Добірка наукової літератури з теми "Film bursting"

The rupture of soap films is traditionally described by a law accounting for a balance between momentum and surface tension forces, derived independently by Taylor and Culick in the 1960s. This law is highly relevant to the dynamics of thin liquid films of jets when viscous effects are negligible. However, the minute amounts of surfactant molecules present in soap films play a major role in interfacial rheology, and may result in complex behaviour. Petit et al. (J. Fluid Mech., vol. 774, 2015, R3) challenge standard thin film dynamics via intriguing experiments conducted with highly elastic surfactants. Unexpected structures reminiscent of faults are observed.

AbstractWe depict and analyse the complete evolution of an air bubble formed in a water bulk, from the time it emerges at the liquid surface, up to its fragmentation into dispersed drops. To this end, experiments describing the drainage of the bubble cap film, its puncture and the resulting bursting dynamics determining the aerosol formation are conducted on tapwater bubbles. We discover that the mechanism of marginal pinching at the bubble foot and associated convection motions in the bubble cap, known as marginal regeneration, both drive the bubble cap drainage rate, and are responsible for its puncture. The resulting original film thickness $h$ evolution law in time, supplemented with considerations about the nucleation of holes piercing the film together culminate in a determination of the cap film thickness at bursting ${h}_{b} \propto {R}^{2} / \mathscr{L}$, where $R$ is the bubble cap radius of curvature, and $\mathscr{L}$ a length which we determine. Subsequent to a hole nucleation event, the cap bursting dynamics conditions the resulting spray. The latter depends both on the bubble shape prescribed by $R/ a$, where $a$ is the capillary length based on gravity, and on ${h}_{b} $. The mean drop size $\langle d\rangle \ensuremath{\sim} {R}^{3/ 8} \hspace{0.167em} { h}_{b}^{5/ 8} $, the number of drops generated per bubble $N\ensuremath{\sim} \mathop{ (R/ a)}\nolimits ^{2} \mathop{ (R/ {h}_{b} )}\nolimits ^{7/ 8} $ and the drop size distribution $P(d)$ are derived, comparing well with measurements. Combined with known bubble production rates over the ocean, our findings offer an adjustable parameter-free prediction for the aerosol flux and spray structure caused by bubble bursting in this precise context.

Thin liquid or gas films are everywhere in nature, from foams to submillimetric bubbles at a free surface, and their rupture leaves a collection of small drops and bubbles. However, the mechanisms at play responsible for the bursting of these films is still in debate. The present study thus aims at understanding the drainage dynamics of the thin air film squeezed by gravity between a millimetric droplet and a smooth solid or a liquid thin film. Solving coupled lubrication equations and analyzing the dominant terms in the solid- and liquid-film cases, we explain why the drainage is much faster in the liquid-film case, leading often to a shorter coalescence time, as observed in recent experiments.

A bubble layer forms in a thin liquid film at drop impact on a hot surface. Bubble coalescence and instability generated by a wave are the reason for irreversible bubble bursting, leading to film breakup at contact boiling.

When nuclear reactor accidents such as steam generator pipe ruptures or core melting occur, radioactive aerosols will remain in the liquid pools. Bubbles may be generated by boiling or gas injection. Film droplets produced by bubble bursts may entrain radioactive aerosols from the liquid to the air. This long-lasting behavior can produce a considerable amount of aerosols. To evaluate radioactive source terms, many physical quantities related to bubble bursting need to be determined, such as bubble burst position, bubble lifetime, cap film roll-up velocity, and cap film thickness, which are very important parameters that influence the releasing of radioactive aerosols. In this research, the phenomenon of bubble bursting was investigated by visualization. The above parameters were measured. We obtained the lifetime distribution of bubbles under different conditions, and we found that the addition of an aerosol increased the lifetime of the bubbles. By comparing the bubble lifetime to the roll-up velocity and cap thickness, we showed that the increase of the liquid temperature thickened the cap at rupture and the increase of the air temperature thinned the cap. The addition of an aerosol increased the film roll-up velocity.

We consider the dynamics of an elastic sheet lubricated by the flow of a thin layer of fluid that separates it from a rigid wall. By considering long wavelength deformations of the sheet, we derive an evolution equation for its motion, accounting for the effects of elastic bending, viscous lubrication and body forces. We then analyze various steady and unsteady problems for the sheet such as peeling, healing, levitating and bursting using a combination of numerical simulation and dimensional analysis. On the macro-scale, we corroborate our theory with a simple experiment, and on the micro-scale, we analyze an oscillatory valve that can transform a continuous stream of fluid into a series of discrete pulses.
NSF

L'éclatement du film océanique est un phénomène où un film liquide mince, représentant le chapeau de la bulle, éclate à la surface de l'océan, produisant des gouttelettes de film. Ce phénomène est crucial dans les échanges océan-atmosphère, en particulier dans le transfert de chaleur, de masse et de quantité de mouvement entre l'océan et l'atmosphère. L'éclatement du film implique une série de dynamiques complexes, telles que le drainage, la perforation, la rétraction du film et la désintégration en gouttelettes. La cicatrisation des trous (c’est-à-dire lorsqu’un trou est trop petit et se referme après sa nucléation) est un paramètre essentiel pouvant influencer la dynamique de l'éclatement du film, en particulier l'épaisseur du film lors de l'éclatement et, par conséquent, le budget liquide pour la production de gouttelettes de film. Cette étude approfondit la dynamique des trous dans les films liquides libres, avec des simulations numériques et des approches analytiques. Utilisant Basilisk, un solveur de flux à deux phases basé sur la méthode Volume-of-Fluid (VoF) et écrit en C, nous avons analysé finement le mécanisme de cicatrisation. Des simulations dichotomiques à maillage adaptatif haute résolution ont permis de déterminer le seuil de cicatrisation. Les approches analytiques ont été utilisées pour développer des hypothèses afin de prédire le seuil de cicatrisation d'un trou sur un film, qui ont été testées contre les résultats numériques. La dynamique critique du trou a été examinée, et des lois de puissance distinctes ont été identifiées pour la courbure de pointe afin d'illustrer le mécanisme moteur. Les variations du seuil de cicatrisation du trou avec d'autres paramètres du problème ont été examinées. Cette étude a d'abord été menée pour un film plat, découvrant que le seuil de cicatrisation est augmenté en augmentant le nombre de Laplace du film. Cet effet était prononcé pour des valeurs allant de 1 à 10000, coïncidant avec la gamme habituelle des nombres de Laplace de film observés pour les bulles éclatantes océaniques. Les effets observés ont également été élaborés, avec des explications physiques. Étant donné que la forme initiale exacte du trou s'est révélée influencer le seuil de cicatrisation, un examen a été effectué pour étudier cet effet sur la cohérence des résultats du changement du nombre de Laplace du film, pris comme exemple pour les autres. Il a été démontré que malgré les variations du seuil pour différentes formes, l'effet du changement du nombre de Laplace du film était indépendant de la forme du trou. Par conséquent, les résultats de la dichotomie se sont avérés indépendants du choix arbitraire de la forme du trou tout au long de l'étude. Une étude similaire a été menée pour un trou dans un chapeau de bulle après une étude détaillée de la dynamique de la bulle et de l'écoulement du gaz. Il a été découvert que l'écoulement de gaz subit un effet Venturi, où un écoulement plus fort, résultant de tailles de bulles plus petites ou de nombres de Laplace de gaz plus élevés, a été montré pour augmenter le seuil de cicatrisation. Une hypothèse a été développée pour prédire l'effet Venturi sur le seuil de cicatrisation, aboutissant à un terme de correction de Venturi qui prédit une dépendance de loi de puissance sur le diamètre de la bulle, ce qui correspondait aux résultats numériques. L'effet Venturi était significatif pour des valeurs élevées du nombre de Laplace du gaz, où le seuil de cicatrisation était doublé en augmentant la courbure moyenne du film d'un film plat à un chapeau de bulle avec une taille 20 fois l'épaisseur du chapeau de bulle. Ces résultats fournissent une compréhension complète du phénomène de cicatrisation des trous, en particulier dans l'éclatement du film océanique. Le présent travail offre également une base pour les futures études sur le phénomène d'éclatement du film impliquant des dynamiques complexes, y compris la cicatrisation des trous
Oceanic film bursting is a phenomenon in which a thin liquid film representing the cap of the bubble bursts at the surface of the ocean, producing film drops. The film bursting phenomenon is critical in ocean-atmosphere exchanges, particularly in transferring heat, mass, and momentum between the ocean and the atmosphere. The film bursting phenomenon comprises a series of complex dynamics, such as drainage, puncture, film retraction, and film disintegration into film drops. The hole healing (i.e., when a hole is too small and is closed after its nucleation) is a critical parameter that could impact the film bursting dynamics, particularly the film thickness at bursting and, thus, the liquid budget for the film drop production. The present work investigates the dynamics of holes in free liquid films, presenting a comprehensive understanding of the hole-healing phenomenon while focusing on the film bursting in the oceanic context. This was achieved through a combination of numerical simulations and analytical approaches. The numerical simulations were carried out using Basilisk. This robust and efficient two-phase flow solver is based on a Volume-of-Fluid (VoF) method and written using the C-programming language. The underlying mechanism for the hole-healing phenomenon was studied in detail. The dichotomy simulations for the determination of the healing threshold carried out in this work have used high-resolution mesh refinement. This was possible by using an adaptive mesh scheme provided by Basilisk. The analytical approaches were used to develop hypotheses to predict the healing threshold of a hole on a film, which were tested against numerical results. The critical dynamics of the hole are examined, and distinct power laws were identified for the tip curvature to illustrate the driving mechanism. The variations in the hole healing threshold with other problem parameters were examined. This study was first carried out for a flat film, discovering that the healing threshold is increased by increasing the film Laplace number. This effect was pronounced for values ranging from 1 to 10000, coinciding with the customary range of film Laplace numbers observed for oceanic bursting bubbles. The observed effects were also elaborated upon, along with physical explanations. Since the exact initial shape of the hole was shown to influence the healing threshold, an examination was carried out to study this effect on the consistency of the results from changing the film Laplace number, taken as an example for the other. It was shown that despite variations in the threshold for different shapes, the effect of changing the film Laplace number was independent of the hole shape. Therefore, the dichotomy results were shown to be independent of the arbitrary choice of the hole shape throughout the study. A similar study was carried out for a hole in a bubble cap after a detailed study of the bubble and gas outflow dynamics. It was discovered that the gas outflow undergoes a Venturi effect, where a stronger outflow, resulting from smaller bubble sizes or higher gas Laplace numbers, was shown to increase the healing threshold. A hypothesis was developed to predict the Venturi effect on the healing threshold, resulting in a Venturi correction term that predicted a power law dependency on the bubble diameter, which agreed with the numerical results. The Venturi effect was significant for high values of the gas Laplace number, where the healing threshold was doubled by increasing the film mean curvature from a flat film to a bubble cap with a size 20 times the bubble cap thickness. These findings provide a comprehensive understanding of the hole-healing phenomenon, particularly in oceanic film bursting. The present work also offers a foundation for future studies on the film-bursting phenomenon involving complex dynamics, including hole healing

博士
國立臺灣大學
物理學系
85
In this thesis, we use a fast line scan CCD camera to study the bursting of soap films and soap bubbles. In the case of soap films, we can clearly observe the aureole formation and shock wave propagation. The time dependence of the shape and velocity of the aureole are obtained for the first time. We found that during bursting the surfactant monolayer in the aureole is highly compressed and behaves like a rigid film. We also calculate the surfactant compression ratio with shock wave theory. New phenomena of detachments of the aureole from the bursting film are also observed. In the case of the soap bubbles, we burst the films of different geometry to understand why the aureole is absent in the bursting of the soap bubbles.

碩士
國立臺灣大學
資訊工程學研究所
101
Enterprises or organizations with existing IT infrastructure are beginning to employ a hybrid cloud model where the enterprise or organization uses its own private resources for the majority of its computing, but then bursts into the cloud when local resources are insufficient. In the paper, we propose a cluster which can dynamically offload job to cloud when local resources are insufficient. It includes a cloud resource manager integrated with distributed resource manager and a content-addressable network file system with optimization for low bandwidth and high latency network between cloud and local server. LevCloud dynamically increases or decreases cloud resources in respond to changes in demand. In our evaluation, we conducted experiments to emulate bursty and showed LevCloud reduce significant job turnaround time by dynamically leveraging cloud resources.

One of Hollywood's first openly Latin stars, Jennifer Lopez has held fast to her New York Bronx roots, while rising above them to become the highest paid Latina actress in history. Her expansive body of work-ranging from film, music, and dance to television production and fashion-has broken down long-standing racial barriers and earned her a place in Forbes' 2007 list of the Top 20 Richest Women in Entertainment. In spite of several box office and a dramatic personal life that has made her the frequent target of tabloid gossip, this determined artist has managed to retain her place at the top of her field and stands poised to make more significant contributions to the entertainment industry. Since bursting into the spotlight with her portrayal of deceased Latin superstar Selena in 1997, Jennifer Lopez has captivated the public eye and carved a niche for herself among Hollywood's elite. One of Hollywood's first openly Latin stars, Jennifer Lopez has held fast to her New York Bronx roots, while rising above them to become the highest paid Latina actress in history. Her expansive body of work-ranging from film, music, and dance to television production and fashion-has broken down long-standing racial barriers and earned her a place in Forbes' 2007 list of the Top 20 Richest Women in Entertainment. Her dramatic personal life-highlighted by a relationship with bad-boy Sean Puffy Combs, two divorces, a highly-publicized broken engagement to Ben Affleck, and marriage to Latin singer Marc Anthony-has earned her as much attention as her career and made her a frequent subject of tabloid gossip. Negative press and several box office flops, however, have done little to diminish J.Lo's popularity. This determined artist has managed hold her place at the top of her field and stand poised to make more important contributions to the entertainment industry. Hollywood journalist Kathleen Tracy explores Jennifer Lopez as both an individual and an entertainer, chronicling the triumphs and pitfalls of her groundbreaking career and intriguing personal life. Complete with a chronology of significant events, illustrations, and a bibliography of print and electronic resources, this detailed biography is ideal for general readers looking to learn more about their favorite star or for students researching the role of race in America's entertainment business.

This chapter maps the science fiction milieu, which includes David Lynch's Dune. It explains how science-fiction cinema had been bursting into new life throughout the late 1970s and early 1980s. It also mentions the influence of Frank Herbert's original novel of Dune on stories of interstellar science fiction, such as the first Star Wars trilogy. The chapter discusses Herbert's approach to fiction and personal biography that provide some of the seeds of what the film version of Dune would become. Since Dune occurs in the shadow of Star Wars, it also provides context for the production and consumption of science-fiction film in the years between the releases of the two movies.

Abstract The convention of bursting into stylized performance has provoked terminological and conceptual debates in film musical scholarship. This article considers the crucial experience of a threshold between an everyday and a musicalized realm, which seems to provide access to a privileged state of existence. Then it explores an additional way in which the film musical pits realism against stylization, concerning the scene of utterance, that is, how musical numbers dramatize social exchange. Musical utterances can be classified as lyric, presentational, or participatory; within each category, scenes can conform to or suspend realism. Anomalous types with no real-life models include scenes of group expression, speechifying, ambient voices, and the virtual show. Analysis of utterance types can provide insights into the double-natured aesthetic of the genre.

Media scholars (and audiences) routinely make useful comparative analyses of films and television series. The problems of grouping texts are well known. This essay proposes a multidimensional approach to this critical activity, one that focuses on formulas, affects, and inflections. Narrative formulas and affects propel our sense of a genre; however, inflections such as stars, target audiences, locales, time periods, verisimilitude, taste markers, or performance styles can radically twist the base into something more complicated. One of the most important sorts of inflections is use of sound: aural effects, voice, and music. Such a multidimensional approach to grouping texts helps to resolve many anomalies in genre categorizing: for instance, the generic category of the musical. Scholars have tended to describe the musical based on Hollywood films created between 1930 and 1960. During this period, most musicals use a standard romance formula and vary the space and time to form several common “subgenres.” The author argues that, from the 1960s, artists begin to turn to other narrative formulas such as the male quest story (Tommy), horror (Sweeney Todd), the fallen-man melodrama (All That Jazz, Pennies from Heaven), and the bio pix (Hamilton). What the musical “is” is inflecting a narrative formula with a particular musical treatment—bursting into song or dance not necessarily provoked by a reasonably motivated diegetic event such as a nightclub act. Such an inflection of musical treatment could be applied to any narrative formula and has been. This essay explores this argument focusing on the comic/horror romance film Zombieland (2009) but with other examples to illustrate the viability of the critical approach and the functions of sound.

Pyrite is an often-overlooked material today although it has been instrumental in enabling many aspects of our modern culture and industry. This bright, brassy mineral is the most abundant metal sulfide in the Earth’s crust and provides a marked chemical contrast to the duller silicates and oxides that constitute most rocks. Most people today are familiar with the mineral, even though they do not know its details, because it stands out in the natural environment and because of the connection with fool’s gold. Pyrite has been a source of both metals and sulfur since ancient times, and both of these commodities have been key to our civilization. The mineral is easily decomposed by heat with the production of sulfur, sulfur oxide gases, and a metal-rich slag. It oxidizes readily in aerated water to form red and yellow ochers that may be used as pigments. It commonly occurs with other valuable metals that may be extracted by leaching or heating with various fluxes. In summary, it is an exceptional mineral whose benefits were readily available to primitive societies and have led to the development of our modern civilization. One of the extraordinary facets of our modern civilization is that we take lighting fires for granted. All you need is a cheap match. However, this is a relatively recent invention. So how did the early Victorians and their predecessors light their fires? Old films and television series, the so-called costume dramas, rarely, if ever, show people lighting fires. One reason for this was that lighting a fire could be a long process, so once it was lit, it was kept going. Even I remember that letting the fire go out was a heinous crime in the days before central heating, when our house was heated by a coal fire. The fire was kept going during the coldest winter weeks: it was banked up at night with coal, which kept it nicely smoldering while we slept. Its heat prevented the water pipes in the house from freezing during the iciest nights and subsequently bursting when they were warmed up again.

Abstract Many studies have been conducted on droplet entrainment in an annular flow regime, but little is known about droplet entrainment caused by nucleate boiling. In this report, visualization results of droplet entrainment caused by nucleate boiling are described. We observed two processes of droplet entrainment. The first one causes bubble bursting at a water surface. The second one causes filament breakup which occurs when the vapor bubble reaches and collapses at the interface between air and liquid. From comparison of the phenomena for the two processes, we found that the diameters of the droplets and vapor bubbles were considerably different. Using the results of this research allows the effect of forced convection to be taken into account. In the future, we plan to expand the amount of data and develop a boiling entrainment model under forced convection conditions.

The phenomenon that bubble bursts at the water surface and results in droplets production is one of the source of radioactive aerosol release, when the gas goes through the aerosol pool. Based on this, a high-speed photographic visualization experimental device was used to visualize the bubble bursting process at liquid surface under different conditions. Experimental studies show that: the bursting process of the bubbles with 7mm–28mm in diameter is a Single point rupture process. The process includes bubble rising, bubble cap draining, punctured point appearing, the liquid film rolling-up which forms the liquid ring, droplets emission as liquid ring breaks. The different punctured position changes the process of bubble bursting and the distribution of the droplets, thus the location of punctured position were divided into different area, which mainly locates at the foot of the bubble cap. Furthermore, the change of liquid phase conditions will affects the location of the punctured position, the number and the sizes of droplets. In the experiments, as temperature of the liquid phase changes from 16°C to 60°C, the process of drainage of bubble cap is shortened, and the probability of punctured position at the bottom increases. When punctured position is the same position, the number of droplets decreased and the diameter of droplet increased as temperature was increasing.

Abstract A novel vibration induced droplet atomization (VIDA) technology is utilized in a two-phase heat transfer cell for cooling of high-power integrated circuits. VIDA is a rapid atomization process whereby discrete liquid drops (or liquid film) are placed on the surface of a diaphragm that is vibrated near or at the coupled resonance of the system. Surface waves that develop on the liquid free surface lead to rapid bursting and the ejection of secondary droplets that are propelled away from the diaphragm. The VIDA-based heat transfer cell is similar to a heat pipe in that cooling is based on the evaporation and condensation of liquid within a closed cell. However, in contrast to a heat pipe where the liquid is delivered to the evaporator by capillary transport within a wicking material, in the VIDA cell the atomized liquid droplets are propelled towards the hot surface thus eliminating the capillary transport limit that is imposed by the wicking material. The vapor condenses near an air-side heat exchanger and the condensate is delivered to the VIDA driver. The rate of atomization and therefore the heat transfer within the cell can be actively controlled and regulated. The present paper focuses on the fundamental aspects of the VIDA atomization process of a single liquid drop. It is shown that VIDA process can be either self-intensifying or self-decaying. The global features of the VIDA, spray droplet size- and velocity distributions, and their interrelation with the external driving parameters are investigated. Finally, the performance of a current prototype of VIDA heat transfer cell is discussed.