Дисертації з теми "Oscillating Drop"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-22 дисертацій для дослідження на тему "Oscillating Drop".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Jaber, Ahmad. "Interfacial Viscoelastic moduli of bare, surfactant-laden and nanoparticle-laden interfaces oscillating in a weak gel." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0104.
We present a study implementing the oscillating drop method to probe the oil/water interface, modifiable by surfactants or nanoparticles, while surrounded by a continuous phase of controllable rheology. The key question posed in this work concerns the effect of the rheological properties of the continuous phase on the measurements of interfacial viscoelastic moduli extracted from the compression/expansion of an oscillating drop. With this in mind, the continuous phase consists of a thermo-reversible hydrogel K-carrageenan, selected for its interfacial inactivity but also for its hysteresis after the sol/gel transition which allows to have a gel or liquid at the same temperature according to the thermal history.In the case of a pure oil/water interface and under conditions where the KC solution is liquid, the elastic modulus of the interface remains weak. When the KC solution becomes a gel, even if it is weak to the point that the solution flows under its own weight, we witness the appearance of an elastic signature in interfacial viscoelastic measures attesting to the contribution of the rheology of the continuous phase being not negligible.The presence of a surfactant at the oil/water interface, generating an interfacial elastic modulus that increases with the concentration of surfactant in the case of a liquid surrounding medium. In the presence of a weak gel, the interfacial modulus decreases by despite that the modulus of the KC gel increases, this is attributed to a pseudo-localization of deformation at the interface. This phenomenon disappears in the case of an interface laden with solid nanoparticles (Pickering effect).All of this work reveals the importance of deconvoluting interfacial and volume contributions in an interfacial viscoelasticity test of the pendant drop
Al-Faize, Mustafa M. "Mass transfer characteristics of large oscillating drops." Thesis, Aston University, 1986. http://publications.aston.ac.uk/10193/.
Ertl, Moritz [Verfasser]. "Direct Numerical Investigations of Non-Newtonian Drop Oscillations and Jet Breakup / Moritz Ertl." München : Verlag Dr. Hut, 2020. http://d-nb.info/121960609X/34.
Ertl, Moritz [Verfasser], and Bernhard [Akademischer Betreuer] Weigand. "Direct numerical investigations of non-Newtonian drop oscillations and jet breakup / Moritz Ertl ; Betreuer: Bernhard Weigand." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2019. http://d-nb.info/1205737022/34.
Abi, Chebel Nicolas. "Dynamique et rhéologie interfaciales à haute fréquence d'une goutte oscillante." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT043G/document.
We present an experimental study of oscillating drop interfacial dynamics at a wide frequency range, especially at high frequency. A characterization method of drops oscillation dynamics has been developed. The oscillations are generated by imposing low amplitude periodic variation of volume to a drop which is attached to a capillary tip. The present method is based on the identification of the drop eigenmodes and the determination of their frequencies and damping rates. It has been applied to characterize several liquid-liquid systems. Three types of interface have been identified. For interfaces of type 1 (heptane/water without added surfactant), each eigenmode is modelled by a weakly damped linear oscillator. Eigenfrequencies and damping rates are well predicted by the linear theory. Interfaces of Types 2 and 3 are obtained by adding crude oil to the disperse phase. Oil native surfactants (asphaltenes, resins) adsorb on the drop interface and provide the latter with viscoelastic behaviour. For young interfaces (type 2 with aging time below 20 minutes), eigenfrequencies remain well predicted by the theory, which deals with non contaminated interfaces, whereas the measured damping rates are significantly higher than the theoretical values. On the other hand, aged interfaces (type 3) exhibit different eigenmodes, of which eigenfrequencies are much higher than the resonance frequencies measured for the young interfaces. At high frequency, the dynamics of aged interfaces are governed by the elasticity of the network constituted by the crude oil amphiphilic species, while the dynamics of young interfaces are governed by interfacial tension. Freely decaying oscillations of a rising drop in a liquid at rest without added surfactant were also considered. Measured frequencies for the first four eigenmodes are in good agreement with the linear theory. However, measured damping rates are much higher than the theoretical rates for non contaminated interfaces. In fact, residual adsorbed species at the heptane/water interface induce Marangoni effects and thus gradients of interfacial tension. Therefore, vorticity production within the boundary layers is enhanced, which explains the observed increase of the oscillation damping rates
Ullah, Asmat. "Separation of oil drops from produced water using a slotted pore membrane." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/15687.
Scofield, Christopher D. "Oscillating microbubbles created by water drops falling on fresh and salt water : amplitude, damping and the effects of temperature and salinity." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/24000.
Sartori, Paolo. "The Role of Interfaces in Microfluidic Systems: Oscillating Sessile Droplets and Confined Bacterial Suspensions." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3423250.
Questa tesi di dottorato prende in esame il ruolo delle interfacce che caratterizzano i sistemi microfluidici, come ad esempio l’interfaccia libera aria/acqua delle gocce o l’interfaccia liquido/solido di fluidi racchiusi in microcanali. Questo lavoro ha un duplice carattere: da una parte, abbiamo studiato la dinamica di gocce sessili soggette ad oscillazioni del substrato; dall’altra, abbiamo investigato come la distribuzione spaziale della concentrazione in sospensioni batteriche, prese come sistema modello per colloidi attivi, venga alterata da un confinamento geometrico. Dinamica di gocce sessili. Il primo argomento rientra nel campo dei fenomeni di bagnabilità e della microfluidica aperta, che tratta il comportamento di gocce, tipicamente nel range dei nano- /microlitri, depositate su superfici aperte. A tali scale di lunghezza, questi sistemi sono dominati dalla capillarità a possono produrre effetti inaspettati che non vengono comunemente osservati alle scale macroscopiche a cui siamo abituati. I nostri studi sono volti al raggiungimento del controllo attivo del moto e della forma delle gocce per mezzo di vibrazioni del substrato, con applicazioni dalla Chimica alla Biologia. In particolare, è stato considerato il moto di gocce su in substrato inclinato sottoposto ad oscillazioni armoniche verticali. Normalmente, su superfici inclinate le goccioline rimangono ferme a causa dell’isteresi dell’angolo di contatto. Quando vengono applicate oscillazioni verticali le goccioline si sbloccano e scivolano giù. Sorprendentemente, per ampiezze di oscillazioni sufficientemente grandi le goccioline si muovono verso l’atro contro la forza di gravità. Un’analisi della risposta delle gocce al variare dell’accelerazione di picco e della frequenza di oscillazione, prendendo in esame fluidi con diverse tensioni superficiali e viscosità, ha permesso il controllo del moto unidimensionale lungo il pianoinclinato. Inoltre, abbiamo studiato le morfologie interfacciali di gocce d’acqua confinate sulla faccia superiore idrofilica di post rettangolari con larghezza 0.5 mm e varie lunghezze. Per piccoli volumi, il film liquido prende la forma di un filamento omogeneo con una cross-section uniforme simile ad un segmento circolare. Per volumi più grandi, l’interfaccia acqua/aria forma un rigonfiamento centrale, che cresce con il volume. Nel caso di post più lunghi di una lunghezza caratteristica, la transizione tra le due forme al variare del volume discontinua e mostra la bistabilità dei due stati morfologici associata ad un fenomeno di isteresi. Applicando al post, con volume d’acqua fissato corrispondente alla bistabilità, vibrazioni verticali con determinate frequenze si più indurre una transizione irreversibile dallo stato di filamento omogeneo a quello rigonfiato. Particelle auto-propulse sotto confinamento geometrico. Il secondo argomento riguarda il comportamento di fluidi attivi, cioè sospensioni di colloidi auto-propulsi che costituiscono sistemi intrinsecamente fuori equilibrio (Materia Attiva). In particolare, in presenza di strutture geometriche, tali sistemi si comportano in modo molto differente rispetto a colloidi Browniani all’equilibrio. Abbiamo analizzato il ruolo di diversi schemi di motilità sulla distribuzione di concentrazione di sospensioni batteriche confinate tra due pareti solide. considerando E. coli a P. aeruginosa wild-type, che si muovono secondo gli schemi Run and Tumble e Run and Reverse, rispettivamente. I profili di concentrazione sono tati ottenuti contando i batteri motili a diverse distanze dalle pareti. In accordo con studi precedenti, si osservato un accumulo di batteri motili in prossimit delle pareti. Sono state testate diverse frazioni di batteri motili e diverse distanze di separazione tra le pareti, nel range tra 100μm e 250 μm. I profili di concentrazione risultano indipendenti dalla distanza tra le pareti e dai differenti schemi di motilità e scalano con la frazione di batteri motili. Questi risultati sono confermati da simulazioni numeriche, basate su una collezione di particelle allungate auto-propulse che interagiscono solo tramite interazioni steriche.
Boichon, Christelle. "Oscillations d'une masse fluide en lévitation aérodynamique." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0076.
Bouillant, Ambre. "Dynamiques spontanées en caléfaction." Thesis, Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAX015.
This work focuses on the Leidenfrost effect. A water drop placed on a hot substrate levitates on a cushion of its own vapor. This vapor layer, continuously renewed, insulates the liquid both mechanically and thermally : it limits evaporation and suppresses boiling. Levitation has other consequences on the liquid. It prevents the liquid from wetting its substrate, giving it the appearance of a liquid pearl, while producing a frictionless situation and giving ii a high mobility.We first discuss the conditions that allow a drop to levitate above a hot substrate, in particular the threshold in temperature. Then, we adopt a dynamic point of view by detailing the three phases of the life of a Leidenfrost drop. Above a certain size, vapor accumulates and forms a thin liquid dome with remarkable stability. Temperature differences on that pure liquid film induce upward surface flows that select the thickness and oppose the film thinning.For smaller volume, liquid oscillations spontaneously and sporadically appear. The mechanism leading to the liquid stars is elucidated: the vapor film has it natural frequency. The vapor cushion oscillations excite the overlying liquid. The drop acts as a resonant cavity and thus responds for some quantified radius by oscillating according to the mode locked by the intrinsic forcing. By further reducing the radius, the liquid acquires spectacular mobility. A Leidenfrost drop hosts strong internal flows, whose symmetry is selected by confinement. Evaporation induces morphological changes and triggers a symmetry breaking. A droplet rolls asymmetrically, which rectifies and tilts its base. This leads to motion and contributes to the spectacular mobility of Leidenfrost droplets. Two strategies to control these elusive globules are eventually proposed, inspired by the work on self-propulsion on surfaces covered with asymmetric teeth. Directional movement is forced by applying a temperature gradient and by gradually texturing the substrate.The evaporation-driven confinement induces various dynamics that illustrate the richness of this system, where phase changes as well as thermal, aerodynamic and hydrodynamic effects conspire to generate new and exploitable properties
Hund-Huart, Muriel. "Etude des transferts interfaciaux en extraction liquide-liquide sous champ électrique." Paris, ENMP, 1988. http://tel.archives-ouvertes.fr/tel-00845221.
Leão, Hugo Leonardo Souza Lara. "Análise experimental dos efeitos do fluido e da orientação do escoamento no desempenho de dissipadores de calor baseados na ebulição convectiva em microcanais." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-19082014-102054/.
This study presents an experimental investigation on the effect of the fluid and the footprint orientation on the performance of a heat spreader based on flow boiling inside micro-scale channels. This heat spreader is used in an electronics cooling application with high-power density. Initially an extensive investigation of the literature concerning single-phase and two-phase flow inside a single microchannels and multi-microchannels was performed. In this literature review the leading predictive methods for heat transfer coefficient and pressure drop are described. The experimental study was carried out in the apparatus developed by Do Nascimento (2012). The heat sink evaluated in the present study is comprised of fifty parallel rectangular microchannels with cross-sectional dimensions of 100 µm width and of 500 µm depth, and total length of 15 mm. The fins between consecutive microchannels are 200 µm thick. Experimental tests were performed for R245fa, low-pressure fluid used in low pressure refrigeration cycles, and R407C, high-pressure fluid used for heat comfort, saturation temperature of 25 and 31°C, mass velocities from 400 to 1500 kg/m² s, degrees of subcooling of the liquid of 5, 10 and 15°C, outlet vapor quality up to 0.38, heat fluxes up to 350 kW/m², and for the following footprint heat sink orientations: horizontal, vertical with the microchannels aligned horizontally and vertical with upward flow. The results were parametrically analyzed and compared again the predictive methods from literature. Average heat transfer coefficients up to 35 kW/m² °C were obtained. The results for R134a from Do Nascimento (2012) for the same heat sink presented heat transfer coefficients higher than R245fa and R407C. The fluid R407C presented oscillation of the temperature due to thermal instability effects with lower frequency and amplitude lower than R134a, and R245fa. None predictive method provided satisfactory heat transfer coefficient and pressure drop predictions of the experimental data. The Homogeneous model with the viscosity given by Cicchitti et al. (1960) provided the best pressure drop prediction while the heat transfer coefficient was best predicted by Bertsch et al. (2009) and Liu and Winterton (1991). The horizontal orientation of the footprint provided the highest heat transfer coefficients while the vertical footprint orientation with upward flow the lowest pressure drops. Images of the two-phase flow were obtained with a high-speed camera and analyzed.
TSAI, MENG-HSIEN, and 蔡孟憲. "Dynamics of vortex-propelled liquid drop on oscillating liquid surface." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/zxu94b.
國立中正大學
物理系研究所
105
Liquid drop can bounce on the surface of vertically oscillating liquid bath with the same liquid for a long time when the oscillating acceleration is larger than g. When the drop collides with the surface, vortex ring is induced by the deformation of liquid surface. Two drops are coupled in quasi-one-dimensional container and oscillate around the position of equilibrium. The motion is caused by the asymmetric vortex rings. We expect that the asymmetric flow field affects the motion of drop and discuss the interaction between the drop and the induced flow. The asymmetric flow field is generated in our experiment by the drop-boundary interaction and the drop-drop interaction. In drop-boundary system, a vortex ring induced by a single drop is shaped by an inclined bottom and becomes asymmetric at shallow zone. On the other, two drops with different size induce two vortices which couple and form an asymmetric field. In those cases, the asymmetric flows both drive the drops propelling on the liquid surface. The velocity field measured by particle image velocimetry technique (PIV) is compared with the theoretical model. The theoretical model simulating by the steady streaming function induced by oscillating bubble is fitting with the experimental result. Due to the distance between drops is relative to the driving frequency, the flow field induced by multi-drops is expected well by the distance and the size of drops.
Sumaria, Kaushal. "Numerical Simulation of Multi-Phase Core-Shell Molten Metal Drop Oscillations." 2017. https://scholarworks.umass.edu/masters_theses_2/586.
Yang, Yao-Jung, and 楊耀榮. "The Analysis of Pressure Drop from Oscillating Flow Through Non- unit Cylinders Post in the Parallel Channel." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/51789916600184505494.
國立臺灣大學
機械工程學系
85
This research paper mainly discussed on pressure dropcaused from oscillating flow through three interval cylinders which are postside-by-side to channel center byy experiment. The pressure drop ismeasured by joing the tubes outside the several holes digged on theperface of up-plate and cylinder.Then,use the camera to shoot the variation of water height in the tube.in addition,use the curve fittingto get a relation function,and use the conservation of momentum principleto get a 2-order nonlinear ordinary differential equation to transferwater height to variation of pressure drop.Finally,analyze and find outthe tendencyy of pressure drop in the channel and around cylinders.
Ansari, Hosseinzadeh Vahideh. "Development of a non-contact blood rheometer using acoustic levitation and laser scattering techniques." Thesis, 2019. https://hdl.handle.net/2144/36142.
2020-06-04T00:00:00Z
Kuan, Chen-Chi, and 管振淇. "Quantitative analysis of oscillation effect on the bubble generation by drop impact." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/59353479778953886083.
臺灣大學
應用力學研究所
98
The impact of a droplet on a liquid pool can result in different fantastic phenomena. Many investigations have been conducted since decades; however, none has been studied for the effects of oscillating drop on the large bubble induced by the impacting droplet since Worthington (1908). In the present study, a newest improved quantitative tracking method has been used to analyze the formation and cavity dynamics of big floating bubbles and large bubbles generated by the drop impacting onto deep liquid pool has been experimentally studied and analyzed. Effects of impact velocity, drop size have been investigated and discussed. And it will to understand more deeply about the corresponding relations of those sequential events of drop impact dynamics. Furthermore, two geometry parameter oscillation parameters sharpness-ratio and offset-ratio of the free-falling droplet before impact and Weber number have been found to be the most important controlling parameters. And new characteristic regimes of large bubble area in the V (impact velocity)-d (diameter of droplet) map have been edited. It have been further investigated and analyzed in this thesis.
Li, Chien-Chuan, and 李健傳. "Study on the Characteristics of Periodic Oscillation Flow over Vertical Drop Energy-Dissipator." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/52032099084157915024.
中興大學
土木工程學系所
95
ABSTRACT A vertical drop pool is frequently used in an open channel to dissipate the energy of the approach flow. As the combination of pool length (L), end sill height (h), and discharge (q) meets neither the napped flow nor the skimming flow conditions, the flow oscillates periodically in the vertical drop pool. The purpose of this study is to investigate the characteristics of the periodic oscillatory flow over a vertical drop pool with a subcritical approach flow experimentally. Free surface oscillations of dropping flows were measured using a wave gauge located in the pool. The primary frequency (f0) of the periodic oscillation was then determined by applying spectral analysis to the time series of the gauge measurements. Two flow visualization techniques were employed to reveal the structures of dropping flows qualitatively. In order to understand the relationship between the periodic oscillatory flow pattern with the discharge of the approach flow and the influence of end sill height, series of experiments were conducted by varying discharge (q) and end sill height ratios (h/H, where H is the dropping depth). The flow behaves as the periodic oscillatory flow for h/H ranging from 0.121 to 0.857 with different discharges. When the h/H was equal to 0.429, the largest range of discharge (q) was obtained from 154.6 ~ 223.5 cm2/s for the periodic oscillatory flow patterns in the vertical drop pool. With analyzing the flow visualization results and the time series measurements of wave gauge, flow patterns of the periodic oscillation could be classified by three different modes as follows: (1) Mode1 shows the trend that the f0 decreases with the increase of q for h/H varying from 0.121 to 0.429. A large amount of air bubbles was entrained to the vortex upon the end sill corner. (2) Mode2 presents the trend that the f0 increases with the increase of q for h/H changing from 0.329 to 0.571. By comparing with Mode1, there is no air bubbles entrained into the vortex upon the end sill corner. (3) Mode3 shows that the f0 decreases with the increase of q as h/H is equal to 0.714. The flow features a falling jet impinging on the corner and vertical wall of the end sill without entraining air bubbles upon the end sill corner.
Teng, Che-Jui, and 鄧哲叡. "Influence of Field Frequency to Rotating Ferrofluid Drops and Oscillating Micro–bead chains." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/71202654193733607960.
國立交通大學
機械工程系所
104
We experimentally investigate the motion of a ferrofluid drop in a rotating magnetic field. Magnetized and driven by the external field, the drop would be stretched to the shape of ellipsoid along the orientation of the field. It is observed that the stretched length of drop decreased when we increase the frequency of the external field. And we use two dimensionless parameters to know the influence of field frequency clearly. Besides, compare these results to the micro-bead chain which subjected to an oscillating field. The amplitude of the chains decreased when we increase the frequency of the oscillating field.
Umashankar, Viverjita. "Edge Effect of Semi-Infinite Rectangular Posts on Impacting Drops." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/3644.
Umashankar, Viverjita. "Edge Effect of Semi-Infinite Rectangular Posts on Impacting Drops." Thesis, 2017. http://etd.iisc.ernet.in/2005/3644.
"Hybrid AC-High Voltage DC Grid Stability and Controls." Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.46197.
Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2017