration response were evaluated. The wind-tunnel investigation indicates that TLCD plays an important role on increasing the flutter critical wind speed. The principles of TLCD design are: proper orifice opening ratio, larger mass of moment inertia and TLCD frequency tuned on the flutter frequency. In this experiment, proper tuned TLCD was found to be able to increase the critical flutter wind speed by 31%. TLCD was also used to decrease the buffeting response of bridges. The efficiency of vibration mitigation depends upon the wind speed. In this investigation, it was found that at higher wind speed, a smaller orifice is required to improve the performance of TLCD. At certain wind speed, application of TLCD can reduce bridge vibration by more than 30%.

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29

Chang, Wen-yin, and 張雯音. "Separation of Liquid Bridge and Meniscus-Climbing Object." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/98912565380178739277.

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碩士
國立中央大學
化學工程與材料工程學系
102
This study contains two topics: separation of liquid bridge and meniscus -climbing object. ＊PART I: Separation of Liquid Bridge Anti-fingerprint or anti-smudge mechanism often involves a liquid bridge formed between two dissimilar surfaces. As the two surfaces are separating, the tendency of the liquid to wet one surface renders the other anti-smudge. In this work, the wetting characteristics of the liquid bridge on two asymmetric surfaces during their separation are investigated both experimentally and theoretically. In general, the contact lines on both surfaces withdraw at the beginning of separation. Before the rupture of the liquid bridge, however, five types of wetting competition are observed: (i) While the contact line remains receding on one surface, it becomes pinned on the other; (ii) The contact line on both surfaces are pinned; (iii) While the contact line is pinned on the one surface, it starts to expand on the other; (iv) While the contact line remains receding on one surface, it start to expand on the other; (v) The contact line on both surfaces are expanded. Our experimental results are in good agreement with the simulation outcomes by Surface Evolver. Evidently, the winning surface is accompanied with the signature of contact angle increment or base diameter expansion before liquid bridge rupture. Further simulation analyses reveal that wetting competition depends on both intrinsic contact angle and contact angle hysteresis. After compression and relaxation of two surfaces, the one with higher contact angle and larger hysteresis may be more wettable than the other with lower contact angle and smaller hysteresis. ＊PART II: Meniscus-Climbing Object In nature, some terrestrial insects evolved to live exclusively on the water surface in order to adapt to the environment, such as water striders. They rely on surface tension for static weight support, and use a variety of means to propel themselves along the surface. When these small insects pass from the water surface to land, they have to overcome the slippery meniscus water surfaces that border the water’s edge. They are unable to climb meniscus by using their own legs, therefore developed the meniscus-climbing technique. By fixing their body posture, the water surface is thus deformed to generate lateral surface tension, and then the insects are propelled upon the meniscus surface without moving their legs. This phenomenon is so called “meniscus-climbing”. In this study, we investigate the behavior of the objects which have meniscus-climbing ability by testing a variety of materials, shapes and densities of the objects. In experiment, we put these objects below the pendant drop successively, and try to observe the influences caused by these conditions to the meniscus-climbing behavior by the high-speed camera. The result shows that the different conditions of objects make significant difference of climbing situations. Specifically, we observe that the objects with climbing ability rotate themselves into vertical direction just before the climbing behavior. Furthermore, the longer object could climb higher. And in the condition of the same area but different shapes, we find the larger aspect ratio, the higher object climbing. Finally, by comparing different densities of the objects, we observe that the lower density, the higher object climbing.

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Wickramasinghe, Dhanuka Navodya. "Effect of G-Jitter on Liquid Bridge Vibrations with & without Marangoni Convection." Thesis, 2011. http://hdl.handle.net/1807/31638.

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Effects of external vibrations (called g-jitter) on Marangoni convection in a liquid bridge were investigated on the International Space Station (ISS) and in ground-based experiments. In ISS, most dominant g-jitter frequency was noted to be ~110 Hz. ISS experiments suggested that the surface vibrations were mainly affected by the aspect ratio (length/diameter ratio), but not the imposed temperature gradient. Liquid bridge surface vibrations agreed well with Ichikawa et al.’s model. Ground-based experiments confirmed that increasing the volume ratio would cause the resonance frequency to increase. When a temperature difference was imposed between the upper and lower disks, for constant aspect and volume ratios, the resonance frequency tended to increase with the decreasing temperature difference. Furthermore, the shift in the resonance frequency due to a temperature difference, was found to be due to Marangoni convection and not due to reduced viscosity or surface tension of the fluid.

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31

Yang, Tung-Po, and 楊棟柏. "non-axisymmetric disturbance with linear stability analysis of thermocapillary convection of liquid bridge." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/18022243665421038933.

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碩士
國立中央大學
機械工程研究所
83
Linear-stability theory has been applied to a basic state of thermocapillary convecton in a model half-zone to determine values of the Marangoni number above which instability is guaranteed. The basic state must be determined numerically since the half-zone is of finite, O(1) aspect ratio with two- dimensional flow and temperature fields.This,in turn,means that the governing equations of basic-state will be solved by finited difference method,and,the governing equations of the linear disturbance will be solve by Spectral-Galerkin method. Our results will be compare with numerical-method,energy-method linear theoey,experiment's results.

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32

Davis, Kenneth Edward. "Three-Dimensional, Time-Dependent Spectral Element Simulations of a Thermocapillary Liquid Bridge with Magnetic Stabilization." Thesis, 2011. http://hdl.handle.net/1911/64417.

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The spectral element method is used to obtain 3D, time-dependent solutions for a thermocapillary driven liquid bridge with magnetic stabilization, which arises from the float-zone crystal growth process. The methods and implementation of the general, in-house developed fluid flow and heat transfer spectral element solver are discussed and the code is benchmarked. This work compares three-dimensional, time-dependent results to perturbations predicted by linear stability theory for the full-zone problem with Prandtl number of 0.02. Critical points, mode numbers, and azimuthal velocity perturbations are matched for the instabilities. Additionally, the simulations extend the study beyond the initial bifurcation point to find modal competition between two steady modes for the zero magnetic field case. Applying an axial magnetic field damps the perturbations and delays instabilities, providing a quiescent interior region that is conducive to growing defect free, uniform composition crystals. Weak magnetic fields are shown to remove the modal competition that leads to undesirable, time-dependent flow with mode switching.

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"High resolution numerical study of a liquid bridge Marangoni flow with applied axial magnetic field for low Prandtl number fluids." Thesis, 2010. http://hdl.handle.net/1911/62073.

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The Full Zone model of the thermocapillary (Marangoni) flow in a liquid bridge with an axial magnetic field, measured by the Hartmann number Ha, is studied using a Chebyshev spectral method for low Prandtl number fluids. By introducing a 2nd order vorticity transport formulation, high resolution Gauss-Lobatto grids can be used to investigate the strong stabilization effects from intermediate magnetic fields, which were impossible with previous formulations. The instability mechanism of the axisymmetric base flow is studied up to Ha=500 for Pr=0.001 and up to Ha=300 for Pr=0.02 using linear stability analyses. Over these parameter spaces, the base flow first transitions to three-dimensional stationary disturbances with different axial symmetries. Solutions from the 2nd order vorticity transport formulation show good agreement with previous studies on weak magnetic fields. This work provides better understanding of the magnetohydrodynamic flow in intermediate field strengths, as well as guidance for optically heated float-zone crystal growth processes.

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Yu, Chih-Kai, and 游智凱. "The Redefinition of a Cold-War Outpost as a Cross-strait Bridge? The inter-regional flow of Kinmen Kaoliang Liquor." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/pj7tat.

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碩士
國立臺灣大學
地理環境資源學研究所
102
Kinmen has played a significant role in the development of cross-strait relations due to its complex political history and geo-spatiality. As a special field for cross-strait relations, this study uses Kinmen Kaoliang Liquor as an example to elaborate the flexible meanings Kinmen is endowed with in the context of the worldwide flow of goods and regionalization. A materiality and cultural discourse analysis approach will be adopted in this study, which aims to illustrate what social relations were changed, shaped or appropriated when Kinmen Kaoliang Liquor crossed the political and cultural boundary that is the Taiwan Strait. This will enable an examination of the range of meanings embodied by Kinmen with relation to Kaoliang liquor as a commodity, one being a rigid representative of a former battlefield, and the other a producer of a local cultural specialty. The construction of this dual identity helped to smoothly re-integrate the traditional Chinese spirits industry and the capital market, however, it can also act as a form of protection, in differentiating between “us” and “others” in terms of commodity governance. Therefore, the concept of ‘nation’ or ‘frontier’ is based on the constant negotiation between national role and capital expansion.

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Dissertations / Theses on the topic 'Liquid bridges'

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