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Journal articles on the topic 'Bubble growth'
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1
Ban, Zhen Hong, Kok Keong Lau, and Mohd Sharif Azmi. "Bubble Nucleation and Growth of Dissolved Gas in Solution Flowing across a Cavitating Nozzle." Applied Mechanics and Materials 773-774 (July 2015): 304–8. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.304.
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Computational modelling of dissolved gas bubble formation and growth in supersaturated solution is essential for various engineering applications, including flash vaporisation of petroleum crude oil. The common mathematical modelling of bubbly flow only caters for single liquid and its vapour, which is known as cavitation. This work aims to simulate the bubble nucleation and growth of dissolved CO2 in water across a cavitating nozzle. The dynamics of bubble nucleation and growth phenomenon will be predicted based on the hydrodynamics in the computational domain. The complex interrelated bubble dynamics, mass transfer and hydrodynamics was coupled by using Computational Fluid Dynamics (CFD) and bubble nucleation and growth model. Generally, the bubbles nucleate at the throat of the nozzle and grow along with the flow. Therefore, only the region after the throat of the nozzle has bubbles. This approach is expected to be useful for various types of bubbly flow modelling in supersaturated condition.
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Martin, Alberto, and Jaume Ventura. "Economic Growth with Bubbles." American Economic Review 102, no. 6 (October 1, 2012): 3033–58. http://dx.doi.org/10.1257/aer.102.6.3033.
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We develop a stylized model of economic growth with bubbles in which changes in investor sentiment lead to the appearance and collapse of macroeconomic bubbles or pyramid schemes. These bubbles mitigate the effects of financial frictions. During bubbly episodes, unproductive investors demand bubbles while productive investors supply them. These transfers of resources improve economic efficiency thereby expanding consumption, the capital stock and output. When bubbly episodes end, there is a fall in consumption, the capital stock and output. We argue that the stochastic equilibria of the model provide a natural way of introducing bubble shocks into business cycle models. (JEL E22, E23, E32, E44, O41)
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DELALE, C. F., G. H. SCHNERR, and J. SAUER. "Quasi-one-dimensional steady-state cavitating nozzle flows." Journal of Fluid Mechanics 427 (January 25, 2001): 167–204. http://dx.doi.org/10.1017/s0022112000002330.
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Quasi-one-dimensional cavitating nozzle flows are considered by employing a homogeneous bubbly liquid flow model. The nonlinear dynamics of cavitating bubbles is described by a modified Rayleigh–Plesset equation that takes into account bubble/bubble interactions by a local homogeneous mean-field theory and the various damping mechanisms by a damping coefficient, lumping them together in the form of viscous dissipation. The resulting system of quasi-one-dimensional cavitating nozzle flow equations is then uncoupled leading to a nonlinear third-order ordinary differential equation for the flow speed. This equation is then cast into a nonlinear dynamical system of scaled variables which describe deviations of the flow field from its corresponding incompressible single-phase value. The solution of the initial-value problem of this dynamical system can be carried out very accurately, leading to an exact description of the hydrodynamic field for the model considered.A bubbly liquid composed of water vapour–air bubbles in water at 20 °C for two different area variations is considered, and the initial cavitation number is chosen in such a way that cavitation can occur in the nozzle. Results obtained, when bubble/bubble interactions are neglected, show solutions with flow instabilities, similar to the flashing flow solutions found recently by Wang and Brennen. Stable steady-state cavitating nozzle flow solutions, either with continuous growth of bubbles or with growth followed by collapse of bubbles, were obtained when bubble/bubble interactions were considered together with various damping mechanisms.
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CHOI, JAEHYUG, CHAO-TSUNG HSIAO, GEORGES CHAHINE, and STEVEN CECCIO. "Growth, oscillation and collapse of vortex cavitation bubbles." Journal of Fluid Mechanics 624 (April 10, 2009): 255–79. http://dx.doi.org/10.1017/s0022112008005430.
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The growth, oscillation and collapse of vortex cavitation bubbles are examined using both two- and three-dimensional numerical models. As the bubble changes volume within the core of the vortex, the vorticity distribution of the surrounding flow is modified, which then changes the pressures at the bubble interface. This interaction can be complex. In the case of cylindrical cavitation bubbles, the bubble radius will oscillate as the bubble grows or collapses. The period of this oscillation is of the order of the vortex time scale, τV = 2πrc/uθ, max, where rc is the vortex core radius and uθ, max is its maximum tangential velocity. However, the period, oscillation amplitude and final bubble radius are sensitive to variations in the vortex properties and the rate and magnitude of the pressure reduction or increase. The growth and collapse of three-dimensional bubbles are reminiscent of the two-dimensional bubble dynamics. But, the axial and radial growth of the vortex bubbles are often strongly coupled, especially near the axial extents of the bubble. As an initially spherical nucleus grows into an elongated bubble, it may take on complex shapes and have volume oscillations that also scale with τV. Axial flow produced at the ends of the bubble can produce local pinching and fission of the elongated bubble. Again, small changes in flow parameters can result in substantial changes to the detailed volume history of the bubbles.
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Battistella, Alessandro, Sander Aelen, Ivo Roghair, and Martin van Sint Annaland. "Euler–Lagrange Modeling of Bubbles Formation in Supersaturated Water." ChemEngineering 2, no. 3 (August 24, 2018): 39. http://dx.doi.org/10.3390/chemengineering2030039.
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Phase transition, and more specifically bubble formation, plays an important role in many industrial applications, where bubbles are formed as a consequence of reaction such as in electrolytic processes or fermentation. Predictive tools, such as numerical models, are thus required to study, design or optimize these processes. This paper aims at providing a meso-scale modelling description of gas–liquid bubbly flows including heterogeneous bubble nucleation using a Discrete Bubble Model (DBM), which tracks each bubble individually and which has been extended to include phase transition. The model is able to initialize gas pockets (as spherical bubbles) representing randomly generated conical nucleation sites, which can host, grow and detach a bubble. To demonstrate its capabilities, the model was used to study the formation of bubbles on a surface as a result of supersaturation. A higher supersaturation results in a faster rate of nucleation, which means more bubbles in the column. A clear depletion effect could be observed during the initial growth of the bubbles, due to insufficient mixing.
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Zhou, Ge. "THE SPIRIT OF CAPITALISM AND RATIONAL BUBBLES." Macroeconomic Dynamics 20, no. 6 (June 30, 2015): 1432–57. http://dx.doi.org/10.1017/s1365100514000972.
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This study provides an infinite-horizon model of rational bubbles in a production economy. A bubble can arise when the pursuit of status is modeled explicitly, capturing the notion of “the spirit of capitalism.” Using a parameterized model, I demonstrate the specific conditions for the existence of bubbles and their implications. Bubbles crowd out investment, stimulate consumption, and slow economic growth. I also discuss a stochastic bubble that bursts with an exogenous probability. I show that there could be multiple stochastic bubbly equilibria. Moreover, I suggest that taxing wealth properly can eliminate bubbles and achieve the social optimum.
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Zhang, Peng-li, and Shu-yu Lin. "Study on Bubble Cavitation in Liquids for Bubbles Arranged in a Columnar Bubble Group." Applied Sciences 9, no. 24 (December 4, 2019): 5292. http://dx.doi.org/10.3390/app9245292.
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In liquids, bubbles usually exist in the form of bubble groups. Due to their interaction with other bubbles, the resonance frequency of bubbles decreases. In this paper, the resonance frequency of bubbles in a columnar bubble group is obtained by linear simplification of the bubbles’ dynamic equation. The correction coefficient between the resonance frequency of the bubbles in the columnar bubble group and the Minnaert frequency of a single bubble is given. The results show that the resonance frequency of bubbles in the bubble group is affected by many parameters such as the initial radius of bubbles, the number of bubbles in the bubble group, and the distance between bubbles. The initial radius of the bubbles and the distance between bubbles are found to have more significant influence on the resonance frequency of the bubbles. When the distance between bubbles increases to 20 times the bubbles’ initial radius, the coupling effect between bubbles can be ignored, and after that the bubbles’ resonance frequency in the bubble group tends to the resonance frequency of a single bubble’s resonance frequency. Fluent software is used to simulate the bubble growth, shrinkage, and collapse of five and seven bubbles under an ultrasonic field. The simulation results show that when the bubble breaks, the two bubbles at the outer field first begin to break and form a micro-jet along the axis line of the bubbles. Our methods and conclusions will provide a reference for further simulations and indicate the significance of the prevention or utilization of cavitation.
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Yao, Shouguang, Tao Huang, Kai Zhao, Jianbang Zeng, and Shuhua Wang. "Simulation of flow boiling of nanofluid in tube based on lattice Boltzmann model." Thermal Science 23, no. 1 (2019): 159–68. http://dx.doi.org/10.2298/tsci160817006y.
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In this study, a lattice Boltzmann model of bubble flow boiling in a tube is established. The bubble growth, integration, and departure of 3% Al2O3-water nanofluid in the process of flow boiling are selected to simulate. The effects of different bubble distances and lateral accelerations a on the bubble growth process and the effect of heat transfer are investigated. Results showed that with an increase in the bubble distance, the bubble coalescence and the effect of heat transfer become gradual. With an increase in lateral acceleration a, the bubble growth is different. When a = 0.5e?7 and a = 0.5e?6, the bubble growth includes the process of bubble growth, coalescence, detachment, and fusion with the top bubble and when a = 0.5e?5 and a = 0.5e?4, the bubbles only experience growth and fusion, and the bubbles do not merge with the top bubble directly to the right movement because the lateral acceleration is too large, resulting in the enhanced effect of heat transfer in the tube.
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Taqieddin, Amir, Yuxuan Liu, Akram N. Alshawabkeh, and Michael R. Allshouse. "Computational Modeling of Bubbles Growth Using the Coupled Level Set—Volume of Fluid Method." Fluids 5, no. 3 (July 23, 2020): 120. http://dx.doi.org/10.3390/fluids5030120.
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Understanding the generation, growth, and dynamics of bubbles as they absorb or release dissolved gas in reactive flows is crucial for optimizing the efficiency of electrochemically gas-evolving systems like alkaline water electrolysis or hydrogen production. To better model these bubbly flow systems, we use a coupled level set and volume of fluid approach integrated with a one-fluid transport of species model to study the dynamics of stationary and rising bubbles in reactive two-phase flows. To accomplish this, source terms are incorporated into the continuity and phase conservation equations to allow the bubble to grow or shrink as the species moves through the interface. Verification of the hydrodynamics of the solver for non-reactive systems demonstrates the requisite high fidelity interface capturing and mass conservation necessary to incorporate transport of species. In reactive systems where the species impacts the bubble volume, the model reproduces the theoretically predicted and experimentally measured diffusion-controlled growth rate (i.e., R(t)∝t0.5). The model is then applied to rising bubbles to demonstrate the impact of transport of species on both the bubble velocity and shape as well as the concentration field in its wake. This improved model enables the incorporation of electric fields and chemical reactions that are essential for studying the physicochemical hydrodynamics in multiphysics systems.
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Su, Chi-Wei, Lu Liu, and Kai-Hua Wang. "Do Bubble Behaviors Exist in Chinese Film Stocks?" SAGE Open 10, no. 4 (October 2020): 215824402098330. http://dx.doi.org/10.1177/2158244020983300.
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This article investigates bubbles in the Chinese film industry to reveal the industry’s boom and bust process that influences employment, citizen’s livelihoods, and even economic growth. We adopt the film stock index to reflect the industry’s trajectory and employ the generalized and backward sup augmented Dickey–Fuller tests to detect bubble periods. Empirical results indicate that there are three positive bubbles in 2007, 2013, and 2015, indicating that the film market continues to expand after temporary frustrations. Meanwhile, one negative bubble is found in 2019, which demonstrates that the bubble’s negative impacts persist and the film industry is still having problems such as declining industrial output. Economic growth, film quality, and industrial policies are common factors for all bubbles. The global financial crisis, capital in- and outflows, internet giants’ entry and sky-high remuneration are reasons for certain bubble behaviors. Hence, market practitioners should actively recognize bubbles and observe their evolution, which will favor industrial stabilization. A perfect legal system, moderate industrial policies, a competitive market environment, and other measures are needed to confront the opportunities and challenges.
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Zhang, Yiping, Mengxian Hu, and Yongchao Zhou. "An Experimental Study on Bubble Growth in Laponite RD as Thixotropic Yield Material." Materials 13, no. 13 (June 27, 2020): 2887. http://dx.doi.org/10.3390/ma13132887.
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The growth and release of the leading major bubble at the tip of a needle in the thixotropic yield material Laponite RD was different from subsequent minor bubbles. The gas injection experiments combined with high-speed camera were conducted. The results showed that the shape of the major bubbles transformed from an inverted carrot shape to an inverted teardrop shape, while the shape of the minor bubbles tended to be elliptical. In addition, the pressure of bubble emergence consisted of hydrostatic pressure, capillary pressure, and cracking pressure. The major and minor bubbles differed only in the cracking pressure. The pressure when the minor bubble detached could be estimated from the lateral hydrostatic pressure. It can be deduced from dimensionless numbers that buoyancy and viscous forces were, respectively, the main driving force and resistance of bubble growth. The yield stress of Laponite RD and inertial force at the initial moment resulted in distinctive behavior of the major bubble. In addition to the viscosity resistance, surface tension, and hydrostatic pressure had a non-negligible influence on minor bubbles and still accounted for 10–20% of the total resistance in the later stage but less than 5% in major bubble growth.
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Walsh, C., E. Stride, U. Cheema, and N. Ovenden. "A combined three-dimensional in vitro–in silico approach to modelling bubble dynamics in decompression sickness." Journal of The Royal Society Interface 14, no. 137 (December 2017): 20170653. http://dx.doi.org/10.1098/rsif.2017.0653.
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The growth of bubbles within the body is widely believed to be the cause of decompression sickness (DCS). Dive computer algorithms that aim to prevent DCS by mathematically modelling bubble dynamics and tissue gas kinetics are challenging to validate. This is due to lack of understanding regarding the mechanism(s) leading from bubble formation to DCS. In this work, a biomimetic in vitro tissue phantom and a three-dimensional computational model, comprising a hyperelastic strain-energy density function to model tissue elasticity, were combined to investigate key areas of bubble dynamics. A sensitivity analysis indicated that the diffusion coefficient was the most influential material parameter. Comparison of computational and experimental data revealed the bubble surface's diffusion coefficient to be 30 times smaller than that in the bulk tissue and dependent on the bubble's surface area. The initial size, size distribution and proximity of bubbles within the tissue phantom were also shown to influence their subsequent dynamics highlighting the importance of modelling bubble nucleation and bubble–bubble interactions in order to develop more accurate dive algorithms.
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Tiwari, A., C. Pantano, and J. B. Freund. "Growth-and-collapse dynamics of small bubble clusters near a wall." Journal of Fluid Mechanics 775 (June 16, 2015): 1–23. http://dx.doi.org/10.1017/jfm.2015.287.
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The violent collapse of bubble clusters is thought to damage adjacent material in both engineering and biomedical applications. Yet the complexities of the root mechanisms have restricted theoretical descriptions to significantly simplified configurations. Reduced-physics models based upon either homogenization or arrays of idealized spherical bubbles do reproduce important gross cluster-scale features. However, these models neglect detailed local bubble–bubble interactions, which are expected to mediate damage mechanisms. To describe these bubble-scale interactions, we simulate the expansion and subsequent collapse of a hemispherical cluster of 50 bubbles adjacent to a plane rigid wall, explicitly representing both the asymmetric dynamics of each bubble within the cluster and the compressible-fluid mechanics of bubble–bubble interactions. Results show that the collapse propagates inward, as visualized in experiments, and that geometric focusing generates high impulsive pressures. This gross behaviour is nearly independent of the specific arrangement of bubbles within the cluster and matches predictions from the corresponding particle and homogenized models we consider. The peak pressure in the detailed simulations is associated with the centremost bubble, which causes a corresponding peak pressure on the nearby wall. However, the peak pressures in all cases are a small fraction – over a factor of ten times smaller in many cases – of those predicted in the corresponding reduced models. This is due to the enhanced focusing in the homogeneous model and the spherical constraint on each bubble in the particle models assessed. These would be important factors to consider in any subsequent predictions of wall damage based upon reduced models.
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Michelin, Sébastien, Giacomo Gallino, François Gallaire, and Eric Lauga. "Viscous growth and rebound of a bubble near a rigid surface." Journal of Fluid Mechanics 860 (December 3, 2018): 172–99. http://dx.doi.org/10.1017/jfm.2018.876.
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Motivated by the dynamics of microbubbles near catalytic surfaces in bubble-powered microrockets, we consider theoretically the growth of a free spherical bubble near a flat no-slip surface in a Stokes flow. The flow at the bubble surface is characterised by a constant slip length allowing us to tune the hydrodynamic mobility of its surface and tackle in one formulation both clean and contaminated bubbles as well as rigid shells. Starting with a bubble of infinitesimal size, the fluid flow and hydrodynamic forces on the growing bubble are obtained analytically. We demonstrate that, depending on the value of the bubble slip length relative to the initial distance to the wall, the bubble will either monotonically drain the fluid separating it from the wall, which will exponentially thin, or it will bounce off the surface once before eventually draining the thin film. Clean bubbles are shown to be a singular limit which always monotonically get repelled from the surface. The bouncing events for bubbles with finite slip lengths are further analysed in detail in the lubrication limit. In particular, we identify the origin of the reversal of the hydrodynamic force direction as due to the change in the flow pattern in the film between the bubble and the surface and to the associated lubrication pressure. Last, the final drainage dynamics of the film is observed to follow a universal algebraic scaling for all finite slip lengths.
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Nguyen, Van Luc, Tomohiro Degawa, and Tomomi Uchiyama. "Numerical simulation of the interaction between a vortex ring and a bubble plume." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 9 (September 2, 2019): 3192–224. http://dx.doi.org/10.1108/hff-12-2018-0734.
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Purpose This paper aims to provide discussions of a numerical method for bubbly flows and the interaction between a vortex ring and a bubble plume. Design/methodology/approach Small bubbles are released into quiescent water from a cylinder tip. They rise under the buoyant force, forming a plume. A vortex ring is launched vertically upward into the bubble plume. The interactions between the vortex ring and the bubble plume are numerically simulated using a semi-Lagrangian–Lagrangian approach composed of a vortex-in-cell method for the fluid phase and a Lagrangian description of the gas phase. Findings A vortex ring can transport the bubbles surrounding it over a distance significantly depending on the correlative initial position between the bubbles and the core center. The motion of some bubbles is nearly periodic and gradually extinguishes with time. These bubble trajectories are similar to two-dimensional-helix shapes. The vortex is fragmented into multiple regions with high values of Q, the second invariant of velocity gradient tensor, settling at these regional centers. The entrained bubbles excite a growth rate of the vortex ring's azimuthal instability with a formation of the second- and third-harmonic oscillations of modes of 16 and 24, respectively. Originality/value A semi-Lagrangian–Lagrangian approach is applied to simulate the interactions between a vortex ring and a bubble plume. The simulations provide the detail features of the interactions.
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Wang, Huigang, Chengyu Zhang, and Hongbing Xiong. "Growth and Collapse Dynamics of a Vapor Bubble near or at a Wall." Water 13, no. 1 (December 24, 2020): 12. http://dx.doi.org/10.3390/w13010012.
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This study investigated the dynamics of vapor bubble growth and collapse for a laser-induced bubble. The smoothed particle hydrodynamics (SPH) method was utilized, considering the liquid and vapor phases as the van der Waals (VDW) fluid and the solid wall as a boundary. We compared our numerical results with analytical solutions of bubble density distribution and radius curve slope near a wall and the experimental bubble shape at a wall, which all obtained a fairly good agreement. After validation, nine cases with varying heating distances (L2 to L4) or liquid heights (h2 to h10) were simulated to reproduce bubbles near or at a wall. Average bubble radius, density, vapor mass, velocity, pressure, and temperature during growth and collapse were tracked. A new recognition method based on bubble density was recommended to distinguish the three substages of bubble growth: (a) inertia-controlled, (b) transition, and (c) thermally controlled. A new precollapse substage (Stage (d)) was revealed between the three growth stages and collapse stage (Stage (e)). These five stages were explained from the out-sync between the bubble radius change rate and vapor mass change rate. Further discussions focused on the occurrence of secondary bubbles, shockwave impact on the wall, system entropy change, and energy conversion. The main differences between bubbles near and at the wall were finally concluded.
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TOMITA, Y., P. B. ROBINSON, R. P. TONG, and J. R. BLAKE. "Growth and collapse of cavitation bubbles near a curved rigid boundary." Journal of Fluid Mechanics 466 (September 10, 2002): 259–83. http://dx.doi.org/10.1017/s0022112002001209.
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Laser-induced cavitation bubbles near a curved rigid boundary are observed experimentally using high-speed photography. An image theory is applied to obtain information on global bubble motion while a boundary integral method is employed to gain a more detailed understanding of the behaviour of a liquid jet that threads a collapsing bubble, creating a toroidal bubble. Comparisons between the theory and experiment show that when a comparable sized bubble is located near a rigid boundary the bubble motion is significantly influenced by the surface curvature of the boundary, which is characterized by a parameter ζ, giving convex walls for ζ < 1, concave walls for ζ > 1 and a flat wall when ζ = 1. If a boundary is slightly concave, the most pronounced migration occurs at the first bubble collapse. The velocity of a liquid jet impacting on the far side of the bubble surface tends to increase with decreasing parameter ζ. In the case of a convex boundary, the jet velocity is larger than that generated in the flat boundary case. Although the situation considered here is restricted to axisymmetric motion without mean flow, this result suggests that higher pressures can occur when cavitation bubbles collapse near a non-flat boundary. Bubble separation, including the pinch-off phenomenon, is observed in the final stage of the collapse of a bubble, with the oblate shape at its maximum volume attached to the surface of a convex boundary, followed by bubble splitting which is responsible for further bubble proliferation.
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Foster, Philip P., Alan H. Feiveson, Roland Glowinski, Michael Izygon, and Aladin M. Boriek. "A model for influence of exercise on formation and growth of tissue bubbles during altitude decompression." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 279, no. 6 (December 1, 2000): R2304—R2316. http://dx.doi.org/10.1152/ajpregu.2000.279.6.r2304.
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In response to exercise performed before or after altitude decompression, physiological changes are suspected to affect the formation and growth of decompression bubbles. We hypothesized that the work to change the size of a bubble is done by gas pressure gradients in a macro- and microsystem of thermodynamic forces and that the number of bubbles formed through time follows a Poisson process. We modeled the influence of tissue O2 consumption on bubble dynamics in the O2transport system in series against resistances, from the alveolus to the microsystem containing the bubble and its surrounding tissue shell. Realistic simulations of experimental decompression procedures typical of actual extravehicular activities were obtained. Results suggest that exercise-induced elevation of O2 consumption at altitude leads to bubble persistence in tissues. At the same time, exercise-enhanced perfusion leads to an overall suppression of bubble growth. The total volume of bubbles would be reduced unless increased tissue motion simultaneously raises the rate of bubble formation through cavitation processes, thus maintaining or increasing total bubble volume, despite the exercise.
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Yao, Shun, Yichong Chen, Yijie Ling, Dongdong Hu, Zhenhao Xi, and Ling Zhao. "Analysis of Bubble Growth in Supercritical CO2 Extrusion Foaming Polyethylene Terephthalate Process Based on Dynamic Flow Simulation." Polymers 13, no. 16 (August 20, 2021): 2799. http://dx.doi.org/10.3390/polym13162799.
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Bubble growth in the polymer extrusion foaming process occurs under a dynamic melt flow. For non-Newtonian fluids, this work successfully coupled the dynamic melt flow simulation with the bubble growth model to realize bubble growth predictions in an extrusion flow. The initial thermophysical properties and dynamic rheological property distribution at the cross section of the die exit were calculated based on the finite element method. It was found that dynamic rheological properties provided a necessary solution for predicting bubble growth during the supercritical CO2 polyethylene terephthalate (PET) extrusion foaming process. The introduction of initial melt stress could effectively inhibit the rapid growth of bubbles and reduce the stable size of bubbles. However, the initial melt stress was ignored in previous work involving bubble growth predictions because it was not available. The simulation results based on the above theoretical model were consistent with the evolution trends of cell morphology and agreed well with the actual experimental results.
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Chen, Rouxi, Yuqin Wan, Na Si, Ji-Huan He, Frank Ko, and Shu-Qiang Wang. "Bubble rupture in bubble electrospinning." Thermal Science 19, no. 4 (2015): 1141–49. http://dx.doi.org/10.2298/tsci1504141c.
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As the distinctive properties and different applications of nanofibers, the demand of nanofibers increased sharply in recently years. Bubble electrospinning is one of the most effective and industrialized methods for nanofiber production. To optimize the set-up of bubble electrospinning and improve its mass production, the dynamic properties of un-charged and charged bubbles are studied experimentally, the growth and rupture process of a bubble are also discussed in this paper.
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Maria, Naomi Sta, and David M. Eckmann. "Model Predictions of Gas Embolism Growth and Reabsorption during Xenon Anesthesia." Anesthesiology 99, no. 3 (September 1, 2003): 638–45. http://dx.doi.org/10.1097/00000542-200309000-00019.
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Background It is not readily obvious whether an intravascular bubble will grow or shrink in a particular tissue bed. This depends on the constituent gases initially present in the bubble, the surrounding tissue, and the delivered gas admixture. The authors used a computational model based on the physics of gas exchange to predict cerebrovascular embolism behavior during xenon anesthesia. Methods The authors estimated values of gas transport parameters missing from the literature. The computational model was used with those parameters to predict bubble size over time for a range of temperatures (18 degrees -39 degrees C) used during extracorporeal circulation. Results Bubble size over time is highly nonlinearly dependent on multiple factors, including diffusivity, solubility, gas partial pressures, magnitude of concentration gradients, vessel diameter, and temperature. Xenon- and oxygen-containing bubbles continue to grow during xenon delivery. Bubble volume doubles from 50 to 100 nl in approximately 3-68 min, depending on initial gas composition and bubble shape. Bubble growth and reabsorption are relatively insensitive to temperature in the physiologic and surgical range. Conclusions Xenon anesthesia results in gas exchange conditions that favor bubble growth, which may worsen neurologic injury from gas embolism. The concentration gradients can be manipulated by discontinuation of xenon delivery to promote reabsorption of xenon-containing bubbles. Estimated growth and reabsorption rates at normothermia can be applied to temperature extremes of cardiopulmonary bypass.
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Stanic, Nikolina, and Espen Sandnes. "Bubble Behavior on Horizontal and Vertical Carbon Anode Surfaces in Cryolite Melt Applying a See-Through Cell." Materials Proceedings 3, no. 1 (February 18, 2021): 8. http://dx.doi.org/10.3390/iec2m-09238.
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Gas bubble behavior on a carbon anode in a cryolite melt has been studied by visual observation using a see-through cell. The bubble phenomena studied have included growth, coalescence, and detachment during electrolysis. Two different anode designs were tested, an anode with a horizontal facing-downwards surface and an anode with a vertical surface. At the horizontal anode, it was found that one large bubble was formed by the growth and coalescence of smaller bubbles, and finally, the large bubble detached periodically. For the vertical anode surface, many smaller bubbles were formed and detached randomly. The bubble diameter was decreasing with increasing current density for both anodes.
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Chu, Jie, and Xiaofei Xu. "Bubble Growth in Poly(methyl methacrylate) and Carbon Dioxide Mixture." Polymers 11, no. 4 (April 9, 2019): 648. http://dx.doi.org/10.3390/polym11040648.
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In this paper, we study bubble nucleation and growth in a poly(methyl methacrylate) and CO 2 mixture by molecular dynamics simulations. It is known in the foaming industry that the bubble size has a more uniform distribution with a higher start-up pressure. The real physical reason remains unclear. In this work, we found that the free volume-rich polymer segments could adsorb many small-size bubbles in the region close to the polymer chain. The existence of these small bubbles limits the number of free CO 2 molecules, which is helpful for bubble stabilization. Moreover, the free volume of polymer segments decreases with an increase of the start-up pressure. As a result, the size of the large bubbles becomes more uniform with a higher startup pressure.
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Wang, Yuliang, Mikhail E. Zaytsev, Guillaume Lajoinie, Hai Le The, Jan C. T. Eijkel, Albert van den Berg, Michel Versluis, et al. "Giant and explosive plasmonic bubbles by delayed nucleation." Proceedings of the National Academy of Sciences 115, no. 30 (July 11, 2018): 7676–81. http://dx.doi.org/10.1073/pnas.1805912115.
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When illuminated by a laser, plasmonic nanoparticles immersed in water can very quickly and strongly heat up, leading to the nucleation of so-called plasmonic vapor bubbles. While the long-time behavior of such bubbles has been well-studied, here, using ultrahigh-speed imaging, we reveal the nucleation and early life phase of these bubbles. After some delay time from the beginning of the illumination, a giant bubble explosively grows, and collapses again within 200 μs (bubble life phase 1). The maximal bubble volume Vmax remarkably increases with decreasing laser power, leading to less total dumped energy E. This dumped energy shows a universal linear scaling relation with Vmax, irrespective of the gas concentration of the surrounding water. This finding supports that the initial giant bubble is a pure vapor bubble. In contrast, the delay time does depend on the gas concentration of the water, as gas pockets in the water facilitate an earlier vapor bubble nucleation, which leads to smaller delay times and lower bubble nucleation temperatures. After the collapse of the initial giant bubbles, first, much smaller oscillating bubbles form out of the remaining gas nuclei (bubble life phase 2). Subsequently, the known vaporization dominated growth phase takes over, and the bubble stabilizes (life phase 3). In the final life phase 4, the bubble slowly grows by gas expelling due to heating of the surrounding. Our findings on the explosive growth and collapse during the early life phase of a plasmonic vapor bubble have strong bearings on possible applications of such bubbles.
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Moreno Soto, Álvaro, Oscar R. Enríquez, Andrea Prosperetti, Detlef Lohse, and Devaraj van der Meer. "Transition to convection in single bubble diffusive growth." Journal of Fluid Mechanics 871 (May 20, 2019): 332–49. http://dx.doi.org/10.1017/jfm.2019.276.
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We investigate the growth of gas bubbles in a water solution at rest with a supersaturation level that is generally associated with diffusive mass transfer. For $\text{CO}_{2}$ bubbles, it has been previously observed that, after some time of growing in a diffusive regime, a density-driven convective flow enhances the mass transfer rate into the bubble. This is due to the lower density of the gas-depleted liquid which surrounds the bubble. In this work, we report on experiments with different supersaturation values, measuring the time $t_{conv}$ it takes for convection to dominate over the diffusion-driven growth. We demonstrate that by considering buoyancy and drag forces on the depleted liquid around the bubble, we can satisfactorily predict the transition time. In fact, our analysis shows that this onset does not only depend on the supersaturation, but also on the absolute pressure, which we corroborate in experiments. Subsequently, we study how the depletion caused by the growth of successive single bubbles influences the onset of convection. Finally, we study the convection onset around diffusively growing nitrogen $\text{N}_{2}$ bubbles. As $\text{N}_{2}$ is much less soluble in water, the growth takes much longer. However, after waiting long enough and consistent with our theory, convection still occurs as for any gas–liquid combination, provided that the density of the solution sufficiently changes with the gas concentration.
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Sato, K. "Occurrence of Bubbles in a Thin Wire at Low Reynolds Number." Journal of Fluids Engineering 114, no. 2 (June 1, 1992): 255–60. http://dx.doi.org/10.1115/1.2910024.
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Thin wires of various diameters from 0.07 to 0.7 mm are examined about appearances and characteristics of bubble occurrence behind them in the range of low Reynolds numbers. The appearance of bubbles is very dependent on diameters of wires. Two different types of bubbles can be observed in the present experiment. One is a streamer-type bubble for smaller wires and the other is a small unspherical bubble for larger wires. The incipient and the desinent values of cavitation number also change greatly with the bubble types. The streamer-type bubble is related to the presence of laminar separation zone and the growth due to air diffusion. The small unspherical bubble can be mainly attributed to the motion of rolled-up vortices and the growth due to vaporization.
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Moreno Soto, Álvaro, Andrea Prosperetti, Detlef Lohse, and Devaraj van der Meer. "Gas depletion through single gas bubble diffusive growth and its effect on subsequent bubbles." Journal of Fluid Mechanics 831 (October 13, 2017): 474–90. http://dx.doi.org/10.1017/jfm.2017.623.
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When a gas bubble grows by diffusion in a gas–liquid solution, it affects the distribution of gas in its surroundings. If the density of the solution is sensitive to the local amount of dissolved gas, there is the potential for the onset of natural convection, which will affect the bubble growth rate. The experimental study of the successive quasi-static growth of many bubbles from the same nucleation site described in this paper illustrates some consequences of this effect. The enhanced growth due to convection causes a local depletion of dissolved gas in the neighbourhood of each bubble beyond that due to pure diffusion. The quantitative data of sequential bubble growth provided in the paper show that the radius-versus-time curves of subsequent bubbles differ from each other due to this phenomenon. A simplified model accounting for the local depletion is able to collapse the experimental curves and to predict the progressively increasing bubble detachment times.
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den Brok, Bas, Cees Passchier, and Michel Sieber. "Fibre growth in wet salt aggregates in a temperature gradient field." Mineralogical Magazine 62, no. 04 (August 1998): 527–32. http://dx.doi.org/10.1180/002646198547792.
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Abstract Intense fibrosity develops in wet porous NaCl crystal aggregates (grain size 250–500 µm) held in a temperature (T) gradient field (0.5–4°C/mm) at temperatures between 20 and 50–60°C. In situ microscopic observation of the process shows that fibre growth is associated with T-gradient driven motion of tiny gas (air, water vapour) bubbles present in the saturated intercrystalline aqueous NaCl solution. Gas bubbles move through the intercrystalline pore fluid into the cold direction. They only move if they are next to an NaCl crystal; bubbles that are ‘free’ do not move. Each bubble is ‘pushed’ into the cold direction by a growing crystal fibre of the same diameter as the bubble itself. Fibres apparently grow due to oversaturation of the NaCl solution at the hot side of the gas bubble. Crystals dissolve at the cold side of the gas bubbles, apparently by undersaturation of the NaCl solution there. Thus, bubbles dissolve their way through NaCl-crystals and aggregates. Intense fibrosity develops within weeks.
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Hu, Xiaowei, Liejin Guo, and Yechun Wang. "In Situ Measurement of Local Hydrogen Production Rate by Bubble-Evolved Recording." International Journal of Photoenergy 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/568206.
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Hydrogen visibly bubbles during photocatalytic water splitting under illumination with above-bandgap radiation, which provides a direct measurement of local gas-evolving reaction rate. In this paper, optical microscopy of superfield depth was used for recording the hydrogen bubble growth on Cd0.5Zn0.5S photocatalyst in reaction liquid and illuminated with purple light. By analyzing change of hydrogen bubble size as a function of time, we understood that hydrogen bubble growth experienced two periods, which were inertia effect dominated period and diffusion effect dominated period, respectively. The tendency of hydrogen bubble growth was similar to that of the gas bubble in boiling, while the difference in bubble diameter and growth time magnitude was great. Meanwhile, we obtained the local hydrogen production rate on photocatalyst active site by measuring hydrogen bubble growth variation characteristics. This method makes it possible to confirm local actual hydrogen evolution rate quantitatively during photocatalytic water splitting.
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CHOI, JAEHYUG, and STEVEN L. CECCIO. "Dynamics and noise emission of vortex cavitation bubbles." Journal of Fluid Mechanics 575 (March 2007): 1–26. http://dx.doi.org/10.1017/s0022112006003776.
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The growth and collapse of a cavitation bubble forming within the core of a line vortex was examined experimentally to determine how the dynamics and noise emission of the elongated cavitation bubble is influenced by the underlying non-cavitating vortex properties. A steady line vortex was formed downstream of a hydrofoil mounted in the test section of a recirculating water channel. A focused pulse of laser light was used to initiate a nucleus in the core of a vortex, allowing for the detailed examination of the growth, splitting and collapse of individual cavitation bubbles as they experience a reduction and recovery of the local static pressure. Images of single-bubble dynamics were captured with two pulse-synchronized high-speed video cameras. The shape and dynamics of single vortex cavitation bubbles are compared to the original vortex properties and the local static pressure in the vortex core, and an analysis was performed to understand the relationship between the non-cavitating vortex properties and the diameter of the elongated cavitation bubble. Acoustic emissions from the bubbles were detected during growing, splitting and collapse, revealing that the acoustic impulse created during collapse was four orders of magnitude higher than the noise emission due to growth and splitting. The dynamics and noise generation of the elongated bubbles are compared to that of spherical cavitation bubbles in quiescent flow. These data indicate that the core size and circulation are insufficient to scale the developed vortex cavitation. The non-cavitating vortex circulation and core size are not sufficient to scale the bubble dynamics, even though the single-phase pressure field is uniquely scaled by these parameters. A simple analytical model of the equilibrium state of the elongated cavitation bubble suggests that there are multiple possible equilibrium values of the elongated bubble radius, each with varying tangential velocities at the bubble interface. Thus, the details of the bubble dynamics and bubble–flow interactions will set the final bubble dimensions.
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Van Liew, Hugh D., and Soumya Raychaudhuri. "Stabilized bubbles in the body: pressure-radius relationships and the limits to stabilization." Journal of Applied Physiology 82, no. 6 (June 1, 1997): 2045–53. http://dx.doi.org/10.1152/jappl.1997.82.6.2045.
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Van Liew, Hugh D., and Soumya Raychaudhuri. Stabilized bubbles in the body: pressure-radius relationships and the limits to stabilization. J. Appl. Physiol.82(6): 2045–2053, 1997.—We previously outlined the fundamental principles that govern behavior of stabilized bubbles, such as the microbubbles being put forward as ultrasound contrast agents. Our present goals are to develop the idea that there are limits to the stabilization and to provide a conceptual framework for comparison of bubbles stabilized by different mechanisms. Gases diffuse in or out of stabilized bubbles in a limited and reversible manner in response to changes in the environment, but strong growth influences will cause the bubbles to cross a threshold into uncontrolled growth. Also, bubbles stabilized by mechanical structures will be destroyed if outside influences bring them below a critical small size. The in vivo behavior of different kinds of stabilized bubbles can be compared by using plots of bubble radius as a function of forces that affect diffusion of gases in or out of the bubble. The two ends of the plot are the limits for unstabilized growth and destruction; these and the curve’s slope predict the bubble’s practical usefulness for ultrasonic imaging or O2 carriage to tissues.
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Lü, M., Z. Ning, K. Yan, J. Fu, and C. H. Sun. "Numerical Simulation of Cavitation Bubble Growth within a Droplet." Journal of Mechanics 32, no. 2 (July 15, 2015): 211–17. http://dx.doi.org/10.1017/jmech.2015.57.
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ABSTRACTCavitation bubbles, which always exist in the diesel jet leaving the nozzle and in diesel droplets breaking up from the jet as a result of supercavitation of the diesel within the injection nozzle, increase the instability of jet and droplets in part due to the two-phase mixture, while the mechanism of this effect is still unclear. Cavitation bubble expansion within the diesel droplet has been simulated numerically based on the volume of fluid (VOF) method, and the control mechanism of bubble growth process is analyzed by Rayleigh-Plesset equation. The process of bubble growth is divided into three parts, including surface tension controlled domain, comprehensive competition controlled domain and inertial force controlled domain. During the first stage, cavitation bubble growth is controlled by the surface tension, and the decrease of the surface tension leads to the increase of the bubble growth rate. During the second stage, the bubble growth rate is controlled by the comprehensive competition of the surface tension, the inertial force and the viscous force. During the third stage, the process of bubble growth is majorly controlled by the inertial force.
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Miller, R. S. "Photographic Observations of Bubble Formation in Flashing Nozzle Flow." Journal of Heat Transfer 107, no. 4 (November 1, 1985): 750–55. http://dx.doi.org/10.1115/1.3247500.
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Visual observations have been made of bubble growth in the nucleation region of flashing flow of initially subcooled water in a converging-diverging nozzle. Experiments performed under various flow rates, saturation temperatures, turbulence levels, noncondensable gas content, and artificial nucleation sites failed to produce isolated spherical bubbles of the size or density predicted by common bubble nucleation and growth models. Heterogeneous nucleation in the bulk flow was never observed and it is concluded from bubble growth rates that the role of convection in the heat and mass transfer environment of the bubbles is an important consideration in the physics of flashing flows near the nucleation region.
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Kendoush, Abdullah Abbas. "Viscous Fluid Displacement by the Growing Bubble." Journal of Heat Transfer 128, no. 1 (July 26, 2005): 100–103. http://dx.doi.org/10.1115/1.2130409.
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Equations were derived for the forces experienced by the growing bubble in displacing the liquid radially. The derivation was based on integrating the viscous dissipation function over the entire surface of the bubble. The resulted equations were applicable to bubbles in boiling and in cavitation. The derived equations were validated by applying them to the heterogeneous nucleation and growth of bubbles from cavities in pool boiling and in cavitation. The derived equations approached asymptotically the familiar equation of heterogeneous nucleation and growth of bubbles.
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Nourhani, Amir, Emil Karshalev, Fernando Soto, and Joseph Wang. "Multigear Bubble Propulsion of Transient Micromotors." Research 2020 (February 21, 2020): 1–9. http://dx.doi.org/10.34133/2020/7823615.
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Transient, chemically powered micromotors are promising biocompatible engines for microrobots. We propose a framework to investigate in detail the dynamics and the underlying mechanisms of bubble propulsion for transient chemically powered micromotors. Our observations on the variations of the micromotor active material and geometry over its lifetime, from initial activation to the final inactive state, indicate different bubble growth and ejection mechanisms that occur stochastically, resulting in time-varying micromotor velocity. We identify three processes of bubble growth and ejection, and in analogy with macroscopic multigear machines, we call each process a gear. Gear 1 refers to bubbles that grow on the micromotor surface before detachment while in Gear 2 bubbles hop out of the micromotor. Gear 3 is similar in nature to Gear 2, but the bubbles are too small to contribute to micromotor motion. We study the characteristics of these gears in terms of bubble size and ejection time, and how they contribute to micromotor displacement. The ability to tailor the shell polarity and hence the bubble growth and ejection and the surrounding fluid flow is demonstrated. Such understanding of the complex multigear bubble propulsion of transient chemical micromotors should guide their future design principles and serve for fine tuning the performance of these micromotors.
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Sarkar, Shahjahan K. A., Piotr M. Machniewski, and Geoffrey M. Evans. "Modelling and Measurement of Bubble Formation and Growth in Electroflotation Processes." Chemical and Process Engineering 34, no. 3 (September 1, 2013): 327–36. http://dx.doi.org/10.2478/cpe-2013-0026.
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Abstract Electroflotation is used in the water treatment industry for the recovery of suspended particles. In this study the bubble formation and release of hydrogen bubbles generated electrolytically from a platinum cathode was investigated. Previously, it was found that both the growth rate and detachment diameter increased with increasing wire diameter. Conversely, current density had little effect on the released bubble size. It was also found that the detached bubbles rapidly increased in volume as they rose through the liquid as a result of decreasing hydrostatic pressure and high levels of dissolved hydrogen gas in the surrounding liquid. The experimental system was computationally modelled using a Lagrangian-Eulerian Discrete Particle approach. It was revealed that desorption of gaseous solutes from the electrolyte solution, other than hydrogen, may have a significant impact on the diameter variation of the formed bubbles. The simulation confirmed that liquid circulation, either forced or induced by the rising bubble plume, influences both the hydrogen supersaturation (concentration) in the neighbourhood of the electrode and the size of the resulting bubbles.
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Randsøe, T., T. M. Kvist, and O. Hyldegaard. "Effect of oxygen and heliox breathing on air bubbles in adipose tissue during 25-kPa altitude exposures." Journal of Applied Physiology 105, no. 5 (November 2008): 1492–97. http://dx.doi.org/10.1152/japplphysiol.90840.2008.
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At altitude, bubbles are known to form and grow in blood and tissues causing altitude decompression sickness. Previous reports indicate that treatment of decompression sickness by means of oxygen breathing at altitude may cause unwanted bubble growth. In this report we visually followed the in vivo changes of micro air bubbles injected into adipose tissue of anesthetized rats at 101.3 kPa (sea level) after which they were decompressed from 101.3 kPa to and held at 25 kPa (10,350 m), during breathing of oxygen or a heliox(34:66) mixture (34% helium and 66% oxygen). Furthermore, bubbles were studied during oxygen breathing preceded by a 3-h period of preoxygenation to eliminate tissue nitrogen before decompression. During oxygen breathing, bubbles grew from 11 to 198 min (mean: 121 min, ±SD 53.4) after which they remained stable or began to shrink slowly. During heliox breathing bubbles grew from 30 to 130 min (mean: 67 min, ±SD 31.0) from which point they stabilized or shrank slowly. No bubbles disappeared during either oxygen or heliox breathing. Preoxygenation followed by continuous oxygen breathing at altitude caused most bubbles to grow from 19 to 179 min (mean: 51 min, ±SD 47.7) after which they started shrinking or remained stable throughout the observation period. Bubble growth time was significantly longer during oxygen breathing compared with heliox breathing and preoxygenated animals. Significantly more bubbles disappeared in preoxygenated animals compared with oxygen and heliox breathing. Preoxygenation enhanced bubble disappearance compared with oxygen and heliox breathing but did not prevent bubble growth. The results indicate that oxygen breathing at 25 kPa promotes air bubble growth in adipose tissue regardless of the tissue nitrogen pressure.
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Randsoe, Thomas, and Ole Hyldegaard. "Effect of oxygen breathing on micro oxygen bubbles in nitrogen-depleted rat adipose tissue at sea level and 25 kPa altitude exposures." Journal of Applied Physiology 113, no. 3 (August 1, 2012): 426–33. http://dx.doi.org/10.1152/japplphysiol.00193.2012.
Full textAbstract:
The standard treatment of altitude decompression sickness (aDCS) caused by nitrogen bubble formation is oxygen breathing and recompression. However, micro air bubbles (containing 79% nitrogen), injected into adipose tissue, grow and stabilize at 25 kPa regardless of continued oxygen breathing and the tissue nitrogen pressure. To quantify the contribution of oxygen to bubble growth at altitude, micro oxygen bubbles (containing 0% nitrogen) were injected into the adipose tissue of rats depleted from nitrogen by means of preoxygenation (fraction of inspired oxygen = 1.0; 100%) and the bubbles studied at 101.3 kPa (sea level) or at 25 kPa altitude exposures during continued oxygen breathing. In keeping with previous observations and bubble kinetic models, we hypothesize that oxygen breathing may contribute to oxygen bubble growth at altitude. Anesthetized rats were exposed to 3 h of oxygen prebreathing at 101.3 kPa (sea level). Micro oxygen bubbles of 500-800 nl were then injected into the exposed abdominal adipose tissue. The oxygen bubbles were studied for up to 3.5 h during continued oxygen breathing at either 101.3 or 25 kPa ambient pressures. At 101.3 kPa, all bubbles shrank consistently until they disappeared from view at a net disappearance rate (0.02 mm2 × min−1) significantly faster than for similar bubbles at 25 kPa altitude (0.01 mm2 × min−1). At 25 kPa, most bubbles initially grew for 2–40 min, after which they shrank and disappeared. Four bubbles did not disappear while at 25 kPa. The results support bubble kinetic models based on Fick's first law of diffusion, Boyles law, and the oxygen window effect, predicting that oxygen contributes more to bubble volume and growth during hypobaric conditions. As the effect of oxygen increases, the lower the ambient pressure. The results indicate that recompression is instrumental in the treatment of aDCS.
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Boziuk, Thomas R., Marc K. Smith, and Ari Glezer. "Dynamics of vapor bubble condensation under directional ultrasonic actuation." Physics of Fluids 35, no. 1 (January 2023): 017126. http://dx.doi.org/10.1063/5.0134326.
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Direct-contact condensation of vapor bubbles injected into a subcooled liquid is enhanced using ultrasonic O(1 MHz) acoustic actuation. In the absence of actuation, the surface tension-driven pinch-off process of the vapor bubble from the injection orifice induces a liquid spear that travels upward through the bubble and ruptures the top interface to form a toroidal bubble. Similarly, the acoustic actuator produces a narrow high-intensity acoustic beam that deforms the top interface of the vapor bubble via radiation pressure to form a liquid spear that travels downward though the bubble and ruptures the bottom interface to form a toroidal bubble. Comparisons between the growth and collapse of vapor bubbles in these two cases were performed using high-speed video imaging and particle image velocimetry. The results show that the actuated bubble collapsed about 35% faster than the unactuated bubble. The flow fields around the bubbles induced by the motion of the liquid spears are similar in both cases. By comparing vapor bubbles under different subcooling conditions with an unactuated, noncondensing air bubble, it was shown that condensation at the liquid–vapor interface strongly influences bubble collapse times and the velocity field surrounding each of the bubbles and that these effects increase as the level of subcooling increases.
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Kolomietz, V. M. "Bubble instability in overheated liquid Helium-3." Modern Physics Letters B 28, no. 28 (November 10, 2014): 1450221. http://dx.doi.org/10.1142/s0217984914502212.
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The generation and the growth of vapor bubbles in metastable liquid Helium-3 are studied. The finite diffuse layer of vapor bubble, the temperature dependence of the surface tension and the relaxation processes are taken into consideration. We show that the growth of bubble in overheated liquid Helium-3 is significantly influenced by the memory effects caused by the dynamic Fermi-surface distortions. In particular, the increase of bubble is strongly hindered and accompanied by the characteristic oscillations of the bubble radius. The oscillations of the bubble radius disappear in a short relaxation-time limit where the memory effects are negligible.
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Liascukiene, Irma, Gabriel Amselem, Jessem Landoulsi, Deniz Z. Gunes, and Charles N. Baroud. "Intermittent dynamics of bubble dissolution due to interfacial growth of fat crystals." Soft Matter 17, no. 44 (2021): 10042–52. http://dx.doi.org/10.1039/d1sm00902h.
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Mohammadein, S. A., and A. F. Abu-Bakr. "The growth of vapour bubble in a superheated liquid between two phase turbulent flow." Canadian Journal of Physics 88, no. 5 (May 2010): 317–24. http://dx.doi.org/10.1139/p10-022.
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In this paper, the growth of a vapour bubble in superheated water for two-phase turbulent flow is studied. The growth problem is formulated by mass and momentum equations under physical assumptions between two finite boundaries. The analytical solution is obtained in terms of the vapour bubble radius. The bubbly growth is affected by thermal diffusivity, superheating, and the Péclet number. The fact that the scale of the bubble is larger than the scale of the turbulence in the mixture surrounding the growing bubble is considered. The previous models of growth for laminar flow are obtained as a special cases of the present model for some values of the parameters a, b, n, and φ0, respectively.
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Randsoe, T., and O. Hyldegaard. "Effect of oxygen breathing and perfluorocarbon emulsion treatment on air bubbles in adipose tissue during decompression sickness." Journal of Applied Physiology 107, no. 6 (December 2009): 1857–63. http://dx.doi.org/10.1152/japplphysiol.00785.2009.
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Decompression sickness (DCS) after air diving has been treated with success by means of combined normobaric oxygen breathing and intravascular perfluorocarbon (PFC) emulsions causing increased survival rate and faster bubble clearance from the intravascular compartment. The beneficial PFC effect has been explained by the increased transport capacity of oxygen and inert gases in blood. However, previous reports have shown that extravascular bubbles in lipid tissue of rats suffering from DCS will initially grow during oxygen breathing at normobaric conditions. We hypothesize that the combined effect of normobaric oxygen breathing and intravascular PFC infusion could lead to either enhanced extravascular bubble growth on decompression due to the increased oxygen supply, or that PFC infusion could lead to faster bubble elimination due to the increased solubility and transport capacity in blood for nitrogen causing faster nitrogen tissue desaturation. In anesthetized rats decompressed from a 60-min hyperbaric exposure breathing air at 385 kPa, we visually followed the resolution of micro-air bubbles injected into abdominal adipose tissue while the rats breathed either air, oxygen, or oxygen breathing combined with PFC infusion. All bubble observations were done at 101.3 kPa pressure. During oxygen breathing with or without combined PFC infusion, bubbles disappeared faster compared with air breathing. Combined oxygen breathing and PFC infusion caused faster bubble disappearance compared with oxygen breathing. The combined effect of oxygen breathing and PFC infusion neither prevented nor increased transient bubble growth time, rate, or growth ratio compared with oxygen breathing alone. We conclude that oxygen breathing in combination with PFC infusion causes faster bubble disappearance and does not exacerbate transient bubble growth. PFC infusion may be a valuable adjunct therapy during the first-aid treatment of DCS at normobaric conditions.
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Brondi, Cosimo, Mercedes Santiago-Calvo, Ernesto Di Maio, and Miguel Ángel Rodríguez-Perez. "Role of Air Bubble Inclusion on Polyurethane Reaction Kinetics." Materials 15, no. 9 (April 26, 2022): 3135. http://dx.doi.org/10.3390/ma15093135.
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In this study, we investigated the influence of mixing conditions on the foaming process of water blown polyurethane (PU) foams obtained at different mixing speeds (50, 500, 1000 and 2000 rpm). In particular, the morphological evolution during the foaming process, in terms of the bubble size and bubble density, was studied via optical observations, while the effects on the reaction kinetics were monitored using in situ FTIR spectroscopy. At the slow mixing speed (50 rpm), no air bubbles were included and the early foaming process was characterized by the formation of new bubbles (CO2 nucleation), provided by the blowing reaction. Later on, it was observed that the coalescence affected the overall foaming process, caused by the gelling reaction, which was inhibited by the indigent mixing conditions and could not withstand the bubbles expansion. As a result, a PU foam with a coarse cellular structure and an average bubble size of 173 µm was obtained. In this case, the bubbles degeneration rate, dN/dt, was −3095 bubble·cm−3·s−1. On the contrary, at 500 rpm, air bubbles were included into the PU reaction system (aeration) and no formation of new bubbles was observed during the foaming process. After this, the air bubbles underwent growth caused by diffusion of the CO2 provided by the blowing reaction. As the gelling reaction was not strongly depleted as in the case at 50 rpm, the coalescence less affected the bubble growth (dN/dt = −2654 bubble·cm−3·s−1), leading to a PU foam with an average bubble size of 94 µm. For the foams obtained at 1000 and 2000 rpm, the bubble degeneration was first affected by coalescence and then by Ostwald ripening, and a finer cellular structure was observed (with average bubble sizes of 62 µm and 63 µm for 1000 rpm and 2000 rpm, respectively). During the first foaming stage, the coalescence was less predominant in the bubble growth (with dN/dt values of −1838 bubble·cm−3·s−1 and −1601 bubble·cm−3·s−1, respectively) compared to 50 rpm and 500 rpm. This occurrence was ascribed to the more balanced process between the bubble expansion and the PU polymerization caused by the more suitable mixing conditions. During the late foaming stage, the Ostwald ripening was only responsible for the further bubble degeneration (with dN/dt values of −89 bubble·cm−3·s−1 and −69 bubble·cm−3·s−1, respectively).
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Brondi, Cosimo, Mercedes Santiago-Calvo, Ernesto Di Maio, and Miguel Ángel Rodríguez-Perez. "Role of Air Bubble Inclusion on Polyurethane Reaction Kinetics." Materials 15, no. 9 (April 26, 2022): 3135. http://dx.doi.org/10.3390/ma15093135.
Full textAbstract:
In this study, we investigated the influence of mixing conditions on the foaming process of water blown polyurethane (PU) foams obtained at different mixing speeds (50, 500, 1000 and 2000 rpm). In particular, the morphological evolution during the foaming process, in terms of the bubble size and bubble density, was studied via optical observations, while the effects on the reaction kinetics were monitored using in situ FTIR spectroscopy. At the slow mixing speed (50 rpm), no air bubbles were included and the early foaming process was characterized by the formation of new bubbles (CO2 nucleation), provided by the blowing reaction. Later on, it was observed that the coalescence affected the overall foaming process, caused by the gelling reaction, which was inhibited by the indigent mixing conditions and could not withstand the bubbles expansion. As a result, a PU foam with a coarse cellular structure and an average bubble size of 173 µm was obtained. In this case, the bubbles degeneration rate, dN/dt, was −3095 bubble·cm−3·s−1. On the contrary, at 500 rpm, air bubbles were included into the PU reaction system (aeration) and no formation of new bubbles was observed during the foaming process. After this, the air bubbles underwent growth caused by diffusion of the CO2 provided by the blowing reaction. As the gelling reaction was not strongly depleted as in the case at 50 rpm, the coalescence less affected the bubble growth (dN/dt = −2654 bubble·cm−3·s−1), leading to a PU foam with an average bubble size of 94 µm. For the foams obtained at 1000 and 2000 rpm, the bubble degeneration was first affected by coalescence and then by Ostwald ripening, and a finer cellular structure was observed (with average bubble sizes of 62 µm and 63 µm for 1000 rpm and 2000 rpm, respectively). During the first foaming stage, the coalescence was less predominant in the bubble growth (with dN/dt values of −1838 bubble·cm−3·s−1 and −1601 bubble·cm−3·s−1, respectively) compared to 50 rpm and 500 rpm. This occurrence was ascribed to the more balanced process between the bubble expansion and the PU polymerization caused by the more suitable mixing conditions. During the late foaming stage, the Ostwald ripening was only responsible for the further bubble degeneration (with dN/dt values of −89 bubble·cm−3·s−1 and −69 bubble·cm−3·s−1, respectively).
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Ronshin, F., A. Sielaff, L. Tadrist, P. Stephan, and O. Kabov. "Dynamics of bubble growth during boiling at microgravity." Journal of Physics: Conference Series 2119, no. 1 (December 1, 2021): 012170. http://dx.doi.org/10.1088/1742-6596/2119/1/012170.
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Abstract The purpose of this investigation is to study the mechanisms of boiling heat transfer in microgravity conditions. The RUBI (Reference mUltiscale Boiling Investigation) is an experiment where the basic phenomena of boiling heat transfer processes on a heated surface are investigated on the ISS (International Space Station). The special focus is paid to the coupling of macroscopic bubble dynamics from nucleation, growth and detachment combined with the microscopic phenomena in the thin films and micro layers on the heater, underneath the boiling bubbles. The image treatment program has been developed in order to extract the bubble volume as well as the contact angle from the experimental images. The first data of the bubble growth dynamics have been obtained and analysed.
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Zhang, Yong, Chuanbao Jia, Jianxin Wang, Bo Zhao, and Chuansong Wu. "Investigation on the bubble dynamic behaviors and corresponding regulation method in underwater flux-cored arc welding." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 233, no. 7 (August 13, 2018): 1808–17. http://dx.doi.org/10.1177/0954405418789983.
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Observed two bubble growth modes indicated that the stability of arc burning and bubble growth relied on each other. Under selected welding parameters, the maximum diameters of generated bubbles complied with approximately normal distribution. Higher preset welding parameters generated larger bubbles with gradually receding influences. Vaporization, condensation, and reactions happened rapidly inside the bubbles even after detachment and when coming to water surface. Gas-assisted underwater flux-cored arc welding was proposed to improve the slag coverage. This method was also effective in achieving better weld appearance.
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d’Auria, Fabrizio, Luca d’Agostino, and Christopher E. Brennen. "Dynamic Response of Ducted Bubbly Flows to Turbomachinery-Induced Perturbations." Journal of Fluids Engineering 118, no. 3 (September 1, 1996): 595–601. http://dx.doi.org/10.1115/1.2817800.
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The present work investigates the dynamics of the three-dimensional, unsteady flow of a bubbly mixture in a cylindrical duct subject to a periodic pressure excitation at one end. One of the purposes is to investigate the bubbly or cavitating flow at inlet to or discharge from a pump whose blade motions would provide such excitation. The flow displays various regimes with radically different wave propagation characteristics. The dynamics effects due to the bubble response may radically alter the fluid behavior depending on the void fraction of the bubbly mixture, the mean bubble size, the pipe diameter, the angular speed of the turbomachine and the mean flow Mach number. This simple linearized analysis illustrates the importance of the complex interactions of the dynamics of the bubbles with the average flow, and provides information on the propagation and growth of the turbopump-induced disturbances in the feed lines operating with bubbly or cavitating liquids. Examples are presented to illustrate the influence of the relevant flow parameters. Finally, the limitations of the theory are outlined.
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Manglik, R. M., M. A. Jog, A. Subramani, and K. Gatne. "Mili-Scale Visualization of Bubble Growth-Translation and Droplet Impact Dynamics." Journal of Heat Transfer 128, no. 8 (August 1, 2006): 736. http://dx.doi.org/10.1115/1.2221299.
Full textAbstract:
The dynamic behavior of an air bubble, emanating from a 0.32 mm i.d., 0.64 mm o.d., vertical capillary-tube orifice with a bubble interval of 0.22–0.28 s at constant pressure and adiabatic (T=25°C) conditions, as well as droplet impact and spreading on a hydrophobic surface are characterized. Images of the mili-scale spatial-temporal evolution of bubbles (embryonic appearance at orifice tip → growth and detachment → translation) as well as droplets were acquired using a high-speed (5000 frames/s) digital video camera fitted with a 8× optical zoom lens. It was triggered through a computer interface to record continuous high-speed video from which any desired frame can be captured by digital-video-processing software; the equivalent departure diameter was estimated by area-averaging using image processing software. The impact, spreading, and recoil behaviors of ethanol and water droplets on a horizontal stainless steel surface are depicted in Fig. 1. For constant Weber number (We∼10), the spreading and recoil dynamics in the two cases are significantly different. Higher wettability of ethanol promotes greater spreading and dampens recoil in comparison with that seen in water. Figure 2 depicts the growth of an air bubble in pools of ethanol and water. While displaying similar ebullience, a bubble of smaller size and surface age is produced in low-surface-tension ethanol. Dynamic shape variations of the air bubble as it translates upwards in the pool are seen in Fig. 3. From a nearly spherical, tear-drop bubble, the shape changes to an oblate ellipsoid during translation, and surface tension effects are manifest only in the size of respective bubbles.
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Tanaka, Tomoya, and Keita Ando. "Simulation of Rayleigh Bubble Growth near a No-Slip Rigid Wall." Solid State Phenomena 314 (February 2021): 192–96. http://dx.doi.org/10.4028/www.scientific.net/ssp.314.192.
Full textAbstract:
In order to study the role of growing cavitation bubbles in the context of ultrasonic cleaning, we perform two-dimensional, axisymmetric Navier-Stokes simulation for compressible, multicomponent flow and examine the so-called Rayleigh growth of an air bubble (with initial radius 33 µm and pressure 10 MPa) near a rigid wall. The simulation suggests that strong shear stress, which is important in physical cleaning such as particle removal, appears as a result of the bubble-growth-induced shock passage. The parametric study with varying a standoff distance of the bubble to the wall shows that the wall shear stress linearly decreases against the standoff distance.