Littérature scientifique sur le sujet « Thermal capillary wave »
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Articles de revues sur le sujet "Thermal capillary wave"
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Kan, Zhe, Qinghua Zhu, Haizhou Ren et Mengyan Shen. « Femtosecond Laser-Induced Thermal Transport in Silicon with Liquid Cooling Bath ». Materials 12, no 13 (26 juin 2019) : 2043. http://dx.doi.org/10.3390/ma12132043.
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Nanostructured regular patterns on silicon surface are made by using femtosecond laser irradiations. This is a novel method that can modify the surface morphology of any large material in an easy, fast, and low-cost way. We irradiate a solid surface with a 400-nm double frequency beam from an 800-nm femtosecond laser, while the solid surface is submerged in a liquid or exposed in air. From the study of multiple-pulses and single-pulse irradiations on silicon, we find the morphologies of nanospikes and capillary waves to follow the same distribution and periodicity. Thermal transport near the solid surface plays an important role in the formation of patterns; a simulation was done to fully understand the mechanism of the pattern formation in single pulse irradiation. The theoretical models include a femtosecond laser pulse function, a two-temperature model (2-T model), and an estimation of interface thermal coupling. The evolution of lattice temperature over time will be calculated first without liquid cooling and then with liquid cooling, which has not been well considered in previous theoretical papers. The lifetime of the capillary wave is found to be longer than the solidification time of the molten silicon only when water cooling is introduced. This allows the capillary wave to be frozen and leaves interesting concentric rings on the silicon surface. The regular nanospikes generated on the silicon surface result from the overlapping capillary waves.
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Duan, Li, Qi Kang et Wenrei Hu. « Characters of surface deformation and surface wave in thermal capillary convection ». Science in China Series E : Technological Sciences 49, no 5 (octobre 2006) : 601–10. http://dx.doi.org/10.1007/s11431-006-2013-2.
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Agrawal, Shubham, Prashanta K. Das et Purbarun Dhar. « Thermo-capillarity in microfluidic binary systems via phase modulated sinusoidal thermal stimuli ». Physics of Fluids 34, no 3 (mars 2022) : 032012. http://dx.doi.org/10.1063/5.0084216.
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In this article, we have explored the theoretical aspects of thermo-capillarity driven hydrodynamics at the interface of an immiscible binary-fluid system within a microfluidic domain. The top and bottom walls of the microfluidic confinement are exposed to sinusoidal thermal stimuli with different mean values, wave numbers, and phase differences. We explore the influence of different governing parameters on the thermal and hydrodynamic transport due to interfacial thermo-capillarity and within the constituent fluids. To this end, we deduce the full solutions for the temperature field, hydrodynamics, and the interfacial deformation characteristics in an analytical framework, by appealing to the assumption of the creeping flow (vanishingly small Reynolds, Marangoni, and Capillary number regime) and nearly un-deformed interface. Complicated spatial distribution of the isotherms is generated across the fluids, leading to spatially varying thermal gradients across and along the interface. This leads to periodic circulation of the fluids within the microchannel due to the sinusoidal thermal stimulus. It is observed that the interfacial flow strength depends on the relative film thickness and the thermal conductivities of the two fluids. Vortex enveloping phenomenon is observed for lower values of film thickness ratio when the thermal conductivity of the lower fluid is higher relative to the upper fluid. The findings may hold significance for the design and development of thermal stimulus-controlled spatial mixing and solute transport mechanisms in reactive micro- and nano-fluidic devices.
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Shah, Maulik S., Volkert van Steijn, Chris R. Kleijn et Michiel T. Kreutzer. « Thermal fluctuations in capillary thinning of thin liquid films ». Journal of Fluid Mechanics 876 (14 août 2019) : 1090–107. http://dx.doi.org/10.1017/jfm.2019.595.
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Thermal fluctuations have been shown to influence the thinning dynamics of planar thin liquid films, bringing predicted rupture times closer to experiments. Most liquid films in nature and industry are, however, non-planar. Thinning of such films not just results from the interplay between stabilizing surface tension forces and destabilizing van der Waals forces, but also from drainage due to curvature differences. This work explores the influence of thermal fluctuations on the dynamics of thin non-planar films subjected to drainage, with their dynamics governed by two parameters: the strength of thermal fluctuations, $\unicode[STIX]{x1D703}$, and the strength of drainage, $\unicode[STIX]{x1D705}$. For strong drainage ($\unicode[STIX]{x1D705}\gg \unicode[STIX]{x1D705}_{tr}$), we find that the film ruptures due to the formation of a local depression called a dimple that appears at the connection between the curved and flat parts of the film. For this dimple-dominated regime, the rupture time, $t_{r}$, solely depends on $\unicode[STIX]{x1D705}$, according to the earlier reported scaling, $t_{r}\sim \unicode[STIX]{x1D705}^{-10/7}$. By contrast, for weak drainage ($\unicode[STIX]{x1D705}\ll \unicode[STIX]{x1D705}_{tr}$), the film ruptures at a random location due to the spontaneous growth of fluctuations originating from thermal fluctuations. In this fluctuations-dominated regime, the rupture time solely depends on $\unicode[STIX]{x1D703}$ as $t_{r}\sim -(1/\unicode[STIX]{x1D714}_{max})\ln (\sqrt{2\unicode[STIX]{x1D703}})^{\unicode[STIX]{x1D6FC}}$, with $\unicode[STIX]{x1D6FC}=1.15$. This scaling is rationalized using linear stability theory, which yields $\unicode[STIX]{x1D714}_{max}$ as the growth rate of the fastest-growing wave and $\unicode[STIX]{x1D6FC}=1$. These insights on if, when and how thermal fluctuations play a role are instrumental in predicting the dynamics and rupture time of non-flat draining thin films.
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Aziz, M. S. Abdul, M. Z. Abdullah, C. Y. Khor, Z. M. Fairuz, A. M. Iqbal, M. Mazlan et Mohd Sukhairi Mat Rasat. « Thermal Fluid-Structure Interaction in the Effects of Pin-Through-Hole Diameter during Wave Soldering ». Advances in Mechanical Engineering 6 (1 janvier 2014) : 275735. http://dx.doi.org/10.1155/2014/275735.
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An effective simulation approach is introduced in this paper to study the thermal fluid-structure interaction (thermal FSI) on the effect of pin-through-hole (PTH) diameter on the wave soldering zone. A 3D single PTH connector and a printed circuit board model were constructed to investigate the capillary flow behavior when passing through molten solder (63SnPb37). In the analysis, the fluid solver FLUENT was used to solve and track the molten solder advancement using the volume of fluid technique. The structural solver ABAQUS was used to examine the von Mises stress and displacement of the PTH connector in the wave soldering process. Both solvers were coupled by MpCCI software. The effects of six different diameter ratios (0.1 < d/ D < 0.97) were studied through a simulation modeling. The use of ratio d/ D = 0.2 yielded a balanced filling profile and low thermal stress. Results revealed that filling level, temperature, and displacement exhibited polynomial behavior to d/ D. Stress of pin varied quadratically with the d/ D. The predicted molten solder profile was validated by experimental results. The simulation results are expected to provide better visualization and understanding of the wave soldering process by considering the aspects of thermal FSI.
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Sharizal Abdul Aziz, Mohd, Mohd Zulkifly Abdullah et Chu Yee Khor. « Influence of PTH offset angle in wave soldering with thermal-coupling method ». Soldering & ; Surface Mount Technology 26, no 3 (27 mai 2014) : 97–109. http://dx.doi.org/10.1108/ssmt-08-2013-0021.
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Purpose – The aim of this study is to investigate the effects of offset angle in wave soldering by using thermal fluid structure interaction modeling with experimental validation. Design/methodology/approach – The authors used a thermal coupling approach that adopted mesh-based parallel code coupling interface between finite volume-and finite element-based software (ABAQUS). A 3D single pin-through-hole (PTH) connector with five offset angles (0 to 20°) on a printed circuit board (PCB) was built and meshed by using computational fluid dynamics preprocessing software called GAMBIT. An implicit volume of fluid technique with a second-order upwind scheme was also applied to track the flow front of solder material (Sn63Pb37) when passing through the solder pot during wave soldering. The structural solver and ABAQUS analyzed the temperature distribution, displacement and von Mises stress of the PTH connector. The predicted results were validated by the experimental solder profile. Findings – The simulation revealed that the PTH offset angle had a significant effect on the filling of molten solder through the PCB. The 0° angle yielded the best filling profile, filling time, lowest displacement and thermal stress. The simulation result was similar to the experimental result. Practical implications – This study provides a better understanding of the process control in wave soldering for PCB assembly. Originality/value – This study provides fundamental guidelines and references for the thermal coupling method to address reliability issues during wave soldering. It also enhances understanding of capillary flow and PTH joint issues to achieve high reliability in PCB assembly industries.
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Peirson, William L., James W. Walker et Michael L. Banner. « On the microphysical behaviour of wind-forced water surfaces and consequent re-aeration ». Journal of Fluid Mechanics 743 (5 mars 2014) : 399–447. http://dx.doi.org/10.1017/jfm.2013.681.
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AbstractA detailed laboratory investigation of the mechanical and low-solubility gas coupling between wind and water has been undertaken using a suite of microphysical measurement techniques. Under a variety of wind conditions and in the presence and absence of mechanically generated short waves, approximately fetch-independent surface conditions have been achieved over short laboratory fetches of several metres. The mechanical coupling of the surface is found to be consistent with Banner (J. Fluid Mech. vol. 211, 1990, pp. 463–495) and Banner & Peirson (J. Fluid Mech. vol. 364, 1998, pp. 115–145). Bulk observations of re-aeration are consistent with previous laboratory studies. The surface kinematical behaviour is in accordance with the observations of Peirson & Banner (J. Fluid Mech. vol. 479, 2003, pp. 1–38). Also, their predictions of a strong enhancement of low-solubility gas flux at the onset of microscale breaking is confirmed and direct observations show a concomitant onset of very thin aqueous diffusion sublayers. It is found that the development of strong parasitic capillary waves towards the incipient breaking limit does not noticeably enhance constituent transfer. Across the broad range of conditions investigated during this study, the local instantaneous constituent transfer rate remains approximately log-normally distributed with an approximately constant standard deviation of $0.62\pm 0.15({\mathrm{log}}_e(\mathrm{m}~ {\mathrm{s}}^{-1}))$. Although wind-forced water surfaces are shown to be punctuated by intense tangential stresses and local surface convergence, localized surface convergence does not appear to be the single critical factor determining exchange rate. Larger-scale orbital wave straining is found to be a significant constituent transfer process in contrast to Witting (J. Fluid Mech. vol. 50, 1971, pp. 321–334) findings for heat fluxes, but the measured effects are consistent with his model. By comparing transfer rates in the presence and absence of microscale breaking, low-solubility gas transfer was decomposed into its turbulent/capillary ripple, gravity-wave-related and microscale breaking contributions. It was found that an efficiency factor of approximately $17\, \%$ needs to be applied to Peirson & Banner’s model, which is extended to field conditions. Although bulk thermal effects were observed and thermal diffusion layers are presumed thicker than their mass diffusion counterparts, significant thermal influences were not observed in the results.
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Da Mota, J. C., A. J. De Souza, D. Marchesin et P. W. Teixeira. « A SIMPLIFIED OXIDATION MODEL FOR TWO-PHASE FLOW IN POROUS MEDIA ». Revista de Engenharia Térmica 1, no 2 (31 décembre 2002) : 09. http://dx.doi.org/10.5380/reterm.v1i2.3504.
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This paper describes a simplified mathematical model for thermal recovery by oxidation for flow of oxygen and oil in porous media. Some neglected important physical effects include gravity, compressibility and heat loss to the rock formation, but heat longitudinal conduction and capillary pressure difference between the phases are considered. The mathematical model is obtained from the mass balance equations for air and oil, energy balance and Darcy's law applied to each phase. Based on this model some typical features in low temperature oxidation concerning the wave structure are captured. Numerical simulations showing saturations and temperature profiles are reported.
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Abdul Aziz, M. S., M. Z. Abdullah et C. Y. Khor. « Effects of Solder Temperature on Pin Through-Hole during Wave Soldering : Thermal-Fluid Structure Interaction Analysis ». Scientific World Journal 2014 (2014) : 1–13. http://dx.doi.org/10.1155/2014/482363.
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An efficient simulation technique was proposed to examine the thermal-fluid structure interaction in the effects of solder temperature on pin through-hole during wave soldering. This study investigated the capillary flow behavior as well as the displacement, temperature distribution, and von Mises stress of a pin passed through a solder material. A single pin through-hole connector mounted on a printed circuit board (PCB) was simulated using a 3D model solved by FLUENT. The ABAQUS solver was employed to analyze the pin structure at solder temperatures of 456.15 K (183°C) <T< 643.15 K (370°C). Both solvers were coupled by the real time coupling software and mesh-based parallel code coupling interface during analysis. In addition, an experiment was conducted to measure the temperature difference (ΔT) between the top and the bottom of the pin. Analysis results showed that an increase in temperature increased the structural displacement and the von Mises stress. Filling time exhibited a quadratic relationship to the increment of temperature. The deformation of pin showed a linear correlation to the temperature. TheΔTobtained from the simulation and the experimental method were validated. This study elucidates and clearly illustrates wave soldering for engineers in the PCB assembly industry.
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Genbach, A. A., D. Yu Bondartsev et A. Y. Shelginsky. « Investigation of nanoscale and microscale structured cooling surfaces of thermal power plants ». Safety and Reliability of Power Industry 15, no 1 (6 mai 2022) : 38–44. http://dx.doi.org/10.24223/1999-5555-2022-15-1-38-44.
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Studies were conducted of the heat exchange crisis depending on the coolant excess (which determined the underheating and flow rate), the thermal-physical properties of the heating surface, and the ejection of liquid droplets from the porous structure. A model of dynamics of vapor bubbles born on the solid surface in porous structures and the vapor-generating wall (substrate) has been developed. The model is based on cinematography with an SKS-1M speed camera. The removal of high heat flows (up to 2·106 W/m2) is provided through the joint action of capillary and mass forces with the use of intensifiers. Equations are obtained of critical heat flows through the thermohydraulic characteristics of the boiling process in woven porous structures. The research is of practical importance in the limiting state region of the steam-generating surface protected by cooling from overburning. Three mineral media (tuff, granite, marble) of Zaili and Dzungarian Alatau mountains near the city of Almaty (Kazakhstan) were considered. The method of holographic interferometry was used to study porous thermodynamic screens. The stress and deformed state of the samples was studied. Simulation of the acoustic field of the blast wave with th e thermodynamic field created by three thermal sources has shown its high efficiency. The created powerful thermal screen, due to the generation of strain and thermal stress fields, is an obstacle to the propagation of the reflected blast wave, causing the emergence and development of destructive cracks. Nanoscale and microscale structured surfaces in the form of coatings and mesh structures have been developed, which give an integrated effect of industrial meshes with natural mineral media coatings and have synergistic advantages of combining these two developments in an integrated technology of their production, expansion of critical thermal loads and management of the limiting state of porous coatings.
Thèses sur le sujet "Thermal capillary wave"
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Zhang, Hao. « Écoulement des fluides et déformation interfaciale : nano-rhéologie et force de portance ». Electronic Thesis or Diss., Bordeaux, 2025. http://www.theses.fr/2025BORD0027.
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Cette thèse examine l'interaction entre l'écoulement des fluides et la déformation interfaciale à l'aide de la Microscopie à Force Atomique (AFM). Tout d'abord, l'AFM a été utilisé pour explorer les fluctuations capillaires thermiques résonantes (RTCF) des surfaces de bulles et de gouttes, permettant ainsi de mesurer l'élasticité de surface et la viscosité en volume «bulk » aux interfaces air/eau chargées en tensioactifs et dans les solutions polymères. Ces mesures ont élargi la plage de fréquence pour les investigations rhéologiques, surmontant les limitations des rhéomètres classiques. Ensuite, nous avons introduit une méthode sans contact pour évaluer les propriétés mécaniques des cellules vivantes, basée sur l'interaction élastohydrodynamique (EHD) entre les vibrations thermiques du levier AFM et les déformations des cellules. Cette méthode a permis de déterminer avec précision le module élastique d'une cellule vivante à différentes fréquences. Enfin, nous avons réalisé la première mesure directe et quantitative de la force de portance agissant sur une sphère se déplaçant le long d'une interface liquide-liquide. Cette force, résultant du couplage entre l'écoulement visqueux et la déformation capillaire de l'interface, a été mesurée en fonction de la distance entre la sphère et l'interface à l'aide de l'AFM. Nous avons étudié diverses interfaces liquides, fréquences de travail, vitesses de glissement et deux rayons de sphère différents. Ces résultats fournissent des informations précieuses sur les phénomènes interfaciaux et améliorent la compréhension des interactions entre l’écoulement des fluides et les interfaces mollesThis thesis investigates the interplay between fluid flow and interfacial deformation using Atomic Force Microscopy (AFM). First, AFM was employed to explore the resonant thermal capillary fluctuations (RTCF) of bubble and drop surfaces, enabling the measurement of surface elasticity and bulk viscosity in surfactant-laden air/water interfaces and polymer solutions. These measurements extended the frequency range for rheological investigations, effectively overcoming the limitations of classical rheometers.Next, we introduced a non-contact method to assess the mechanical properties of living cells based on the elastohydrodynamic (EHD) interaction between the thermal vibrations of the AFM cantilever and the cell deformations. This method enabled the precise determination of the elastic modulus of a living cell for different frequencies.Finally, we conducted the first direct and quantitative measurement of the lift force acting on a sphere moving along a liquid-liquid interface. This force, arising from the coupling between viscous flow and capillary deformation of the interface, was measured as a function of the distance between the sphere and the interface using an atomic force microscope (AFM). We investigated various liquid interfaces, working frequencies, sliding velocities, and two different sphere radii. The findings provide valuable insights into interfacial phenomena and enhance the understanding of interactions between fluid flow and soft interfaces
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Gugliotti, Marcos Eduardo Sedra. « Novas aplicações de técnicas fototérmicas para o estudo de interfaces ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-23012002-154950/.
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Este trabalho apresenta o desenvolvimento de novas instrumentações baseadas em efeitos fototérmicos para o estudo de interfaces sólido-líquido e líquido-gás, incluindo no último caso o efeito de surfactantes. O trabalho está dividido em capítulos, cada um enfocando o desenvolvimento e/ou aplicação de uma nova técnica. O Capítulo I apresenta uma introdução aos fenômenos fototérmicos e desecreve a construção de instrumentos clássicos de Lente Térmica (LT) nas configurações de simples e duplo feixe. Interfaces sólido-líquido foram estudadas nos capítulos II-IV usando variações da instrumentação clássica de LT. Um novo sinal fototérmico foi caracterizado, indicando a formação de uma lente térmica invertida na interface. Experimentos de varredura-z na configuração por reflexão foram usados para determinar a mudança no índice de refração da interface próximo ao ângulo crítico, e uma metodologia similar foi utilizada para a medida da difusividade térmica de amostras opacas. Nos capítulos V-VII, a deformação de superfícies líquidas foi estudada pelo efeito Marangoni induzido por laser e pela geração de ondas capilares. A transferência de calor pela interface líquido-gás foi monitorada por Deflexão Fototérmica Transversal. Em todos os casos, a influência de surfactantes foi estudada pela formação de uma monocamada na superfície dos líquidos. Observou-se que uma pequena quantidade de surfactante é capaz de cessar a movimentação de líquidos induzida por gradientes de tensão superficial e aumentar significativamente a transferência de calor pela interface. Os resultados indicam uma correlação entre as transições de fase das monocamadas e a atenuação da deformação superficial bem como o aumento na transferência de calor. Finalmente, o capítulo VIII apresenta uma coleção de trabalhos que derivaram dos estudos relacionados com as instrumentações desenvolvidas.This work presents the development of new instrumentations based on photothermal phenomena to study solid-liquid and liquid-gas interfaces, including in the latter the effect of surfactants. The work is divided into chapters, each one focusing on the development and/or application of a new technique. Chapter I presents an introduction to photothermal phenomena and describes the construction of classical Thermal Lens (TL) instruments in the single and double-beam configurations. Solid-liquid interfaces were studied in chapters II-IV using variations of the classical TL instrumentation. A new photothermal signal was characterized, indicating the formation of an inverted thermal lens at the interface. Z-scan experiments in the reflection configuration were used to determine the change in the refractive index of an interface close to the critical angle, and a similar methodolody was used to measure the thermal diffusivity of opaque samples. In Chapters V-VII, the deformation of liquid surfaces was studied by laser-induced Marangoni effect and the generation of capillary waves. Heat transfer through the liquid-gas interface was monitored by Transverse Photothermal Deflection. In all cases, the influence of surfactants was studied by forming a monolayer on the surface of the liquids. It was observed that a tiny amount of surfactants was able to cease the motion of liquid induced by surface tension gradients and to increase significantly the heat transfer through the interface. The results indicate a correlation between phase transitions of the monolayers and the attenuation of the surface deformation as well as the increase in the heat transfer. Finally, chapter VIII is a collection of other works that derived from the studies related to the instrumentations developed.
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Thapa, Nabin K. « Characterizing Liquid-Fluid Interfaces Using Surface Light Scattering Spectroscopy ». Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1564059703319064.
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Michel, Guillaume. « Parois et ondes de surface : dissipation, effet Doppler et interactions non linéaires ». Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEE038/document.
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Dans cette thèse, nous étudions comment la présence de parois affecte les ondes de surface. La dissipation associée au mouillage, objet central des premiers chapitres, est abordée expérimentalement. Nous mesurons son évolution avec la taille du ménisque et montrons qu’en mouillage total des non-linéarités apparaissent dès que l’oscillation du ménisque atteint l’épaisseur des couches limites. Dans un deuxième temps, nous quantifions les échanges d’énergie ayant lieu lors de laréflexion d’une onde de surface sur une paroi oscillante, appelés effet Doppler généralisé. Après une mise en évidence expérimentale, une approche théorique les évalue et illustre comment leurs effets cumulatifs peuvent mener à des spectres en compétition avec ceux de la turbulence d’ondes. Finalement, nous traitons les interactions entre paquets d’ondes. En géométrie confinée, nous montrons que des résonances à trois ondes gravitaires sont autorisées. Dépassant la problématique des parois, nous caractérisons les interactions entre ondes gravitaires en milieu infini, puis décrivons les grandes échelles de la turbulence d’ondes capillaireIn this thesis, we study the impact of solid boudaries on surface waves. We first consider the dissipation caused by dynamical wetting. We experimentally show how the damping of surface waves evolves with the size of the meniscus and demonstrate that in perfect wetting it leads to a nonlinear behavior as soon as the meniscus oscillation amplitude compares to the thickness of the boundary layer. Secondly, we investigate energy exchanges through scales occuring when a surface wave reflects on an oscillating wall, the so-called generalized Doppler effect. We evidence the creation of Doppler-shifted waves, compute their amplitudes and illustrate how the continuous bouncing of surface waves on wavemakers may lead to self-similar spectra competing with the ones of wave turbulence. Finally, we focus on nonlinear interaction between surface waves. We prove that gravity waves can undergo triad resonances in confined geometry. Going beyond the consequencies of solid boundaries, we perform experiments on four-wave interactions in the gravity regime and describe large scales in capillary wave turbulence
Livres sur le sujet "Thermal capillary wave"
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Aarts, D. G. A. L. Soft interfaces : the case of colloid–polymer mixtures. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198789352.003.0013.
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In this chapter we discuss the interface of a phase separated colloid-polymer mixture. We start by highlighting a number of experimental studies, illustrating the richness of colloidal interface phenomena. This is followed by a derivation of the bulk phase behaviour within free volume theory. We subsequently calculate the interfacial tension using a squared gradient approach. The interfacial tension turns out to be ultralow, easily a million times smaller than a molecular interfacial tension. From the bulk and interface calculations we obtain the capillary length and compare to experiments, where good overall agreement is found. Finally, we focus on the thermal capillary waves of the interface and derive the static and dynamic height–height correlation functions, which describe the experimental data very well. We end with an outlook, where we address some outstanding questions concerning the behaviour of interfaces, to which colloids may provide unique insights.
Chapitres de livres sur le sujet "Thermal capillary wave"
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Robinett, Richard W. « Warm-up : Dimensional analysis confronts data ». Dans Dimensional Analysis Across the Landscape of Physics, 47–68. Oxford University PressOxford, 2024. https://doi.org/10.1093/oso/9780192867551.003.0002.
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Abstract To illustrate the predictive power of dimensional analysis, we explore problems from the research literature, historical and recent. We then compare the scaling predictions for several physical processes with experimental data, emphasizing the importance of being able to perform power-law fits. Some of the processes that are considered include capillary (surface tension) and plasma (ionized gas) oscillations, blast waves, thermal and electrical conduction, gravitational bound states of neutrons, and viscosity and entropy values in quantum fluids, ranging from cold atoms to quark gluon systems.
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V., Viacheslav, et Reinhold Kneer. « Heat Transfer Phenomena in Laminar Wavy Falling Films : Thermal Entry Length, Thermal-Capillary Metastable Structures, Thermal-Capillary Breakdown ». Dans Heat Transfer - Theoretical Analysis, Experimental Investigations and Industrial Systems. InTech, 2011. http://dx.doi.org/10.5772/13652.
Texte intégralActes de conférences sur le sujet "Thermal capillary wave"
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Duan, Li, et Qi Kang. « Optical methods on measuring surface deformation and surface wave in the thermal capillary convection ». Dans Optical Technology and Image Processing fo rFluids and solids Diagnostics 2002, sous la direction de Gong Xin Shen, Soyoung S. Cha, Fu-Pen Chiang et Carolyn R. Mercer. SPIE, 2003. http://dx.doi.org/10.1117/12.509846.
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Haustein, Herman D., Wilko Rohlfs, Faruk Al-Sibai et Reinhold Kneer. « Development of Heat Transfer in a Two-Dimensional Wavy Falling Film of Water and its Influence on Wave Stability ». Dans ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17453.
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Heat exchangers employing falling films are relevant to a multitude of industrial applications using water-based liquids. In the present study, periodic, two-dimensional waves are imposed by excitation on a vertically falling film of water, which is then heated by a uniform heat flux, within the laminar and transitional flow range (39<Re<200). Liquid-film thickness is measured by confocal chromatic imaging and surface temperature is measured by high-speed IR thermography. As the 2D waves travel downstream they destabilize in the spanwise direction and evolve 3D structures (bumps). Further wave destabilization, under relatively low heating, was observed to coincide with the appearance of local thermal flows (“hot streaks”), though no deformation of the liquid surface could be measured. These flows are understood to be induced by thermo-capillary forces, which in extreme cases are known to lead to the formation of rivulets, film rupture and heater burnout. Understanding these initial stages of thermo-capillary flow is crucial to its suppression. Analysis of the thermal images reveals several significant streamwise length scales: a thermal inlet length based on the emergence of the thermal boundary layer (Lt), a thermal inlet length based on reaching thermally developed conditions (Lh), and the length at which “hot-streaks” first appear (Ls). In addition the dominant (most unstable) spanwise wavelength of the hot streaks, Lz, was identified through FFT analysis of the thermal profile beyond Ls. First the independence of the thermal inlet lengths from the heat-flux was established. Next, the influence of the nominal flow conditions (Reynolds number and excitation frequency) on Lt, Lh and Lz was examined — thereby extending the range of previous studies to higher Reynolds numbers. The thermal inlet lengths Lt and Lh were found to increase with flow rate, whereas they had opposing trends with regard to frequency. Lz consistently decreased with an increase of the flow rate, as smaller (turbulent) scales became more dominant, and it was found to be indifferent to excitation frequency over a wide range. Some future directions and methods of hot streak suppression are discussed, as well.
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Kino, Chiaki, Tomoaki Kunugi et Zensaku Kawara. « Numerical Simulation on Heat Transfer of Falling Film Flow Along a Vertical Wall ». Dans ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32002.
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Numerical simulations based on the MARS (Multi-interface Advection and Reconstruction Solver) developed by one of the authors have been performed in order to understand the heat transfer mechanism of falling film flows along a vertical wall. In the present study, we focused on an internal structure, i.e. velocity profile and heat transfer. In this study, the velocity profiles in a falling film are categorized into three regions: substrate film region, solitary wave region, and capillary wave region with each characteristic. Moreover, small vortices can be found in the capillary wave region. Additionally, numerical results indicate that heat transfer mechanism is different for these three regions. We proposed new heat transfer evaluation manner as a function of the Prandtl number for these regions. This manner could contribute to a design work of falling film flow device.
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Laser, Daniel J. « Temporal Modulation of Electroosmotic Micropumps ». Dans ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13960.
Texte intégralRésumé :
This paper reports on analytical and experimental studies of transient effects in electroosmotic (EO) micropumps, focusing on an EO micropump operational paradigm of practical importance: the use of variable-duty-cycle square wave driving voltages. Models of transient effects in EO micropumps are evaluated and developed, and load inertia as well as thermal and diffusion effects are considered. Detailed models, based on solutions for electroosmotic flow between infinite parallel plates, are presented for slit capillary array EO micropumps with slit half-width on the order of one micron. Driving typical microfluidic system loads, analysis by analogy to Stokes' second problem predicts pseudosteady electroosmotic flow in these micropumps for input frequencies up to 100 Hz, with attenuation of high-frequency components of square-wave inputs due to load inertial effects. In experiments with slit capillary array electroosmotic micropumps driven by 10 Hz square waves, micropump output is observed to be generally nonlinear with duty cycle, with significant flow rate enhancement relative to constant-voltage operation at duty cycles above 40%. Lateral diffusion during temporary zero-field conditions may lead to a slight increase in time-averaged zeta potential for square-wave-driven EO micropumps.
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Haber, Elad, Mark Douvidzon et Tal Carmon. « Finesse-Enhanced Measurement of Thermal Capillary-Waves at Liquid-Phase Boundaries ». Dans CLEO : Applications and Technology. Washington, D.C. : OSA, 2021. http://dx.doi.org/10.1364/cleo_at.2021.jtu3a.128.
Texte intégral
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Vukasinovic, Bojan, Samuel N. Heffington, Marc K. Smith et Ari Glezer. « Vibration-Induced Droplet Atomization (VIDA) for Two-Phase Thermal Management ». Dans ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/epp-24702.
Texte intégralRésumé :
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.
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DeShazer, LARRY G. « Survey of phase-matchable fibers for nonlinear optics ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.wb3.
Texte intégralRésumé :
A variety of methods have emerged to fabricate single-crystal nonlinear optical fibers. As a class of crystals, nonlinear materials encompass the entire range of thermal behavior possible in compounds. Therefore, it has become increasingly clear that no one method of single-crystal fiber growth can accommodate the disparities of all the nonlinear crystals. Traveling-zone, Bridgman, and Czochralski methods of crystal growth have all been successfully adopted in producing single-crystal fibers. The traveling-zone method converted polycrystalline fibers to single-crystal fibers by using a submillimeter melt zone produced by a small electrical heater. Crystal fibers of CuCI were grown by this method. A Bridgman method produced single-crystal fibers in which the melt is vapor-pressure stabilized. This method was applicable to nearly congruent melting materials such as KDP-isomorph crystals. A capillary-fed Czochralski method was developed to grow fibers of congruently melting materials such as NaNO3. Capillary designs overcame the thermal steady-state limitations of the conventional Czochralski technique applied to fiber growth. All these methods of growing nonlinear optical fibers showed dimensional irregularities of the crystal fibers, to varying degrees. Because the efficiency of phase-matched processes in nonlinear fibers is sharply reduced by surface imperfections, an alternative hybrid approach was developed. This approach combined the desirable uniformity of glass fibers with bulk nonlinear crystals. The evanescent portion of guided waves in the glass core can be coupled to the nonlinear polarization of the crystal clad.
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Smith, Elizabeth T., William W. Schultz et Elijah Kannatey-Asibu. « Modeling Oscillations During Conduction Mode Laser Welding ». Dans ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0725.
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Abstract Thermal, optical, and acoustic signals are generated during laser welding by the many physical phenomena which govern the laser beam-material interactions involved in welding. The objective of this study is to analyze one potential source of these signals — oscillations of the molten weld pool. Weld pool oscillations are modeled as gravity-capillary waves in a partially penetrating, conduction mode weld pool. The weld pool is assumed to be stationary and cylindrical, containing inviscid, incompressible, irrotational liquid metal. Dynamic and kinematic boundary conditions are imposed at the free surface of the pool, with impenetrability providing a boundary condition at solid boundaries. Two different edge conditions are examined. First, the free surface is assumed to meet the boundary orthogonally. Second, the contact line is assumed to remain fixed during pool motion. Solution of the governing equations subject to the boundary conditions provides the natural frequencies of oscillation and mode shapes governing pool motion. Results from the analytic model agree well with preliminary experimental data. The dominant mode of oscillation can be characterized as a sloshing of material from the front to the back of the pool, occurring at approximately 700Hz for the conditions examined.