In this thesis, we develop a physical understanding of the effects of viscosity and geometry on the dynamics of interfacial flows in drops and bubbles. We first consider the coalescence of pairs of conical water droplets surrounded by air. Droplet pairs can form cones under the influence of an electric field and have been observed to coalesce or recoil depending on the angle of this cone. With high resolution numerical simulations we show the coalescence and non-coalescence of these drop pairs is negligibly affected by the electric field and can be understood through a purely hydrodynamic process. The coalescence and recoil dynamics are shown to be self similar, demonstrating that for these conical droplet pairs viscosity has a negligible effect on the observed behavior. We generalize this result to the coalescence and recoil of droplets with different cone angles, and focus on droplets coalescing with a liquid bath and flat substrate. From the simulations of these droplets with different cone angles, an equivalent angle is found that describes the coalescence and recoil behavior for all water cones of any cone angle. While viscosity is found to negligibly affect the coalescence of conical water drops, it plays a key role in regulating the coalescence process of bursting gas bubbles. When these gas bubbles burst, a narrow liquid jet is formed that can break up into tiny liquid jet drops. Through consideration of the effects of viscosity, we show that these jet drops can be over an order of magnitude smaller than previously thought. Here, viscosity plays a key role in balancing surface tension and inertial forces and determining the size of the jet drops. Finally, we investigate the drainage of surfactant free, ultra-viscous bubbles where surface tension serves only to set the initial shape of the bubble. We use interferometry to find the thickness profiles of draining bubble films up to the point the of rupture. A theoretical film drainage model considering the balance of viscous and gravitational stresses is developed and numerically computed. The numerical results are found to be consistent with the experimentally obtained thickness profiles. In this work we provide insight into the role of viscosity in the outlined interfacial flows. The results of this thesis will advance the understanding of drop production in clouds, the marine climate, and the degassing of glass melts.

In this study, the associated dynamic of water droplets at low impact velocity on the Superhydrophobic surface have been investigated. The experiment is conducted on superhydrophobic surface (SH), (Contact Angel > 1500) while varying the impact velocity (V0). When the drop hits the surface, large oscillation starts, and the capillary waves travel up to the upper of the drop where a cylindrical cavity can be formed inside the drop. The cavity closes up in a self-similar way until collapse, followed by a violent singular jet which can reach up to 35 m/s. The study showed that during drop receding, the cavity can collapse in different scenarios based on the impact velocity and the surface wettability. More importantly, the collapse is observed for the first time at very high-speed video, up to 5 million fps. Furthermore, we correct the optical distortion of the cavity due to the curvature of the drop surface. This study classifies all of the 5 encountered behaviors of the cavity collapse. The jet formation and speed are strongly dependent on the specific cavity configuration. Very fast jetting behavior is observed when the collapse is pinch-off singularity which reaches zero value in the middle of the drop. Other behaviors of the collapse such the unsymmetrical closing of the cavity or bubble entrapment is discussed. The optical distortion factor is calculated through 3 different approaches. The first one is an experimental calibration technique where a small cylinder is inserted into the drop. While the other two approaches are indirect implantations of theoretical models presented in the literature to fit the instantaneous geometrical shape of the cavity inside the drop. The distortion factor (DF) gives in all cases a similar value. Therefore, the averaged distortion value is calculated, and it is a magnification of 33% increase of the actual size. The experiment results of the cavity radius are compared with power-laws and the modified Rayleigh-Plesset equation for free cylindrical flow and good agreement is shown.

Page iii was not included in the thesis. / Abstract Not Provided. / Thesis / Master of Engineering (MEngr)

No description available.

Orientador: Elenice Deffune / Resumo: Introdução: A Síndrome do Olho Seco (SOS) é uma doença multifatorial das lágrimas e da superfície ocular que resulta em desconforto, distúrbios visuais e instabilidade do filme lacrimal e afeta principalmente adultos com mais de 50 anos e mulheres. É uma doença que pode ter grande impacto negativo na qualidade de vida dos pacientes. A abordagem terapêutica com soro autólogo tem sido preconizada desde 1986 com prós e contras na literatura. Esta pesquisa teve como objetivo realizar uma revisão sistemática e metanálise para analisar a efetiva contribuição do Soro Autólogo segundo os protocolos, ensaios terapêuticos publicados nos últimos 10 anos e o atendimento dos pacientes portadores de Síndrome do olho seco (SOS) no Hospital das Clínicas da Faculdade de Medicina de Botucatu .Objetivos: 1) realizar revisão sistemática e metanálise para avaliar a eficácia do uso do soro autólogo em comparação com lágrimas artificiais comerciais no tratamento para adultos com olho seco. 2) realizar um trabalho retrospectivo da contribuição do soro autólogo de uso ocular no tratamento da SOS nos pacientes do ambulatório do Hospital das Clínicas de 2014-2018 comparando com o período anterior (2008-2013). Materiais e Métodos: Para a revisão sistemática e metanálise foi pesquisado na base de dados do Pubmed não usando restrições de língua, apenas trabalhos dos últimos 10 anos. Para os desfechos primários e secundários foi utilizado um intervalo de confiança de 95%. O levantamento de dados dos pacien... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: Dry Eye Syndrome is a multifactorial disease of tears and ocular surface that results into discomfort, visual disturbances and tear film instability and affects mainly female adults, over 50 years. It is a disease which may cause a great negative impact on the patients’ quality of life. The therapeutic approach employing autologous serum has been advocated in 1986, with pros and cons in the literature. This study aimed to perform a systematic review and a meta-analysis to investigate the effective contribution of Autologus Serum according to the protocols and clinical trials published in the last 10 years, and the SOS patients care at Hospital das Clínicas, during two periods: 2008-2013 and 2014- 2018.Objectives: 1) to perform a systematic review and meta-analysis to evaluate the efficacy of the autologous serum, in comparison to commercial artificial tears for the treatment of dry eye in adults. 2) to carry out a retrospective study of the ocular autologous serum contribution for SOS out patients’ treatment, at Hospital das Clínicas (2014 to 2018), comparing with the previous period (2008-2013).Materials and Methods: For the systematic review and meta-analysis, searches were realized in Pubmed databases, with no language restrictions, for papers published in the last 10 years, with full text availability, for researches dated until 10/12/2018. For the primary and secondary outcomes, a 95% confidence interval was used. For the outpatients’ data collection, each ... (Complete abstract click electronic access below) / Mestre

Les interactions entre des gouttes ou des bulles sont rencontrées dans de nombreuses applications industrielles et/ou environnementales. Ici, nous nous intéressons à l’électro-coalescence qui a des applications importantes comme par exemple la séparation eau/pétrole (coalescence de gouttelettes d'eau dans du pétrole). L’étude a été consacrée à l’élaboration et à la mise point de modèles basés sur les équations de Navier-Stokes et les équations régissant les champs électriques au niveau d’une seule goutte ainsi que l’interaction entre deux gouttes et plus particulièrement l’effet des forces hydrodynamiques et électrostatiques sur le mécanisme d’amincissement du film séparant les deux gouttes. Selon les cas traités, le suivi de l’interface est réalisé soit à l’aide de la méthode LS (Level Set) ou bien à l’aide de la méthode MM (Moving Mesh). Les solutions numériques ont été obtenues à l’aide du code de calcul COMSOL Multiphysics. Dans une première étape, nous avons analysé l’effet d’un champ électrique sur la déformation d’une seule goutte suspendue dans un autre fluide visqueux, pour différentes propriétés physiques et électriques des deux fluides. Le modèle a été testé et validé par confrontation avec les solutions analytiques existantes et avec des études numériques de la littérature. Nous avons examiné aussi l’influence du champ électrique sur la génération d’une goutte secondaire lors de la coalescence entre une goutte et une interface liquide-liquide déformable. Dans une seconde étape, nous avons étudié le drainage et la déformation de deux gouttes en interaction sous l’action d’une force constante. Contrairement à la théorie de lubrification basée entre autre sur l’hypothèse d’une petite déformation de l’interface, aucune hypothèse simplificatrice n’a été utilisée pour la résolution des équations, ce qui a permis d’obtenir des solutions numériques aussi bien pour les petites que pour les grandes déformations. Dans une troisième étape, nous avons examiné l’ascension d’une goutte isolée ou de deux gouttes de n-butanol dans l’eau sous l’influence de la force de flottabilité. L’évolution des vitesses terminales d’ascension des gouttes (goutte de tête/goutte suiveuse) et le drainage du film séparant les deux gouttes ont été analysées en présence et en l’absence de champ électrique. / Drops and bubbles interactions are encountered in various industrial and environmental applications. In this work, we focus on the electro-coalescence which has important industrial uses such as the destabilization of water / oil emulsions (coalescence of water droplets in oil). This study was devoted to the development and the elaboration of numerical models based on the Navier-Stokes equations and those describing the electrical field on a single drop as well as the interaction between two drops, and more particularly the effect of hydrodynamic and electrostatic forces on the thinning mechanism of the film separating the two drops. According to the treated cases, the interface tracking is achieved either by using the LS method (Level Set) or using the MM method (Moving Mesh). Numerical solutions were obtained using the commercial CFD software COMSOL Multiphysics. During the first step, we analyzed the effect of an electrical field on the deformation of a single suspended drop in another viscous fluid, for different physical and electrical properties of the two fluids. The model was tested and validated by comparison with existing analytical solutions and numerical studies found in the literature. We also analyzed the influence of the electric field on the generation of a secondary drop during the coalescence between a drop and a deformable liquid-liquid interface. In a second step, we investigated the drainage and deformation of two drops in interaction under the effect of a constant force. Unlike the lubrication theory which is based among others, on the assumption of a small interface deformation, in this work, no simplifying assumptions were used for the solution of equations, which allowed us to obtain numerical solutions for both small and large deformations. For the third step, we examined the rise of two drops of n-butanol in water under the influence of buoyancy force. The evolution of the drops terminal ascension velocity (leading drop/trailing drop), and the drainage of the film separating the two drops were analyzed in the presence and in the absence of electrical field.

Thesis (MEng)--University of Stellenbosch, 1995. / AFRIKAANSE OPSOMMING: Die moontlikheid om die warmteoordrag in die reensone van 'n natuurlike trek nat koeltoring te vcrbeter deur die gemiddelde druppel diameter van die sproei te verminder is ondersoek. Eksperimentele wcrk was daarop gerig om tipiese druppelgrootte verspreidings onder druppakking te bepaal, asook die verkryging van werklike verrigtings-data vir verskiJlende pakking en reensone kombinasies in 'n koeltoring toetsfasiliteit. 'n Fotografiese metode wat gebruik maak van beeldverwerkingstegniekc is ontwikkel om die druppelgrootte verspreidings wat in die )meltoring toetsfasiliteit gevind word te bepaal. 'n Rekenaar simulasieprogram wat ontwikkel is deur Dreyer [940Rl] is verder gebruik om reensone verrigtingsdata ( oordragskarakteristieke en druppelgrootte verspreidings) teoreties te vcorspel, vir vergelyking met en evalusie van die eksperimentele resultate. Dit is bewys dat die plasing van 'n laag spatroosters reg onder druppakking die gerniddelde druppeldiameter in die reensone verrninder het, wat gelei het tot 'n ooreenstemmende toename in oordragskarakteristiek. Met die gebruik van 'n rekenaar simulasie program is bereken dat hierdie opstelling die termiese kapasiteit van 'n koeltoring met tot 5 % kan verbeter. / ENGLISH ABSTRACT: The possibility of improving the heat transfer in the rain zone of large natural draft wet cooling towers, by decreasing the mean drop diameter in this region, has been investigated. Experimental studies were aimed at determining typical drop size distributions under trickle packs and obtaining actual performance data for packing and rain zone combinations in a cooling tower test facility. A photography-based method, which utilizes image processing techniques, was develo!Jed t() determine the drop size distributions found in the test facility. A computer simulation program developed by Dreyer [94DRI] was used to theoretically predict rain zone performance data (i.e., transfer coefficients and drop size distribution data) for comparison with and evaluation of the experimental data. I: was found that by placing a layer of splash grids beneath a trickle pack the mean drop diameter in the rain zone was decreased, resulting in corresponding increases in transfer characteristic. Using a computer simulation program it was calculated that this arrangement could increase the thermal capacity of a large natural draft cooling tower by up to 5 %.

Bakgrund: Glaukom är en kronisk progressiv ögonsjukdom och en av den främsta orsaken till blindhet i världen. Intraockulärt trycksänkande ögondroppar är den vanligaste behandlingsmetoden och följsamhet är mycket viktigt för att minska progression av sjukdomen och risken att bli blind. Tidigare studier har visat att det finns en bristande följsamhet hos patienter med denna behandling. Syfte: Att belysa de faktorer som påverkar patientens följsamhet så att sjuksköterskan ska få en bättre förståelse och kunna vägleda patienten till en bättre följsamhet. Metod: En systematisk litteraturstudie genomfördes baserad på 14 vetenskapliga artiklar med både kvalitativ och kvantitativ ansats. Resultat: Det finns många olika faktorer som påverkar patientens följsamhet i behandlingen med ögondroppar. Det kan vara faktorer som är orsakade av sjukvårdspersonal, av patienten själv samt av miljö/socioekonomiska skäl. Slutsats: Det är viktigt att fortsätta forska på de faktorer som påverkar patienters följsamhet vid ögondroppsbehandling för att sjuksköterskan ska kunna vägleda till en ökad följsamhet. / Background: Glaucoma is a progressive chronic eye disease and is the leading cause of blindness in the world. Eye drops which are lowering the intraocular pressure are the most common treatment and adherence is essential to reduce progression of the disease and the risk of becoming blind. Previous studies have shown that there is a lack of compliance in patients with this treatment. Aim: The aim of this study was to elucidate the factors affecting patient adherence so that the nurse can get a better understanding and be able to guide the patient to a better adherence. Method: A systematic literature review, based on 14 scientific articles with both qualitative and quantitative approach. Results: There are many different factors that affect the patient´s adherence to treatment with eye drops. It can be factors that are caused by medical staff, by the patient himself, as well as environmental/socio-economic reasons. Conclusion: It is important to continue research on the factors that affect patients´ adherence with eye drop treatment so that the nurse should be able to guide to an increased adherence.

First we define microscopic sets on the real axis and study their relation to the sets of Hausdorff and Lebesgue measure zero and the sets of first category. In the second part, we prove the Ekeland's variational principle and its equivalence with the the Daneš's drop theorem, the Brézis-Browder's theorem, the Phelps' lemma and the Caristi-Kirks's theorem. Furthermore, we discuss its relation to the Bishop-Phelps' theorem. Doing so we define the notion of a drop as the convex hull of a set and a point. In the third part we prove that the drop property equals reflexivity in some sense. A space has the drop property if it is possible to find the drop from the Daneš's theorem even in a more general case than the theorem itself guarantees. Furthermore, we characterize this property using the approximative compactness. Last, we study the microscopic drop property that is more relaxed than the original drop property. We find out that those two notions are for certain sets in reflexive spaces equivalent.

La physique de mouillage et de séchage de sang n’est pas encore bien connue. Dans le cadre d’un travail collaboratif, une étude est réalisée afin d’apporter de nouveaux outils aux équipes d’investigations criminelles. L’objectif est de comprendre les dynamiques qui entrent en jeu dans la formation de traces de sang, un fluide complexe. Nous nous intéressons aux traces dites passives telles que l’égouttement ou l’accumulation, qui résultent de l’action de la pesanteur. Nous considérons d’abord les gouttes passives. Le comportement d’impact de gouttes de fluides complexes est un sujet qui a été largement étudié mais suscite encore de vifs débats. Bien que le séchage d’une goutte déposée ait déjà été étudié, ceci n’est pas le cas pour des gouttes qui viennent impacter perpendiculairement une surface, tombant depuis une certaine hauteur. Parallèlement nous étudions le séchage de flaques de sang car leur dynamique de séchage n’a pas été étudiée jusqu’à présent. Différents paramètres tels que la nature des substrats, l’humidité et la température sont pris en compte afin de comprendre le lien entre la typologie des motifs séchés et les phénomènes observés en vue de répondre à des applications criminelles. Enfin des relations empiriques sont établies. Grace à des méthodes inverses, ces relations permettent, par la suite, d’obtenir une estimation de la vitesse d’impact de gouttes séchées. / The physics behind wetting and drying of blood is not yet completely understood. In the context of a collaborative project, new techniques have been developed to provide evidence for investigators in crime solving. Given that blood is a complex fluid, the major aim has been to investigate the dynamics involved in the patterns of stain formation. Interest is focused on passive stains, which result from the action of gravity in dripping or blood flow accumulation. In the case of drip stains, the impact behaviour of complex fluid droplets, despite many studies, raises much debate. Although the drying dynamics of a deposited drop of blood were already studied, this is not the case for drops of blood impacting perpendicularly a surface, falling from a certain height. Beside this, until the present work, little attention has been paid to the dynamics controlling the drying of blood pools. In both situations, the influence of different parameters such as substrates, humidity and temperature are examined. Empirical relations are established between final dried blood patterns and the generating mechanism, yielding possible application in blood pattern analysis for forensic investigations. Finally, using inverse methods, the empirical relations allow estimating an impact velocity, for dried drip stains.