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Sample records for volume gas bubble

  1. Mathematical model of diffusion-limited gas bubble dynamics in unstirred tissue with finite volume.

    Science.gov (United States)

    Srinivasan, R Srini; Gerth, Wayne A; Powell, Michael R

    2002-02-01

    Models of gas bubble dynamics for studying decompression sickness have been developed by considering the bubble to be immersed in an extravascular tissue with diffusion-limited gas exchange between the bubble and the surrounding unstirred tissue. In previous versions of this two-region model, the tissue volume must be theoretically infinite, which renders the model inapplicable to analysis of bubble growth in a finite-sized tissue. We herein present a new two-region model that is applicable to problems involving finite tissue volumes. By introducing radial deviations to gas tension in the diffusion region surrounding the bubble, the concentration gradient can be zero at a finite distance from the bubble, thus limiting the tissue volume that participates in bubble-tissue gas exchange. It is shown that these deviations account for the effects of heterogeneous perfusion on gas bubble dynamics, and are required for the tissue volume to be finite. The bubble growth results from a difference between the bubble gas pressure and an average gas tension in the surrounding diffusion region that explicitly depends on gas uptake and release by the bubble. For any given decompression, the diffusion region volume must stay above a certain minimum in order to sustain bubble growth.

  2. A MODEL TO ESTIMATE VOLUME CHANGE DUE TO RADIOLYTIC GAS BUBBLES AND THERMAL EXPANSION IN SOLUTION REACTORS

    Energy Technology Data Exchange (ETDEWEB)

    F. SOUTO; A HEGER

    2001-02-01

    Aqueous homogeneous solution reactors have been proposed for the production of medical isotopes. However, the reactivity effects of fuel solution volume change, due to formation of radiolytic gas bubbles and thermal expansion, have to be mitigated to allow steady-state operation of solution reactors. The results of the free run experiments analyzed indicate that the proposed model to estimate the void volume due to radiolytic gas bubbles and thermal expansion in solution reactors can accurately describe the observed behavior during the experiments. This void volume due to radiolytic gas bubbles and fuel solution thermal expansion can then be used in the investigation of reactivity effects in fissile solutions. In addition, these experiments confirm that the radiolytic gas bubbles are formed at a higher temperature than the fuel solution temperature. These experiments also indicate that the mole-weighted average for the radiolytic gas bubbles in uranyl fluoride solutions is about 1 {micro}m. Finally, it should be noted that another model, currently under development, would simulate the power behavior during the transient given the initial fuel solution level and density. The model is based on Monte Carlo simulation with the MCNP computer code [Briesmeister, 1997] to obtain the reactor reactivity as a function of the fuel solution density, which, in turn, changes due to thermal expansion and radiolytic gas bubble formation.

  3. A model to estimate volume change due to radiolytic gas bubbles and thermal expansion in solution reactors

    Energy Technology Data Exchange (ETDEWEB)

    Souto, F.J. [NIS-6: Advanced Nuclear Technology, Los Alamos National Lab., Los Alamos, NM (United States); Heger, A.S. [ESA-EA: Engineering Sciences and Application, Los Alamos National Lab., Los Alamos, NM (United States)

    2001-07-01

    To investigate the effects of radiolytic gas bubbles and thermal expansion on the steady-state operation of solution reactors at the power level required for the production of medical isotopes, a calculational model has been developed. To validate this model, including its principal hypotheses, specific experiments at the Los Alamos National Laboratory SHEBA uranyl fluoride solution reactor were conducted. The following sections describe radiolytic gas generation in solution reactors, the equations to estimate the fuel solution volume change due to radiolytic gas bubbles and thermal expansion, the experiments conducted at SHEBA, and the comparison of experimental results and model calculations. (author)

  4. Structure of nanoscale gas bubbles in metals

    Energy Technology Data Exchange (ETDEWEB)

    Caro, A., E-mail: caro@lanl.gov; Schwen, D.; Martinez, E. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

    2013-11-18

    A usual way to estimate the amount of gas in a bubble inside a metal is to assume thermodynamic equilibrium, i.e., the gas pressure P equals the capillarity force 2γ/R, with γ the surface energy of the host material and R the bubble radius; under this condition there is no driving force for vacancies to be emitted or absorbed by the bubble. In contrast to the common assumption that pressure inside a gas or fluid bubble is constant, we show that at the nanoscale this picture is no longer valid. P and density can no longer be defined as global quantities determined by an equation of state (EOS), but they become functions of position because the bubble develops a core-shell structure. We focus on He in Fe and solve the problem using both continuum mechanics and empirical potentials to find a quantitative measure of this effect. We point to the need of redefining an EOS for nanoscale gas bubbles in metals, which can be obtained via an average pressure inside the bubble. The resulting EOS, which is now size dependent, gives pressures that differ by a factor of two or more from the original EOS for bubble diameters of 1 nm and below.

  5. Gas transfer in a bubbly wake flow

    Science.gov (United States)

    Karn, A.; Gulliver, J. S.; Monson, G. M.; Ellis, C.; Arndt, R. E. A.; Hong, J.

    2016-05-01

    The present work reports simultaneous bubble size and gas transfer measurements in a bubbly wake flow of a hydrofoil, designed to be similar to a hydroturbine blade. Bubble size was measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. A lower gas flow rate, greater liquid velocities, and a larger angle of attack all resulted in an increased number of small size bubbles and a reduced weighted mean bubble size. Bubble-water gas transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for gas transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The coefficient was found to stay constant at a particular hydrofoil configuration while it varied within a narrow range of 0.52-0.60 for different gas/water flow conditions.

  6. Mathematical model of diffusion-limited evolution of multiple gas bubbles in tissue.

    Science.gov (United States)

    Srinivasan, R Srini; Gerth, Wayne A; Powell, Michael R

    2003-04-01

    Models of gas bubble dynamics employed in probabilistic analyses of decompression sickness incidence in man must be theoretically consistent and simple, if they are to yield useful results without requiring excessive computations. They are generally formulated in terms of ordinary differential equations that describe diffusion-limited gas exchange between a gas bubble and the extravascular tissue surrounding it. In our previous model (Ann. Biomed. Eng. 30: 232-246, 2002), we showed that with appropriate representation of sink pressures to account for gas loss or gain due to heterogeneous blood perfusion in the unstirred diffusion region around the bubble, diffusion-limited bubble growth in a tissue of finite volume can be simulated without postulating a boundary layer across which gas flux is discontinuous. However, interactions between two or more bubbles caused by competition for available gas cannot be considered in this model, because the diffusion region has a fixed volume with zero gas flux at its outer boundary. The present work extends the previous model to accommodate interactions among multiple bubbles by allowing the diffusion region volume of each bubble to vary during bubble evolution. For given decompression and tissue volume, bubble growth is sustained only if the bubble number density is below a certain maximum.

  7. Gas bubble dynamics in soft materials.

    Science.gov (United States)

    Solano-Altamirano, J M; Malcolm, John D; Goldman, Saul

    2015-01-01

    Epstein and Plesset's seminal work on the rate of gas bubble dissolution and growth in a simple liquid is generalized to render it applicable to a gas bubble embedded in a soft elastic solid. Both the underlying diffusion equation and the expression for the gas bubble pressure were modified to allow for the non-zero shear modulus of the medium. The extension of the diffusion equation results in a trivial shift (by an additive constant) in the value of the diffusion coefficient, and does not change the form of the rate equations. But the use of a generalized Young-Laplace equation for the bubble pressure resulted in significant differences on the dynamics of bubble dissolution and growth, relative to an inviscid liquid medium. Depending on whether the salient parameters (solute concentration, initial bubble radius, surface tension, and shear modulus) lead to bubble growth or dissolution, the effect of allowing for a non-zero shear modulus in the generalized Young-Laplace equation is to speed up the rate of bubble growth, or to reduce the rate of bubble dissolution, respectively. The relation to previous work on visco-elastic materials is discussed, as is the connection of this work to the problem of Decompression Sickness (specifically, "the bends"). Examples of tissues to which our expressions can be applied are provided. Also, a new phenomenon is predicted whereby, for some parameter values, a bubble can be metastable and persist for long times, or it may grow, when embedded in a homogeneous under-saturated soft elastic medium.

  8. Gas Bubble Growth in Muddy Sediments

    Science.gov (United States)

    2016-06-07

    it is fairly easy to show that R ~ eat (a = S/ρg), i.e. exponential growth , which is a far faster than has been suggested previously. We expect this...Gas Bubble Growth in Muddy Sediments Bernard P. Boudreau Department of Oceanography Dalhousie University Halifax, Nova Scotia B3H 4J1, Canada phone...objective is a working model for the growth of a single, isolated bubble in a marine sediment, validated with bubble growth data obtained in laboratory

  9. Liquid jet pumped by rising gas bubbles

    Science.gov (United States)

    Hussain, N. A.; Siegel, R.

    1975-01-01

    A two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. Bubbles provide a large buoyancy force and the associated drag on the liquid moves the liquid upward. The liquid pumped upward consists of the bubble wakes and the liquid brought into the jet region by turbulent entrainment. The expansion of the gas bubbles as they rise through the liquid is taken into account. The continuity and momentum equations are solved numerically for an axisymmetric air jet submerged in water. Water pumping rates are obtained as a function of air flow rate and depth of submergence. Comparisons are made with limited experimental information in the literature.

  10. Three-dimensional measurement of bubble volume based on dual perspective imaging

    Science.gov (United States)

    Xue, Ting; Zhang, Shao-jie; Wu, Bin

    2017-01-01

    This paper presents a new three-dimensional (3D) volume measurement approach of bubble in gas-liquid two-phase flow. According to the dual perspective imaging principle, bubble feature images can be captured from two different view angles. The least square ellipse fitting algorithm is used to figure out the feature parameters from the captured images. Then the 3D volume of bubble can be quantitatively measured. Compaerd with the traditional volume estimation methods based on single perspective imaging, it can effectively reduce the loss of bubble feature information. In the experiment, the 3D volume reconstruction of bubbles from dual perspective images is conducted, and the variation of bubble volume in the bubble rising process is studied. The results show that the measurement accuracy based on the proposed 3D method is higher than those based on traditional methods. The volume of rising bubble is periodically changed, which indicates that bubble achieves periodic rotation and deformation in the rising process.

  11. Bubbling behaviors induced by gas-liquid mixture permeating through a porous medium

    Science.gov (United States)

    Hu, Liang; Li, Mingbo; Chen, Wenyu; Xie, Haibo; Fu, Xin

    2016-08-01

    This paper investigates the bubbling behaviors induced by gas-liquid mixture permeating through porous medium (PM), which was observed in developing immersion lithography system and was found having great differences with traditional bubbling behaviors injected with only gas phase through the PM. An experimental setup was built up to investigate the bubbling characteristics affected by the mixed liquid phase. Both the flow regimes of gas-liquid mixture in micro-channel (upstream of the PM) and the bubbling flow regimes in water tank (downstream of the PM) were recorded synchronously by high-speed camera. The transitions between the flow regimes are governed by gas and liquid Weber numbers. Based on the image analysis, the characteristic parameters of bubbling region, including the diameter of bubbling area on PM surface, gas-phase volume flux, and dispersion angle of bubbles in suspending liquid, were studied under different proportions of gas and liquid flow rate. Corresponding empirical correlations were developed to describe and predict these parameters. Then, the pertinent bubble characteristics in different bubbling flow regimes were systematically investigated. Specifically, the bubble size distribution and the Sauter mean diameter affected by increasing liquid flow rate were studied, and the corresponding analysis was given based on the hydrodynamics of bubble-bubble and bubble-liquid interactions. According to dimensionless analysis, the general prediction equation of Sauter mean diameter under different operating conditions was proposed and confirmed by experimental data. The study of this paper is helpful to improve the collection performance of immersion lithography and aims to reveal the differences between the bubbling behaviors on PM caused by only gas flow and gas-liquid mixture flow, respectively, for the researches of fluid flow.

  12. Dynamic behavior of gas bubble in single bubble sonoluminescence - vibrator model

    Institute of Scientific and Technical Information of China (English)

    QIAN Menglu; CHENG Qian; GE Caoyan

    2002-01-01

    Single bubble sonoluminescence is a process of energy transformation from soundto light. Therefore the motion equations of near spherical vibration of a gas bubble in anincompressible and viscous liquid can be deduced by Lagrangian Equation with dissipationfunction when the bubble is considered as a vibrator surrounded by liquid. The analyticalsolutions in the bubble expanding, collapsing and rebounding stages can be obtained by solvingthese motion equations when some approximations are adopted. And the dynamic behaviorsof the bubble in these three stages are discussed.

  13. Gas Holdups of Small and Large Bubbles in a Large-scale Bubble Column with Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    JIN Hai-bo; YANG Suo-he; ZHANG Tong-wang; TONG Ze-min

    2004-01-01

    Gas holdups of large bubbles and small bubbles were measured by means of dynamic gas disengagement approach in the pressured bubble column with a diameter of 0. 3 m and a height of 6. 6 m. The effects of superficial gas velocity, liquid surface tension, liquid viscosity andsystem pressure on gas holdups of small bubbles and large bubbles were investigated. The holdup of large bubbles increases and the holdup of small bubbles decreases with an increase of liquid viscosity. Meanwhile, the holdup of large bubbles decreases with increasing the system pressure. A correlation for the holdup of small bubbles was obtained from the experimental data.

  14. Rise characteristics of gas bubbles in a 2D rectangular column: VOF simulations vs experiments

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, R.; Baten, J.M. van

    1999-10-01

    About five centuries ago, Leonardo da Vinci described the sinuous motion of gas bubbles rising in water. The authors have attempted to simulate the rise trajectories of bubbles of 4, 5, 7, 8, 9, 12, and 20 mm in diameter rising in a 2D rectangular column filled with water. The simulations were carried out using the volume-of-fluid (VOF) technique developed by Hirt and Nichols (J. Computational Physics, 39, 201--225 (1981)). To solve the Navier-Stokes equations of motion the authors used a commercial solver, CFX 4.1c of AEA Technology, UK. They developed their own bubble-tracking algorithm to capture sinuous bubble motions. The 4 and 5 mm bubbles show large lateral motions observed by Da Vinci. The 7, 8 and 9 mm bubble behave like jellyfish. The 12 mm bubble flaps its wings like a bird. The extent of lateral motion of the bubbles decreases with increasing bubble size. Bubbles larger than 20 mm in size assume a spherical cap form and simulations of the rise characteristics match experiments exactly. VOF simulations are powerful tools for a priori determination of the morphology and rise characteristics of bubbles rising in a liquid. Bubble-bubble interactions are also properly modeled by the VOF technique.

  15. Effect of gas expansion on the front shape of a Taylor bubble: an experimental contribution

    Directory of Open Access Journals (Sweden)

    Santos Laura

    2014-03-01

    Full Text Available An experimental study where an individual Taylor bubble rises through water with different bubble volume expansion rates is presented with the (front bubble shape determination as main objective. A combination of two techniques, Particle Image Velocimetry (PIV and Pulsed Shadowgraphy (PS, was used to collect images for further treatment in order to characterize the liquid flow pattern in front of the bubble and the bubble shape. Processing the images acquired with pulsed illumination from behind the bubble it was possible to define with precision the bubble shape at different stages when it was expanding. The operation conditions used allowed a wide range of volume expansion rates (0 to 28.5 × 10-6 m3/s with a significant effect on the Taylor bubble velocity; increases in bubble velocity up to 21% were observed relatively to constant volume system condition. Nevertheless, it seems that the front shape of Taylor bubbles does not change significantly with the upward liquid flow rates induced by gas expansion, at least for the volume expansion rates used in the experiments.

  16. Suppression of cavitation inception by gas bubble injection: a numerical study focusing on bubble-bubble interaction.

    Science.gov (United States)

    Ida, Masato; Naoe, Takashi; Futakawa, Masatoshi

    2007-10-01

    The dynamic behavior of cavitation and gas bubbles under negative pressure has been studied numerically to evaluate the effect of gas bubble injection into a liquid on the suppression of cavitation inception. In our previous studies, it was demonstrated by direct observation that cavitation occurs in liquid mercury when mechanical impacts are imposed, and this will cause cavitation damage in spallation neutron sources, in which liquid mercury is bombarded by a high-power proton beam. In the present paper, we describe numerical investigations of the dynamics of cavitation bubbles in liquid mercury using a multibubble model that takes into account the interaction of a cavitation bubble with preexisting gas bubbles through bubble-radiated pressure waves. The numerical results suggest that, if the mercury includes gas bubbles whose equilibrium radius is much larger than that of the cavitation bubble, the explosive expansion of the cavitation bubble (i.e., cavitation inception) is suppressed by the positive-pressure wave radiated by the injected bubbles, which decreases the magnitude of the negative pressure in the mercury.

  17. Parameters Relevant to Bubble Detachment when Gas-injecting into Polymer Melt Flow Field

    Institute of Scientific and Technical Information of China (English)

    CHEN Zailiang; CAI Yebin; GUO Mingcheng; PENG Yucheng

    2005-01-01

    The bubble deformation processes were reported when gas was injected into polymer melt flow field in another paper, the experiments showed that the deformation was severely affected by the volume of the bubble, and in turn, for the different bubbles, several different deformation processes were presented during their movement along the flow channel. In addition, we could find that the magnitude of the bubble volume was dependent upon the pressure difference of the gas injection pressure and the melt pressure. In this paper, more experimental conditions were changed to investigate the parameters relevant to the detachment of bubbles from the injection nozzle. The experimental results show that the pressure difference, the melt flow velocity as well as the melt pressure were all critical for the parameters, such as the bubble detachment time, the maximum bubble diameters and the magnitude of the bubble volume. The morphology changes of bubble were very large when the flow field was abruptly changed, and the situations were more complicated.

  18. A Study of Three Dimensional Bubble Velocities at Co-current Gas-liquid Vertical Upward Bubbly Flows

    CERN Document Server

    Kuntoro, Hadiyan Yusuf; Deendarlianto,

    2015-01-01

    Recently, experimental series of co-current gas-liquid upward bubbly flows in a 6 m-height and 54.8 mm i.d. vertical titanium pipe had been conducted at the TOPFLOW thermal hydraulic test facility, Helmholtz-Zentrum Dresden-Rossendorf, Germany. The experiments were initially performed to develop a high quality database of two-phase flows as well as to validate new CFD models. An ultrafast dual-layer electron beam X-ray tomography, named ROFEX, was used as measurement system with high spatial and temporal resolutions. The gathered cross sectional grey value image results from the tomography scanning were reconstructed, segmented and evaluated to acquire gas bubble parameters for instance bubble position, size and holdup. To assign the correct paired bubbles from both measurement layers, a bubble pair algorithm was implemented on the basis of the highest probability values of bubbles in position, volume and velocity. Hereinafter, the individual characteristics of bubbles were calculated include instantaneous th...

  19. Optically actuated thermocapillary movement of gas bubbles on an absorbing substrate.

    Science.gov (United States)

    Ohta, Aaron T; Jamshidi, Arash; Valley, Justin K; Hsu, Hsan-Yin; Wu, Ming C

    2007-08-14

    The authors demonstrate an optical manipulation mechanism of gas bubbles for microfluidic applications. Air bubbles in a silicone oil medium are manipulated via thermocapillary forces generated by the absorption of a laser in an amorphous silicon thin film. In contrast to previous demonstrations of optically controlled thermally driven bubble movement, transparent liquids can be used, as the thermal gradient is formed from laser absorption in the amorphous silicon substrate, and not in the liquid. A variety of bubbles with volumes ranging from 19 pl to 23 nl was transported at measured velocities of up to 1.5 mm/s.

  20. How does gas pass? Bubble transport through sediments

    Science.gov (United States)

    Fauria, K. E.; Rempel, A. W.

    2009-12-01

    The transport of gas through marine sediments is critical for both the formation and the ultimate fate of gas that is housed temporarily within hydrates. We monitored the gas flux produced by repeated bubble injections into a particle layer that was initially saturated with liquid. The size of ejected bubbles and the period between ejection events were different from the input size and period. Our observations clearly demonstrate bubble break-up as well as coalescence and the formation of preferred bubble migration pathways. We develop an elementary, semi-empirical model to interpret aspects of these results and predict the gas flux expected from a given size distribution of bubble inputs as a function of basic host sediment characteristics. Models of gas transport that use simple modifications to Darcy's law are not adequate to cope with bubble dynamics in the parameter regime that we observe.

  1. Effects of Gas Dynamics on Rapidly Collapsing Bubbles

    CERN Document Server

    Bauman, Spenser

    2013-01-01

    The dynamics of rapidly collapsing bubbles are of great interest due to the high degree of energy focusing that occurs withing the bubble. Molecular dynamics provides a way to model the interior of the bubble and couple the gas dynamics with the equations governing the bubble wall. While much theoretical work has been done to understand how a bubble will respond to an external force, the internal dynamics of the gas system are usually simplified greatly in such treatments. This paper shows how the gas system dynamics affect bubble collapse and illustrates what effects various modeling assumptions can have on the motion of the bubble wall. In addition, we present a method of adaptively partitioning space to improve the performance of collision intersection calculations when using an energy dependent collision cross section.

  2. Volume Displacement Effects in Bubble-laden Flows

    Science.gov (United States)

    Cihonski, Andrew; Finn, Justin; Apte, Sourabh

    2012-11-01

    When a few bubbles are entrained in a traveling vortex ring, it has been shown that even at extremely low volume loadings, their presence can significantly affect the structure of the vortex core (Sridhar & Katz 1999). A typical Euler-Lagrange point-particle model with two-way coupling for this dilute system, wherein the bubbles are assumed subgrid and momentum point-sources are used to model their effect on the flow, is shown to be unable to accurately capture the experimental trends of bubble settling location and vortex distortion for a range of bubble parameters and vortex strengths. The bubbles experience a significant amount of drag, lift, added mass, pressure, and gravity forces. However, these forces are in balance of each other, as the bubbles reach a mean settling location away from the vortex core. Accounting for fluid volume displacement due to bubble motion, using a model termed as volumetric coupling, experimental trends on vortex distortion and bubble settling location are well captured. The fluid displacement effects are studied by introducing a notion of a volumetric coupling force, the net force on the fluid due to volumetric coupling, which is found to be dominant even at the low volume loadings investigated here.

  3. Two-phase flow equations for a dilute dispersion of gas bubbles in liquid

    NARCIS (Netherlands)

    Biesheuvel, A.; Wijngaarden, van L.

    1984-01-01

    Equations of motion correct to the first order of the gas concentration by volume are derived for a dispersion of gas bubbles in liquid through systematic averaging of the equations on the microlevel. First, by ensemble averaging, an expression for the average stress tensor is obtained, which is non

  4. Mechanical interaction between gas bubbles and micro-crystals in magma

    Science.gov (United States)

    Dinger, Florian; Bobrowski, Nicole; Bredemeyer, Stefan; Arellano, Santiago; Platt, Ulrich; Wagner, Thomas

    2017-04-01

    The magnitude of volcanic gas emissions from low viscosity magmas is controlled by many factors. The buoyancy driven ascent of gas bubbles in the volcanic conduit is one of them. During the ascent the bubbles may collide with micro-crystals, slide along the crystal faces, and finally leave the crystal at the crystal tip. We investigate the mechanical consequences of this interaction in a static volume of magma assuming constant pressure, temperature and chemical composition and neglecting thermodynamic processes between bubbles and crystals. Explicitly, we focus on tabular crystals whose extensions are about one order of magnitude larger than the bubbles. The mechanical interaction changes the motion of both the bubbles and the crystals. The buoyancy force of the bubbles results in a torque on the crystal which ultimately orients the long axis of the crystal to the vertical direction. On the other hand, bubbles change their ascent path and velocity if they slide along a crystal face. This change in the bubble motion may have two opposing impacts on the magnitude of volcanic emissions: First, the reduced ascent velocity results in a bubble accumulation and thus enhanced bubble coalescence rate in the proximity of crystals. Second, the crystals align the bubbles in rise channels starting at the crystal tips while no bubbles access the magma volume immediately located above the crystal cross section, which we call "crystal shadow". Now, volatile degassing from supersaturated magma is a diffusive short-distance process which accelerate in the proximity of pre-existing gas bubbles. We thus infer that the orientation of the crystals influences the bulk volatile degassing rate and thus the volcanic gas emission rate due to the crystal shadow. The mechanical model suggests that all crystals get erected by the bubble-induced torque within time periods in the order of weeks to months. This has to be compared to the crystal nucleation rate in order to obtain a steady state

  5. Experimental Investigation of Rising Gas Bubble Characteristics from a Vertical Tube under CCFL Condition

    Directory of Open Access Journals (Sweden)

    Kunihito Matsumura

    2012-01-01

    Full Text Available This paper describes an experimental study of gas/liquid countercurrent flow in a vertical circular tube. CCFL experiments were carried out with three different water levels in the upper plenum, two different tube diameters. Measurements were made for liquid and gas flow rates, time variations of pressure at locations of the upper entry of the tube and lower plenum. Visual observations were also conducted to investigate the relationship between rising gas bubble characteristics and time variation of gas pressure at the upper entry of the tube. The results indicate that one bubble formation cycle (e.g., bubble growth, expansion, and detachment into the water pool corresponds to one pressure fluctuation cycle. For the 20 mm diameter tube, it was confirmed that there was a characteristic waiting time between bubble cycles in which no bubble was formed at the upper entry of the tube. The waiting time is a favorable time for a liquid introduction into the tube from the upper plenum. The bubble volumes are compared with existing bubble formation correlations.

  6. Gas distribution effects on waste properties: Viscosities of bubbly slurries

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, P.A.; Shah, R.R.; Davis, R.L.

    1994-09-01

    The retention and episodic release of flammable gases are critical safety concerns for double-shell tanks that contain waste slurries. The rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles. The presence of gas bubbles is expected to affect the rheology of the sludge, but essentially no literature data are available to assess the effect of bubbles. Accordingly, the objectives of this study are to develop models for the effect of gas bubbles on the viscosity of a particulate slurry, develop an experimental method (capillary rheometer), collect data on the viscosity of a bubbly slurry, and develop a theoretical basis for interpreting the experimental data from the capillary rheometer.

  7. Adhesion of solid particles to gas bubbles. Part 1: Modelling

    NARCIS (Netherlands)

    Omota, Florin; Dimian, Alexandre C.; Bliek, A.

    2006-01-01

    Particle-to-bubble adhesion is important in the areas of anti-foaming, in flotation processes and in multiphase slurry reactors. In the present work we particularly address the latter. The behaviour of fine catalyst particles adhering to gas bubbles in aqueous media is governed by the surface

  8. Axial and Radial Gas Holdup in Bubble Column Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Wagh, Sameer M.; Ansari, Mohashin E Alan; Kene, Pragati T. [RTMNU Nagpur, Nagpur (India)

    2014-06-15

    Bubble column reactors are considered the reactor of choice for numerous applications including oxidation, hydrogenation, waste water treatment, and Fischer-Tropsch (FT) synthesis. They are widely used in a variety of industrial applications for carrying out gas-liquid and gas-liquid-solid reactions. In this paper, the computational fluid dynamics (CFD) model is used for predicting the gas holdup and its distribution along radial and axial direction are presented. Gas holdup increases linearly with increase in gas velocity. Gas bubbles tends to concentrate more towards the center of the column and follows a wavy path.

  9. Jet formation in shock-heavy gas bubble interaction

    Institute of Scientific and Technical Information of China (English)

    Zhi-Gang Zhai; Ting Si; Li-Yong Zou; Xi-Sheng Luo

    2013-01-01

    The influences of the acoustic impedance and shock strength on the jet formation in shock-heavy gas bubble interaction are numerically studied in this work.The process of a shock interacting with a krypton or a SF6 bubble is studied by the numerical method VAS2D.As a validation,the experiments of a SF6 bubble accelerated by a planar shock were performed.The results indicate that,due to the mismatch of acoustic impedance,the way of jet formation in heavy gas bubble with different species is diversified under the same initial condition.With respect to the same bubble,the manner of jet formation is also distinctly different under different shock strengths.The disparities of the acoustic impedance result in different effects of shock focusing in the bubble,and different behaviors of shock wave inside and outside the bubble.The analyses of the wave pattern and the pressure variation indicate that the jet formation is closely associated with the pressure perturbation.Moreover,the analysis of the vorticity deposition,and comparisons of circulation and baroclinic torque show that the baroclinic vorticity also contributes to the jet formation.It is concluded that the pressure perturbation and baroclinic vorticity deposition are the two dominant factors for the jet formation in shock-heavy gas bubble interaction.

  10. Bubble coalescence dynamics and supersaturation in electrolytic gas evolution

    Energy Technology Data Exchange (ETDEWEB)

    Stover, R.L. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering]|[Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.

    1996-08-01

    The apparatus and procedures developed in this research permit the observation of electrolytic bubble coalescence, which heretofore has not been possible. The influence of bubble size, electrolyte viscosity, surface tension, gas type, and pH on bubble coalescence was examined. The Navier-Stokes equations with free surface boundary conditions were solved numerically for the full range of experimental variables that were examined. Based on this study, the following mechanism for bubble coalescence emerges: when two gas bubbles coalesce, the surface energy decreases as the curvature and surface area of the resultant bubble decrease, and the energy is imparted into the surrounding liquid. The initial motion is driven by the surface tension and slowed by the inertia and viscosity of the surrounding fluid. The initial velocity of the interface is approximately proportional to the square root of the surface tension and inversely proportional to the square root of the bubble radius. Fluid inertia sustains the oblate/prolate oscillations of the resultant bubble. The period of the oscillations varies with the bubble radius raised to the 3/2 power and inversely with the square root of the surface tension. Viscous resistance dampens the oscillations at a rate proportional to the viscosity and inversely proportional to the square of the bubble radius. The numerical simulations were consistent with most of the experimental results. The differences between the computed and measured saddle point decelerations and periods suggest that the surface tension in the experiments may have changed during each run. By adjusting the surface tension in the simulation, a good fit was obtained for the 150-{micro}m diameter bubbles. The simulations fit the experiments on larger bubbles with very little adjustment of surface tension. A more focused analysis should be done to elucidate the phenomena that occur in the receding liquid film immediately following rupture.

  11. A study of gas bubbles in liquid mercury in a vertical Hele-Shaw cell

    Science.gov (United States)

    Klaasen, B.; Verhaeghe, F.; Blanpain, B.; Fransaer, J.

    2014-01-01

    High-quality observations of mesoscopic gas bubbles in liquid metal are vital for a further development of pyrometallurgical gas injection reactors. However, the opacity of metals enforces the use of indirect imaging techniques with limited temporal or spatial resolution. In addition, accurate interface tracking requires tomography which further complicates the design of a high-temperature experimental setup. In this paper, an alternative approach is suggested that circumvents these two main restrictions. By injecting gas in a thin layer of liquid metal entrapped between two flat and closely spaced plates, bubbles in a Hele-Shaw flow regime are generated. The resulting quasi-2D multiphase flow phenomena can be fully captured from a single point of view and, when using a non-wetted transparent plate material, the bubbles can be observed directly. The feasibility of this approach is demonstrated by observations on buoyancy-driven nitrogen bubbles in liquid mercury in a vertical Hele-Shaw cell. By using a moving high-speed camera to make continuous close up recordings of individual bubbles, the position and geometry of these bubbles are quantified with a high resolution along their entire path. After a thorough evaluation of the experimental accuracy, this information is used for a detailed analysis of the bubble expansion along the path. While the observed bubble growth is mainly caused by the hydrostatic pressure gradient, a careful assessment of the volume variations for smaller bubbles shows that an accurate bubble description should account for significant dynamic pressure variations that seem to be largely regime dependent.

  12. Numerical study to invistigate the effect of inlet gas velocity and Reynolds number on bubble formation in a viscous liquid

    Directory of Open Access Journals (Sweden)

    Islam Tariqul

    2015-01-01

    Full Text Available Bubble formation dynamics has great value in mineral recovery and the oil industry. In this paper, a single bubble formation process through an orifice in a rectangle domain is modelled to study the bubble formation characteristics using the volume of fluid (VOF with the continuum surface force (CSF method. The effect of gas inlet velocities, Ug ~ 0.1 - 0.3 m/s on bubble formation stages (i.e., expansion, elongation and pinch off, bubble contact angle, dynamics and static pressure, bubble departure diameter etc. was investigated through an orifice diameter of 1 mm. The method was also used to study the effect of Reynolds number, Reμ ~ 1.32 - 120 on bubble formation when all other parameters were kept constant. It is found that a high inlet gas velocity accelerated the reducing of the bubble contact angle from an obtuse angle to an acute angle and the faster development of hemispherical shape of the bubble. It is also found that an increasing of Reynolds number caused speeding up of the bubble pinch-off and formed a smaller bubble neck height due to stronger vortex ring around the bubble neck.

  13. Concentration distribution around a growing gas bubble in tissue.

    Science.gov (United States)

    Mohammadein, S A; Mohamed, K G

    2010-05-01

    This paper presents the concentration distribution around a growing nitrogen gas bubble in the blood and other tissues of divers who surface too quickly, when the ambient pressure through the decompression process is variable and constant. This effort is a modification of Sirinivasan et al. model (1999) [9]. The mathematical model is solved analytically to find the growth rate of a gas bubble in a tissue after decompression in the ambient pressure. Moreover, the concentration distribution around the growing bubble is introduced. The growth process is affected by ascent rate alpha (t), tissue diffusivity D(T), initial concentration difference DeltaC(0), surface tension sigma and void fraction varphi(0).

  14. The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo

    CERN Document Server

    Miller, Matthew J

    2016-01-01

    The Fermi bubbles are two lobes filled with non-thermal particles that emit gamma rays, extend $\\approx$10 kpc vertically from the Galactic center, and formed from either nuclear star formation or accretion activity on Sgr A*. Simulations predict a range of shock strengths as the bubbles expand into the surrounding hot gas halo distribution ($T_{halo} \\approx 2 \\times 10^6$ K), but with significant uncertainties in the energetics, age, and thermal gas structure. The bubbles should contain thermal gas with temperatures between $10^6$ and $10^8$ K, with potential X-ray signatures. In this work, we constrain the bubbles' thermal gas structure by modeling the OVII and OVIII emission line strengths from archival XMM-Newton and Suzaku data. Our emission model includes a hot thermal volume-filled bubble component cospatial with the gamma-ray region, and a shell of compressed material. We find that a bubble/shell model with $n \\approx 1 \\times 10^{-3}$ cm$^{-3}$ and with log($T$) $\\approx$ 6.60-6.70 is consistent wit...

  15. Production of Gas Bubbles in Reduced Gravity Environments

    Science.gov (United States)

    Oguz, Hasan N.; Takagi, Shu; Misawa, Masaki

    1996-01-01

    In a wide variety of applications such as waste water treatment, biological reactors, gas-liquid reactors, blood oxygenation, purification of liquids, etc., it is necessary to produce small bubbles in liquids. Since gravity plays an essential role in currently available techniques, the adaptation of these applications to space requires the development of new tools. Under normal gravity, bubbles are typically generated by forcing gas through an orifice in a liquid. When a growing bubble becomes large enough, the buoyancy dominates the surface tension force causing it to detach from the orifice. In space, the process is quite different and the bubble may remain attached to the orifice indefinitely. The most practical approach to simulating gravity seems to be imposing an ambient flow to force bubbles out of the orifice. In this paper, we are interested in the effect of an imposed flow in 0 and 1 g. Specifically, we investigate the process of bubble formation subject to a parallel and a cross flow. In the case of parallel flow, we have a hypodermic needle in a tube from which bubbles can be produced. On the other hand, the cross flow condition is established by forcing bubbles through an orifice on a wall in a shear flow. The first series of experiments have been performed under normal gravity conditions and the working fluid was water. A high quality microgravity facility has been used for the second type and silicone oil is used as the host liquid.

  16. Characterization of intergranular fission gas bubbles in U-Mo fuel.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. S.; Hofman, G.; Rest, J.; Shevlyakov, G. V.; Nuclear Engineering Division; SSCR RIAR

    2008-04-14

    plates were also performed and compared with the calculated quantities. Bubble density per unit grain boundary surface area was calculated by using the density per unit grain boundary length data. These data were used as input for mechanistic modeling described in section 4. Volumetric bubble density was calculated by using density per unit grain boundary surface area. Based on these data, bubble volumetric fraction was calculated. Bubble volume fraction was also calculated by using the density per unit cross section area. Bubble volume fraction was also directly measured for some plates. These three results are comparable although the direct measurement data are slightly larger than the others. Bubble volume fraction increased as a function of burnup, reaching {approx}2% of fuel volume at 3 x 10{sup 21} f/cm{sup 3}. Fission gas bubble swelling is minor compared to that of solid fission product swelling.

  17. Decompression-induced bubble formation in salmonids: comparison to gas bubble disease.

    Science.gov (United States)

    Beyer, D L; D'Aoust, B G; Smith, L S

    1976-12-01

    The relationship of gas bubble disease (GBD) in fish to decompression-induced bubble formation was investigated with salmonids. Acute bioassays were used to determine equilibration times for critical effects in fish decompressed from depths to 200 fsw. It was found that equilibration of critical tissues was complete in 60-90 min. Salmonids and air-breathers are sensitive to decompressions at similar levels of supersaturation if elimination of excess gas following decompression is unrestricted. However, if elimination is restricted, bubble formation and growth increase accordingly. Tests with mixtures of He-O2, Ar-O2, N2-O2 (80% inert gas: 20% O2) and pure oxygen demonstrated that gas solubility as well as supersaturation (delta P), pressure ratio (initial pressure: final pressure), and absolute pressure must be considered in setting tolerance limits for any decompression. Gases with higher solubility are more likely to produce bubbles upon decompression. Oxygen, however, does not follow this relationship until higher pressures are reached, probably owing to its function in metabolism and in binding with hemoglobin. Tissue responses observed in both GBD and decompressed fish involved similar pathological effects at acute exposures. The circulatory system was consistently affected by bubbles that occluded vessels and blocked flow through the heart.

  18. Fluid dynamics of gas-liquid bubble columns

    NARCIS (Netherlands)

    Delnoij, E.

    1999-01-01

    Gas-liquid bubble columns are used extensively in the process industries. The gas-liquid twophase flow prevailing in this type of process equipment is extremely complex, inherently unsteady and dominated by phenomena with widely varying time- and length-scales. it is for this reason that many

  19. THE INFLUENCE OF GAS-DENSITY AND LIQUID PROPERTIES ON BUBBLE BREAKUP

    NARCIS (Netherlands)

    WILKINSON, PM; VANSCHAYK, A; SPRONKEN, JPM; VANDIERENDONCK, LL

    1993-01-01

    On the basis of a literature review of bubble breakup experiments, it is demonstrated that both liquid viscosity and surface tension have an influence on bubble stability and, thus, bubble breakup, for small as well as large bubbles. Possible influences of the gas properties on bubble breakup have u

  20. GAS BUBBLE-FACILITATED TRANSPORT OF METALS IN LITHOSPHERE

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A physicochemical model for transport of mobile forms of occurrence of elements by gas bubbles in porous medium-gas bubble-facilitated transport of metals in the lithosphere is proposed and its corresponding mathematical model is discussed. The physico-chemical model consists of three phases: water with dissolved metallic elements, gas bubbles and solid matrix of the porous medium. In the model the gas bubbles act as carriers to transport the elements in the pore water from the depth in the lithosphere to the Earth's surface. In the process of transportation the elements dissipate in porous rocks and consequently a new kind of geochemical halo-jet halo of dispersion is formed in the rocks. In order to describe the transport and fate of the elements in the porous rocks a nonlinear quasiconvection mathematical model is developed, in which the transport of elements is modeled by a quasiconvection of gas bubbles with the elements and the interaction of elements with the porous medium is represented by a second-order chemical kinetics. A finite difference scheme is provided to solve the nonlinear quasiconvection model. From the numerical solutions a stabilization effect of concentration front in the transportation of elements in the porous medium is discovered. The sensitivities of the stabilization effect to model parameters are analyzed. To verify the reality of the mathematical model, physicochemical modeling experiments are conducted. The obtained experimental data support the proposed model in this work.

  1. Effects of heterogeneous structure and diffusion permeability of body tissues on decompression gas bubble dynamics.

    Science.gov (United States)

    Nikolaev, V P

    2000-07-01

    To gain insight into the special nature of gas bubbles that may form in astronauts, aviators and divers, we developed a mathematical model which describes the following: 1) the dynamics of extravascular bubbles formed in intercellular cavities of a hypothetical tissue undergoing decompression; and 2) the dynamics of nitrogen tension in a thin layer of intercellular fluid and in a thick layer of cells surrounding the bubbles. This model is based on the assumption that, due to limited cellular membrane permeability for gas, a value of effective nitrogen diffusivity in the massive layer of cells in the radial direction is essentially lower compared to conventionally accepted values of nitrogen diffusivity in water and body tissues. Due to rather high nitrogen diffusivity in intercellular fluid, a bubble formed just at completion of fast one-stage reduction of ambient pressure almost instantly grows to the size determined by the initial volume of the intercellular cavity, surface tension of the fluid, the initial nitrogen tension in the tissue, and the level of final pressure. The rate of further bubble growth and maximum bubble size depend on comparatively low effective nitrogen diffusivity in the cell layer, the tissue perfusion rate, the initial nitrogen tension in the tissue, and the final ambient pressure. The tissue deformation pressure performs its conservative action on bubble dynamics only in a limited volume of tissue (at a high density of formed bubbles). Our model is completely consistent with the available data concerning the random latency times to the onset of decompression sickness (DCS) symptoms associated with hypobaric decompressions simulating extravehicular activity. We believe that this model could be used as a theoretical basis for development of more adequate methods for the DCS risk prediction.

  2. MRI-guided gas bubble enhanced ultrasound heating in in vivo rabbit thigh.

    Science.gov (United States)

    Sokka, S D; King, R; Hynynen, K

    2003-01-21

    thermometry closely correlated with the resulting lesion as examined by T2-weighted imaging. The lesions created with the gas-bubble-enhanced heating exposures were 2-3 times larger by volume, consistently more spherical in shape and closer to the transducer than the control exposures. The study demonstrates that gas bubbles can reliably be used to create significantly larger lesions in vivo. MRI thermometry techniques were successfully used to monitor the thermal effects mediated by the bubble-enhanced exposures.

  3. Estimating Trapped Gas Concentrations as Bubbles Within Lake Ice Using Ground Penetrating Radar

    Science.gov (United States)

    Fantello, N.; Parsekian, A.; Walter Anthony, K. M.

    2015-12-01

    Climate warming is currently one of the most important issues that we are facing. The degradation of permafrost beneath thermokarst lakes has been associated with enhanced methane emissions and it presents a positive feedback to climate warming. Thermokarst lakes release methane to the atmosphere mainly by ebullition (bubbling) but there are a large number of uncertainties regarding the magnitude and variability of these emissions. Here we present a methodology to estimate the amount of gas released from thermokarst lakes through ebullition using ground-penetrating radar (GPR). This geophysical technique is well suited for this type of problem because it is non-invasive, continuous, and requires less effort and time than the direct visual inspection. We are studying GPR data collected using 1.2 GHz frequency antennas in Brooklyn Lake, Laramie, WY, in order to quantify the uncertainties in the method. Although this is not a thermokarst lake, gas bubbles are trapped in the ice and spatial variability in bubble concentration within the ice is evident. To assess the variability in bulk physical properties of the ice due to bubbles, we gathered GPR data from different types of ice. We compared the velocity of the groundwave and reflection obtained from radargrams, and found on each case a larger value for the groundwave velocity suggesting a non-homogeneous medium and that the concentration of bubbles is prone to be near the surface instead of at greater depths. We use a multi-phase dielectric-mixing model to estimate the amount of gas present in a sample of volume of ice and found an uncertainty in relative permittivity (estimated using reflection velocity) of 0.0294, which translates to an uncertainty of 1.1% in gas content; and employing groundwave velocity we found 0.0712 and 2.9%, respectively. If locations of gas seeps in lakes could be detected and quantified using GPR along with field measurements, this could help to constrain future lake-source carbon gas

  4. Numerical simulation of ultrasound-induced dynamics of a gas bubble neighboring a rigid wall

    Science.gov (United States)

    Kobayashi, Tatsuya; Ando, Keita

    2016-11-01

    Cavitation erosion has been a technical issue in ultrasonic cleaning under which cavitation bubbles appear near target surfaces to be cleaned. In the present study, we numerically study the interaction of ultrasonic standing waves with a gas bubble in the neighborhood of a rigid wall. We solve multicomponent Euler equations that ignore surface tension and phase change at interfaces, by the finite-volume WENO scheme with interface capturing. The pressure amplitude of the ultrasound is set at several atmospheres and the ultrasound wavelength is tuned to obtain the situation near resonance. In the simulation, we observe jetting flow toward the rigid wall at violent bubble collapse that may explain cavitation erosion in ultrasonic cleaning.

  5. Gas dispersion and bubble-to-emulsion phase mass exchange in a gas-solid bubbling fluidized bed: a computational and experimental study

    NARCIS (Netherlands)

    Patil, Dhaneshwar J.; Sint Annaland, van Martin; Kuipers, J.A.M.

    2003-01-01

    Knowledge of gas dispersion and mass exchange between the bubble and the emulsion phases is essential for a correct prediction of the performance of fluidized beds, particularly when catalytic reactions take place. Test cases of single rising bubble and a bubbling fluidized bed operated with a jet w

  6. Modeling biogenic gas bubbles formation and migration in coarse sand

    Science.gov (United States)

    Ye, S.

    2011-12-01

    Shujun Ye Department of Hydrosciences, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China; sjye@nju.edu.cn Brent E. Sleep Department of Civil Engineering, University of Toronto, Toronto, ON, M5S 1A4 CANADA; sleep@ecf.utoronto.ca Methane gas generation in porous media was investigated in an anaerobic two-dimensional sand-filled cell. Inoculation of the lower portion of the cell with a methanogenic culture and addition of methanol to the bottom of the cell led to biomass growth and formation of a gas phase. The formation, migration, distribution and saturation of gases in the cell were visualized by the charge-coupled device (CCD) camera. Gas generated at the bottom of the cell in the biologically active zone moved upwards in discrete fingers, so that gas phase saturations (gas-filled fraction of void space) in the biologically active zone at the bottom of the cell did not exceed 40-50%, while gas accumulation at the top of the cell produced gas phase saturations as high as 80%. Macroscopic invasion percolation (MIP) at near pore scale[Glass, et al., 2001; Kueper and McWhorter, 1992]was used to model gas bubbles growth in porous media. The nonwetting phase migration pathway can be yielded directly by MIP. MIP was adopted to simulate the expansion, fragmentation, and mobilization of gas clusters in the cell. The production of gas, and gas phash saturations were simulated by a continuum model - compositional simulator (COMPSIM) [Sleep and Sykes, 1993]. So a combination of a continuum model and a MIP model was used to simulate the formation, fragmentation and migration of biogenic gas bubbles. Key words: biogenic gas; two dimensional; porous media; MIP; COMPSIM

  7. Formation mechanism of gas bubble superlattice in UMo metal fuels: Phase-field modeling investigation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burkes, Douglas E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Senor, David J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Setyawan, Wahyu [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Xu, Zhijie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-08

    Nano-gas bubble superlattices are often observed in irradiated UMo nuclear fuels. However, the for- mation mechanism of gas bubble superlattices is not well understood. A number of physical processes may affect the gas bubble nucleation and growth; hence, the morphology of gas bubble microstructures including size and spatial distributions. In this work, a phase-field model integrating a first-passage Monte Carlo method to investigate the formation mechanism of gas bubble superlattices was devel- oped. Six physical processes are taken into account in the model: 1) heterogeneous generation of gas atoms, vacancies, and interstitials informed from atomistic simulations; 2) one-dimensional (1-D) migration of interstitials; 3) irradiation-induced dissolution of gas atoms; 4) recombination between vacancies and interstitials; 5) elastic interaction; and 6) heterogeneous nucleation of gas bubbles. We found that the elastic interaction doesn’t cause the gas bubble alignment, and fast 1-D migration of interstitials along $\\langle$110$\\rangle$ directions in the body-centered cubic U matrix causes the gas bubble alignment along $\\langle$110$\\rangle$ directions. It implies that 1-D interstitial migration along [110] direction should be the primary mechanism of a fcc gas bubble superlattice which is observed in bcc UMo alloys. Simulations also show that fission rates, saturated gas concentration, and elastic interaction all affect the morphology of gas bubble microstructures.

  8. Formation mechanism of gas bubble superlattice in UMo metal fuels: Phase-field modeling investigation

    Science.gov (United States)

    Hu, Shenyang; Burkes, Douglas E.; Lavender, Curt A.; Senor, David J.; Setyawan, Wahyu; Xu, Zhijie

    2016-10-01

    Nano-gas bubble superlattices are often observed in irradiated UMo nuclear fuels. However, the formation mechanism of gas bubble superlattices is not well understood. A number of physical processes may affect the gas bubble nucleation and growth; hence, the morphology of gas bubble microstructures including size and spatial distributions. In this work, a phase-field model integrating a first-passage Monte Carlo method to investigate the formation mechanism of gas bubble superlattices was developed. Six physical processes are taken into account in the model: 1) heterogeneous generation of gas atoms, vacancies, and interstitials informed from atomistic simulations; 2) one-dimensional (1-D) migration of interstitials; 3) irradiation-induced dissolution of gas atoms; 4) recombination between vacancies and interstitials; 5) elastic interaction; and 6) heterogeneous nucleation of gas bubbles. We found that the elastic interaction doesn't cause the gas bubble alignment, and fast 1-D migration of interstitials along directions in the body-centered cubic U matrix causes the gas bubble alignment along directions. It implies that 1-D interstitial migration along [110] direction should be the primary mechanism of a fcc gas bubble superlattice which is observed in bcc UMo alloys. Simulations also show that fission rates, saturated gas concentration, and elastic interaction all affect the morphology of gas bubble microstructures.

  9. Progression and severity of gas bubble trauma in juvenile salmonids

    Science.gov (United States)

    Mesa, M.G.; Weiland, L.K.; Maule, A.G.

    2000-01-01

    We conducted laboratory experiments to assess the progression and to quantify the severity of signs of gas bubble trauma (GBT) in juvenile chinook salmon Oncorhynchus tshawytscha and steelhead Oncorhynchus mykiss exposed to different levels of total dissolved gas (TDG), and we attempted to relate these signs to the likelihood of mortality. When fish were exposed to 110% TDG for up to 22 d, no fish died, and there were few signs of GBT in the lateral line or gills. Bubbles in the fins, however, were relatively common, and they progressively worsened over the experimental period. When fish were exposed to 120% TDG for up to 140 h, chinook salmon had an LT20 (time necessary to kill 20% of the fish) ranging from 40 to 120 h, whereas steelhead had LT20s ranging from 20 to 35 h. In steelhead, bubbles in the lateral line, fins, and gills displayed poor trends of worsening over time, showed substantial interindividual variability, and were poorly related to mortality. In chinook salmon, only bubbles in the lateral line showed a distinct worsening over time, and the severity of bubbles in the lateral line was highly correlated with mortality. When fish were exposed to 130% TDG for up to 11 h, LT20s for chinook salmon ranged from 3 to 6 h, whereas those for steelhead ranged from 5 to 7 h. In chinook salmon, bubbles in the lateral line and fins, but not those in the gills, showed distinct trends of worsening over time. In steelhead, bubbles in the lateral line displayed the most significant trend of progressive severity. In both species at 130% TDG, the severity of all GBT signs was highly correlated with mortality. The progressive nature of GBT and the methods we developed to examine fish for GBT may be useful for monitoring programs that aim to assess the severity of dissolved gas supersaturation exposures experienced by fish in the wild. However, the efficacy of such programs seems substantially hindered by problems associated with (1) the variable persistence of GBT signs

  10. A three-demensional CFD model for gas-liquid bubble columns.

    NARCIS (Netherlands)

    Delnoij, E.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    1999-01-01

    This paper discusses the development of a three-dimensional Euler¿Lagrange CFD model for a gas¿liquid bubble column. The model resolves the time-dependent, three-dimensional motion of small, spherical gas bubbles in a liquid. Our model incorporates all relevant forces acting on a bubble rising in a

  11. Superwettability of Gas Bubbles and Its Application: From Bioinspiration to Advanced Materials.

    Science.gov (United States)

    Yu, Cunming; Zhang, Peipei; Wang, Jingming; Jiang, Lei

    2017-09-13

    Gas bubbles in aqueous media are common and inevitable in, for example, agriculture and industrial processes. The behaviors of gas bubbles on solid interfaces, including generation, growth, coalescence, release, transport, and collection, are crucial to gas-bubble-related applications, which are always determined by gas-bubble wettability on solid interfaces. Here, the recent progress regarding the study of interfaces with gas-bubble superwettability in aqueous media, i.e., superaerophilicity and superaerophobicity, is summarized. Some examples illustrate how to design microstructures and chemical compositions to achieve reliable and effective manipulation of gas-bubble wettability on artificial interfaces. These designed interfaces exhibit excellent performance in gas-evolution reactions, gas-adsorption reactions, and directional gas-bubble transportation. Moreover, progress in the theoretical investigation of gas-bubble superwettability is reported. Lastly, some challenges are presented, such as the reliable manipulation of gas-bubble wettability and the establishment of mature theory for exactly and systematically explaining gas-bubble wetting phenomena. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Isobaric bubble growth: a consequence of altering atmospheric gas.

    Science.gov (United States)

    Strauss, R H; Kunkle, T D

    1974-11-01

    During certain treatments of decompression sickness following dives made with compressed air, the U.S. Navy advocates breathing helium-oxygen mixtures. However, stable nitrogen bubbles created within gelatin by decompression have been found to enlarge when the atmosphere was switched from nitrogen to helium without changing ambient pressure. This suggests that decompression sickness would be worsened by switching from nitrogen to helium in the breathing gas mixture.

  13. Use of optical probes to characterize bubble behavior in gas-solid fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Mainland, M.E.; Welty, J.R. (Oregon State Univ., Corvallis, OR (United States). Dept. of Mechanical Engineering)

    1995-02-01

    Optical probes are used to study gas-solid fluidized-bed hydrodynamics. The probes each consisting of a light source and photodetector separated by a gap are suitable for use at combustion-level temperatures. The methodology to process the signal for calculation of bubble properties such as bubble frequency, local bubble residence time, bubble velocity, pierced length, bubble size, and visible bubble flow is presented. The signal processing technique is independent of bed operating conditions. The probe signal processing methodology is validated by comparing calculated bubble properties based on the probe signal with properties observed on videotapes of a 2-D bed.

  14. Warm Pressurant Gas Effects on the Liquid Hydrogen Bubble Point

    Science.gov (United States)

    Hartwig, Jason W.; McQuillen, John B.; Chato, David J.

    2013-01-01

    This paper presents experimental results for the liquid hydrogen bubble point tests using warm pressurant gases conducted at the Cryogenic Components Cell 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device. Three fine mesh screen samples (325 x 2300, 450 x 2750, 510 x 3600) were tested in liquid hydrogen using cold and warm noncondensible (gaseous helium) and condensable (gaseous hydrogen) pressurization schemes. Gases were conditioned from 0 to 90 K above the liquid temperature. Results clearly indicate a degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over noncondensible pressurization. Degradation in the bubble point pressure is inversely proportional to screen porosity, as the coarsest mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.

  15. Gas Bubble Growth Dynamics in a Supersaturated Solution: Henry's and Sievert's Solubility Laws

    CERN Document Server

    Gor, Gennady Yu; Kuni, Fedor M

    2012-01-01

    Theoretical description of diffusion growth of a gas bubble after its nucleation in supersaturated liquid solution is presented. We study the influence of Laplace pressure on the bubble growth. We consider two different solubility laws: Henry's law, which is fulfilled for the systems where no gas molecules dissociation takes place and Sievert's law, which is fulfilled for the systems where gas molecules completely dissociate in the solvent into two parts. We show that the difference between Henry's and Sievert's laws for chemical equilibrium conditions causes the difference in bubble growth dynamics. Assuming that diffusion flux of dissolved gas molecules to the bubble is steady we obtain differential equations on bubble radius for both solubility laws. For the case of homogeneous nucleation of a bubble, which takes place at a significant pressure drop bubble dynamics equations for Henry's and Sievert's laws are solved analytically. For both solubility laws three characteristic stages of bubble growth are mar...

  16. Pulsed electrical discharge in gas bubbles in water

    Science.gov (United States)

    Gershman, Sophia

    A phenomenological picture of pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging methods. The discharge is generated by applying one microsecond long 5 to 20 kilovolt pulses between the needle and disk electrodes submerged in water. A gas bubble is generated at the tip of the needle electrode. The study includes detailed experimental investigation of the discharge in argon bubbles and a brief look at the discharge in oxygen bubbles. Imaging, electrical characteristics, and time-resolved optical emission data point to a fast streamer propagation mechanism and formation of a plasma channel in the bubble. Spectroscopic methods based on line intensity ratios and Boltzmann plots of line intensities of argon, atomic hydrogen, and argon ions and the examination of molecular emission bands from molecular nitrogen and hydroxyl radicals provide evidence of both fast beam-like electrons and slow thermalized ones with temperatures of 0.6 -- 0.8 electron-volts. The collisional nature of plasma at atmospheric pressure affects the decay rates of optical emission. Spectroscopic study of rotational-vibrational bands of hydroxyl radical and molecular nitrogen gives vibrational and rotational excitation temperatures of the discharge of about 0.9 and 0.1 electron-volt, respectively. Imaging and electrical evidence show that discharge charge is deposited on the bubble wall and water serves as a dielectric barrier for the field strength and time scales of this experiment. Comparing the electrical and imaging information for consecutive pulses applied at a frequency of 1 Hz indicates that each discharge proceeds as an entirely new process with no memory of the previous discharge aside from long-lived chemical species, such as ozone and oxygen. Intermediate values for the discharge gap and pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique

  17. Kinetics of CH4 and CO2 hydrate dissociation and gas bubble evolution via MD simulation.

    Science.gov (United States)

    Uddin, M; Coombe, D

    2014-03-20

    Molecular dynamics simulations of gas hydrate dissociation comparing the behavior of CH4 and CO2 hydrates are presented. These simulations were based on a structurally correct theoretical gas hydrate crystal, coexisting with water. The MD system was first initialized and stabilized via a thorough energy minimization, constant volume-temperature ensemble and constant volume-energy ensemble simulations before proceeding to constant pressure-temperature simulations for targeted dissociation pressure and temperature responses. Gas bubble evolution mechanisms are demonstrated as well as key investigative properties such as system volume, density, energy, mean square displacements of the guest molecules, radial distribution functions, H2O order parameter, and statistics of hydrogen bonds. These simulations have established the essential similarities between CH4 and CO2 hydrate dissociation. The limiting behaviors at lower temperature (no dissociation) and higher temperature (complete melting and formation of a gas bubble) have been illustrated for both hydrates. Due to the shift in the known hydrate stability curves between guest molecules caused by the choice of water model as noted by other authors, the intermediate behavior (e.g., 260 K) showed distinct differences however. Also, because of the more hydrogen-bonding capability of CO2 in water, as reflected in its molecular parameters, higher solubility of dissociated CO2 in water was observed with a consequence of a smaller size of gas bubble formation. Additionally, a novel method for analyzing hydrate dissociation based on H-bond breakage has been proposed and used to quantify the dissociation behaviors of both CH4 and CO2 hydrates. Activation energies Ea values from our MD studies were obtained and evaluated against several other published laboratory and MD values. Intrinsic rate constants were estimated and upscaled. A kinetic reaction model consistent with macroscale fitted kinetic models has been proposed to

  18. Gas structure and dynamics towards bipolar infrared bubble

    Science.gov (United States)

    Xu, Jin-Long; Yu, Naiping; Zhang, Chuan-Peng; Liu, Xiao-Lan

    2017-09-01

    We present multi-wavelength analysis for four bipolar bubbles (G045.386-0.726, G049.998-0.125, G050.489+0.993, and G051.610-0.357) to probe the structure and dynamics of their surrounding gas. The 12CO J=1-0, 13CO J=1-0 and C18O J=1-0 observations are made with the Purple Mountain Observation (PMO) 13.7 m radio telescope. For the four bipolar bubbles, the bright 8.0 μm emission shows the bipolar structure. Each bipolar bubble is associated with an H ii region. From CO observations we find that G045.386-0.726 is composed of two bubbles with different distances, not a bipolar bubble. Each of G049.998-0.125 and G051.610-0.357 is associated with a filament. The filaments in CO emission divide G049.998-0.125 and G051.610-0.357 into two lobes. We suggest that the exciting stars of both G049.998-0.125 and G051.610-0.357 form in a sheet-like structure clouds. Furthermore, G050.489+0.993 is associated with a clump, which shows a triangle-like shape with a steep integrated intensity gradient towards the two lobes of G050.489+0.993. We suggest that the two lobes of G050.489+0.993 have simultaneously expanded into the clump.

  19. Bubbles

    DEFF Research Database (Denmark)

    Dholakia, Nikhilesh; Turcan, Romeo V.

    2013-01-01

    A goal of our ongoing research stream is to develop a multidisciplinary metatheory of bubbles. In this viewpoint paper we put forward a typology of bubbles by comparing four types of assets – entertainment, commodities, financial securities (stocks), and housing properties – where bubbles could a...

  20. Atomistic simulations of thermodynamic properties of Xe gas bubbles in U10Mo fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang; Setyawan, Wahyu; Joshi, Vineet V.; Lavender, Curt A.

    2017-04-15

    Xe gas bubble superlattice formation is observed in irradiated uranium–10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble growth and superlattice formation are not well known. In this work, molecular dynamics is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the molecular dynamics simulations, the embedded-atom method (EAM) potential of U10Mo-Xe (Smirnova et al. 2013) is employed. Initial gas bubbles with low Xe concentration are generated in a U10Mo single crystal. Then Xe atom atoms are continuously added into the bubbles, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that the gas bubble growth is accompanied by partial dislocation emission, which results in a star-shaped dislocation structure and an anisotropic stress field. The emitted partial dislocations have a Burgers vector along the <111> direction and a slip plane of (11-2). Dislocation loop punch-out was not observed. A tensile stress was found along <110> directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in body-centered cubic U10Mo fuels.

  1. Re-solution of fission gas - A review: Part I. Intragranular bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Olander, D.R. [Department of Nuclear Engineering, University of California, Berkeley, CA 94720-1730 (United States)]. E-mail: fuelpr@nuc.berkeley.edu; Wongsawaeng, D. [Department of Nuclear Engineering, University of California, Berkeley, CA 94720-1730 (United States)

    2006-08-01

    Theories of fission-fragment-driven re-solution of fission-gas atoms from intragranular bubbles in irradiated UO{sub 2} nuclear fuel are reviewed. Two mechanisms of re-solution are generally accepted: the heterogeneous process destroys entire bubbles in the path of fission fragments and returns the gas to the solid as individual atoms; the homogeneous process re-solves fission-gas atoms singly by scattering collisions with fission fragments and uranium recoils whose paths intersect the bubbles. Coupling of these two re-solution models with the bubble nucleation analogs determines the size and number density of the intragranular bubble population. Two approaches are reviewed: the single-size theory, in which all bubbles are accorded one size, and the bubble distribution theory, which seeks to determine the variation of bubble number density with size.

  2. Generation and characterization of gas bubbles in liquid metals

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, S.; Gerbeth, G.; Witke, W.

    1996-06-01

    There is an ongoing research performed in the RCR on local transport phenomena in turbulent liquid metal (LM) duct flows exposed to external magnetic fields. In this context so-called MHD flow phenomena can be observed, which are unknown in usual hydraulic engineering. The field of interest covers also the influence of magnetic fields on the behaviour of liquid metal - gas mixtures. Profound knowledge on these LMMHD two-phase flow plays an important role in a variety of technological applications, in particular, in the design of Liquid-Metal MHD generators or for several metallurgical processes employing gas-stirred reactors. However, the highly empirical nature of two-phase flow analysis gives little hope for the prediction of MHD two-phase flows without extensive experimental data. A summary is given about the authors research activities focussing on two directions: (a) Momentum transfer between gas and liquid metal in a bubbly flow regime to investigate the influence of the external magnetic field on the velocity slip ration S (b) Peculiarities of the MHD turbulence to use small gas bubbles as local tracers in order to study the turbulent mass transfer.

  3. Optical measurements of gas bubbles in oil behind a cavitating micro-orifice flow

    Science.gov (United States)

    Iben, Uwe; Wolf, Fabian; Freudigmann, Hans-Arndt; Fröhlich, Jochen; Heller, Winfried

    2015-06-01

    In hydraulic systems, it is common for air release to occur behind valves or throttles in the form of bubbles. These air bubbles can affect the behavior and the performance of these systems to a substantial extent. In the paper, gas release in a liquid flow behind an orifice is analyzed by optical methods for various operation points. The bubbles are observed with a digital camera, and a detection algorithm based on the Hough transformation is used to determine their number and size. The appearance of gas bubbles is very sensitive to the inlet and outlet pressure of the orifice. Gas bubbles are only observed if choking cavitation occurs. An empirical relationship between an adjusted cavitation number and the appearance of gas release is presented. It is assumed that the observed bubbles contain mostly air. With the applied pressure differences, up to 30 % of the dissolved air was degassed in the form of bubbles.

  4. Kinetics of hydrate formation using gas bubble suspended in water

    Institute of Scientific and Technical Information of China (English)

    马昌峰; 陈光进; 郭天民

    2002-01-01

    An innovative experimental technique, which was devised to study the effects of temperature and pressure on the rate of hydrate formation at the surface of a gas bubble suspended in a stagnant water phase, was adapted in this work. Under such conditions, the hydrate-growth process is free from dynamic mass transfer factors. The rate of hydrate formation of methane and carbon dioxide has been systematically studied. The measured hydrate-growth data were correlated by using the molar Gibbs free energy as driving force. In the course of the experiments, some interesting surface phenomena were observed.

  5. Experimental Investigation of Gas Hydrate Production at Injection of Liquid Nitrogen into Water with Bubbles of Freon 134A

    Directory of Open Access Journals (Sweden)

    Meleshkin Anton V.

    2016-01-01

    Full Text Available The hydrodynamic processes during the injection of the cryogenic liquid into the volume of water with bubbles of gas freon 134a are studding experimentally. A processes during the explosive boiling of liquid nitrogen in the volume of water are registered. Video recording of identified gas hydrate flakes formed during this process is carried out by high speed camera. These results may be useful for the study of the new method of producing gas hydrates, based on the shock-wave method.

  6. An examination of the parameters that govern the acoustic behavior of sea bed sediments containing gas bubbles.

    Science.gov (United States)

    Gardner, T N; Sills, G C

    2001-10-01

    The acoustic properties of sea bed sediments containing occluded gas are dominated by the volume of gas contained in bubbles, the size of bubbles, and the elastic properties of the soil matrix. This study evaluated current theory developed by Anderson and Hampton to determine the sound speed and resonance frequency of gassy soils, and the models they used to determine the elastic properties of the soils. It compared calculated sound speeds, based on material properties simulated by the models, with measured sound speeds on "large bubble" laboratory soils produced in a similar manner to natural sea bed gassy soils. There was some evidence that the Anderson and Hampton equations accurately predicted sound speed at lower frequencies of bubbles resonance and below, but results were sensitive to inappropriate values for the elastic and damping properties of the soil. The bounds of sound speed based on the elastic properties of models that simulate "compressible fluid" or "suspension" behavior were grossly misleading when applied to large bubble soils. Conversely, sound speed based on models that correctly simulate the "bulk" or "matrix" properties of large bubble soils, at strain magnitudes and strain rates equivalent to acoustic signals, agreed well with measured data.

  7. Extended models of nonlinear waves in liquid with gas bubbles

    CERN Document Server

    Kudryashov, Nikolay A

    2016-01-01

    In this work we generalize the models for nonlinear waves in a gas--liquid mixture taking into account an interphase heat transfer, a surface tension and a weak liquid compressibility simultaneously at the derivation of the equations for nonlinear waves. We also take into consideration high order terms with respect to the small parameter. Two new nonlinear differential equations are derived for long weakly nonlinear waves in a liquid with gas bubbles by the reductive perturbation method considering both high order terms with respect to the small parameter and the above mentioned physical properties. One of these equations is the perturbation of the Burgers equation and corresponds to main influence of dissipation on nonlinear waves propagation. The other equation is the perturbation of the Burgers--Korteweg--de Vries equation and corresponds to main influence of dispersion on nonlinear waves propagation.

  8. The influence of polymeric membrane gas spargers on hydrodynamics and mass transfer in bubble column bioreactors

    DEFF Research Database (Denmark)

    Tirunehe, Gossay; Norddahl, B.

    2016-01-01

    Gas sparging performances of a flat sheet and tubular polymeric membranes were investigated in 3.1 m bubble column bioreactor operated in a semi batch mode. Air–water and air–CMC (Carboxymethyl cellulose) solutions of 0.5, 0.75 and 1.0 % w/w were used as interacting gas–liquid mediums. CMC...... solutions were employed in the study to simulate rheological properties of bioreactor broth. Gas holdup, bubble size distribution, interfacial area and gas–liquid mass transfer were studied in the homogeneous bubbly flow hydrodynamic regime with superficial gas velocity (UG) range of 0.0004–0.0025 m....../s. The study indicated that the tubular membrane sparger produced the highest gas holdup and densely populated fine bubbles with narrow size distribution. An increase in liquid viscosity promoted a shift in bubble size distribution to large stable bubbles and smaller specific interfacial area. The tubular...

  9. A transient method for measuring the gas volume fraction in a mixed gas-liquid flow using acoustic resonance spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper, the feasibility of measuring the gas volume fraction in a mixed gas-liquid flow by using an acoustic resonant spectroscopy (ARS) method in a transient way is studied theoretically and experimentally. Firstly, the effects of sizes and locations of a single air bubble in a cylindrical cavity with two open ends on resonant frequencies are investigated numerically. Then, a transient measurement system for ARS is established, and the trends of the resonant frequencies (RFs) and resonant amplitudes (RAs) in the cylindrical cavity with gas flux inside are investigated experimentally. The measurement results by the proposed transient method are compared with those by steady-state ones and numerical ones. The numerical results show that the RFs of the cavity are highly sensitive to the volume of the single air bubble. A tiny bubble volume perturbation may cause a prominent RF shift even though the volume of the air bubble is smaller than 0.1% of that of the cavity. When the small air bubble moves, the RF shift will change and reach its maximum value as it is located at the middle of the cavity. As the gas volume fraction of the two-phase flow is low, both the RFs and RAs from the measurement results decrease dramatically with the increasing gas volume, and this decreasing trend gradually becomes even as the gas volume fraction increases further. These experimental results agree with the theoretical ones qualitatively. In addition, the transient method for ARS is more suitable for measuring the gas volume fraction with randomness and instantaneity than the steady-state one, because the latter could not reflect the random and instant characteristics of the mixed fluid due to the time consumption for frequency sweeping. This study will play a very important role in the quantitative measurement of the gas volume fraction of multiphase flows.

  10. The translational oscillations of a cylindrical bubble in a bounded volume of a liquid with free deformable interface

    Science.gov (United States)

    Alabuzhev, A. A.; Kaysina, M. I.

    2016-02-01

    We consider the eigen and forced translation oscillations of a cylindrical gas bubble surrounded by an incompressible fluid with free deformable interface. The bubble has an equilibrium cylindrical shape and is bounded axially by two parallel solid surfaces. Dynamics of contact lines is taken into account by an effective boundary condition: velocity of the contact line is assumed to be proportional to contact angle deviation from the equilibrium value. The equilibrium contact angle is right. Eigen frequency decreases with liquid outer free surface radius decreasing and increases with the radius-to-height ratio increasing. We found that the main translational frequency of eigen oscillation vanishes at a certain value of the Hocking parameter (the so-called wetting parameter). The eigen frequencies of the bubble are higher than the eigen frequencies of fluid volume.

  11. Suppressing dissociation in sonoluminescing bubbles: The effect of excluded volume

    NARCIS (Netherlands)

    Tögel, R.; Hilgenfeldt, Sascha; Lohse, Detlef

    2002-01-01

    Recent theoretical work in single-bubble sonoluminescence has suggested that water vapor in the collapsing bubble leads to energy-consuming chemical reactions, restricting the peak temperatures to values for which hardly any light emission could occur. Analyzing the reaction thermodynamics within

  12. Collapse and rebound of a gas-filled spherical bubble immersed in a diagnostic ultrasonic field.

    Science.gov (United States)

    Aymé-Bellegarda, E J

    1990-08-01

    This work is concerned with the influence of the finite-amplitude distortion of a driving diagnostic ultrasonic field on the collapse and rebound of a gas-filled spherical microbubble, present in the exposed compressible liquid. Such an analysis is especially important since one of the mechanisms for cavitation damage comes from the very large gas pressures generated at bubble collapse and in the subsequent pressure wave formed by bubble rebound. Gilmore's model [F.R. Gilmore, "The growth or collapse of a spherical bubble in a viscous compressible liquid," Hydrodynamics Lab. Rep. No. 26-4, California Institute of Technology, Pasadena, CA (1952)] for bubble dynamics is used to obtain the motion of the bubble interface when subjected to a pulsed diagnostic ultrasonic field of large amplitude. Knowledge of the bubble motion allows one to derive the pressure distribution around the bubble. Numerical results over a range of initial bubble sizes, acoustic pressures, and frequencies relevant to medical use show that the strength of the pressure spikes radiated by the rebounding bubble depends upon (i) the acoustic frequency (f), (ii) the initial bubble size (R0), and (iii) the magnitude of the pressure amplitude of the fundamental (PF) in a Fourier series description of the distorted pulse. As the pressure spikes propagate outward from the bubble wall, their strength is attenuated as the reciprocal of the distance from the center of collapse.

  13. Decompression vs. Decomposition: Distribution, Amount, and Gas Composition of Bubbles in Stranded Marine Mammals.

    Science.gov (United States)

    de Quirós, Yara Bernaldo; González-Diaz, Oscar; Arbelo, Manuel; Sierra, Eva; Sacchini, Simona; Fernández, Antonio

    2012-01-01

    Gas embolic lesions linked to military sonar have been described in stranded cetaceans including beaked whales. These descriptions suggest that gas bubbles in marine mammal tissues may be more common than previously thought. In this study we have analyzed gas amount (by gas score) and gas composition within different decomposition codes using a standardized methodology. This broad study has allowed us to explore species-specific variability in bubble prevalence, amount, distribution, and composition, as well as masking of bubble content by putrefaction gases. Bubbles detected within the cardiovascular system and other tissues related to both pre- and port-mortem processes are a common finding on necropsy of stranded cetaceans. To minimize masking by putrefaction gases, necropsy, and gas sampling must be performed as soon as possible. Before 24 h post mortem is recommended but preferably within 12 h post mortem. At necropsy, amount of bubbles (gas score) in decomposition code 2 in stranded cetaceans was found to be more important than merely presence vs. absence of bubbles from a pathological point of view. Deep divers presented higher abundance of gas bubbles, mainly composed of 70% nitrogen and 30% CO(2), suggesting a higher predisposition of these species to suffer from decompression-related gas embolism.

  14. Acoustic streaming produced by a cylindrical bubble undergoing volume and translational oscillations in a microfluidic channel

    Science.gov (United States)

    Doinikov, Alexander A.; Combriat, Thomas; Thibault, Pierre; Marmottant, Philippe

    2016-09-01

    A theoretical model is developed for acoustic streaming generated by a cylindrical bubble confined in a fluid channel between two planar elastic walls. The bubble is assumed to undergo volume and translational oscillations. The volume oscillation is caused by an imposed acoustic pressure field and generates the bulk scattered wave in the fluid gap and Lamb-type surface waves propagating along the fluid-wall interfaces. The translational oscillation is induced by the velocity field of an external sound source such as another bubble or an oscillatory fluid flow. The acoustic streaming is assumed to result from the interaction of the volume and the translational modes of the bubble oscillations. The general solutions for the linear equations of fluid motion and the equations of acoustic streaming are calculated with no restrictions on the ratio between the viscous penetration depth and the bubble size. Approximate solutions for the limit of low viscosity are provided as well. Simulations of streamline patterns show that the geometry of the streaming resembles flows generated by a source dipole, while the vortex orientation is governed by the driving frequency, bubble size, and the distance of the bubble from the source of translational excitation. Experimental verification of the developed theory is performed using data for streaming generated by bubble pairs.

  15. Acoustic streaming produced by a cylindrical bubble undergoing volume and translational oscillations in a microfluidic channel.

    Science.gov (United States)

    Doinikov, Alexander A; Combriat, Thomas; Thibault, Pierre; Marmottant, Philippe

    2016-09-01

    A theoretical model is developed for acoustic streaming generated by a cylindrical bubble confined in a fluid channel between two planar elastic walls. The bubble is assumed to undergo volume and translational oscillations. The volume oscillation is caused by an imposed acoustic pressure field and generates the bulk scattered wave in the fluid gap and Lamb-type surface waves propagating along the fluid-wall interfaces. The translational oscillation is induced by the velocity field of an external sound source such as another bubble or an oscillatory fluid flow. The acoustic streaming is assumed to result from the interaction of the volume and the translational modes of the bubble oscillations. The general solutions for the linear equations of fluid motion and the equations of acoustic streaming are calculated with no restrictions on the ratio between the viscous penetration depth and the bubble size. Approximate solutions for the limit of low viscosity are provided as well. Simulations of streamline patterns show that the geometry of the streaming resembles flows generated by a source dipole, while the vortex orientation is governed by the driving frequency, bubble size, and the distance of the bubble from the source of translational excitation. Experimental verification of the developed theory is performed using data for streaming generated by bubble pairs.

  16. Local Measurement of Gas-Liquid Bubbly Flow with a Double-Sensor Probe

    Institute of Scientific and Technical Information of China (English)

    孙科霞; 张鸣远; 陈学俊

    2000-01-01

    A double-sensor probe was used to measure local interfacial parameters of a gas-liquid bubbly flow in a horizontal tube. The parameters included void fraction, interfacial concentration, bubble size distribution, bubble frequency and bubble interface velocity. The authors paid special attention to the probe design and construction for minimizing measurement errors. Measures were also taken in the design of sensor ends for preventing corrosions in the flow. This is an effort to improve the current double-sensor probe technique to meet the ever-increasing needs to local varameter measurements in gas-liquid two-phase flows.

  17. The rate of gas-bubble growth in tissue under decompression. Mathematical modelling.

    Science.gov (United States)

    Kislyakov YuYa; Kopyltsov, A V

    1988-03-01

    A mathematical model simulating the formation of gas bubbles in biological tissues under decompression is presented. It is written as a system of partial differential equations solved on a computer. For the nitrogen-oxygen gas mixture, used for respiration in deep-water immersions, the effects of the physico-chemical properties of the gases, the magnitude of pressure differentials and the density of bubble-formation centres on the bubble size and rate of growth were studied. It is shown that in the case of drastic pressure differentials the formation of bubbles capable of producing microcirculatory disturbances is accomplished within a few seconds.

  18. Adhesion of solid particles to gas bubbles. Part 2: Experimental

    NARCIS (Netherlands)

    Omota, Florin; Dimian, Alexandre C.; Bliek, Alfred

    2006-01-01

    In slurry bubble columns, the adhesion of solid catalyst particles to bubbles may significantly affect the G–L mass transfer and bubble size distribution. This feature may be exploited in design by modifying the hydrophilic or hydrophobic nature of the particles used. Previously we have proposed a g

  19. Contribution to irradiation creep arising from gas-driven bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Woo, C.H. [Hong Kong Polytechnic Univ., Kowloon (Hong Kong); Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    In a previous paper the relationship was defined between void swelling and irradiation creep arising from the interaction of the SIPA and SIG creep-driven deformation and swelling-driven deformation was highly interactive in nature, and that the two contributions could not be independently calculated and then considered as directly additive. This model could be used to explain the recent experimental observation that the creep-swelling coupling coefficient was not a constant as previously assumed, but declined continuously as the swelling rate increased. Such a model thereby explained the creep-disappearance and creep-damping anomalies observed in conditions where significant void swelling occurred before substantial creep deformation developed. At lower irradiation temperatures and high helium/hydrogen generation rates, such as found in light water cooled reactors and some fusion concepts, gas-filled cavities that have not yet exceeded the critical radius for bubble-void conversion should also exert an influence on irradiation creep. In this paper the original concept is adapted to include such conditions, and its predictions then compared with available data. It is shown that a measurable increase in the creep rate is expected compared to the rate found in low gas-generating environments. The creep rate is directly related to the gas generation rate and thereby to the neutron flux and spectrum.

  20. Dynamics of gas bubble growth in a supersaturated solution with Sievert's solubility law.

    Science.gov (United States)

    Gor, G Yu; Kuchma, A E

    2009-07-21

    This paper presents a theoretical description of diffusion growth of a gas bubble after its nucleation in supersaturated liquid solution. We study systems where gas molecules completely dissociate in the solvent into two parts, thus making Sievert's solubility law valid. We show that the difference between Henry's and Sievert's laws for chemical equilibrium conditions causes the difference in bubble growth dynamics. Assuming that diffusion flux is steady we obtain a differential equation on bubble radius. Bubble dynamics equation is solved analytically for the case of homogeneous nucleation of a bubble, which takes place at a significant pressure drop. We also obtain conditions of diffusion flux steadiness. The fulfillment of these conditions is studied for the case of nucleation of water vapor bubbles in magmatic melts.

  1. Linear oscillation of gas bubbles in a viscoelastic material under ultrasound irradiation

    Science.gov (United States)

    Hamaguchi, Fumiya; Ando, Keita

    2015-11-01

    Acoustically forced oscillation of spherical gas bubbles in a viscoelastic material is studied through comparisons between experiments and linear theory. An experimental setup has been designed to visualize bubble dynamics in gelatin gels using a high-speed camera. A spherical gas bubble is created by focusing an infrared laser pulse into (gas-supersaturated) gelatin gels. The bubble radius (up to 150 μm) under mechanical equilibrium is controlled by gradual mass transfer of gases across the bubble interface. The linearized bubble dynamics are studied from the observation of spherical bubble oscillation driven by low-intensity, planar ultrasound driven at 28 kHz. It follows from the experiment for an isolated bubble that the frequency response in its volumetric oscillation was shifted to the high frequency side and its peak was suppressed as the gelatin concentration increases. The measurement is fitted to the linearized Rayleigh-Plesset equation coupled with the Voigt constitutive equation that models the behavior of linear viscoelastic solids; the fitting yields good agreement by tuning unknown values of the viscosity and rigidity, indicating that more complex phenomena including shear thinning, stress relaxation, and retardation do not play an important role for the small-amplitude oscillations. Moreover, the cases for bubble-bubble and bubble-wall systems are studied. The observed interaction effect on the linearized dynamics can be explained as well by a set of the Rayleigh-Plesset equations coupled through acoustic radiation among these systems. This suggests that this experimental setup can be applied to validate the model of bubble dynamics with more complex configuration such as a cloud of bubbles in viscoelastic materials.

  2. Linear oscillation of gas bubbles in a viscoelastic material under ultrasound irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hamaguchi, Fumiya; Ando, Keita, E-mail: kando@mech.keio.ac.jp [Department of Mechanical Engineering, Keio University, Yokohama 223-8522 (Japan)

    2015-11-15

    Acoustically forced oscillation of spherical gas bubbles in a viscoelastic material is studied through comparisons between experiments and linear theory. An experimental setup has been designed to visualize bubble dynamics in gelatin gels using a high-speed camera. A spherical gas bubble is created by focusing an infrared laser pulse into (gas-supersaturated) gelatin gels. The bubble radius (up to 150 μm) under mechanical equilibrium is controlled by gradual mass transfer of gases across the bubble interface. The linearized bubble dynamics are studied from the observation of spherical bubble oscillation driven by low-intensity, planar ultrasound driven at 28 kHz. It follows from the experiment for an isolated bubble that the frequency response in its volumetric oscillation was shifted to the high frequency side and its peak was suppressed as the gelatin concentration increases. The measurement is fitted to the linearized Rayleigh–Plesset equation coupled with the Voigt constitutive equation that models the behavior of linear viscoelastic solids; the fitting yields good agreement by tuning unknown values of the viscosity and rigidity, indicating that more complex phenomena including shear thinning, stress relaxation, and retardation do not play an important role for the small-amplitude oscillations. Moreover, the cases for bubble-bubble and bubble-wall systems are studied. The observed interaction effect on the linearized dynamics can be explained as well by a set of the Rayleigh–Plesset equations coupled through acoustic radiation among these systems. This suggests that this experimental setup can be applied to validate the model of bubble dynamics with more complex configuration such as a cloud of bubbles in viscoelastic materials.

  3. Instability of interfaces of gas bubbles in liquids under acoustic excitation with dual frequency.

    Science.gov (United States)

    Zhang, Yuning; Du, Xiaoze; Xian, Haizhen; Wu, Yulin

    2015-03-01

    Instability of interfaces of gas bubbles in liquids under acoustic excitation with dual frequency is theoretically investigated. The critical bubble radii dividing stable and unstable regions of bubbles under dual-frequency acoustic excitation are strongly affected by the amplitudes of dual-frequency acoustic excitation rather than the frequencies of dual-frequency excitation. The limitation of the proposed model is also discussed with demonstrating examples.

  4. Molecular dynamics study of fission gas bubble nucleation in UO2

    Science.gov (United States)

    Liu, X.-Y.; Andersson, D. A.

    2015-07-01

    Molecular dynamics (MD) simulations are used to study helium and xenon gas bubble nucleation in UO2. For helium bubbles, the pressure release mechanism is by creating defects on the oxygen sublattice. Helium atoms diffuse away from the bubbles into nearby bulk UO2, thus forming a diffuse interface. For xenon bubbles, over-pressurized bubbles containing xenon can displace uranium atoms, which tend to aggregate around the xenon bubble as a pressure release mechanism. MD simulations of xenon atoms in pre-existing voids suggest that xenon atoms and the replaced uranium atoms occur in a 1:1 ratio, although kinetic factors may reduce that ratio depending on availability of xenon atoms and vacancies around the bubble. Finally, MD simulations suggest that for small bubbles (1-5 xenon atoms), the xenon bubble nucleus at UO2 grain-boundaries has much lower formation energy compared to that of bubbles of similar sizes in the bulk. However, when the xenon bubble grows into larger sizes, this energy difference is reduced.

  5. Influence of small amounts of additives on gas hold-up, bubble size, and interfacial area

    NARCIS (Netherlands)

    Cents, A. H. G.; Jansen, D. J. W.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    The gas-liquid interfacial area, which is determined by the gas hold-up and the Sauter mean bubble diameter, determines the production rate in many industrial processes. The effect of additives on this interfacial area is, especially in multiphase systems (gas-liquid-solid, gas-liquid-liquid), often

  6. Influence of small amounts of additives on gas hold-up, bubble size, and interfacial area

    NARCIS (Netherlands)

    Cents, A. H. G.; Jansen, D. J. W.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    The gas-liquid interfacial area, which is determined by the gas hold-up and the Sauter mean bubble diameter, determines the production rate in many industrial processes. The effect of additives on this interfacial area is, especially in multiphase systems (gas-liquid-solid, gas-liquid-liquid), often

  7. Kinetic energy and added mass of hydrodynamically interacting gas bubbles in liquid

    NARCIS (Netherlands)

    Kok, Jacobus B.W.

    1988-01-01

    By averaging the basic equations on microscale, expressions are derived for the effective added mass density and the kinetic energy density of a mixture of liquid and gas bubbles. Due to hydrodynamic interaction between the bubbles there appears to be a difference between the effective added mass

  8. Eulerian modeling of reactive gas-liquid flow in a bubble column

    NARCIS (Netherlands)

    Zhang, D.

    2007-01-01

    Despite the widespread application of bubble columns and intensive research efforts devoted to understand their complex behavior, detailed knowledge on the fluid flow, mass transfer and chemical reactions as well as their interactions is currently very limited. Gas-liquid flow in bubble column

  9. Eulerian modeling of reactive gas-liquid flow in a bubble column

    NARCIS (Netherlands)

    Zhang, Dongsheng

    2007-01-01

    Despite the widespread application of bubble columns and intensive research efforts devoted to understand their complex behavior, detailed knowledge on the fluid flow, mass transfer and chemical reactions as well as their interactions is currently very limited. Gas-liquid flow in bubble column react

  10. Bubble composition of natural gas seeps discovered along the Cascadia Continental Margin

    Science.gov (United States)

    Baumberger, T.; Merle, S. G.; Embley, R. W.; Seabrook, S.; Raineault, N.; Lilley, M. D.; Evans, L. J.; Walker, S. L.; Lupton, J. E.

    2016-12-01

    Gas hydrates and gas-filled pockets present in sedimentary deposits have been recognized as large reservoirs for reduced carbon in the Earth's crust. This is particularly relevant in geological settings with high carbon input, such as continental margins. During expedition NA072 on the E/V Nautilus (operated by the Ocean Exploration Trust Inc.) in June 2016, the U.S. Cascadia Continental Margin (Washington, Oregon and northern California) was explored for gas seepage from sediments. During this expedition, over 400 bubble plumes at water depths ranging from 125 and 1640 m were newly discovered, and five of them were sampled for gas bubble composition using specially designed gas tight fluid samplers mounted on the Hercules remotely operated vehicle (ROV). These gas bubble samples were collected at four different depths, 494 m (rim of Astoria Canyon), 615 and 620 m (SW Coquille Bank), 849 m (floor of Astoria Canyon) and 1227 m (Heceta SW). At the two deeper sites, exposed hydrate was present in the same area where bubbles were seeping out from the seafloor. Other than the escaping gas bubbles, no other fluid flow was visible. However, the presence of bacterial mats point to diffuse fluid flow present in the affected area. In this study we present the results of the currently ongoing geochemical analysis of the gas bubbles released at the different sites and depths. Noble gas analysis, namely helium and neon, will give information about the source of the helium as well as about potential fractionation between helium and neon associated with gas hydrates. The characterization of these gas samples will also include total gas (CO2, H2, N2, O2, Ar, CH4 and other hydrocarbons) and stable isotope analysis (C and H). This dataset will reveal the chemical composition of the seeping bubbles as well as give information about the possible sources of the carbon contained in the seeping gas.

  11. Evidence of injury caused by gas bubbles in a live marine mammal: barotrauma in a California sea lion Zalophus californianus.

    Science.gov (United States)

    Van Bonn, W; Montie, E; Dennison, S; Pussini, N; Cook, P; Greig, D; Barakos, J; Colegrove, K; Gulland, F

    2011-09-09

    A yearling male California sea lion Zalophus californianus with hypermetric ataxia and bilateral negative menace reflexes was brought to The Marine Mammal Center, Sausalito, California, U.S.A., in late 2009 for medical assessment and treatment. The clinical signs were due to multiple gas bubbles within the cerebellum. These lesions were intraparenchymal, multifocal to coalescing, spherical to ovoid, and varied from 0.5 to 2.4 cm diameter. The gas composed 21.3% of the total cerebellum volume. Three rib fractures were also noted during diagnostic evaluation and were presumed to be associated with the gas bubbles in the brain. The progression of clinical signs and lesion appearance were monitored with magnetic resonance imaging, cognitive function testing and computed tomography. Gas filled voids in the cerebellum were filled with fluid on follow up images. Clinical signs resolved and the sea lion was released with a satellite tag attached. Post release the animal travelled approximately 75 km north and 80 km south of the release site and the tag recorded dives of over 150 m depth. The animal re-stranded 25 d following release and died of a subacute bronchopneumonia and pleuritis. This is the first instance of clinical injury due to gas bubble formation described in a living pinniped and the first sea lion with quantifiable cerebellar damage to take part in spatial learning and memory testing.

  12. A Study of Bubble and Slug Gas-Liquid Flow in a Microgravity Environment

    Science.gov (United States)

    McQuillen, J.

    2000-01-01

    The influence of gravity on the two-phase flow dynamics is obvious.As the gravity level is reduced,there is a new balance between inertial and interfacial forces, altering the behavior of the flow. In bubbly flow,the absence of drift velocity leads to spherical-shaped bubbles with a rectilinear trajectory.Slug flow is a succession of long bubbles and liquid slug carrying a few bubbles. There is no flow reversal in the thin liquid film as the long bubble and liquid slug pass over the film. Although the flow structure seems to be simpler than in normal gravity conditions,the models developed for the prediction of flow behavior in normal gravity and extended to reduced gravity flow are unable to predict the flow behavior correctly.An additional benefit of conducting studies in microgravity flows is that these studies aide the development of understanding for normal gravity flow behavior by removing the effects of buoyancy on the shape of the interface and density driven shear flows between the gas and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated bubbles in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated bubbles and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the bubbles in accelerated or decelerated flows,and the dynamics of isolated cylindrical bubbles, their deformation in accelerated/decelerated flows (in converging or diverging channels), and bubble/bubble interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical bubble and single and two cylindrical bubble behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of bubbly and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from bubbly to slug flow (effect of fluid properties and

  13. Alma Observations of Massive Molecular Gas Filaments Encasing Radio Bubbles in the Phoenix Cluster

    Science.gov (United States)

    Russell, H. R.; McDonald, M.; McNamara, B. R.; Fabian, A. C.; Nulsen, P. E. J.; Bayliss, M. B.; Benson, B. A.; Brodwin, M.; Carlstrom, J. E.; Edge, A. C.; Hlavacek-Larrondo, J.; Marrone, D. P.; Reichardt, C. L.; Vieira, J. D.

    2017-02-01

    We report new ALMA observations of the CO(3-2) line emission from the 2.1+/- 0.3× {10}10 {M}ȯ molecular gas reservoir in the central galaxy of the Phoenix cluster. The cold molecular gas is fueling a vigorous starburst at a rate of 500{--}800 {M}ȯ {{yr}}-1 and powerful black hole activity in the forms of both intense quasar radiation and radio jets. The radio jets have inflated huge bubbles filled with relativistic plasma into the hot, X-ray atmospheres surrounding the host galaxy. The ALMA observations show that extended filaments of molecular gas, each 10{--}20 {kpc} long with a mass of several billion solar masses, are located along the peripheries of the radio bubbles. The smooth velocity gradients and narrow line widths along each filament reveal massive, ordered molecular gas flows around each bubble, which are inconsistent with gravitational free-fall. The molecular clouds have been lifted directly by the radio bubbles, or formed via thermal instabilities induced in low-entropy gas lifted in the updraft of the bubbles. These new data provide compelling evidence for close coupling between the radio bubbles and the cold gas, which is essential to explain the self-regulation of feedback. The very feedback mechanism that heats hot atmospheres and suppresses star formation may also paradoxically stimulate production of the cold gas required to sustain feedback in massive galaxies.

  14. History effects on the gas exchange between a bubble and a liquid

    Science.gov (United States)

    Chu, Shigan; Prosperetti, Andrea

    2016-11-01

    History effects are a distinctive feature of diffusive processes. For a diffusing gas bubble at rest in a liquid, such effects arise when the concentration of dissolved gas at the bubble surface, connected to the gas pressure by Henry's law, depends on time. This time dependence can be caused by several factors, such as varying ambient pressure, mole fraction in a multicomponent gas bubble, surface tension and others. In this study we consider history effects in the three situations mentioned above. More specifically, rectified diffusion in an oscillating ambient pressure field is explored under conditions when the diffusion length is larger than the bubble radius. History effects are found to be important in determining the threshold conditions for rectified diffusion. In contrast, history effects are small in the other two cases. Supported by the BP/The Gulf of Mexico Research Initiative through the University of Texas Marine Science Institute (DROPPS II consortium: "Dispersion Research on Oil: Physics and Plankton Studies").

  15. Vesicularity, bubble formation and noble gas fractionation during MORB degassing

    CERN Document Server

    Aubry, G; Guillot, B

    2013-01-01

    The objective of this study is to use molecular dynamics simulation (MD) to evaluate the vesicularity and noble gas fractionation, and to shed light on bubble formation during MORB degassing. A previous simulation study (Guillot and Sator (2011) GCA 75, 1829-1857) has shown that the solubility of CO2 in basaltic melts increases steadily with the pressure and deviates significantly from Henry's law at high pressures (e.g. 9.5 wt% CO2 at 50 kbar as compared with 2.5 wt% from Henry's law). From the CO2 solubility curve and the equations of state of the two coexisting phases (silicate melt and supercritical CO2), deduced from the MD simulation, we have evaluated the evolution of the vesicularity of a MORB melt at depth as function of its initial CO2 contents. An excellent agreement is obtained between calculations and data on MORB samples collected at oceanic ridges. Moreover, by implementing the test particle method (Guillot and Sator (2012) GCA 80, 51-69), the solubility of noble gases in the two coexisting pha...

  16. Gas diffusion and temperature dependence of bubble nucleation during irradiation

    DEFF Research Database (Denmark)

    Foreman, A. J. E.; Singh, Bachu Narain

    1986-01-01

    of the diatomic nucleation of helium bubbles, assuming helium to diffuse substitutionally, with radiation-enhanced diffusion at lower temperatures. The calculated temperature dependence of the bubble density shows excellent agreement with that observed in 600 MeV proton irradiations, including a reduction...

  17. Dissolved and Bubble Gas Concentrations in Sandy Surficial Sediments of the West Florida Sand Sheet

    Science.gov (United States)

    2016-06-21

    Dissolved and Bubble Gas Concentrations in Sandy Surficial Sediments of the West Florida Sand Sheet Christopher Martens Dept. of Marine Sciences CB...TITLE AND SUBTITLE Dissolved and Bubble Gas Concentrations in Sandy Surficial Sediments of the West Florida Sand Sheet 5a. CONTRACT NUMBER 5b. GRANT...was noted that there was substantially higher organic material in the shallow troughs of the sand ripples than on the crests. Most of this appears

  18. Two-Dimensional Numerical Simulations of Ultrasound in Liquids with Gas Bubble Agglomerates: Examples of Bubbly-Liquid-Type Acoustic Metamaterials (BLAMMs).

    Science.gov (United States)

    Vanhille, Christian

    2017-01-17

    This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding gas bubbles of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and several monodisperse bubble populations confined in restricted areas of a liquid have on ultrasound by calculating their nonlinear interaction. The filtering of an input ultrasonic pulse performed by a net of bubbly-liquid cells is analyzed. The generation of a low-frequency component from a single cell impinged by a two-frequency harmonic wave is also studied. These effects rely on the particular dispersive character of attenuation and nonlinearity of such bubbly fluids, which can be extremely high near bubble resonance. They allow us to observe how gas bubbles can change acoustic signals. Variations of the bubbly medium parameters induce alterations of the effects undergone by ultrasound. Results suggest that acoustic signals can be manipulated by bubbles. This capacity to achieve the modification and control of sound with oscillating gas bubbles introduces the concept of bubbly-liquid-based acoustic metamaterials (BLAMMs).

  19. The influence of polymeric membrane gas spargers on hydrodynamics and mass transfer in bubble column bioreactors.

    Science.gov (United States)

    Tirunehe, Gossaye; Norddahl, B

    2016-04-01

    Gas sparging performances of a flat sheet and tubular polymeric membranes were investigated in 3.1 m bubble column bioreactor operated in a semi batch mode. Air-water and air-CMC (Carboxymethyl cellulose) solutions of 0.5, 0.75 and 1.0 % w/w were used as interacting gas-liquid mediums. CMC solutions were employed in the study to simulate rheological properties of bioreactor broth. Gas holdup, bubble size distribution, interfacial area and gas-liquid mass transfer were studied in the homogeneous bubbly flow hydrodynamic regime with superficial gas velocity (U(G)) range of 0.0004-0.0025 m/s. The study indicated that the tubular membrane sparger produced the highest gas holdup and densely populated fine bubbles with narrow size distribution. An increase in liquid viscosity promoted a shift in bubble size distribution to large stable bubbles and smaller specific interfacial area. The tubular membrane sparger achieved greater interfacial area and an enhanced overall mass transfer coefficient (K(L)a) by a factor of 1.2-1.9 compared to the flat sheet membrane.

  20. Prospects for bubble fusion

    Energy Technology Data Exchange (ETDEWEB)

    Nigmatulin, R.I. [Tyumen Institute of Mechanics of Multiphase Systems (TIMMS), Marx (Russian Federation); Lahey, R.T. Jr. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1995-09-01

    In this paper a new method for the realization of fusion energy is presented. This method is based on the superhigh compression of a gas bubble (deuterium or deuterium/thritium) in heavy water or another liquid. The superhigh compression of a gas bubble in a liquid is achieved through forced non-linear, non-periodic resonance oscillations using moderate amplitudes of forcing pressure. The key feature of this new method is a coordination of the forced liquid pressure change with the change of bubble volume. The corresponding regime of the bubble oscillation has been called {open_quotes}basketball dribbling (BD) regime{close_quotes}. The analytical solution describing this process for spherically symmetric bubble oscillations, neglecting dissipation and compressibility of the liquid, has been obtained. This solution shown no limitation on the supercompression of the bubble and the corresponding maximum temperature. The various dissipation mechanisms, including viscous, conductive and radiation heat losses have been considered. It is shown that in spite of these losses it is possible to achieve very high gas bubble temperatures. This because the time duration of the gas bubble supercompression becomes very short when increasing the intensity of compression, thus limiting the energy losses. Significantly, the calculated maximum gas temperatures have shown that nuclear fusion may be possible. First estimations of the affect of liquid compressibility have been made to determine possible limitations on gas bubble compression. The next step will be to investigate the role of interfacial instability and breaking down of the bubble, shock wave phenomena around and in the bubble and mutual diffusion of the gas and the liquid.

  1. Effects of Orifice Orientation and Gas-Liquid Flow Pattern on Initial Bubble Size

    Institute of Scientific and Technical Information of China (English)

    刘长军; 梁斌; 唐盛伟; 闵恩泽

    2013-01-01

    In many gas-liquid processes, the initial bubble size is determined by a series of operation parameters along with the sparger design and gas-liquid flow pattern. Bubble formation models for variant gas-liquid flow pat-terns have been developed based on force balance. The effects of the orientation of gas-liquid flow, gas velocity, liquid velocity and orifice diameter on the initial bubble size have been clarified. In ambient air-water system, the suitable gas-liquid flow pattern is important to obtain smaller bubbles under the low velocity liquid cross-flow con-ditions with stainless steel spargers. Among the four types of gas-liquid flow patterns discussed, the horizontal orifice in a vertically upward liquid flow produces the smallest initial bubbles. However the orientation effects of gas and liquid flow are found to be insignificant when liquid velocity is higher than 3.2 m·s-1 or the orifice diameter is small enough.

  2. Characterization of gas transfer and mixing in a bubble column equipped with a rubber membrane diffuser

    Science.gov (United States)

    Poulsen; Iversen

    1998-06-20

    Gas transfer and mixing were characterized in a 32-L bubble column reactor equipped with a commercially available rubber membrane diffuser. The performance of the membrane diffuser indicates that the slits in the membrane are best described as holes with elastic lids, acting as valves cutting off bubbles from the gas stream. The membrane diffuser thus functions as a one-way valve preventing backflow of liquid. Our design of the bottom plate of the reactor enabled us to optimize the aeration by changing the tension of the membrane. We thereby achieved mass transfer coefficients higher than those previously reported in bubble columns. A strong dependence of mass transfer on gas holdup and bubble size was indicated by estimates based on these two variables. The microalga, Rhodomonas sp. , sensitive to chemical and physical stress, was maintained for 8 months in continuous culture with a productivity identical to cultures grown in stirred tank reactors. Copyright 1998 John Wiley & Sons, Inc.

  3. Effect of grain morphology on gas bubble swelling in UMo fuels – A 3D microstructure dependent Booth model

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang; Burkes, Douglas; Lavender, Curt A.; Joshi, Vineet

    2016-11-01

    A three dimensional microstructure dependent swelling model is developed for studying the fission gas swelling kinetics in irradiated nuclear fuels. The model is extended from the Booth model [1] in order to investigate the effect of heterogeneous microstructures on gas bubble swelling kinetics. As an application of the model, the effect of grain morphology, fission gas diffusivity, and spatial dependent fission rate on swelling kinetics are simulated in UMo fuels. It is found that the decrease of grain size, the increase of grain aspect ratio for the grain having the same volume, and the increase of fission gas diffusivity (fission rate) cause the increase of swelling kinetics. Other heterogeneities such as second phases and spatial dependent thermodynamic properties including diffusivity of fission gas, sink and source strength of defects could be naturally integrated into the model to enhance the model capability.

  4. Effect of Orifice Diameter on Bubble Generation Process in Melt Gas Injection to Prepare Aluminum Foams

    Science.gov (United States)

    Yuan, Jianyu; Li, Yanxiang; Wang, Ningzhen; Cheng, Ying; Chen, Xiang

    2016-06-01

    The bubble generation process in conditioned A356 alloy melt through submerged spiry orifices with a wide diameter range (from 0.07 to 1.0 mm) is investigated in order to prepare aluminum foams with fine pores. The gas flow rate and chamber pressure relationship for each orifice is first determined when blowing gas in atmospheric environment. The effects of chamber pressure ( P c) and orifice diameter ( D o) on bubble size are then analyzed separately when blowing gas in melt. A three-dimensional fitting curve is obtained illustrating both the influences of orifice diameter and chamber pressure on bubble size based on the experimental data. It is found that the bubble size has a V-shaped relationship with orifice diameter and chamber pressure neighboring the optimized parameter ( D o = 0.25 mm, P c = 0.4 MPa). The bubble generation mechanism is proposed based on the Rayleigh-Plesset equation. It is found that the bubbles will not be generated until a threshold pressure difference is reached. The threshold pressure difference is dependent on the orifice diameter, which determines the time span of pre-formation stage and bubble growth stage.

  5. The Real—gas Effect in Single—bubble Sonoluminescence

    Institute of Scientific and Technical Information of China (English)

    LiYUAN; WeiWEI; 等

    1999-01-01

    The full set of hydrodynamic equations governing the oscilltion of a bubble is solved nomerically by using a modified equation of state with ionization.We show that the hydro-thermal process in the form of compression waves and low-level ionization are dominant inside a sonoluminescing bubble for a wide range of driving pressure.The resulting thermal bremsstrahlung radiation has pulse heights and widths that agree with experimental data for cases considered in this paper.

  6. N131: A dust bubble was born from the disruption of a gas filament?

    Science.gov (United States)

    Zhang, Chuan-Peng

    2017-03-01

    N131 is an infrared dust bubble residing in a molecular filament. We aim to study the formation and fragmentation of this bubble with multi-wavelength dust and gas observations. Towards the bubble N131, we analyzed archival multi-wavelength observations including 3.6, 4.5, 5.8, 8.0, 24, 70, 160, 250, 350, 500 μm, 1.1 mm, and 21 cm. In addition, we performed new observations of CO (2-1), CO (1-0), and 13CO (1-0) with the IRAM 30-m telescope. Multi-wavelength dust and gas observations reveal a ringlike shell with compact fragments, two filamentary structures, and a secondary bubble N131-A. The bubble N131 is a rare object with a large hole at 24 μm and 21 cm in the direction of its center. The dust and gas clumps are compact and might have been compressed at the inner edge of the ringlike shell, while they are extended and might be pre-existing at the outer edge. The column density, excitation temperature, and velocity show a potentially hierarchical distribution from the inner to outer edge of the ringlike shell. We also detected the front and back sides of the secondary bubble N131-A in the direction of its center. The derived Lyman-continuum ionizing photon flux within N131-A is equivalent to an O9.5 star. Based on the above, we suggest that the bubble N131 might be triggered by the strong stellar winds from a group of massive stars inside the bubble. We propose a scenario in which the bubble N131 forms from the disruption of a gas filament by expansion of H II region, strong stellar winds, and fragments under self-gravity.

  7. The role of bubbles during air-sea gas exchange

    Science.gov (United States)

    Emerson, Steven; Bushinsky, Seth

    2016-06-01

    The potential for using the air-sea exchange rate of oxygen as a tracer for net community biological production in the ocean is greatly enhanced by recent accuracy improvements for in situ measurements of oxygen on unmanned platforms. A limiting factor for determining the exchange process is evaluating the air-sea flux contributed by bubble processes produced by breaking waves, particularly during winter months under high winds. Highly accurate measurements of noble gases (Ne, Ar & Kr) and nitrogen, N2, in seawater are tracers of the importance of bubble process in the surface mixed layer. We use measured distributions of these gases in the ventilated thermocline of the North Pacific and an annual time series of N2 in the surface ocean of the NE Subarctic Pacific to evaluate four different air-water exchange models chosen to represent the range of model interpretation of bubble processes. We find that models must have an explicit bubble mechanism to reproduce concentrations of insoluble atmospheric gases, but there are periods when they all depart from observations. The recent model of Liang et al. (2013) stems from a highly resolved model of bubble plumes and categorizes bubble mechanisms into those that are small enough to collapse and larger ones that exchange gases before they resurface, both of which are necessary to explain the data.

  8. Distributions of crystals and gas bubbles in reservoir ice during winter growth period

    Directory of Open Access Journals (Sweden)

    Zhi-jun LI

    2011-06-01

    Full Text Available In order to understand the dominant factors of ice physical properties for ice thermodynamics and mechanics, in-situ observations of ice growth and decay processes were carried out. Two samplings were done, in the stages of fast ice growth and steady ice growth. These ice samples were used to observe ice crystals and gas bubbles in ice, and to measure ice density. Vertical profiles of the ice crystal type, ice crystal size, gas bubble shape and size, gas bubble content, as well as ice density were ontained. The results reveal that the upper part of the samples is granular ice and the lower part is columnar ice, the average grain size increases along ice depth and keeps steady within fast and steady ice growth stages; the shape of gas bubbles in ice upper layer is spherical with higher total content, and the shape in the middle and lower layers is cylinder with lower total content; the gas bubble size and content are active along with the ice growth stage; ice density decreases with the gas content increasing.

  9. Bubble dynamics in a two-dimensional gas-solid fluidized bed

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Related referential studies on gas-solid two-phase flows were briefly reviewed. Bubble ascending in a two-dimensional (2D) gas-solid fluidized bed was studied both experimentally and numerically. A modified continuum model expressed in the conservation form was used in numerical simulation. Solid-phase pressure was modeled via local sound speed; gas-phase turbulence was described by the K-ε two-equation model. The modified implicit multiphase formulation (IMF) scheme was used to solve the model equations in 2D Cartesian/cylindrical coordinates. The bubble ascending velocity and particle motion in the 2D fluidized bed were measured using the photochromic dye activation (PDA) technique, which was based on UV light activation of particles impregnated with the dye. Effects of bed height and superficial gas velocity on bubble formation and ascent were investigated numerically. The numerically obtained bubble ascending velocities were compared with experimental measurements. Gas bubble in jetting gas-solids fluidized bed was also simulated numerically.

  10. Vapor-Gas Bubble Evolution and Growth in Extremely Viscous Fluids Under Vacuum

    Science.gov (United States)

    Kizito, John; Balasubramaniam, R.; Nahra, Henry; Agui, Juan; Truong, Duc

    2008-01-01

    Formation of vapor and gas bubbles and voids is normal and expected in flow processes involving extremely viscous fluids in normal gravity. Practical examples of extremely viscous fluids are epoxy-like filler materials before the epoxy fluids cure to their permanent form to create a mechanical bond between two substrates. When these fluids flow with a free liquid interface exposed to vacuum, rapid bubble expansion process may ensue. Bubble expansion might compromise the mechanical bond strength. The potential sources for the origin of the gases might be incomplete out-gassing process prior to filler application; regasification due to seal leakage in the filler applicator; and/or volatiles evolved from cure reaction products formed in the hardening process. We embarked on a study that involved conducting laboratory experiments with imaging diagnostics in order to deduce the seriousness of bubbling caused by entrained air and volatile fluids under space vacuum and low gravity environment. We used clear fluids with the similar physical properties as the epoxy-like filler material to mimic the dynamics of bubbles. Another aspect of the present study was to determine the likelihood of bubbling resulting from dissolved gases nucleating from solution. These experimental studies of the bubble expansion are compared with predictions using a modified Rayleigh- Plesset equation, which models the bubble expansion.

  11. Mechanisms for Oscillations in Volume of Single Spherical Bubble Due to Sound Excitation in Water

    Institute of Scientific and Technical Information of China (English)

    REN Sheng; ZHANG Jia-Zhong; LI Kai-Lun

    2012-01-01

    Mechanisms for the evolution of a single spherical bubble subjected to sound excitation in water are studied from the viewpoint of nonlinear dynamics. First, the shooting method is combined with a Poincare map to obtain the fixed point for the case of forced oscillation in volume. Then, the stabilities are judged by Floquet theory and the bifurcation theorem. Moreover, the transitions of bubble oscillation in volume due to sound excitation in water are explained from the viewpoint of nonlinear dynamics in detail. The results show that with an increase in sound frequency, the period-1 oscillation becomes unstable, and oscillation behaves in a double-periodic manner, then a quasi-periodic manner, and finally chaotically. Additionally, with an increase of the amplitude of the sound pressure, the bubble eventually oscillates with chaos via a series of period-doubling bifurcations.%Mechanisms for the evolution of a single spherical bubble subjected to sound excitation in water are studied from the viewpoint of nonlinear dynamics.First,the shooting method is combined with a Poincaré map to obtain the fixed point for the case of forced oscillation in volume.Then,the stabilities are judged by Floquet theory and the bifurcation theorem.Moreover,the transitions of bubble oscillation in volume due to sound excitation in water are explained from the viewpoint of nonlinear dynamics in detail.The results show that with an increase in sound frequency,the period-1 oscillation becomes unstable,and oscillation behaves in a double-periodic manner,then a quasi-periodic manner,and finally chaotically.Additionally,with an increase of the amplitude of the sound pressure,the bubble eventually oscillates with chaos via a series of period-doubling bifurcations.

  12. A THEORETICAL-MODEL FOR THE INFLUENCE OF GAS PROPERTIES AND PRESSURE ON SINGLE-BUBBLE FORMATION AT AN ORIFICE

    NARCIS (Netherlands)

    WILKINSON, PM; VANDIERENDONCK, LL

    1994-01-01

    A number of authors have on the basis of experiments determined that pressure and gas density can have an influence on bubble formation size. Usually this influence is attributed to the gas momentum force, generated by gas flowing into the bubble during its formation. In this article the theoretical

  13. Gas-Liquid Mass Transfer in a Slurry Bubble Column Reactor under High Temperature and

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gas-liquid mass transfer of H2 and CO in a high temperature and high-pressure three-phase slurry bubble column reactor is studied. The gas-liquid volumetric mass transfer coefficients κLα are obtained by measuring the dissolution rate of H2 and CO. The influences of the main operation conditions, such as temperature, pressure, superficial gas velocity and solid concentration, are studied systematically. Two empirical correlations are proposed to predict κLα values for H2 and CO in liquid paraffin/solid particles slurry bubble column reactors.

  14. Algebraic model for bubble tracking in horizontal gas-liquid flow

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Felipe G.C. de; Tisserant, Hendy R. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Morales, Rigoberto E.M. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica e de Materiais; Mazza, Ricardo A.; Rosa, Eugenio S. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica

    2008-07-01

    The current work extends the concept of unit-cell applied in gas-liquid slug flow models to predict the evolution of the gas and liquid flow properties along a horizontal pipe. The motivation of this model is its simplicity, easiness of application and low computational cost. It is a useful tool of reference data generation in order to check the consistency of numerical slug tracking models. The potential of the model is accessed by comparing the gas bubbles and liquid slug sizes, the translational bubble velocity and the pressure drop against experimental data. (author)

  15. Notes on radial oscillations of gas bubbles in liquids: thermal effects.

    Science.gov (United States)

    Zhang, Yuning; Li, S C

    2010-11-01

    For oscillations of gas bubbles in liquids, the polytropic exponent and thermal damping constant for the high frequency region have been re-evaluated based on the framework by Prosperetti [J. Acoust. Soc. Am. 61, 17-27 (2007)]. It is seen that the approximation of G(1)≪ 1 in Prosperetti (1977) should be dropped for G(1)≥ 10(-2). The ratios of bubble radii to wavelengths are the paramount parameters categorizing the behavior into three different regions.

  16. Gas Bubble Disease Monitoring and Research of Juvenile Salmonids : Annual Report 1996.

    Energy Technology Data Exchange (ETDEWEB)

    Maule, Alec G.; Beeman, John W.; Hans, Karen M.; Mesa, M.G.; Haner, P.; Warren, J.J. [Geological Survey, Cook, WA (United States). Columbia River Research Lab.

    1997-10-01

    This document describes the project activities 1996--1997 contract year. This report is composed of three chapters which contain data and analyses of the three main elements of the project: field research to determine the vertical distribution of migrating juvenile salmonids, monitoring of juvenile migrants at dams on the Snake and Columbia rivers, and laboratory experiments to describe the progression of gas bubble disease signs leading to mortality. The major findings described in this report are: A miniature pressure-sensitive radio transmitter was found to be accurate and precise and, after compensation for water temperature, can be used to determine the depth of tagged-fish to within 0.32 m of the true depth (Chapter 1). Preliminary data from very few fish suggest that depth protects migrating juvenile steelhead from total dissolved gas supersaturation (Chapter 1). As in 1995, few fish had any signs of gas bubble disease, but it appeared that prevalence and severity increased as fish migrated downstream and in response to changing gas supersaturation (Chapter 2). It appeared to gas bubble disease was not a threat to migrating juvenile salmonids when total dissolved gas supersaturation was < 120% (Chapter 2). Laboratory studies suggest that external examinations are appropriate for determining the severity of gas bubble disease in juvenile salmonids (Chapter 3). The authors developed a new method for examining gill arches for intravascular bubbles by clamping the ventral aorta to reduce bleeding when arches were removed (Chapter 3). Despite an outbreak of bacterial kidney disease in the experimental fish, the data indicate that gas bubble disease is a progressive trauma that can be monitored (Chapter 3).

  17. Shadow imaging in bubbly gas-liquid two-phase flow in porous structures

    Science.gov (United States)

    Altheimer, Marco; Häfeli, Richard; Wälchli, Carmen; Rudolf von Rohr, Philipp

    2015-09-01

    Shadow imaging is used for the investigation of bubbly gas-liquid two-phase flow in a porous structure. The porous structure is made of Somos WaterShed XC 11122, a clear epoxy resin used in rapid prototyping. Optical access is provided by using an aqueous solution of sodium iodide and zinc iodide having the same refractive index as the structure material (). Nitrogen is injected into the continuous phase at volumetric transport fractions in the range of resulting in a hold-up of . The obtained images of overlapping bubble shadows are processed to measure the bubble dimensions. Therefore, a new processing sequence is developed to determine bubble dimensions from overlapping bubble shadows by ellipse fitting. The accuracy of the bubble detection and sizing routine is assessed processing synthetic images. It is shown that the developed technique is suitable for volumetric two-phase flow measurements. Important global quantities such as gas hold-up and total interfacial area can be measured with only one camera. Operation parameters for gas-liquid two-phase flows are determined to improve mass and heat transfer between the phases.

  18. Vapor Bubbles

    Science.gov (United States)

    Prosperetti, Andrea

    2017-01-01

    This article reviews the fundamental physics of vapor bubbles in liquids. Work on bubble growth and condensation for stationary and translating bubbles is summarized and the differences with bubbles containing a permanent gas stressed. In particular, it is shown that the natural frequency of a vapor bubble is proportional not to the inverse radius, as for a gas bubble, but to the inverse radius raised to the power 2/3. Permanent gas dissolved in the liquid diffuses into the bubble with strong effects on its dynamics. The effects of the diffusion of heat and mass on the propagation of pressure waves in a vaporous bubbly liquid are discussed. Other topics briefly touched on include thermocapillary flow, plasmonic nanobubbles, and vapor bubbles in an immiscible liquid.

  19. Bubble Clouds in Coastal Waters and Their Role in Air-Water Gas Exchange of CO2

    Directory of Open Access Journals (Sweden)

    Joseph R. Crosswell

    2015-08-01

    Full Text Available Bubbles generated by breaking waves can drive significant gas exchange between the ocean and atmosphere, but the role of bubble-mediated gas transfer in estuaries is unknown. Here, backscatter data from 41 acoustic Doppler current profiler stations was analyzed to assess subsurface bubble distributions in nine estuaries along the U.S. East and Gulf Coast. Wind speed, wind direction, and current velocity were the dominant controls on bubble entrainment, but the relative importance of these physical drivers depended on local geomorphology. Bubble entrainment in high-current or shallow, long-fetch estuaries began at wind speeds <5 m s−1. In deep or fetch-limited estuaries, bubble entrainment was less frequent and generally began at higher wind speeds. Data observed during several storms suggests that episodic bubble-driven gas exchange may be an important component of annual CO2 fluxes in large, shallow estuaries but would be less significant in other coastal systems.

  20. On the role of sea-state in bubble-mediated air-sea gas flux during a winter storm

    Science.gov (United States)

    Liang, Jun-Hong; Emerson, Steven R.; D'Asaro, Eric A.; McNeil, Craig L.; Harcourt, Ramsey R.; Sullivan, Peter P.; Yang, Bo; Cronin, Meghan F.

    2017-04-01

    Oceanic bubbles play an important role in the air-sea exchange of weakly soluble gases at moderate to high wind speeds. A Lagrangian bubble model embedded in a large eddy simulation model is developed to study bubbles and their influence on dissolved gases in the upper ocean. The transient evolution of mixed-layer dissolved oxygen and nitrogen gases at Ocean Station Papa (50°N, 145°W) during a winter storm is reproduced with the model. Among different physical processes, gas bubbles are the most important in elevating dissolved gas concentrations during the storm, while atmospheric pressure governs the variability of gas saturation anomaly (the relative departure of dissolved gas concentration from the saturation concentration). For the same wind speed, bubble-mediated gas fluxes are larger during rising wind with smaller wave age than during falling wind with larger wave age. Wave conditions are the primary cause for the bubble gas flux difference: when wind strengthens, waves are less-developed with respect to wind, resulting in more frequent large breaking waves. Bubble generation in large breaking waves is favorable for a large bubble-mediated gas flux. The wave-age dependence is not included in any existing bubble-mediated gas flux parameterizations.

  1. Effects of air bubbles and tube transportation on blood oxygen tension in arterial blood gas analysis.

    Science.gov (United States)

    Lu, Jin Ying; Kao, Jau Tsuen; Chien, Tzu I; Lee, Tai Fen; Tsai, Keh Sung

    2003-04-01

    Pneumatic tube transport has been reported to aggravate the error in partial pressure of oxygen (PO(2)) measurements caused by air bubbles. The aim of this study was to clarify the effect of manual and pneumatic tube methods of sample transportation and different amounts of air bubbles on arterial blood gas analysis. Blood gas samples from 15 patients and a pooled wasted blood mixture with 3 different levels of PO(2) were analyzed to determine the effects of air bubbles and manual versus pneumatic tube transportation on PO(2) levels. PO(2) increased significantly in samples containing 10% air bubbles and was exaggerated by pneumatic tube transport (from 115.63 +/- 9.31 mm Hg to 180.51 +/- 11.29 mm Hg, p transportation or the amount of air bubbles contained in the specimen. However, in samples with medium and high PO(2) (> 70 mm Hg), aberrances in measurements were noted even with only 0.5% air bubbles and regardless of whether the sample was transported by manual methods or pressurized tube. The increments of PO(2) correlated positively with the amount of air introduced into the specimens. Thus, the measured PO(2) increased 8.13 and 31.77 mm Hg when 0.5% and 10% air bubbles were introduced, respectively, to samples with medium PO(2) (p transportation was significant (p gas analysis should be carried in ambient pressure to the laboratory because pneumatic tube delivery systems significantly aggravate the air bubble-related aberrance in PO(2) measurement.

  2. A COUPLING MODEL OF WATER FLOWS AND GAS FLOWS IN EXHAUSTED GAS BUBBLE ON MISSILE LAUNCHED UNDERWATER

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The gas and water flows during an underwater missile launch are numerically studied. For the gas flow, the explicit difference scheme of Non-oscillation and Non-free-parameter Dissipation (NND) is utilized to solve the Euler equations for compressible fluids in the body-fitted coordinates. For the water flow, the Hess-Smith method is employed to solve the Laplace equation for the velocity potential of irrotational water flows based on the potential theory and the boundary element method. The hybrid Eulerian-Lagrangian formulation for the free boundary conditions is used to compute the changes of the free surface of the exhausted gas bubble in time stepping. On the free surface of the exhausted gas bubble, the matched conditions of both the normal velocities and pressures are satisfied. From the numerical simulation, it is found that the exhausted gas bubble grows more rapidly in the axial direction than in the radial direction and the bubble will shrink at its "neck" finally. Numerical results of the movement of the shock wave and the distribution of the Mach number and the gas pressure within the bubble were presented, which reveals that at some time, the gas flow in the Laval nozzle is subsonic and the gas pressure in the nozzle is very high. Influences of various initial missile velocities and chamber total pressures and water depths on both the time interval when the gas flow in the nozzle is subsonic and the peak of the gas pressure at the nozzle end were discussed. It was suggested that a reasonable adjustment of the chamber total pressure can improve the performance of the engine during the underwater launch of missiles.

  3. Accuracy of bubble velocity measurement with a four-point optical fibre probe

    NARCIS (Netherlands)

    Bai, Wei; Deen, Niels G.; Mudde, Robert F.; Kuipers, J.A.M.

    2008-01-01

    For the operation of high void fraction bubbly flows in bubble columns, insight in primary parameters such as bubble size, shape and velocity as well as gas volume fraction is essential. At high gas volume fractions the flow system becomes opaque, ruling out non-intrusive optical techniques. As an a

  4. Computational modelling of the interaction of shock waves with multiple gas-filled bubbles in a liquid

    Science.gov (United States)

    Betney, M. R.; Tully, B.; Hawker, N. A.; Ventikos, Y.

    2015-03-01

    This study presents a computational investigation of the interactions of a single shock wave with multiple gas-filled bubbles in a liquid medium. This work illustrates how multiple bubbles may be used in shock-bubble interactions to intensify the process on a local level. A high resolution front-tracking approach is used, which enables explicit tracking of the gas-liquid interface. The collapse of two identical bubbles, one placed behind the other is investigated in detail, demonstrating that peak pressures in a two bubble arrangement can exceed those seen in single bubble collapse. Additionally, a parametric investigation into the effect of bubble separation is presented. It is found that the separation distance has a significant effect on both the shape and velocity of the main transverse jet of the second bubble. Extending this analysis to effects of relative bubble size, we show that if the first bubble is sufficiently small relative to the second, it may become entirely entrained in the second bubble main transverse jet. In contrast, if the first bubble is substantially larger than the second, it may offer it significant protection from the incident shock. This protection is utilised in the study of a triangular array of three bubbles, with the central bubble being significantly smaller than the outer bubbles. It is demonstrated that, through shielding of bubbles until later in the collapse process, pressures over five times higher than the maximum pressure observed in the single bubble case may be achieved. This corresponds to a peak pressure that is approximately 40 times more intense than the incident shock wave. This work has applications in a number of different fields, including cavitation erosion, explosives, targeted drug delivery/intensification, and shock wave lithotripsy.

  5. Creating Small Gas Bubbles in Flowing Mercury Using Turbulence at an Orifice

    Energy Technology Data Exchange (ETDEWEB)

    Wendel, Mark W [ORNL; Abdou, Ashraf A [ORNL; Paquit, Vincent C [ORNL; Felde, David K [ORNL; Riemer, Bernie [ORNL

    2010-01-01

    Pressure waves created in liquid mercury pulsed spallation targets have been shown to create cavitation damage to the target container. One way to mitigate such damage would be to absorb the pressure pulse energy into a dispersed population of small bubbles, however, creating such a population in mercury is difficult due to the high surface tension and particularly the non-wetting behavior of mercury on gas-injection hardware. If the larger injected gas bubbles can be broken down into small bubbles after they are introduced to the flow, then the material interface problem is avoided. Research at the Oak Ridge National Labarotory is underway to develop a technique that has shown potential to provide an adequate population of small-enough bubbles to a flowing spallation target. This technique involves gas injection at an orifice of a geometry that is optimized to the turbulence intensity and pressure distribution of the flow, while avoiding coalescence of gas at injection sites. The most successful geometry thus far can be described as a square-toothed orifice having a 2.5 bar pressure drop in the nominal flow of 12 L/s for one of the target inlet legs. High-speed video and high-resolution photography have been used to quantify the bubble population on the surface of the mercury downstream of the gas injection sight. Also, computational fluid dynamics has been used to optimize the dimensions of the toothed orifice based on a RANS computed mean flow including turbulent energies such that the turbulent dissipation and pressure field are best suited for turbulent break-up of the gas bubbles.

  6. Evolution of a gas bubble in porous matrix filled by methane hydrate

    Science.gov (United States)

    Tsiberkin, Kirill; Lyubimov, Dmitry; Lyubimova, Tatyana; Zikanov, Oleg

    2013-04-01

    Behavior of a small isolated hydrate-free inclusion (a bubble) within hydrate-bearing porous matrix is studied analytically and numerically. An infinite porous matrix of uniform properties with pores filled by methane hydrates and either water (excessive water situation) or methane gas (excessive gas situation) is considered. A small spherical hydrate-free bubble of radius R0 exists at initial moment within the matrix due to overheating relative to the surrounding medium. There is no continuing heat supply within the bubble, so new hydrate forms on its boundary, and its radius decreases with time. The process is analysed in the framework of the model that takes into account the phase transition and accompanying heat and mass transport processes and assumes spherical symmetry. It is shown that in the case of small (~ 10-2-10-1 m) bubbles, convective fluxes are negligible and the process is fully described by heat conduction and phase change equations. A spherically symmetric Stefan problem for purely conduction-controlled evolution is solved analytically for the case of equilibrium initial temperature and pressure within the bubble. The self-similar solution is verified, with good results, in numerical simulations based on the full filtration and heat transfer model and using the isotherm migration method. Numerical simulations are also conducted for a wide range of cases not amenable to analytical solution. It is found that, except for initial development of an overheated bubble, its radius evolves with time following the self-similar formula: R(t) ( t)1-2 R0-= 1 - tm- , (1) where tm is the life-time of bubble (time of its complete freezing). The analytical solution shows that tm follows 2 tm ~ (R0-?) , (2) where ? is a constant determined by the temperature difference ΔT between the bubble's interior and far field. We consider implications for natural hydrate deposits. As an example, for a bubble with R0 = 4 cm and ΔT = 0.001 K, we find tm ~ 5.7 ? 106 s (2

  7. Bioinspired gas bubble spontaneous and directional transportation effects in an aqueous medium.

    Science.gov (United States)

    Ma, Rui; Wang, Jingming; Yang, Zhongjia; Liu, Meng; Zhang, Jingjing; Jiang, Lei

    2015-04-08

    A series of well-ordered, 3D gradient porous interconnected network surfaces composed of micro-nano hierarchical geometries is constructed on a copper wire. A continuous gas film can be trapped around its interface in an aqueous medium acting as an effective channel for gas transportation. Driving by the difference of the Laplace pressure, gas bubbles can be transported spontaneously and directionally. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. New interferometric technique to evaluate the electric charge of gas bubbles in liquids.

    Science.gov (United States)

    Corti, Mario; Bonomo, Marco; Raudino, Antonio

    2012-04-10

    We report a new interferometric technique to measure the electric charge at the gas-liquid interface of a bubble in a liquid. The bubble rests by buoyancy against an electrode, and an alternating electric field excites its capillary oscillations. The oscillation amplitude of the quadrupolar mode frequency is measured by the interferometer, and it is used to evaluate the electric charge. The mode frequency scales with the square root of the interfacial tension and with a -(3)/(2) power law as a function of the bubble radius. For bubbles in the millimeter diameter range in pure water, the measured negative charge scales with the square of the radius, hence, giving a constant surface charge density on the order of 1.8 × 10(-5) C m(-2), which is rather consistent with the electrophoretic values reported in the literature.

  9. Growth of a gas bubble in a supersaturated and slightly compressible liquid at low Mach number

    Science.gov (United States)

    Mohammadein, S. A.; Mohamed, K. G.

    2011-12-01

    In this paper, the growth of a gas bubble in a supersaturated and slightly compressible liquid is discussed. The mathematical model is solved analytically by using the modified Plesset and Zwick method. The growth process is affected by: sonic speed in the liquid, polytropic exponent, diffusion coefficient, initial concentration difference, surface tension, viscosity, adjustment factor and void fraction. The famous formula of Plesset and Zwick is produced as a special case of the result at some values of the adjustment factor. Moreover, the resultant formula is implemented to the case of the growth of underwater gas bubble.

  10. High-speed visualization and radiated pressure measurement of a laser-induced gas bubble in glycerin-water solutions

    Science.gov (United States)

    Nakajima, Takehiro; Kondo, Tomoki; Ando, Keita

    2016-11-01

    We study the dynamics of a spherical gaseous bubble created by focusing a nanosecond laser pulse at 532 nm into a large volume of glycerin-water solutions. Free oscillation of the bubble and shock wave emission from the bubble dynamics are recorded by a high-speed camera together with a pulse laser stroboscope; concurrently, pressure radiated from the oscillating bubble is measured by a hydrophone. The bubble achieves a mechanical equilibrium after free oscillation is damped out; the equilibrium state stays for a while, unlike vapor bubbles. We speculate that the bubble content is mainly gases originally dissolved in the liquid (i.e., air). The bubble dynamics we observed are compared to Rayleigh-Plesset-type calculations that account for diffusive effects; the (unknown) initial pressure just after laser focusing is tuned to obtain agreement between the experiment and the calculation. Moreover, viscous effects on the shock propagation are examined with the aid of compressible Navier-Stokes simulation.

  11. Decompression sickness bubbles: are gas micronuclei formed on a flat hydrophobic surface?

    Science.gov (United States)

    Arieli, R; Marmur, A

    2011-06-30

    It is a long-standing hypothesis that the bubbles which evolve as a result of decompression have their origin in stable gas micronuclei lodged in hydrophobic crevices, micelles of surface-active molecules, or tribonucleation. Recent findings supported by atomic force microscopy have indicated that tiny, flat nanobubbles form spontaneously on smooth, hydrophobic surfaces submerged in water. We propose that these nanobubbles may be the gas micronuclei responsible for the bubbles that evolve to cause decompression sickness. To support our hypothesis, we used hydrophilic and monolayer-covered hydrophobic smooth silicon wafers. The experiment was conducted in three main stages. Double distilled water was degassed at the low pressure of 5.60 kPa; hydrophobic and hydrophilic silicon wafers were placed in a bowl of degassed water and left overnight at normobaric pressure. The bowl was then placed in the hyperbaric chamber for 15 h at a pressure of 1013 kPa (=90 m sea water). After decompression, bubbles were observed and photographed. The results showed that bubbles only evolved on the hydrophobic surfaces following decompression. There are numerous hydrophobic surfaces within the living body (e.g., in the large blood vessels), which may thus be the sites where nanobubbles that serve as gas micronuclei for bubble evolution following decompression are formed.

  12. Leak testing of bubble-tight dampers using tracer gas techniques

    Energy Technology Data Exchange (ETDEWEB)

    Lagus, P.L. [Lagus Applied Technology, Inc., San Diego, CA (United States); DuBois, L.J. [Commonwealth Edison, Zion, IL (United States); Fleming, K.M. [NCS Corporation, Columbus, OH (United States)] [and others

    1995-02-01

    Recently tracer gas techniques have been applied to the problem of measuring the leakage across an installed bubble-tight damper. A significant advantage of using a tracer gas technique is that quantitative leakage data are obtained under actual operating differential pressure conditions. Another advantage is that leakage data can be obtained using relatively simple test setups that utilize inexpensive materials without the need to tear ducts apart, fabricate expensive blank-off plates, and install test connections. Also, a tracer gas technique can be used to provide an accurate field evaluation of the performance of installed bubble-tight dampers on a periodic basis. Actual leakage flowrates were obtained at Zion Generating Station on four installed bubble-tight dampers using a tracer gas technique. Measured leakage rates ranged from 0.01 CFM to 21 CFM. After adjustment and subsequent retesting, the 21 CFM damper leakage was reduced to a leakage of 3.8 CFM. In light of the current regulatory climate and the interest in Control Room Habitability issues, imprecise estimates of critical air boundary leakage rates--such as through bubble-tight dampers--are not acceptable. These imprecise estimates can skew radioactive dose assessments as well as chemical contaminant exposure calculations. Using a tracer gas technique, the actual leakage rate can be determined. This knowledge eliminates a significant source of uncertainty in both radioactive dose and/or chemical exposure assessments.

  13. Particle Dispersion Behaviors of Dense Gas-Particle Flows in Bubble Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Sihao Lv

    2013-01-01

    Full Text Available An Euler-Euler two-fluid model incorporating a developed momentum transfer empirical coefficient is developed to study the particle dispersion behaviors of dense gas-particle flows in gas-fluidization reactor. In this model, the four-way couplings among gas-particles, particle-gas, and particle-particle collisions are fully considered based on kinetic theory of granular flows and an improved smooth continuous drag coefficient is utilized. Gas turbulent flow is solved by large eddy simulation. The particle fraction, the time-averaged axial particle velocity, the histogram of particle fluctuation velocity, and the wavelet analysis of pressure signals are obtained. The results are in good agreement with experimental measurements. The mean value and the variance of axial particle velocity are greater than those of radial particle velocities. Particle collision frequencies at bubble vibrant movement regions along axial direction are much higher than those of radial direction and attenuated along height increase. Low-frequency component of pressure signal indicating the bubble movement behaviors in the center of reactor is stronger than wall regions. Furthermore, the negative values represent the passed bubble and positive peak values disclose the continuous motion of single bubble.

  14. Self-organization of hydrogen gas bubbles rising above laser-etched metallic aluminum in a weakly basic aqueous solution.

    Science.gov (United States)

    Barmina, E V; Kuzmin, P G; Shafeev, G A

    2011-10-01

    Self-organization of hydrogen bubbles is reported under etching of metallic Aluminum in a weakly basic solution. The ascending gas bubbles drift to the areas with higher density of bubbles. As a result, ascending bubbles form various stationary structures whose symmetry is determined by the symmetry of the etched area. Bubbles are aligned along the bisectors of the contour of the etched area. The special laser-assisted profiling of the etched area in shape of a vortex induces a torque in the fluid above the etched area. The process is interpreted on the basis of Bernoulli equation.

  15. The effect of thixotropy on a rising gas bubble: A numerical study

    Science.gov (United States)

    Sadeghy, Kayvan; Vahabi, Mohammad

    2016-08-01

    The deformation of a single, two-dimensional, circular gas bubble rising in an otherwise stationary thixotropic liquid in a confined rectangular vessel is numerically studied using the smoothed particle hydrodynamics method (SPH). The thixotropic liquid surrounding the bubble is assumed to obey the Moore model. The main objective of the work is to investigate the effect of the destruction-to-rebuild ratio (referred to by the thixotropy number in dimensionless form) in this model on the bubble's shape, velocity, and center-ofmass during its rise in the liquid. Based on the numerical results obtained in this work, it is found that the bubble moves faster in the Moore fluid as compared with its Newtonian counterpart. An increase in the thixotropy number is also shown to increase the bubble's speed at any given instant of time. The effect of thixotropy number is found to be noticeable only when it is large. For Moore fluid, a large thixotropy number means that the fluid is basically a shear-thinning fluid. Therefore, it is concluded that the shear-thinning behavior of the Moore model easily masks its thixotropic behavior in the bubble rise problem. The effect of thixotropy number is weakened when the Reynolds number is increased.

  16. Effects of gas bubble production on heat transfer from a volumetrically heated liquid pool

    Science.gov (United States)

    Bull, Geoffrey R.

    Aqueous solutions of uranium salts may provide a new supply chain to fill potential shortfalls in the availability of the most common radiopharmaceuticals currently in use worldwide, including Tc99m which is a decay product of Mo99. The fissioning of the uranium in these solutions creates Mo99 but also generates large amounts of hydrogen and oxygen from the radiolysis of the water. When the dissolved gases reach a critical concentration, bubbles will form in the solution. Bubbles in the solution affect both the fission power and the heat transfer out of the solution. As a result, for safety and production calculations, the effects of the bubbles on heat transfer must be understood. A high aspect ratio tank was constructed to simulate a section of an annulus with heat exchangers on the inner and outer steel walls to provide cooling. Temperature measurements via thermocouples inside the tank and along the outside of the steel walls allowed the calculation of overall and local heat transfer coefficients. Different air injection manifolds allowed the exploration of various bubble characteristics and patterns on heat transfer from the pool. The manifold type did not appear to have significant impact on the bubble size distributions in water. However, air injected into solutions of magnesium sulfate resulted in smaller bubble sizes and larger void fractions than those in water at the same injection rates. One dimensional calculations provide heat transfer coefficient values as functions of the superficial gas velocity in the pool.

  17. Gas bubbles in rats after heliox saturation and different decompression steps and rates.

    Science.gov (United States)

    Skogland, Steffen; Segadal, Kåre; Sundland, Harald; Hope, Arvid

    2002-06-01

    Effects of pressure reduction, decompression rate, and repeated exposure on venous gas bubble formation were determined in five groups (GI, GII, GIII, GIV, and GV) of conscious and freely moving rats in a heliox atmosphere. Bubbles were recorded with a Doppler ultrasound probe implanted around the inferior caval vein. Rats were held for 16 h at 0.4 MPa (GI), 0.5 MPa (GII and GIII), 1.7 MPa (GIVa), or 1.9 MPa (GIV and GV), followed by decompression to 0.1 MPa in GI to GIII and to 1.1 MPa in GIV and GV. A greater decompression step, but at the same rate (GII vs. GI and GIVb vs. GIVa), resulted in significantly more bubbles (P < 0.01). A twofold decompression step resulted in equal amount of bubbles when decompressing to 1.1 MPa compared with 0.1 MPa. The faster decompression in GII and GVa (10.0 kPa/s) resulted in significantly more bubbles (P < 0.01) compared with GIII and GVb (2.2 kPa/s). No significant difference was observed in cumulative bubble score when comparing first and second exposure. With the present animal model, different decompression regimes may be evaluated.

  18. Relationships between atmospheric positive electric charge densities and gas bubble concentrations in the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Zygmunt Klusek

    2004-12-01

    Full Text Available Simultaneous measurements of bubble density in the sea subsurface and positive ions in the lower atmosphere were performed in the Baltic Sea in the summer of 1999. Bubbles in two size ranges, around 27 and 100 µm, were measured acoustically. Airborne positive charge was measured with a Gerdien instrument. Observed concentrations of air ions varied from 60 cm-3 up to 600 cm-3.      The relative role of bubbles and wind speed on the positive air ion concentrations over the brackish water of the Baltic Sea is discussed. The parameters of a model of a log-log dependence between charge concentration and bubble density are calculated.      The correlation functions between time series of concentrations of positive charges over the sea and gas bubbles averaged over a depth range from 0.4 to 4 m and wind speed are presented. There was zero lag between the cross-correlation maxima of charge and bubbles, but there was a phase lag of one and a half hours between charge and wind speed.

  19. Notes on the path and wake of a gas bubble rising in pure water

    NARCIS (Netherlands)

    de Vries, A.W.G.; Biesheuvel, A.; van Wijngaarden, L.; van Wijngaarden, L.

    2002-01-01

    This paper is concerned with the structure of the wake behind gas bubbles rising at high Reynolds numbers in highly purified water. It describes a schlieren optics technique to visualise the wake. The technique does not contaminate the water, and so does not affect the zero-stress condition at the

  20. In situ visualization study of CO 2 gas bubble behavior in DMFC anode flow fields

    Science.gov (United States)

    Yang, H.; Zhao, T. S.; Ye, Q.

    This paper reports on a visual study of the CO 2 bubble behavior in the anode flow field of an in-house fabricated transparent Direct Methanol Fuel Cell (DMFC), which consisted of a membrane electrode assembly (MEA) with an active area of 4.0 × 4.0 cm 2, two bipolar plates with a single serpentine channel, and a transparent enclosure. The study reveals that at low current densities, small discrete bubbles appeared in the anode flow field. At moderate current densities, a number of gas slugs formed, in addition to small discrete bubbles. And at high current densities, the flow field was predominated by rather long gas slugs. The experiments also indicate that the cell orientation had a significant effect on the cell performance, especially at low methanol flow rates; for the present flow field design the best cell performance could be achieved when the cell was orientated vertically. It has been shown that higher methanol solution flow rates reduced the average length and the number of gas slugs in the flow field, but led to an increased methanol crossover. In particular, the effect of methanol solution flow rates on the cell performance became more pronounced at low temperatures. The effect of temperature on the bubble behavior and the cell performance was also examined. Furthermore, for the present flow field consisting of a single serpentine channel, the channel-blocking phenomenon caused by CO 2 gas slugs was never encountered under all the test conditions in this work.

  1. Influence of Small Amounts of Additives on Gas Hold-Up, Bubble Size, and Interfacial Area

    NARCIS (Netherlands)

    Cents, A.H.G.; Jansen, D.J.W.; Brilman, D.W.F.; Versteeg, G.F.

    2005-01-01

    The gas−liquid interfacial area, which is determined by the gas hold-up and the Sauter mean bubble diameter, determines the production rate in many industrial processes. The effect of additives on this interfacial area is, especially in multiphase systems (gas−liquid−solid, gas−liquid−liquid), often

  2. Influence of small amounts of additives on gas hold-up, bubble size, and interfacial areas

    NARCIS (Netherlands)

    Cents, A.H.G.; Jansen, D.J.W.; Jansen, D.J.W.; Brilman, Derk Willem Frederik; Versteeg, Geert

    2005-01-01

    The gas−liquid interfacial area, which is determined by the gas hold-up and the Sauter mean bubble diameter, determines the production rate in many industrial processes. The effect of additives on this interfacial area is, especially in multiphase systems (gas−liquid−solid, gas−liquid−liquid), often

  3. Prediction of Gas Holdup in Bubble Columns Using Artificial Neural Network

    Institute of Scientific and Technical Information of China (English)

    吴元欣; 罗湘华; 陈启明; 李定或; 李世荣; M.H.Al-Dahhan; M.P.Dudukovic

    2003-01-01

    A new correlation for the prediction of gas hod up in bubble columns was proposed based on an extensive experimental database set up from the literature published over last 30 years .The updated estimation method relying on artificial neural network,dimensional analysis and phenomenological approaches was used and the model prediction agreed with the experimental data with average relative error less than 10%.

  4. ALMA observations of massive molecular gas filaments encasing radio bubbles in the Phoenix cluster

    CERN Document Server

    Russell, H R; McNamara, B R; Fabian, A C; Nulsen, P E J; Bayliss, M B; Benson, B A; Brodwin, M; Carlstrom, J E; Edge, A C; Hlavacek-Larrondo, J; Marrone, D P; Reichardt, C L; Vieira, J D

    2016-01-01

    We report new ALMA observations of the CO(3-2) line emission from the $2.7\\pm0.4\\times10^{10}\\rm\\thinspace M_{\\odot}$ molecular gas reservoir in the central galaxy of the Phoenix cluster. The cold molecular gas is fuelling a vigorous starburst at a rate of $500-800\\rm\\thinspace M_{\\odot}\\rm\\; yr^{-1}$ and powerful black hole activity in the form of both intense quasar radiation and radio jets. The radio jets have inflated huge bubbles filled with relativistic plasma into the hot, X-ray atmospheres surrounding the host galaxy. The ALMA observations show that extended filaments of molecular gas, each $10-20\\rm\\; kpc$ long with a mass of several billion solar masses, are located along the peripheries of the radio bubbles. The smooth velocity gradients and narrow line widths along each filament reveal massive, ordered molecular gas flows around each bubble, which are inconsistent with gravitational free-fall. The molecular clouds have been lifted directly by the radio bubbles, or formed via thermal instabilities ...

  5. Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography

    Science.gov (United States)

    Jin, Haibo; Yuhuan, Han; Suohe, Yang

    2009-02-01

    Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup and mean holdups are investigated in a 0.160 m i. d. bubble column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the gas phase, tap water as liquid phase, and a series of experiments were done by adding KCl, ethanol, oil sodium, and glycerol to change liquid conductivity, liquid surface tension and viscosity. The superficial gas velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial gas holdup distribution is discussed. The results showed that the gas holdup decrease with the increase of surface tension and increase with the increase of viscosity. Meanwhile, the settings of initial liquid conductivity slightly influence the gas holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.

  6. The effect of gas bubbles on electrical breakdown in transformer oil

    Science.gov (United States)

    Tyuftyaev, A. S.; Gadzhiev, M. Kh; Sargsyan, M. A.; Akimov, P. L.; Demirov, N. A.

    2016-11-01

    To study the breakdown of transformer oil with gas bubbles an experimental setup was created that allows to determine electrical and optical properties of the discharge. Oil was sparged with air and sulfur hexafluoride gas. It was found that sparging oil with gas lowers the breakdown voltage of the oil. When a gas bubble is present between the electrodes at a considerable distance from the electrodes at first there is a spherically shape flash observed, resulting in the discharge gap overlapping by a conductive channel. These leads to discharges forming in the discharge gap with the frequency of hundreds Hz and higher. Despite the slightly lower breakdown voltage of oil sparged with sulfur hexafluoride the advantage of this medium to clean oil can serve as a two-phase medium damping properties, which may be sufficient to prevent the destruction of the body in the breakdown of oil-filled equipment.

  7. Technical Note: Detection of gas bubble leakage via correlation of water column multibeam images

    Directory of Open Access Journals (Sweden)

    J. Schneider von Deimling

    2012-03-01

    Full Text Available Hydroacoustic detection of natural gas release from the seafloor has been conducted in the past by using singlebeam echosounders. In contrast, modern multibeam swath mapping systems allow much wider coverage, higher resolution, and offer 3-D spatial correlation. Up to the present, the extremely high data rate hampers water column backscatter investigations and more sophisticated visualization and processing techniques are needed. Here, we present water column backscatter data acquired with a 50 kHz prototype multibeam system over a period of 75 seconds. Display types are of swath-images as well as of a "re-sorted" singlebeam presentation. Thus, individual and/or groups of gas bubbles rising from the 24 m deep seafloor clearly emerge in the acoustic images, making it possible to estimate rise velocities. A sophisticated processing scheme is introduced to identify those rising gas bubbles in the hydroacoustic data. We apply a cross-correlation technique adapted from particle imaging velocimetry (PIV to the acoustic backscatter images. Temporal and spatial drift patterns of the bubbles are assessed and are shown to match very well to measured and theoretical rise patterns. The application of this processing to our field data gives clear results with respect to unambiguous bubble detection and remote bubble rise velocimetry. The method can identify and exclude the main source of misinterpretations, i.e. fish-mediated echoes. Although image-based cross-correlation techniques are well known in the field of fluid mechanics for high resolution and non-inversive current flow field analysis, we present the first application of this technique as an acoustic bubble detector.

  8. The effect of exercise and rest duration on the generation of venous gas bubbles at altitude

    Science.gov (United States)

    Dervay, Joseph P.; Powell, Michael R.; Butler, Bruce; Fife, Caroline E.

    2002-01-01

    BACKGROUND: Decompression, as occurs with aviators and astronauts undergoing high altitude operations or with deep-sea divers returning to surface, can cause gas bubbles to form within the organism. Pressure changes to evoke bubble formation in vivo during depressurization are several orders of magnitude less than those required for gas phase formation in vitro in quiescent liquids. Preformed micronuclei acting as "seeds" have been proposed, dating back to the 1940's. These tissue gas micronuclei have been attributed to a minute gas phase located in hydrophobic cavities, surfactant-stabilized microbubbles, or arising from musculoskeletal activity. The lifetimes of these micronuclei have been presumed to be from a few minutes to several weeks. HYPOTHESIS: The greatest incidence of venous gas emboli (VGE) will be detected by precordial Doppler ultrasound with depressurization immediately following lower extremity exercise, with progressively reduced levels of VGE observed as the interval from exercise to depressurization lengthens. METHODS: In a blinded cross-over design, 20 individuals (15 men, 5 women) at sea level exercised by performing knee-bend squats (150 knee flexes over 10 min, 235-kcal x h(-1)) either at the beginning, middle, or end of a 2-h chair-rest period without an oxygen prebreathe. Seated subjects were then depressurized to 6.2 psia (6,706 m or 22,000 ft altitude equivalent) for 120 min with no exercise performed at altitude. RESULTS: Of the 20 subjects with VGE in the pulmonary artery, 10 demonstrated a greater incidence of bubbles with exercise performed just prior to depressurization, compared with decreasing bubble grades and incidence as the interval of rest increased prior to depressurization. No decompression illness was reported. CONCLUSIONS: There is a significant increase in decompression-induced bubble formation at 6.2 psia when lower extremity exercise is performed just prior to depressurization as compared with longer rest intervals

  9. Steady-state composition of a two-component gas bubble growing in a liquid solution: self-similar approach

    CERN Document Server

    Gor, G Yu

    2009-01-01

    The paper presents an analytical description of the growth of a two-component bubble in a binary liquid-gas solution. We obtain asymptotic self-similar time dependence of the bubble radius and analytical expressions for the non-steady profiles of dissolved gases around the bubble. We show that the necessary condition for the self-similar regime of bubble growth is the constant, steady-state composition of the bubble. The equation for the steady-state composition is obtained. We reveal the dependence of the steady-state composition on the solubility laws of the bubble components. Besides, the universal, independent from the solubility laws, expressions for the steady-state composition are obtained for the case of strong supersaturations, which are typical for the homogeneous nucleation of a bubble.

  10. Natural gas annual 1994: Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-01

    The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. This report, Volume 2, presents historical data fro the Nation from 1930 to 1994, and by State from 1967 to 1994.

  11. Removal of dichloromethane from waste gas streams using a hybrid bubble column/biofilter bioreactor.

    Science.gov (United States)

    Abtahi, Mehrnoosh; Naddafi, Kazem; Mesdaghinia, Alireza; Yaghmaeian, Kamyar; Nabizadeh, Ramin; Jaafarzadeh, Nematollah; Rastkari, Noushin; Nazmara, Shahrokh; Saeedi, Reza

    2014-01-09

    The performance of a hybrid bubble column/biofilter (HBCB) bioreactor for the removal of dichloromethane (DCM) from waste gas streams was studied in continuous mode for several months. The HBCB bioreactor consisted of two compartments: bubble column bioreactor removing DCM from liquid phase and biofilter removing DCM from gas phase. Effect of inlet DCM concentration on the elimination capacity was examined in the DCM concentration range of 34-359 ppm with loading rates ranged from 2.2 to 22.8 g/m3.h and constant total empty bed retention time (EBRT) of 200 s. In the equal loading rates, the elimination capacity and removal efficiency of the biofilter were higher than the corresponding values of the bubble column bioreactor. The maximum elimination capacity of the HBCB bioreactor was determined to be 15.7 g/m3.h occurred in the highest loading rate of 22.8 g/m3.h with removal efficiency of 69%. The overall mineralization portion of the HBCB bioreactor was in the range of 72-79%. The mixed liquor acidic pH especially below 5.5 inhibited microbial activity and decreased the elimination capacity. Inhibitory effect of high ionic strength was initiated in the mixed liquor electrical conductivity of 12.2 mS/cm. This study indicated that the HBCB bioreactor could benefit from advantages of both bubble column and biofilter reactors and could remove DCM from waste gas streams in a better manner.

  12. Molecular gas and star formation towards the IR dust bubble S24 and its environs

    CERN Document Server

    Cappa, C E; Firpo, V; Vasquez, J; López-Caraballo, C H; Rubio, M; Vazzano, M M

    2016-01-01

    We present a multi-wavelength analysis of the infrared dust bubble S24, and its environs, with the aim of investigating the characteristics of the molecular gas and the interstellar dust linked to them, and analyzing the evolutionary status of the young stellar objects (YSOs) identified there. Using APEX data, we mapped the molecular emission in the CO(2-1), $^{13}$CO(2-1), C$^{18}$O(2-1), and $^{13}$CO(3-2) lines in a region of about 5'x 5' in size around the bubble. The cold dust distribution was analyzed using ATLASGAL and Herschel images. Complementary IR and radio data were also used.The molecular gas linked to the S24 bubble, G341.220-0.213, and G341.217-0.237 has velocities between -48.0 km sec$^{-1}$ and -40.0 km sec$^{-1}$. The gas distribution reveals a shell-like molecular structure of $\\sim$0.8 pc in radius bordering the bubble. A cold dust counterpart of the shell is detected in the LABOCA and Herschel images.The presence of extended emission at 24 $\\mu$m and radio continuum emission inside the b...

  13. Bubble Size Effect on the Gas-lift Technique

    NARCIS (Netherlands)

    Guet, S.C.L.

    2004-01-01

    The gas-lift technique uses gas injection in vertical oil wells to decrease the gravitational pressure drop. The decreased pressure in the production pipe results in an increase of the pressure drop from the reservoir to the oil well and enhances the oil production. In this thesis we investigated th

  14. Bubble Size Effect on the Gas-lift Technique

    NARCIS (Netherlands)

    Guet, S.C.L.

    2004-01-01

    The gas-lift technique uses gas injection in vertical oil wells to decrease the gravitational pressure drop. The decreased pressure in the production pipe results in an increase of the pressure drop from the reservoir to the oil well and enhances the oil production. In this thesis we investigated th

  15. Numerical simulation of gas-liquid two-phase jet flow in air-bubble generator

    Institute of Scientific and Technical Information of China (English)

    陈文义; 王静波; 姜楠; 赵斌; 王振东

    2008-01-01

    Air-bubble generator is the key part of the self-inspiration type swirl flotation machines,whose flow field structure has a great effect on flotation.The multiphase volume of fluid(VOF),standard k-ε turbulent model and the SIMPLE method were chosen to simulate the present model;the first order upwind difference scheme was utilized to perform a discrete solution for momentum equation.The distributing law of the velocity,pressure,turbulent kinetic energy of every section along the flow direction of air-bubble generator was analyzed.The results indicate that the bubbles are heavily broken up in the middle cross section of throat sect and the entrance of diffuser sect along the flow direction,and the turbulent kinetic energy of diffuser sect is larger than the entrance of throat sect and mixing chamber.

  16. Catalytic microtubular jet engines self-propelled by accumulated gas bubbles.

    Science.gov (United States)

    Solovev, Alexander A; Mei, Yongfeng; Bermúdez Ureña, Esteban; Huang, Gaoshan; Schmidt, Oliver G

    2009-07-01

    Strain-engineered microtubes with an inner catalytic surface serve as self-propelled microjet engines with speeds of up to approximately 2 mm s(-1) (approximately 50 body lengths per second). The motion of the microjets is caused by gas bubbles ejecting from one opening of the tube, and the velocity can be well approximated by the product of the bubble radius and the bubble ejection frequency. Trajectories of various different geometries are well visualized by long microbubble tails. If a magnetic layer is integrated into the wall of the microjet engine, we can control and localize the trajectories by applying external rotating magnetic fields. Fluid (i.e., fuel) pumping through the microtubes is revealed and directly clarifies the working principle of the catalytic microjet engines.

  17. Simulation of Interaction of Strong Shocks with Gas Bubbles using the Direct Simulation Monte Carlo Method

    Science.gov (United States)

    Puranik, Bhalchandra; Watvisave, Deepak; Bhandarkar, Upendra

    2016-11-01

    The interaction of a shock with a density interface is observed in several technological applications such as supersonic combustion, inertial confinement fusion, and shock-induced fragmentation of kidney and gall-stones. The central physical process in this interaction is the mechanism of the Richtmyer-Meshkov Instability (RMI). The specific situation where the density interface is initially an isolated spherical or cylindrical gas bubble presents a relatively simple geometry that exhibits all the essential RMI processes such as reflected and refracted shocks, secondary instabilities, turbulence and mixing of the species. If the incident shocks are strong, the calorically imperfect nature needs to be modelled. In the present work, we have carried out simulations of the shock-bubble interaction using the DSMC method for such situations. Specifically, an investigation of the shock-bubble interaction with diatomic gases involving rotational and vibrational excitations at high temperatures is performed, and the effects of such high temperature phenomena will be presented.

  18. The speed of sound in a gas-vapour bubbly liquid.

    Science.gov (United States)

    Prosperetti, Andrea

    2015-10-01

    In addition to the vapour of the liquid, bubbles in cavitating flows usually contain also a certain amount of permanent gas that diffuses out of the liquid as they grow. This paper presents a simplified linear model for the propagation of monochromatic pressure waves in a bubbly liquid with these characteristics. Phase change effects are included in detail, while the gas is assumed to follow a polytropic law. It is shown that even a small amount of permanent gas can have a major effect on the behaviour of the system. Particular attention is paid to the low-frequency range, which is of special concern in flow cavitation. Numerical results for water and liquid oxygen illustrate the implications of the model.

  19. Compositional discrimination of decompression and decomposition gas bubbles in bycaught seals and dolphins.

    Directory of Open Access Journals (Sweden)

    Yara Bernaldo de Quirós

    Full Text Available Gas bubbles in marine mammals entangled and drowned in gillnets have been previously described by computed tomography, gross examination and histopathology. The absence of bacteria or autolytic changes in the tissues of those animals suggested that the gas was produced peri- or post-mortem by a fast decompression, probably by quickly hauling animals entangled in the net at depth to the surface. Gas composition analysis and gas scoring are two new diagnostic tools available to distinguish gas embolisms from putrefaction gases. With this goal, these methods have been successfully applied to pathological studies of marine mammals. In this study, we characterized the flux and composition of the gas bubbles from bycaught marine mammals in anchored sink gillnets and bottom otter trawls. We compared these data with marine mammals stranded on Cape Cod, MA, USA. Fresh animals or with moderate decomposition (decomposition scores of 2 and 3 were prioritized. Results showed that bycaught animals presented with significantly higher gas scores than stranded animals. Gas composition analyses indicate that gas was formed by decompression, confirming the decompression hypothesis.

  20. Plasma Discharges in Gas Bubbles in Liquid Water: Breakdown Mechanisms and Resultant Chemistry

    Science.gov (United States)

    Gucker, Sarah M. N.

    The use of atmospheric pressure plasmas in gases and liquids for purification of liquids has been investigated by numerous researchers, and is highly attractive due to their strong potential as a disinfectant and sterilizer. However, the fundamental understanding of plasma production in liquid water is still limited. Despite the decades of study dedicated to electrical discharges in liquids, many physical aspects of liquids, such as the high inhomogeneity of liquids, complicate analyses. For example, the complex nonlinearities of the fluid have intricate effects on the electric field of the propagating streamer. Additionally, the liquid material itself can vaporize, leading to discontinuous liquid-vapor boundaries. Both can and do often lead to notable hydrodynamic effects. The chemistry of these high voltage discharges on liquid media can have circular effects, with the produced species having influence on future discharges. Two notable examples include an increase in liquid conductivity via charged species production, which affects the discharge. A second, more complicated scenario seen in some liquids (such as water) is the doubling or tripling of molecular density for a few molecule layers around a high voltage electrode. These complexities require technological advancements in optical diagnostics that have only recently come into being. This dissertation investigates several aspects of electrical discharges in gas bubbles in liquids. Two primary experimental configurations are investigated: the first allows for single bubble analysis through the use of an acoustic trap. Electrodes may be brought in around the bubble to allow for plasma formation without physically touching the bubble. The second experiment investigates the resulting liquid phase chemistry that is driven by the discharge. This is done through a dielectric barrier discharge with a central high voltage surrounded by a quartz discharge tube with a coil ground electrode on the outside. The plasma

  1. Gas bubble retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, P.A.; Rassat, S.D.; Powell, M.R. [and others

    1995-08-01

    Several of the underground nuclear storage tanks at Hanford have been placed on a flammable gas watch list, because the waste is either known or suspected to generate, store, and episodically release flammable gases. Because retention and episodic release of flammable gases from these tanks containing radioactive waste slurries are critical safety concerns, Pacific Northwest Laboratory (PNL) is studying physical mechanisms and waste properties that contribute to the episodic gas release from these storage tanks. This study is being conducted for Westinghouse Hanford Company as part of the PNL Flammable Gas project. Previous investigations have concluded that gas bubbles are retained by the slurry or sludge that has settled at the bottom of the tanks; however, the mechanisms responsible for the retention of these bubbles are not well understood. Understanding the rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles and the dynamics of how these bubbles are released from the waste. The presence of gas bubbles is expected to affect the rheology of the sludge, specifically its viscosity and tensile and shear strengths, but essentially no literature data are available to assess the effect of bubbles. The objectives of this study were to conduct experiments and develop theories to understand better how bubbles are retained by slurries and sludges, to measure the effect of gas bubbles on the viscosity of simulated slurries, and to measure the effect of gas bubbles on the tensile and shear strengths of simulated slurries and sludges. In addition to accomplishing these objectives, this study developed correlations, based on the new experimental data, that can be used in large-scale computations of waste tank physical phenomena.

  2. Gas Bubble Trauma Monitoring and Research of Juvenile Salmonids, 1994-1995 Progress Report.

    Energy Technology Data Exchange (ETDEWEB)

    Hans, Karen M.

    1997-07-01

    This report describes laboratory and field monitoring studies of gas bubble trauma (GBT) in migrating juvenile salmonids in the Snake and Columbia rivers. The first chapter describes laboratory studies of the progression of GBT signs leading to mortality and the use of the signs for GBT assessment. The progression and severity of GBT signs in juvenile salmonids exposed to different levels of total dissolved gas (TDG) and temperatures was assessed and quantified. Next, the prevalence, severity, and individual variation of GBT signs was evaluated to attempt to relate them to mortality. Finally, methods for gill examination in fish exposed to high TDG were developed and evaluated. Primary findings were: (1) no single sign of GBT was clearly correlated with mortality, but many GBT signs progressively worsened; (2) both prevalence and severity of GBT signs in several tissues is necessary; (3) bubbles in the lateral line were the earliest sign of GBT, showed progressive worsening, and had low individual variation but may develop poorly during chronic exposures; (4) fin bubbles had high prevalence, progressively worsened, and may be a persistent sign of GBT; and (5) gill bubbles appear to be the proximate cause of death but may only be relevant at high TDG levels and are difficult to examine. Chapter Two describes monitoring results of juvenile salmonids for signs of GBT. Emigrating fish were collected and examined for bubbles in fins and lateral lines. Preliminary findings were: (1) few fish had signs of GBT, but prevalence and severity appeared to increase as fish migrated downstream; (2) there was no apparent correlation between GBT signs in the fins, lateral line, or gills; (3) prevalence and severity of GBT was suggestive of long-term, non-lethal exposure to relatively low level gas supersaturated water; and (4) it appeared that GBT was not a threat to migrating juvenile salmonids. 24 refs., 26 figs., 3 tabs.

  3. Gas diffusion and temperature dependence of bubble nucleation during irradiation

    DEFF Research Database (Denmark)

    Foreman, A. J. E.; Singh, Bachu Narain

    1986-01-01

    The continuous production of gases at relatively high rates under fusion irradiation conditions may enhance the nucleation of cavities. This can cause dimensional changes and could induce embrittlement arising from gas accumulation on grain boundaries. Computer calculations have been made of the ...

  4. Gas volume contents within a container, smart volume instrument

    Science.gov (United States)

    Kelley, Anthony R. (Inventor); Van Buskirk, Paul D. (Inventor)

    2008-01-01

    A method for determining the volume of an incompressible gas in a system including incompressible substances in a zero-gravity environment. The method includes inducing a volumetric displacement within a container and measuring the resulting pressure change. From this data, the liquid level can be determined.

  5. The Bubble Box: Towards an Automated Visual Sensor for 3D Analysis and Characterization of Marine Gas Release Sites.

    Science.gov (United States)

    Jordt, Anne; Zelenka, Claudius; von Deimling, Jens Schneider; Koch, Reinhard; Köser, Kevin

    2015-12-05

    Several acoustic and optical techniques have been used for characterizing natural and anthropogenic gas leaks (carbon dioxide, methane) from the ocean floor. Here, single-camera based methods for bubble stream observation have become an important tool, as they help estimating flux and bubble sizes under certain assumptions. However, they record only a projection of a bubble into the camera and therefore cannot capture the full 3D shape, which is particularly important for larger, non-spherical bubbles. The unknown distance of the bubble to the camera (making it appear larger or smaller than expected) as well as refraction at the camera interface introduce extra uncertainties. In this article, we introduce our wide baseline stereo-camera deep-sea sensor bubble box that overcomes these limitations, as it observes bubbles from two orthogonal directions using calibrated cameras. Besides the setup and the hardware of the system, we discuss appropriate calibration and the different automated processing steps deblurring, detection, tracking, and 3D fitting that are crucial to arrive at a 3D ellipsoidal shape and rise speed of each bubble. The obtained values for single bubbles can be aggregated into statistical bubble size distributions or fluxes for extrapolation based on diffusion and dissolution models and large scale acoustic surveys. We demonstrate and evaluate the wide baseline stereo measurement model using a controlled test setup with ground truth information.

  6. The Bubble Box: Towards an Automated Visual Sensor for 3D Analysis and Characterization of Marine Gas Release Sites

    Directory of Open Access Journals (Sweden)

    Anne Jordt

    2015-12-01

    Full Text Available Several acoustic and optical techniques have been used for characterizing natural and anthropogenic gas leaks (carbon dioxide, methane from the ocean floor. Here, single-camera based methods for bubble stream observation have become an important tool, as they help estimating flux and bubble sizes under certain assumptions. However, they record only a projection of a bubble into the camera and therefore cannot capture the full 3D shape, which is particularly important for larger, non-spherical bubbles. The unknown distance of the bubble to the camera (making it appear larger or smaller than expected as well as refraction at the camera interface introduce extra uncertainties. In this article, we introduce our wide baseline stereo-camera deep-sea sensor bubble box that overcomes these limitations, as it observes bubbles from two orthogonal directions using calibrated cameras. Besides the setup and the hardware of the system, we discuss appropriate calibration and the different automated processing steps deblurring, detection, tracking, and 3D fitting that are crucial to arrive at a 3D ellipsoidal shape and rise speed of each bubble. The obtained values for single bubbles can be aggregated into statistical bubble size distributions or fluxes for extrapolation based on diffusion and dissolution models and large scale acoustic surveys. We demonstrate and evaluate the wide baseline stereo measurement model using a controlled test setup with ground truth information.

  7. Gas-Liquid Mass Transfer Characteristics in a Gas-Liquid-Solid Bubble Column under Elevated Pressure and Temperature

    Institute of Scientific and Technical Information of China (English)

    Haibo Jin; Suohe Yang; Guangxiang He; Delin Liu; Zemin Tong; Jianhua Zhu

    2014-01-01

    abstract The volumetric mass transfer coefficient kLa of gases (H2, CO, CO2) and mass transfer coefficient kL on liquid par-affin side were studied using the dynamic absorption method in slurry bubble column reactors under elevated temperature and elevated pressure. Meanwhile, gas-holdup and gas-liquid interfacial area a were obtained. The effects of temperature, pressure, superficial gas velocity and solid concentration on the mass transfer coeffi-cient were discussed. Experimental results show that the gas-liquid volumetric mass transfer coefficient kLa and interfacial area a increased with the increase of pressure, temperature, and superficial gas velocity, and decreased with the slurry concentration. The mass transfer coefficient kL increased with increasing superficial gas velocity and temperature and decreased with higher slurry concentration, while it changed slightly with pressure. Ac-cording to analysis of experimental data, an empirical correlation is obtained to calculate the values of kLa for H2 (CO, CO2) in the gas-paraffin-quartz system in a bubble column under elevated temperature and elevated pressure.

  8. The concentration distribution around a growing gas bubble in a bio tissue under the effect of suction process.

    Science.gov (United States)

    Mohammadein, S A

    2014-07-01

    The concentration distribution around a growing nitrogen gas bubble in the blood and other bio tissues of divers who ascend to surface too quickly is obtained by Mohammadein and Mohamed model (2010) for variant and constant ambient pressure through the decompression process. In this paper, the growing of gas bubbles and concentration distribution under the effect of suction process are studied as a modification of Mohammadein and Mohamed model (zero suction). The growth of gas bubble is affected by ascent rate, tissue diffusivity, initial concentration difference, surface tension and void fraction. Mohammadein and Mohamed model (2010) is obtained as a special case from the present model. Results showed that, the suction process activates the systemic blood circulation and delay the growth of gas bubbles in the bio tissues to avoid the incidence of decompression sickness (DCS).

  9. Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

    Science.gov (United States)

    2012-09-30

    clearly demonstrates that gas bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen...We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present. Although benthic...Jan Rines (Graduate School of Oceanography / University of Rhode Island = GSO/URI) to identify the benthic microalgae in the samples. Following the

  10. Numerical Simulations of Interactions of Solid Particles and Deformable Gas Bubbles in Viscous Liquids

    OpenAIRE

    Qin, Tong

    2013-01-01

    Studying the interactions of solid particles and deformable gasbubbles in viscous liquids is very important in many applications,especially in mining and chemical industries. These interactionsinvolve liquid-solid-air multiphase flows and anarbitrary-Lagrangian-Eulerican (ALE) approach is used for the directnumerical simulations. In the system of rigid particles anddeformable gas bubbles suspended in viscous liquids, theNavier-Stokes equations coupled with the equations of motion of thepartic...

  11. Simulations of Bubble Motion in an Oscillating Liquid

    Science.gov (United States)

    Kraynik, A. M.; Romero, L. A.; Torczynski, J. R.

    2010-11-01

    Finite-element simulations are used to investigate the motion of a gas bubble in a liquid undergoing vertical vibration. The effect of bubble compressibility is studied by comparing "compressible" bubbles that obey the ideal gas law with "incompressible" bubbles that are taken to have constant volume. Compressible bubbles exhibit a net downward motion away from the free surface that does not exist for incompressible bubbles. Net (rectified) velocities are extracted from the simulations and compared with theoretical predictions. The dependence of the rectified velocity on ambient gas pressure, bubble diameter, and bubble depth are in agreement with the theory. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Marangoni effect visualized in two-dimensions Optical tweezers for gas bubbles

    Science.gov (United States)

    Miniewicz, A.; Bartkiewicz, S.; Orlikowska, H.; Dradrach, K.

    2016-10-01

    In the report we demonstrate how, using laser light, effectively trap gas bubbles and transport them through a liquid phase to a desired destination by shifting the laser beam position. The physics underlying the effect is complex but quite general as it comes from the limited to two-dimension, well-known, Marangoni effect. The experimental microscope-based system consists of a thin layer of liquid placed between two glass plates containing a dye dissolved in a solvent and a laser light beam that is strongly absorbed by the dye. This point-like heat source locally changes surface tension of nearby liquid-air interface. Because of temperature gradients a photo-triggered Marangoni flows are induced leading to self-amplification of the effect and formation of large-scale whirls. The interface is bending toward beam position allowing formation of a gas bubble upon suitable beam steering. Using various techniques (employing luminescent particles or liquid crystals), we visualize liquid flows propelled by the tangential to interface forces. This helped us to understand the physics of the phenomenon and analyze accompanying effects leading to gas bubble trapping. The manipulation of sessile droplets moving on the glass surface induced via controlled with laser light interface bending (i.e. “droplet catapult”) is demonstrated as well.

  13. A mathematical model and numerical simulation of pressure wave in horizontal gas-liquid bubbly flow

    Institute of Scientific and Technical Information of China (English)

    HUANG Fei; BAI Bofeng; GUO Liejin

    2004-01-01

    By using an ensemble-averaged two-fluid model,with valid closure conditions of interfacial momentum exchange due to virtual mass force,viscous shear stress and drag force,a model for pressure wave propagation in a horizontal gas-liquid bubbly flow is proposed.According to the small perturbation theory and solvable condition of one-order linear uniform equations,a dispersion equation of pressure wave is induced.The pressure wave speed calculated from the model is compared and in good agreement with existing data.According to the dispersion equation,the propagation and attenuation of pressure wave are investigated systemically.The factors affecting pressure wave,such as void fraction,pressure,wall shear stress,perturbation frequency,virtual mass force and drag force,are analyzed.The result shows that the decrease in system pressure,the increase in void fraction and the existence of wall shear stress,will cause a decrease in pressure wave speed and an increase in the attenuation coefficient in the horizontal gas-liquid bubbly flow.The effects of perturbation frequency,virtual mass and drag force on pressure wave in the horizontal gas-liquid bubbly flow at low perturbation frequency are different from that at high perturbation frequency.

  14. Influence of structured packing on gas holdup in a three-phase bubble column

    DEFF Research Database (Denmark)

    Monsalvo, Matias Alfonso; Böhm, Ursula

    2007-01-01

    In this work, the influence of structured packing on gas holdup in gas-liquid-solid dispersions has been studied. The experiments were carried out in an empty column and in column containing structured packing operating under identical conditions. Glass beads and silicon carbide particles were used....... The influence of structured packing on the total gas holdup for different superficial gas velocities was found to be similar with and without suspended solids. Therefore, the results obtained in this work were analysed on the basis of correlations derived earlier for gas-liquid dispersions. Excepting...... as the solid material and the volumetric fraction of solids was varied from 0% to around 10%. The liquid viscosity was strongly modified using water, CMC solution and glycerol. The experimental results obtained with both columns were compared with previous results obtained in two-phase bubble columns...

  15. Natural gas annual 1992: Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-22

    This document provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and education institutions. The 1992 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production top its end use. Tables summarizing natural gas supply and disposition from 1988 to 1992 are given for each Census Division and each State. Annual historical data are shown at the national level. Volume 2 of this report presents State-level historical data.

  16. Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

    Science.gov (United States)

    Leifer, Ira; Chernykh, Denis; Shakhova, Natalia; Semiletov, Igor

    2017-06-01

    Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s-1 to derive the in situ calibration curve (Q(σ)). These nonlinear curves related flux (Q) to sonar return (σ) for a multibeam echosounder (MBES) and a single-beam echosounder (SBES) for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering - precluding the use of a theoretical approach to derive Q(σ) from the product of the bubble σ(r) and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function (Ψ(σ)) with respect to Q found Ψ(σ) for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. Ψ(σ) for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core. Ψ(σ) was bimodal for all but the weakest plumes. Q(σ) was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes (Qm) were 5.56, 42.73, and 4.88 mmol s-1 for MBES data with good to reasonable agreement (4-37 %) between the SBES and MBES systems. The seepage flux occurrence probability distribution function (Ψ(Q)) was bimodal, with weak Ψ(Q) in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost.

  17. A stochastic model of bubble distribution in gas-solid fluidized beds

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    On the basis of the Langevin equation and the Fokker-Planck equation, a stochastic model of bubble distribution in a gas-solid fluidized bed was developed. A fluidized bed with a cross section of 0.3 m×0.02 m and a height of 0.8m was used to investigate the bubble distribution with the photographic method. Two distributors were used with orifice diameters of 3 and 6 mm and opening ratios of 6.4% and 6.8%, respectively. The particles were color glass beads with diameters of 0.3, 0.5 and 0.8 mm (Geldart group B particles). The model predictions are reasonable in accordance with the experiment data. The research results indicated that the distribution of bubble concentration was affected by the particle diameter, the fluidizing velocity, and the distributor style. The fluctuation extension of the distribution of bubble concentration narrowed as the particle diameter, fluidizing velocity and opening ratio of the distributor increased. For a given distributor and given particles the distribution was relatively steady along the bed height as the fluidizing velocity changed.

  18. Direct contact condensation of steam bubbles with non-condensable gas%含不凝气体蒸汽泡直接接触冷凝

    Institute of Scientific and Technical Information of China (English)

    屈晓航; 田茂诚; 张冠敏; 罗林聪

    2014-01-01

    通过可视化实验研究了含空气蒸汽泡的冷凝行为和传热特性,气泡中蒸汽质量含量在0.5~0.8之间。在两种不同的过冷水温度下,混合气体气泡分别由直径1.5 mm和3 mm的喷嘴以不同的速度喷入静止的过冷水空间中。通过高速摄像机记录气泡冷凝过程,通过气泡体积变化状况计算气泡热力学参数,进而计算气泡的冷凝传热系数。结果表明,气泡在冷凝过程中不断变形,且在冷凝开始时,气泡出现中空现象;冷水温度越低,冷凝传热系数越低;气泡体积越大,冷凝传热系数越低;喷嘴直径对冷凝传热影响不明显;不凝气体的加入恶化了冷凝传热。对实验中65个气泡传热系数的数值进行了拟合,获得了传热系数关联式。%The condensation behavior and heat transfer characteristics of steam bubbles with air were investigated by visual experiments, with steam mass fraction between 0.5 and 0.8. Bubbles of gas mixture were injected into cool water at two different temperatures through nozzles of diameter 1.5 and 3 mm. The condensing processes of bubbles were recorded by high speed camera and the thermodynamic parameters of bubbles were obtained by the variation of bubble volumes, from which the condensing heat transfer coefficients were calculated. The results show that the bubble deforms continuously when it condenses and a hollow forms in the middle of the bubble at the beginning of the condensing process. The condensing heat transfer coefficient decreases as cool water temperature decreases and bubble volume increases, while it is not affected by the nozzle diameter. The condensing heat transfer is deteriorated by the noncondensing gas. A correlation to predict the heat transfer coefficients is established using all the 65 data obtained in this experiment.

  19. Lateral line pore diameters correlate with the development of gas bubble trauma signs in several Columbia River fishes

    Science.gov (United States)

    Morris, R.G.; Beeman, J.W.; VanderKooi, S.P.; Maule, A.G.

    2003-01-01

    Gas bubble trauma (GBT) caused by gas supersaturation of river water continues to be a problem in the Columbia River Basin. A common indicator of GBT is the percent of the lateral line occluded with gas bubbles; however, this effect has never been examined in relation to lateral line morphology. The effects of 115, 125 and 130% total dissolved gas levels were evaluated on five fish species common to the upper Columbia River. Trunk lateral line pore diameters differed significantly (Psucker>largescale sucker>northern pikeminnow???chinook salmon???redside shiner). At all supersaturation levels evaluated, percent of lateral line occlusion exhibited an inverse correlation to pore size but was not generally related to total dissolved gas level or time of exposure. This study suggests that the differences in lateral line pore diameters between species should be considered when using lateral line occlusion as an indicator of gas bubble trauma. ?? 2003 Elsevier Science Inc. All rights reserved.

  20. Tuning bubbly structures in microchannels.

    Science.gov (United States)

    Vuong, Sharon M; Anna, Shelley L

    2012-06-01

    Foams have many useful applications that arise from the structure and size distribution of the bubbles within them. Microfluidics allows for the rapid formation of uniform bubbles, where bubble size and volume fraction are functions of the input gas pressure, liquid flow rate, and device geometry. After formation, the microchannel confines the bubbles and determines the resulting foam structure. Bubbly structures can vary from a single row ("dripping"), to multiple rows ("alternating"), to densely packed bubbles ("bamboo" and dry foams). We show that each configuration arises in a distinct region of the operating space defined by bubble volume and volume fraction. We describe the boundaries between these regions using geometric arguments and show that the boundaries are functions of the channel aspect ratio. We compare these geometric arguments with foam structures observed in experiments using flow-focusing, T-junction, and co-flow designs to generate stable nitrogen bubbles in aqueous surfactant solution and stable droplets in oil containing dissolved surfactant. The outcome of this work is a set of design parameters that can be used to achieve desired foam structures as a function of device geometry and experimental control parameters.

  1. Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models

    Science.gov (United States)

    Warzinski, Robert P.; Lynn, Ronald; Haljasmaa, Igor; Leifer, Ira; Shaffer, Frank; Anderson, Brian J.; Levine, Jonathan S.

    2014-10-01

    Predicting the fate of subsea hydrocarbon gases escaping into seawater is complicated by potential formation of hydrate on rising bubbles that can enhance their survival in the water column, allowing gas to reach shallower depths and the atmosphere. The precise nature and influence of hydrate coatings on bubble hydrodynamics and dissolution is largely unknown. Here we present high-definition, experimental observations of complex surficial mechanisms governing methane bubble hydrate formation and dissociation during transit of a simulated oceanic water column that reveal a temporal progression of deep-sea controlling mechanisms. Synergistic feedbacks between bubble hydrodynamics, hydrate morphology, and coverage characteristics were discovered. Morphological changes on the bubble surface appear analogous to macroscale, sea ice processes, presenting new mechanistic insights. An inverse linear relationship between hydrate coverage and bubble dissolution rate is indicated. Understanding and incorporating these phenomena into bubble and bubble plume models will be necessary to accurately predict global greenhouse gas budgets for warming ocean scenarios and hydrocarbon transport from anthropogenic or natural deep-sea eruptions.

  2. Contortionist bubbles in andesitic enclaves: implications for gas migration and phase segregation in crystal-rich magmas.

    Science.gov (United States)

    Oppenheimer, J. C.; Cashman, K. V.; Rust, A.; Dobson, K. J.; Bacon, C. R.; Dingwell, D. B.

    2016-12-01

    In order to constrain gas migration behaviors in crystal-rich magmas, we compare results of analogue experiments to frozen structures in andesitic enclaves. In the analogue experiments air was injected into mixtures of syrup and particles sandwiched between glass plates. We observed a significant increase in bubble deformation and coalescence when particle fractions increased beyond a critical value (the random loose packing). At high particle fractions, bubble growth re-organized (compacted) the particles adjacent to the bubble walls. This caused liquid segregation into patches within the particle suspension and into large void spaces near the outer edge of experiments. We compare these experiments to void morphologies in a 58 x 70 x 73 cm andesitic enclave from silicic-andesite lava flows of Mt Mazama, Oregon (Bacon, 1986). This enclave is zoned, with a vesicle-rich center and a glass-rich rim, suggesting gas-driven melt segregation from the center to the rim. We use both 2D (optical microscopy and SEM) and 3D (X-ray tomography) techniques to image crystal textures and bubble shapes. The center of the enclave bears scattered patches of groundmass in the main phenocryst framework. These patches are similar to those observed in experiments, and thus melt segregation in the enclave may have occurred both toward the rim and toward these patches. Bubble morphologies reveal two main types of bubbles. (1) Lobate and finger-like bubbles, similar to the deformed bubbles in experiments, are found exclusively in the groundmass patches. They are also often associated with compacted crystal structures at the bubble walls. (2) Diktytaxitic textures - angular bubbles flattened against phenocrysts - are abundant in the crystal networks. These voids are entirely connected in 3D and formed the gas-rich center of the enclave. They likely represent a gas migration regime where the expanding gas front cannot deform the crystal structure but instead invades the pore-space between

  3. Evidence for a heated gas bubble inside the "cooling flow" region of MKW3s

    CERN Document Server

    Mazzotta, P; Paerels, F B S; Ferrigno, C; Colafrancesco, Sergio; Mewe, R; Forman, W R

    2002-01-01

    We report on the deep Chandra observation of central r=200kpc region of the cluster of galaxies MKW3s which was previously identified as a moderate cooling flow cluster. The Chandra image reveals two striking features -- a 100kpc long and 21kpc wide filament, extending from the center to the south-west and a nearly circular, 50kpc diameter depression 90 kpc south of the X-ray peak. The temperature map shows that the filamentary structure is colder while the surface brightness depression is hotter than the average cluster temperature at any radius. The hot and the cold regions indicate that both cooling and heating processes are taking place in the center of MKW3s. We argue that the surface brightness depression is produced by a heated, low-density gas bubble along the line of sight. We suggest that the heated bubble is produced by short-lived nuclear outbursts from the central galaxy.

  4. Spitzer IRS Observations of the Galactic Center: Shocked Gas in the Radio Arc Bubble

    CERN Document Server

    Simpson, Janet P; Cotera, Angela S; Erickson, Edwin F; Hollenbach, David J; Kaufman, Michael J; Rubin, Robert H

    2007-01-01

    We present Spitzer IRS spectra (R ~600, 10 - 38 micron) of 38 positions in the Galactic Center (GC), all at the same Galactic longitude and spanning plus/minus 0.3 degrees in latitude. Our positions include the Arches Cluster, the Arched Filaments, regions near the Quintuplet Cluster, the ``Bubble'' lying along the same line-of-sight as the molecular cloud G0.11-0.11, and the diffuse interstellar gas along the line-of-sight at higher Galactic latitudes. From measurements of the [O IV], [Ne II], [Ne III], [Si II], [S III], [S IV], [Fe II], [Fe III], and H_2 S(0), S(1), and S(2) lines we determine the gas excitation and ionic abundance ratios. The Ne/H and S/H abundance ratios are ~ 1.6 times that of the Orion Nebula. The main source of excitation is photoionization, with the Arches Cluster ionizing the Arched Filaments and the Quintuplet Cluster ionizing the gas nearby and at lower Galactic latitudes including the far side of the Bubble. In addition, strong shocks ionize gas to O^{+3} and destroy dust grains, ...

  5. Experimental investigation of remote seismic triggering by gas bubble growth in groundwater

    Science.gov (United States)

    Crews, J. B.; Cooper, C. A.

    2014-12-01

    Remotely triggered seismicity is the process by which an earthquake at one location initiates others after a time delay ranging from seconds to days, over distances up to thousands of kilometers. Candidate mechanisms have been proposed, but none specifically address the role of carbon dioxide (CO2) gas bubble growth in groundwater as a driver of remote seismic triggering in active volcanic and geothermal regions, where shallow crustal CO2 gas is abundant. In the present study, we hypothesize that a seismic wave from a distant source can initiate rapid gas bubble growth in CO2-rich groundwater, resulting in a persistent increase in pore fluid pressure and a reduction of effective stress, which can trigger failure on a critically loaded geologic fault. Under conditions representative of a confined aquifer, a Berea sandstone core flooded with an aqueous CO2 solution was subjected to a six-period burst of 0.05-0.3 Hz, 0.1-0.4 MPa confining stress oscillations. After the oscillations were terminated, the pore fluid pressure exceeded its initial value by 13-60 cm equivalent freshwater head, scaling with the amplitude and frequency - a surplus that is consistent with borehole water level changes [Roeloffs et al. (1995) USGS Open File Report, 95-42] observed in response to the June 28 1992 MW 7.3 Landers, California earthquake Rayleigh wave in Parkfield and Long Valley caldera, California, where remotely triggered earthquakes occurred [Hill et al. (1993) Science, 260(5114); Hill et al. (1995) Journal of Geophysical Research, 100(B7)]. Our experimental results indicate that seismically initiated gas bubble growth in groundwater is a physically plausible mechanism for remote seismic triggering in active volcanic and geothermal regions, suggesting that the aqueous CO2 saturation state in a confined aquifer may be used to assess susceptibility to remote seismic triggering.

  6. Bernoulli Suction Effect on Soap Bubble Blowing?

    Science.gov (United States)

    Davidson, John; Ryu, Sangjin

    2015-11-01

    As a model system for thin-film bubble with two gas-liquid interfaces, we experimentally investigated the pinch-off of soap bubble blowing. Using the lab-built bubble blower and high-speed videography, we have found that the scaling law exponent of soap bubble pinch-off is 2/3, which is similar to that of soap film bridge. Because air flowed through the decreasing neck of soap film tube, we studied possible Bernoulli suction effect on soap bubble pinch-off by evaluating the Reynolds number of airflow. Image processing was utilized to calculate approximate volume of growing soap film tube and the volume flow rate of the airflow, and the Reynolds number was estimated to be 800-3200. This result suggests that soap bubbling may involve the Bernoulli suction effect.

  7. Trapped bubbles keep pumice afloat and gas diffusion makes pumice sink

    Science.gov (United States)

    Fauria, Kristen E.; Manga, Michael; Wei, Zihan

    2017-02-01

    Pumice can float on water for months to years - long enough for pumice to travel across oceans and facilitate the spread of species. Long-lived pumice floatation is unexpected, however, because pumice pores are highly connected and water wets volcanic glass. As a result, observations of long floating times have not been reconciled with predictions of rapid sinking. We propose a mechanism to resolve this paradox - the trapping of gas bubbles by water within the pumice. Gas trapping refers to the isolation of gas by water within pore throats such that the gas becomes disconnected from the atmosphere and unable to escape. We use X-ray microtomography to image partially saturated pumice and demonstrate that non-condensable gas trapping occurs in both ambient temperature and hot (500 °C) pumice. Furthermore, we show that the size distribution of trapped gas clusters matches predictions of percolation theory. Finally, we propose that diffusion of trapped gas determines pumice floatation time. Experimental measurements of pumice floatation support a diffusion control on pumice buoyancy and we find that floatation time τ scales as τ ∝ L2/Dθ2 where L is the characteristic length of pumice, D is the gas-water diffusion coefficient, and θ is pumice water saturation. A mechanistic understanding of pumice floatation is a step towards understanding how pumice is partitioned into floating and sinking components and provides an estimate for the lifetime of pumice rafts in the ocean.

  8. Electrochemistry of single nanobubbles. Estimating the critical size of bubble-forming nuclei for gas-evolving electrode reactions.

    Science.gov (United States)

    German, Sean R; Edwards, Martin A; Chen, Qianjin; Liu, Yuwen; Luo, Long; White, Henry S

    2016-12-12

    In this article, we address the fundamental question: "What is the critical size of a single cluster of gas molecules that grows and becomes a stable (or continuously growing) gas bubble during gas evolving reactions?" Electrochemical reactions that produce dissolved gas molecules are ubiquitous in electrochemical technologies, e.g., water electrolysis, photoelectrochemistry, chlorine production, corrosion, and often lead to the formation of gaseous bubbles. Herein, we demonstrate that electrochemical measurements of the dissolved gas concentration, at the instant prior to nucleation of an individual nanobubble of H2, N2, or O2 at a Pt nanodisk electrode, can be analyzed using classical thermodynamic relationships (Henry's law and the Young-Laplace equation - including non-ideal corrections) to provide an estimate of the size of the gas bubble nucleus that grows into a stable bubble. We further demonstrate that this critical nucleus size is independent of the radius of the Pt nanodisk employed (gas. For example, the measured critical surface concentration of H2 of ∼0.23 M at the instant of bubble formation corresponds to a critical H2 nucleus that has a radius of ∼3.6 nm, an internal pressure of ∼350 atm, and contains ∼1700 H2 molecules. The data are consistent with stochastic fluctuations in the density of dissolved gas, at or near the Pt/solution interface, controlling the rate of bubble nucleation. We discuss the growth of the nucleus as a diffusion-limited process and how that process is affected by proximity to an electrode producing ∼10(11) gas molecules per second. Our study demonstrates the advantages of studying a single-entity, i.e., an individual nanobubble, in understanding and quantifying complex physicochemical phenomena.

  9. Numerical Simulation of Particle Mixing in Dispersed Gas-Liquid-Solid Flows using a Combined Volume of Fluid and Discrete Particle Approach

    NARCIS (Netherlands)

    Deen, Niels G.; Sint Annaland, van Martin; Kuipers, J.A.M.

    2007-01-01

    In this paper a hybrid model is presented for the numerical simulation of gas-liquid-solid flows using a combined Volume Of Fluid (VOF) and Discrete Particle (DP) approach applied for respectively dispersed gas bubbles and solid particles present in the continuous liquid phase. The hard sphere DP mo

  10. Direct numerical simulation of particle mixing in dispersed gas-liquid-solid flows using a combined volume of fluid and discrete particle approach

    NARCIS (Netherlands)

    Deen, Niels G.; Sint Annaland, van Martin; Kuipers, J.A.M.

    2006-01-01

    In this paper a hybrid model is presented for the numerical simulation of gas-liquid-solid flows using a combined Volume Of Fluid (VOF) and Discrete Particle (DP) approach applied for respectively dispersed gas bubbles and solid particles present in the continuous liquid phase. The hard sphere DP mo

  11. The Evolution of the Gold Bubble in NIF Ignition Gas-Filled Hohlraums

    Science.gov (United States)

    Schneider, Marilyn; MacLaren, Steve; Widmann, Klaus; Meezan, Nathan; Hammer, James; Bell, Perry; Benedetti, Robin; Bradley, David; Callahan, Deborah; Dewald, Eduard; Doeppner, Tilo; Hinkel, Denise; Jones, Oggie; Landen, O. L.; Michel, Pierre; Milovich, Jose; Moody, John; Moore, Alastair

    2015-11-01

    At the National Ignition Facility (NIF), the energy from 192 laser beams is converted to an x-ray drive in a gas-filled gold hohlraum. The x-ray drive heats and implodes a fuel capsule. The ViewFactor platform uses a truncated hohlraum to measure the x-ray drive from the capsule point-of-view. This platform also affords excellent diagnostic views of the hohlraum interior, in particular, of the region in which the outer beams deposit their energy (the ``gold bubble'') Time-resolved and time-integrated images in the hard x-ray range (>3 keV) reveal an 8-fold symmetry in the gold bubble. The Au plasma in the bubble from the eight 50 degree quads expands faster than that from the interleaved 44.5 degree quads. The variation in this structure with laser intensity, with pulse shape and cross beam energy transfer, and comparison to models, will be discussed. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  12. The Physical and Dynamical Properties of Gas that Molds the Fermi Bubbles

    Science.gov (United States)

    Jenkins, Edward

    2012-10-01

    Two sharply defined lobes of gamma-ray emission emerging from the center of our Galaxy, called the Fermi Bubbles, have been discovered in the Galactic halo. Their emissivity appears to be uniform and extends up to 8 kpc on either side of the plane. Accompanying the Fermi Bubbles are excess emissions seen in X-rays and microwaves. It is generally believed that cosmic ray particles emitted from the central portion of the Galactic disk {or perhaps the nucleus itself} are responsible for these emissions. These particles must have been advected into the halo by a wind or shock. Our goal is to gain a better understanding of the nature of this gaseous transport by viewing the UV spectra of bright, extragalactic sources behind one of the Fermi Bubbles and its surrounding regions. We plan to obtain COS spectra of 5 such objects, with the goal of measuring absorption features from Si III, Si IV, C IV and N V. We expect that our mapping of column densities and kinematics of the gases will help us to distinguish a shock from a wind. Moreover, if a shock is present, we should be able to evaluate the product of its age and the density of the gas by comparing the column densities of different species.

  13. Gas-Liquid Mass Transfer in a Slurry Bubble Column Reactor under High Temperature andHigh Pressure

    Institute of Scientific and Technical Information of China (English)

    杨卫国; 王金福; 金涌

    2001-01-01

    The gas-liquid mass transfer of H2 and CO in a high temperature and high-pressure three-phase slurry bubble column reactor is studied. The gas-liquid volumetric mass transfer coefficients kLa are obtained by measuring the dissolution rate of H2 and CO. The influences of the main operation conditions, such as temperature, pressure,superficial gas velocity and solid concentration, are studied systematically. Two empirical correlations are proposed to predict kLa values for H2 and CO in liquid paraffln/solid particles slurry bubble column reactors.

  14. A Study of Vertical Gas Jets in a Bubbling Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Ceccio, Steven [Univ. of Michigan, Ann Arbor, MI (United States); Curtis, Jennifer [Univ. of Florida, Gainesville, FL (United States)

    2011-04-15

    A detailed experimental study of a vertical gas jet impinging a fluidized bed of particles has been conducted with the help of Laser Doppler Velocimetry measurements. Mean and fluctuating velocity profiles of the two phases have been presented and analyzed for different fluidization states of the emulsion. The results of this work would be greatly helpful in understanding the complex two-phase mixing phenomenon that occurs in bubbling beds, such as in coal and biomass gasification, and also in building more fundamental gas-solid Eulerian/Lagrangian models which can be incorporated into existing CFD codes. Relevant simulations to supplement the experimental findings have also been conducted using the Department of Energy's open source code MFIX. The goal of these simulations was two-fold. One was to check the two-dimensional nature of the experimental results. The other was an attempt to improve the existing dense phase Eulerian framework through validation with the experimental results. In particular the sensitivity of existing frictional models in predicting the flow was investigated. The simulation results provide insight on wall-bounded turbulent jets and the effect frictional models have on gas-solid bubbling flows. Additionally, some empirical minimum fluidization correlations were validated for non-spherical particles with the idea of extending the present study to non-spherical particles which are more common in industries.

  15. Gas bubble disease in the brain of a living California sea lion (Zalophus californianus

    Directory of Open Access Journals (Sweden)

    William George Van Bonn

    2013-01-01

    Full Text Available A yearling California sea lion (Zalophus californianus was admitted into rehabilitation with signs of cerebellar pathology. Diagnostic imaging that included radiography and magnetic resonance imaging (MRI demonstrated space-occupying lesions predominantly in the cerebellum that were filled partially by CSF-like fluid and partially by gas, and cerebral lesions that were fluid filled. Over a maximum period of four months, the brain lesions reduced in size and the gas resorbed and was replaced by CSF-like fluid. To test the animal in this study for motor memory deficits, an alternation task in a two-choice maze was utilized. The sea lion performed poorly similar to another case of pneumocerebellum previously reported, and contrary to data acquired from a group of sea lions with specific hippocampal injury. The learning deficits were attributed to the cerebellar injury. These data provide important insight both to the clinical presentation and behavioral observations of cerebellar injury in sea lions, as well as providing an initial model for long-term outcome following cerebellar injury. The specific etiology of the gas could not be determined. The live status of the patient with recovery suggests that the most likely etiologies for the gas are either de novo formation or air emboli secondary to trauma. A small air gun pellet was present within and was removed from soft tissues adjacent to the tympanic bulla. While no evidence to support the pellet striking bone was found, altered dive pattern associated with this human interaction may have provided the opportunity for gas bubble formation to occur. The similarity in distribution of the gas bubble related lesions in this case compared with another previously published case of pneumocerebellum suggests that preferential perfusion of the brain, and more specifically the cerebellum, may occur during diving events.

  16. Characterization of fission gas bubbles in irradiated U-10Mo fuel

    Energy Technology Data Exchange (ETDEWEB)

    Casella, Andrew M.; Burkes, Douglas E.; MacFarlan, Paul J.; Buck, Edgar C.

    2017-09-01

    Irradiated U-10Mo fuel samples were prepared with traditional mechanical potting and polishing methods with in a hot cell. They were then removed and imaged with an SEM located outside of a hot cell. The images were then processed with basic imaging techniques from 3 separate software packages. The results were compared and a baseline method for characterization of fission gas bubbles in the samples is proposed. It is hoped that through adoption of or comparison to this baseline method that sample characterization can be somewhat standardized across the field of post irradiated examination of metal fuels.

  17. Use of a porous membrane for gas bubble removal in microfluidic channels: physical mechanisms and design criteria

    CERN Document Server

    Xu, Jie; Attinger, Daniel; 10.1007/s10404-010-0592-5

    2010-01-01

    We demonstrate and explain a simple and efficient way to remove gas bubbles from liquid-filled microchannels, by integrating a hydrophobic porous membrane on top of the microchannel. A prototype chip is manufactured in hard, transparent polymer with the ability to completely filter gas plugs out of a segmented flow at rates up to 7.4 microliter/s per mm2 of membrane area. The device involves a bubble generation section and a gas removal section. In the bubble generation section, a T-junction is used to generate a train of gas plugs into a water stream. These gas plugs are then transported towards the gas removal section, where they slide along a hydrophobic membrane until complete removal. The system has been successfully modeled and four necessary operating criteria have been determined to achieve a complete separation of the gas from the liquid. The first criterion is that the bubble length needs to be larger than the channel diameter. The second criterion is that the gas plug should stay on the membrane fo...

  18. Observation and theoretic analysis of gas-bubble formation and growth in water-model

    Institute of Scientific and Technical Information of China (English)

    WU Rui-zhi; SHU Da; SUN Bao-de; WANG Jun; LU Yan-ling

    2005-01-01

    The behavior of bubbles is observed with high-speed digital camera in water-model. It is found that each bubble has three processes: bubble formation, bubble coalescence and bubble division. Bubble shape is spherical firstly, then elliptical and spherical crown after coalescence, and spherical again after division. These phenomena are explained theoretically. And the bubble size is defined newly. The so-defined bubble size is measured through digital camera and LECO graphical analyzer. And the measured results are compared with those in literatures.

  19. Laboratory investigation of the factors impact on bubble size, pore blocking and enhanced oil recovery with aqueous Colloidal Gas Aphron.

    Science.gov (United States)

    Shi, Shenglong; Wang, Yefei; Li, Zhongpeng; Chen, Qingguo; Zhao, Zenghao

    Colloidal Gas Aphron as a mobility control in enhanced oil recovery is becoming attractive; it is also designed to block porous media with micro-bubbles. In this paper, the effects of surfactant concentration, polymer concentration, temperature and salinity on the bubble size of the Colloidal Gas Aphron were studied. Effects of injection rates, Colloidal Gas Aphron fluid composition, heterogeneity of reservoir on the resistance to the flow of Colloidal Gas Aphron fluid through porous media were investigated. Effects of Colloidal Gas Aphron fluid composition and temperature on residual oil recovery were also studied. The results showed that bubble growth rate decreased with increasing surfactant concentration, polymer concentration, and decreasing temperature, while it decreased and then increased slightly with increasing salinity. The obvious increase of injection pressure was observed as more Colloidal Gas Aphron fluid was injected, indicating that Colloidal Gas Aphron could block the pore media effectively. The effectiveness of the best blend obtained through homogeneous sandpack flood tests was modestly improved in the heterogeneous sandpack. The tertiary oil recovery increased 26.8 % by Colloidal Gas Aphron fluid as compared to 20.3 % by XG solution when chemical solution of 1 PV was injected into the sandpack. The maximum injected pressure of Colloidal Gas Aphron fluid was about three times that of the XG solution. As the temperature increased, the Colloidal Gas Aphron fluid became less stable; the maximum injection pressure and tertiary oil recovery of Colloidal Gas Aphron fluid decreased.

  20. Modelling of bubble-mediated gas transfer: Fundamental principles and a laboratory test

    NARCIS (Netherlands)

    Woolf, D.K.; Leifer, I.S.; Nightingale, P.D.; Rhee, T.S.; Bowyer, P.; Caulliez, G.; Leeuw, G. de; Larsen, S.E.; Liddicoat, M.; Baker, J.; Andreae, M.O.

    2007-01-01

    The air-water exchange of gases can be substantially enhanced by wave breaking and specifically by bubble-mediated transfer. A feature of bubble-mediated transfer is the additional pressure on bubbles resulting from the hydrostatic forces on a submerged bubble and from surface tension and curvature.

  1. Effect of Gas- and Liquid-injection Methods on Formation of Bubble and Liquid Slug at Merging Micro T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Kyoung [Kyungnam Univ., Changwon (Korea, Republic of); Lee, Chi Young [Pukyong Nat’l Univ., Busan (Korea, Republic of)

    2016-04-15

    In the present experimental study, the effect of gas- and liquid-injected methods on the formation of bubble and liquid slug at the merging micro T-junction of a square microchannel with dimensions 600 μm × 600 μm was investigated. Nitrogen and water were used as test fluids. The superficial velocities of the liquid and gas were in the range of 0.05 - 1 m/s, and 0.1 - 1 m/s, respectively, where the Taylor flow was observed. The bubble length, liquid slug length, bubble velocity, and bubble generation frequency were measured by analyzing the images captured using a high-speed camera. Under similar inlet superficial velocity conditions, in the case of gas injection to the main channel at the merging T-junction (T{sub g}as-liquid), the lengths of the bubble and liquid slug were longer, and the bubble generation frequency was lower than in the case of liquid injection to the main channel at the merging T-junction (T{sub l}iquid-gas). On the other hand, in both cases, the bubble velocity was almost the same. The previous correlation proposed using experimental data for T{sub l}iquid-gas had predicted the present experimental data of bubble length, bubble velocity, liquid slug length, and bubble generation frequency for T{sub g}as-liquid to be ~24%, ~9%, ~39%, ~55%, respectively.

  2. Advanced gas-emission anode design for microfluidic fuel cell eliminating bubble accumulation

    Science.gov (United States)

    Zhang, Hao; Xuan, Jin; Leung, Dennis Y. C.; Wang, Huizhi; Xu, Hong; Zhang, Li

    2017-10-01

    A microfluidic fuel cell is a low cost, easily fabricated energy device and is considered a promising energy supplier for portable electronics. However, the currently developed microfluidic fuel cells that are fed with hydrocarbon fuels are confronted with a bubble problem especially when operating at high current density conditions. In this work, a gas-emission anode is presented to eliminate the gas accumulation at the anode. This gas-emission anode is verified as a valid design for discharging gaseous products, which is especially beneficial for stable operation of microfluidic fuel cells. The electrochemical performance of a counter-flow microfluidic fuel cell equipped with a gas-emission anode was measured. The results indicate that the specific design of the gas-emission anode is essential for reducing the oxygen reduction reaction parasitic effect at the anode. Fuel utilization of 76.4% was achieved at a flow rate of 0.35 µl min‑1. Current–voltage curves of single electrodes were measured and the parasitic effect at the anode was identified as the main performance limiting factor in the presented anode design.

  3. Free Surface Lattice Boltzmann with Enhanced Bubble Model

    CERN Document Server

    Anderl, Daniela; Rauh, Cornelia; Rüde, Ulrich; Delgado, Antonio

    2016-01-01

    This paper presents an enhancement to the free surface lattice Boltzmann method (FSLBM) for the simulation of bubbly flows including rupture and breakup of bubbles. The FSLBM uses a volume of fluid approach to reduce the problem of a liquid-gas two-phase flow to a single-phase free surface simulation. In bubbly flows compression effects leading to an increase or decrease of pressure in the suspended bubbles cannot be neglected. Therefore, the free surface simulation is augmented by a bubble model that supplies the missing information by tracking the topological changes of the free surface in the flow. The new model presented here is capable of handling the effects of bubble breakup and coalesce without causing a significant computational overhead. Thus, the enhanced bubble model extends the applicability of the FSLBM to a new range of practically relevant problems, like bubble formation and development in chemical reactors or foaming processes.

  4. How man-made interference might cause gas bubble emboli in deep diving whales

    Directory of Open Access Journals (Sweden)

    Andreas eFahlman

    2014-01-01

    Full Text Available Recent cetacean mass strandings in close temporal and spatial association with sonar activity has raised the concern that anthropogenic sound may harm breath-hold diving marine mammals. Necropsy results of the stranded whales have shown evidence of bubbles in the tissues, similar to those in human divers suffering from decompression sickness (DCS. It has been proposed that changes in behavior or physiological responses during diving could increase tissue and blood N2 levels, thereby increasing DCS risk. Dive data recorded from sperm, killer, long-finned pilot, Blainville’s beaked and Cuvier’s beaked whales before and during exposure to low- (1-2 kHz and mid- (2-7 kHz frequency active sonar were used to estimate the changes in blood and tissue N2 tension (PN2. Our objectives were to determine if differences in 1 dive behavior or 2 physiological responses to sonar are plausible risk factors for bubble formation. The theoretical estimates indicate that all species may experience high N2 levels. However, unexpectedly, deep diving generally result in higher end-dive PN2 as compared with shallow diving. In this focused review we focus on three possible explanations: 1 We revisit an old hypothesis that CO2, because of its much higher diffusivity, form bubble precursors that continue to grow in N2 supersaturated tissues. Such a mechanism would be less dependent on the alveolar collapse depth but affected by elevated levels of CO2 following a burst of activity during sonar exposure. 2 During deep dives, a greater duration of time might be spent at depths where gas exchange continues as compared with shallow dives. The resulting elevated levels of N2 in deep diving whales might also make them more susceptible to anthropogenic disturbances. 3 Extended duration of dives even at depths beyond where the alveoli collapse could result in slow continuous accumulation of N2 in the adipose tissues that eventually becomes a liability.

  5. Hydrate film growth on the surface of a gas bubble suspended in water.

    Science.gov (United States)

    Peng, B Z; Dandekar, A; Sun, C Y; Luo, H; Ma, Q L; Pang, W X; Chen, G J

    2007-11-01

    The lateral film growth rate of CH4, C2H4, CO2, CH4 + C2H4, and CH4 + C3H8 hydrates in pure water were measured at four fixed temperatures of 273.4, 275.4, 277.4, and 279.4 K by means of suspending a single gas bubble in water. The results showed that the lateral growth rates of mixed-gas CH4 + C2H4 hydrate films were slower than that of pure gas (CH4 or C2H4) for the same driving force and that of mixed-gas CH4 + C3H8 hydrate film growth was the slowest. The dependence of the thickness of hydrate film on the driving force was investigated, and it was demonstrated that the thickness of hydrate film was inversely proportional to the driving force. It was found that the convective heat transfer control model reported in the literature could be used to formulate the lateral film growth rate v(f) with the driving force DeltaT perfectly for all systems after introduction of the assumption that the thickness of hydrate films is inversely proportional to the driving force DeltaT; i.e., v(f) = psiDeltaT(5/2) is correct and independent of the composition of gas and the type of hydrate. The thicknesses of different gas hydrate films were estimated, and it is demonstrated that the thicknesses of mixed-gas hydrate films were thicker than those of pure gases, which was qualitatively consistent with the experimental result.

  6. Testing for Nonlinearity in Dynamic Characteristics of Vertical Upward Oil-Gas-Water Three-phase Bubble and Slug Flows

    Institute of Scientific and Technical Information of China (English)

    朱雷; 金宁德; 高忠科; 杜萌; 王振亚

    2012-01-01

    Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characteristics of oil-in-water type bubble and slug flows. The results indicate that oil-in-water type bubble flow will turn to deterministic motion with the increase of oil phase fraction f o and superficial gas velocity U sg under fixed flowrate of oil-water mixture Q mix . The dynamics of oil-in-water type slug flow becomes more complex with the increase of U sg under fixed flowrate of oil-water mixture. The change of f o leads to irregular influence on the dynamics of slug flow. These interesting findings suggest that the surrogate data method can be a faithful tool for characterizing dynamic characteristics of oil-in-water type bubble and slug flows.

  7. A pilot-scale jet bubbling reactor for wet flue gas desulfurization with pyrolusite

    Institute of Scientific and Technical Information of China (English)

    SU Shi-jun; ZHU Xiao-fan; LIU Yong-jun; JIANG Wen-ju; JIN Yan

    2005-01-01

    MnO2 in pyrolusite can react with SO2 in flue gas and obtain by-product MnSO4· H2 O. A pilot scale jet bubbling reactor was applied in this work. Different factors affecting both SO2 absorption efficiency and Mn2+ extraction rate have been investigated, these factors include temperature of inlet gas flue, ration of liquid/solid mass flow rate(L/S), pyrolusite grade, and SO2 concentration in the inlet flue gas. In the meantime, the procedure of purification of absorption liquid was also discussed. Experiment results indicated that the increase of temperature from 30 to 70 K caused the increase of SO2 absorption efficiency from 81.4% to 91.2%. And when SO2 concentration in the inlet flue gas increased from 500 to 3000 ppm, SO2 absorption efficiency and Mn2+ extraction rate decreased from 98.1% to 82.2% and from 82.8% to 61.7%, respectively. The content of MnO2 in pyrolusite had a neglectable effect on SO2 absorption efficiency. Low L/S was good for both removal of SO2 and Mn2+ extraction. The absorption liquid was filtrated and purified to remove Si,standards.

  8. CFD simulation of bubbling and collapsing characteristics in a gas-solid fluidized bed

    Institute of Scientific and Technical Information of China (English)

    Pei Pei; Zhang Kai; Lu Erwei; Wen Dongsheng

    2009-01-01

    Computational Fluid Dynamics (CFD) has become an alternative method to experiments for understanding the fluid dynamics of multiphase flow. A two-fluid model, which contains additional terms in both the gas- and solid-phase momentum equations, is used to investigate the fluidization quality in a fluidized bed. A case study for quartz sand with a density of 2,660 kg/m3 and a diameter of 500 μm,whose physical property is similar to a new kind of catalyst for producing clean fuels through the residue fluid catalytic cracking process, is simulated in a two-dimensional fluidized bed with 0.57 m width and 1.00 m height. Transient bubbling and collapsing characteristics are numerically investigated in the platform of CFX 4.4 by integrating user-defined Fortran subroutines. The results show that the fluidization and collapse process is in fair agreement with the classical theory of Geldart B classification, but the collapse time is affected by bubbles at the interface between the dense phase and freeboard.

  9. Universal correlation for the rise velocity of long gas bubbles in round pipes

    Science.gov (United States)

    Viana, Flavia; Pardo, Raimundo; Yánez, Rodolfo; Trallero, José L.; Joseph, Daniel D.

    2003-11-01

    We collected all of the published data we could find on the rise velocity of long gas bubbles in stagnant fluids contained in circular tubes. Data from 255 experiments from the literature and seven new experiments at PDVSA Intevep for fluids with viscosities ranging from 1 mPa s up to 3900 mPa s were assembled on spread sheets and processed in log log plots of the normalized rise velocity, Fr {=} U/(gD)(1/2) Froude velocity vs. buoyancy Reynolds number, R {=} (D(3) g (rho_{l}-rho_{g}) rho_{l})(1/2) /mu for fixed ranges of the Eötvös number, Eo {=} grho_{l}D(2) /sigma where D is the pipe diameter, rho_{l}, rho_{g} and sigma are densities and surface tension. The plots give rise to power laws in Eo; the composition of these separate power laws emerge as bi-power laws for two separate flow regions for large and small buoyancy Reynolds. For large R (>200) we find [hboxFr = {0.34}/(1+3805/hboxEo^{3.06})^{0.58}.] For small R (PDVSA-Intevep on the rise of Taylor bubbles is presented.

  10. 水平管泡状流局部实验参数的概率统计方法%STATISTICAL METHOD TO CALCULATE LOCAL INTERFACIAL VARIABLES IN HORIZONTAL GAS-LIQUID BUBBLY FLOWS

    Institute of Scientific and Technical Information of China (English)

    杨建; 张鸣远; 苏玉亮; 张超杰; 王金照

    2002-01-01

    This paper presents a statistical method to calculate local interfacial variables in horizontal gas-liquid bubbly flows based on the data measured with a double-sensor probe.The geometrical relationship between the apparent and actual bubble velocities and the relationship between the chord intersected by the sensor and bubble diameter were determined.A probability density function was introduced to consider the effect of both axial and radial movements of bubbles on bubble velocity and bubble size.

  11. Automated gas bubble imaging at sea floor – a new method of in situ gas flux quantification

    Directory of Open Access Journals (Sweden)

    K. Thomanek

    2010-02-01

    Full Text Available Photo-optical systems are common in marine sciences and have been extensively used in coastal and deep-sea research. However, due to technical limitations in the past photo images had to be processed manually or semi-automatically. Recent advances in technology have rapidly improved image recording, storage and processing capabilities which are used in a new concept of automated in situ gas quantification by photo-optical detection. The design for an in situ high-speed image acquisition and automated data processing system is reported ("Bubblemeter". New strategies have been followed with regards to back-light illumination, bubble extraction, automated image processing and data management. This paper presents the design of the novel method, its validation procedures and calibration experiments. The system will be positioned and recovered from the sea floor using a remotely operated vehicle (ROV. It is able to measure bubble flux rates up to 10 L/min with a maximum error of 33% for worst case conditions. The Bubblemeter has been successfully deployed at a water depth of 1023 m at the Makran accretionary prism offshore Pakistan during a research expedition with R/V Meteor in November 2007.

  12. Automated gas bubble imaging at sea floor – a new method of in situ gas flux quantification

    Directory of Open Access Journals (Sweden)

    G. Bohrmann

    2010-06-01

    Full Text Available Photo-optical systems are common in marine sciences and have been extensively used in coastal and deep-sea research. However, due to technical limitations in the past photo images had to be processed manually or semi-automatically. Recent advances in technology have rapidly improved image recording, storage and processing capabilities which are used in a new concept of automated in situ gas quantification by photo-optical detection. The design for an in situ high-speed image acquisition and automated data processing system is reported ("Bubblemeter". New strategies have been followed with regards to back-light illumination, bubble extraction, automated image processing and data management. This paper presents the design of the novel method, its validation procedures and calibration experiments. The system will be positioned and recovered from the sea floor using a remotely operated vehicle (ROV. It is able to measure bubble flux rates up to 10 L/min with a maximum error of 33% for worst case conditions. The Bubblemeter has been successfully deployed at a water depth of 1023 m at the Makran accretionary prism offshore Pakistan during a research expedition with R/V Meteor in November 2007.

  13. Near-wall measurements of the bubble- and Lorentz-force-driven convection at gas-evolving electrodes

    Science.gov (United States)

    Baczyzmalski, Dominik; Weier, Tom; Kähler, Christian J.; Cierpka, Christian

    2015-08-01

    Chemical energy storage systems, e.g., in the form of hydrogen or methanol, have a great potential for the establishment of volatile renewable energy sources due to the large energy density. The efficiency of hydrogen production through water electrolysis is, however, limited by gas bubbles evolving at the electrode's surface and can be enhanced by an accelerated bubble detachment. In order to characterize the complex multi-phase flow near the electrode, simultaneous measurements of the fluid velocities and the size and trajectories of hydrogen bubbles were performed in a water electrolyzer. The liquid phase velocity was measured by PIV/PTV, while shadowgraphy was used to determine the bubble trajectories. Special measurement and evaluation techniques had to be applied as the measurement uncertainty is strongly affected by the high void fraction close to the wall. In particular, the application of an advanced PTV scheme allowed for more precise fluid velocity measurements closer to electrode. Based on these data, stability characteristics of the near-wall flow were evaluated and compared to that of a wall jet. PTV was used as well to investigate the effect of Lorentz forces on the near-wall fluid velocities. The results show a significantly increased wall parallel liquid phase velocity with increasing Lorentz forces. It is presumed that this enhances the detachment of hydrogen bubbles from the electrode surface and, consequently, decreases the fractional bubble coverage and improves the efficiency. In addition, the effect of large rising bubbles with path oscillations on the near-wall flow was investigated. These bubbles can have a strong impact on the mass transfer near the electrode and thus affect the performance of the process.

  14. Gas bubbles evolution peculiarities in ferritic-martensitic and austenitic steels and alloys under helium-ion irradiation

    NARCIS (Netherlands)

    Chernov, [No Value; Kalashnikov, AN; Kahn, BA; Binyukova, SY

    2003-01-01

    Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe C system, ferritic-martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion it. radiation up to a fluence of 5 x 10(20) m(-2) at the temperature of 920 K. It

  15. Acoustic Characterization of Fluorinert FC-43 Liquid with Helium Gas Bubbles: Numerical Experiments

    Directory of Open Access Journals (Sweden)

    Christian Vanhille

    2017-01-01

    Full Text Available In this work, we define the acoustic characteristics of a biphasic fluid consisting of static helium gas bubbles in liquid Fluorinert FC-43 and study the propagation of ultrasound of finite amplitudes in this medium. Very low sound speed and high sound attenuation are found, in addition to a particularly high acoustic nonlinear parameter. This result suggests the possibility of using this medium as a nonlinear enhancer in various applications. In particular, parametric generation of low ultrasonic frequencies is studied in a resonator cavity as a function of driving pressure showing high conversion efficiency. This work suggests that this medium could be used for applications such as parametric arrays, nondestructive testing, diagnostic medicine, sonochemistry, underwater acoustics, and ultrasonic imaging and to boost the shock formation in fluids.

  16. Fuel Performance Experiments and Modeling: Fission Gas Bubble Nucleation and Growth in Alloy Nuclear Fuels

    Energy Technology Data Exchange (ETDEWEB)

    McDeavitt, Sean [Texas A & M Univ., College Station, TX (United States); Shao, Lin [Texas A & M Univ., College Station, TX (United States); Tsvetkov, Pavel [Texas A & M Univ., College Station, TX (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Kennedy, Rory [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-04-07

    Advanced fast reactor systems being developed under the DOE's Advanced Fuel Cycle Initiative are designed to destroy TRU isotopes generated in existing and future nuclear energy systems. Over the past 40 years, multiple experiments and demonstrations have been completed using U-Zr, U-Pu-Zr, U-Mo and other metal alloys. As a result, multiple empirical and semi-empirical relationships have been established to develop empirical performance modeling codes. Many mechanistic questions about fission as mobility, bubble coalescience, and gas release have been answered through industrial experience, research, and empirical understanding. The advent of modern computational materials science, however, opens new doors of development such that physics-based multi-scale models may be developed to enable a new generation of predictive fuel performance codes that are not limited by empiricism.

  17. Passive acoustic derived bubble flux and applications to natural gas seepage in the Mackenzie Delta, NWT, Canada and Coal Oil Point, CA

    Science.gov (United States)

    Culling, D.; Leifer, I.; Dallimore, S.; Alcala, K.

    2012-12-01

    Methane is a prominent greenhouse gas that escapes naturally from thermogenic reservoirs as seepage from marine and lacustrine biogenic sources as bubble ebullition. Geologic methane emissions are critically important contributors to the global methane budget however, few quantitative flux measurements are available for shallow waters. This gap in knowledge is critical as in these settings gas can easily transit as bubbles through the water column and directly influence global atmospheric budgets. Video and active acoustic (sonar) measurements of bubble flux have spatial limitations requiring predictable bubble emission location. Passive acoustics are less affected by these limitations, in addition, they can provide data in water too shallow for effective sonar bubble observations. Lab tests were undertaken to quantify the acoustic signature of bubbles formed in non-cohesive sediments. specifically focusing on mechanisms that complicate interpretation of acoustic data. Lab tests then were compared to field data to provide measurement calibration/validation. The principles behind the acoustic analysis method are based on the Minnaert equation, which relates a bubble radius and acoustic frequency. Bubble size and the resultant acoustic frequency from known flows and capillary tube diameters are well documented; however changing sediment pathways adds to the complexity of bubble formation and the resultant bubble acoustic signal. These complex signals were investigated in a lab tank with a thick, cohesive fine-grained sediment bed, through which bubbles produced by a syringe pump migrated to the sediment-water interface. Then, the resultant bubbles were diverted into clear water and measured from high speed, high definition video, while the acoustic signature of bubble formation was recorded concurrently by a hydrophone. Bubble formation is influenced by currents, which shifts the acoustical signal towards a higher frequency with a more complex pattern than the

  18. Three-Dimensional Reconstruction of a Gas Bubble Trajectory in Liquid

    Directory of Open Access Journals (Sweden)

    Augustyniak Jakub

    2014-01-01

    Full Text Available The identification of the shape of the bubble trajectory is crucial for understanding the mechanism of bubble motion in liquid. In the paper it has been presented the technique of 3D bubble trajectory reconstruction using a single high speed camera and the system of mirrors. In the experiment a glass tank filled with distilled water was used. The nozzle through which the bubbles were generated was placed in the centre of the tank. The movement of the bubbles was recorded with a high speed camera, the Phantom v1610 at a 600 fps. The techniques of image analysis has been applied to determine the coordinates of mass centre of each bubble image. The 3D trajectory of bubble can be obtained by using triangulation methods. In the paper the measurement error of imaging computer tomography has been estimated. The maximum measurement error was equal to ±0,65 [mm]. Trajectories of subsequently departing bubbles were visualized.

  19. Dynamics of gas bubble growth in oil-refrigerant mixtures under isothermal decompression

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Joao Paulo; Barbosa Junior, Jader R.; Prata, Alvaro T. [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. of Mechanical Engineering], Emails: jpdias@polo.ufsc.br, jrb@polo.ufsc.br, prata@polo.ufsc.br

    2010-07-01

    This paper proposes a numerical model to predict the growth of gaseous refrigerant bubbles in oil-refrigerant mixtures with high contents of oil subjected to isothermal decompression. The model considers an Elementary Cell (EC) in which a spherical bubble is surrounded by a concentric and spherical liquid layer containing a limited amount of dissolved liquid refrigerant. The pressure reduction in the EC generates a concentration gradient at the bubble interface and the refrigerant is transported to the bubble by molecular diffusion. After a sufficiently long period of time, the concentration gradient in the liquid layer and the bubble internal pressure reach equilibrium and the bubble stops growing, having attained its stable radius. The equations of momentum and chemical species conservation for the liquid layer, and the mass balance at the bubble interface are solved via a coupled finite difference procedure to determine the bubble internal pressure, the refrigerant radial concentration distribution and the bubble growth rate. Numerical results obtained for a mixture of ISO VG10 ester oil and refrigerant HFC-134a showed that bubble growth dynamics depends on model parameters like the initial bubble radius, initial refrigerant concentration in the liquid layer, decompression rate and EC temperature. Despite its simplicity, the model showed to be a potential tool to predict bubble growth and foaming which may result from important phenomena occurring inside refrigeration compressors such as lubrication of sliding parts and refrigerant degassing from the oil stored in oil sump during compressor start-up. (author)

  20. Experimental investigation of a pilot-scale jet bubbling reactor for wet flue gas desulphurisation

    DEFF Research Database (Denmark)

    Zheng, Yuanjing; Kiil, Søren; Johnsson, Jan Erik

    2003-01-01

    In the present work, an experimental parameter study was conducted in a pilot-scale jet bubbling reactor for wet flue gas desulphurisation (FGD). The pilot plant is downscaled from a limestone-based, gypsum producing full-scale wet FGD plant. Important process parameters, such as slurry pH, inlet...... flue gas concentration of SO2, reactor temperature, and slurry concentration of Cl- have been varied. The degree of desulphurisation, residual limestone content of the gypsum, liquid phase concentrations, and solids content of the slurry were measured during the experimental series. The SO2 removal...... efficiency increased from 66.1% to 71.5% when the reactor slurry pH was changed from 3.5 to 5.5. Addition of Cl(in the form of CaCl2 . 2H(2)O) to the slurry (25 g Cl-/l) increased the degree of desulphurisation to above 99%, due to the onset of extensive foaming, which substantially increased the gas...

  1. Self assembly, mobilization, and flotation of crude oil contaminated sand particles as granular shells on gas bubbles in water.

    Science.gov (United States)

    Tansel, Berrin; Boglaienko, Daria

    2017-01-01

    Contaminant fate and transport studies and models include transport mechanisms for colloidal particles and dissolved ions which can be easily moved with water currents. However, mobilization of much larger contaminated granular particles (i.e., sand) in sediments have not been considered as a possible mechanism due to the relatively larger size of sand particles and their high bulk density. We conducted experiments to demonstrate that oil contaminated granular particles (which exhibit hydrophobic characteristics) can attach on gas bubbles to form granular shells and transfer from the sediment phase to the water column. The interactions and conditions necessary for the oil contaminated granular particles to self assemble as tightly packed granular shells on the gas bubbles which transfer from sediment phase to the water column were evaluated both experimentally and theoretically for South Louisiana crude oil and quartz sand particles. Analyses showed that buoyancy forces can be adequate to move the granular shell forming around the air bubbles if the bubble radius is above 0.001mm for the sand particles with 0.28mm diameter. Relatively high magnitude of the Hamaker constant for the oil film between sand and air (5.81×10(-20)J for air-oil-sand) indicates that air bubbles have high affinity to attach on the oil film that is on the sand particles in comparison to attaching to the sand particles without the oil film in water (1.60×10(-20)J for air-water-sand). The mobilization mechanism of the contaminated granular particles with gas bubbles can occur in natural environments resulting in transfer of granular particles from sediments to the water column. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Mechanics of Bubbles in Sludges and Slurries Modeling Studies of Particulate Materials

    Energy Technology Data Exchange (ETDEWEB)

    Phillip A. Gauglitz; Guillermo Terrones; Susan J. Muller; Morton M. Denn; William R. Rossen

    2002-01-07

    The Hanford Site has 177 underground waste storage tanks that are known to retain and release bubbles composed of flammable gases. Characterizing and understanding the behavior of these bubbles is important for the safety issues associated with the flammable gases for both ongoing waste storage and future waste-retrieval operations. The retained bubbles are known to respond to small barometric pressure changes, though in a complex manner with unusual hysteresis occurring in some tanks in the relationship between bubble volume and pressure, or V-P hysteresis. With careful analysis, information on the volume of retained gas and the interactions of the waste and the bubbles can be determined.

  3. Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial.

    Directory of Open Access Journals (Sweden)

    Vincent Souday

    Full Text Available To test the hypothesis whether enriched air nitrox (EAN breathing during simulated diving reduces decompression stress when compared to compressed air breathing as assessed by intravascular bubble formation after decompression.Human volunteers underwent a first simulated dive breathing compressed air to include subjects prone to post-decompression venous gas bubbling. Twelve subjects prone to bubbling underwent a double-blind, randomized, cross-over trial including one simulated dive breathing compressed air, and one dive breathing EAN (36% O2 in a hyperbaric chamber, with identical diving profiles (28 msw for 55 minutes. Intravascular bubble formation was assessed after decompression using pulmonary artery pulsed Doppler.Twelve subjects showing high bubble production were included for the cross-over trial, and all completed the experimental protocol. In the randomized protocol, EAN significantly reduced the bubble score at all time points (cumulative bubble scores: 1 [0-3.5] vs. 8 [4.5-10]; P < 0.001. Three decompression incidents, all presenting as cutaneous itching, occurred in the air versus zero in the EAN group (P = 0.217. Weak correlations were observed between bubble scores and age or body mass index, respectively.EAN breathing markedly reduces venous gas bubble emboli after decompression in volunteers selected for susceptibility for intravascular bubble formation. When using similar diving profiles and avoiding oxygen toxicity limits, EAN increases safety of diving as compared to compressed air breathing.ISRCTN 31681480.

  4. Soap bubbles in analytical chemistry. Conductometric determination of sub-parts per million levels of sulfur dioxide with a soap bubble.

    Science.gov (United States)

    Kanyanee, Tinakorn; Borst, Walter L; Jakmunee, Jaroon; Grudpan, Kate; Li, Jianzhong; Dasgupta, Purnendu K

    2006-04-15

    Soap bubbles provide a fascinating tool that is little used analytically. With a very low liquid volume to surface area ratio, a soap bubble can potentially provide a very useful interface for preconcentration where mass transfer to an interfacial surface is important. Here we use an automated system to create bubbles of uniform size and film thickness. We utilize purified Triton-X 100, a nonionic surfactant, to make soap bubbles. We use such bubbles as a gas-sampling interface. Incorporating hydrogen peroxide into the bubble provides a system where electrical conductance increases as the bubble is exposed to low concentrations of sulfur dioxide gas. We theoretically derive the conductance of a hollow conducting spherical thin film with spherical cap electrodes. We measure the film thickness by incorporating a dye in the bubble making solution and laser transmission photometry and find that it agrees well with the geometrically computed thickness. With the conductance of the bubble-making soap solution being measured by conventional methods, we show that the measured values of the bubble conductance with known bubble and electrode dimensions closely correspond to the theoretically computed value. Finally, we demonstrate that sub-ppm levels of SO(2) can readily be detected by the conductivity change of a hydrogen peroxide-doped soap bubble, measured in situ, when the gas flows around the bubble.

  5. Gas bubbling-enhanced film boiling of Freon-11 on liquid metal pools. [PWR; BWR

    Energy Technology Data Exchange (ETDEWEB)

    Greene, G.A.

    1985-01-01

    In the analysis of severe core damage accidents in LWRs, a major driving force which must be considered in evaluating containment loading and fission product transport is the ex-vessel interaction between molten core debris and structural concrete. Two computer codes have been developed for this purpose, the CORCON-MOD2 model of ex-vessel, core concrete interactions and the VANESA model for aerosol generation and fission product release as a result of molten core-concrete interactions. Under a wide spectrum of reactor designs and accident sequences, it is possible for water to come into contact with the molten core debris and form a coolant pool overlying the core debris which is attacking the concrete. As the concrete decomposes, noncondensable gases are released, which bubble through the melt and across the boiling interface, affecting the liquid-liquid boiling process. Currently, the CORCON code includes the classical Berenson model for film boiling over a horizontal flat plate for this phenomenon. The objectives of this activity are to investigate the influence of transverse noncondensable gas flux on the magnitude of the stable liquid-liquid film boiling heat flux and develop a gas flux-enhanced, liquid-liquid film boiling model for incorporation into the CORCON-MOD2 computer code to replace or modify the Berenson model.

  6. Removal of volatile iodine from gas bubbles rising in water pools: review and assessment of pool scrubbing codes

    Energy Technology Data Exchange (ETDEWEB)

    Polo, J.; Herranz, L.E.; Peyres, V.; Escudero, M. [CIEMAT, Nuclear Technology Institute, Madrid (Spain)

    1996-12-01

    During a hypothetical nuclear reactor accident with core damage the fission products released from the degrading fuel bundles often pass through aqueous beds before entering the containment, mitigating in part the source term. Several computer codes have been developed for predicting the fission product and aerosols removal in pool scrubbing scenarios. In addition to particle removal, these codes simulate the retention of some volatile iodine compounds. In this work a review of volatile iodine removal models included in SPARC and BUSCA codes is presented. Besides, the results and discussions of a validation of both codes against the available experimental data are summarized. SPARC and BUSCA codes model the diffusion of iodine toward the bubble interface by using the film penetration theory, which assumes a double layer gas-liquid at the interface. However, there are some differences between the two models, mainly related to the boundary conditions in the aqueous volume for the diffusion of molecular iodine. In SPARC, a set of fast reactions in the liquid phase control both the molecular iodine concentration in the pool and the partition coefficient of iodine at the interface. Thus, the aqueous chemistry plays an important role in the boundary conditions for the diffusion process. On the contrary, the BUSCA model has no chemical considerations at all, and assumes a null iodine concentration in the water bulk. Several sensitivity studies have been made in order to weight the effect of these differences. The variables examined in these studies were the pool temperature and the incoming iodine concentration in the pool. Additionally, sensitivity studies focused on the steam mass fraction of the injected gas were performed to study the effect of the different approach of both models for the condensation process. The results showed a different sensitivity of SPARC and BUSCA to the incoming concentration. (author) 5 tabs., 26 refs.

  7. Gas bubbles evolution peculiarities in ferritic-martensitic and austenitic steels and alloys under helium-ion irradiation

    Science.gov (United States)

    Chernov, I. I.; Kalashnikov, A. N.; Kalin, B. A.; Binyukova, S. Yu

    2003-12-01

    Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe-C system, ferritic-martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion irradiation up to a fluence of 5 × 10 20 m -2 at the temperature of 920 K. It was shown that helium-ion irradiation at high temperature resulted in formation of bubbles with a greater size and a smaller density in Fe and ferritic-martensitic steels than those in nickel and austenitic steels. Large gaseous bubbles in ferritic component are uniformly distributed in grains body in Fe-C alloys as well as in ferritic-martensitic steels. The bubbles with a higher density and a smaller size than those in ferritic component are formed in martensitic grains of steels and Fe-C alloys with a high carbon content ( NC>0.01 wt%), which leads to a small level of swelling of martensite in comparison with that of ferrite. In addition, the bubbles in martensitic grains have a tendency to ordered distribution.

  8. Gas bubbles evolution peculiarities in ferritic-martensitic and austenitic steels and alloys under helium-ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, I.I. E-mail: chernov@phm.mephi.ru; Kalashnikov, A.N.; Kalin, B.A.; Binyukova, S.Yu

    2003-12-01

    Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe-C system, ferritic-martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion irradiation up to a fluence of 5 x 10{sup 20} m{sup -2} at the temperature of 920 K. It was shown that helium-ion irradiation at high temperature resulted in formation of bubbles with a greater size and a smaller density in Fe and ferritic-martensitic steels than those in nickel and austenitic steels. Large gaseous bubbles in ferritic component are uniformly distributed in grains body in Fe-C alloys as well as in ferritic-martensitic steels. The bubbles with a higher density and a smaller size than those in ferritic component are formed in martensitic grains of steels and Fe-C alloys with a high carbon content (N{sub C}>0.01 wt%), which leads to a small level of swelling of martensite in comparison with that of ferrite. In addition, the bubbles in martensitic grains have a tendency to ordered distribution.

  9. Bubble formation in a quiescent pool of gold nanoparticle suspension.

    Science.gov (United States)

    Vafaei, Saeid; Wen, Dongsheng

    2010-08-11

    This paper begins with an extensive review of the formation of gas bubbles, with a particular focus on the dynamics of triple lines, in a pure liquid and progresses into an experimental study of bubble formation on a micrometer-sized nozzle immersed in a quiescent pool of aqueous gold nanofluid. Unlike previous studies of triple line dynamics in a nanofluid under evaporation or boiling conditions, which are mainly caused by the solid surface modification due to particle sedimentation, this work focuses on the roles of nanoparticles suspended in the liquid phase. The experiments are conducted under a wide range of flow rates and nanoparticle concentrations, and many interesting phenomena are revealed. It is observed that nanofluids prevent the spreading of the triple line during bubble formation, i.e. the triple line is pinned somewhere around the middle of the tube wall during the rapid bubble formation stage whereas it spreads to the outer edge of the tube for pure water. A unique 'stick-slip' movement of the triple line is also observed for bubbles forming in nanofluids. At a given bubble volume, the radius of the contact line is found to be smaller for higher particle concentrations, but a reverse trend is found for the dynamic bubble contact angle. With the increase of particle concentration, the bubble frequency is raised and the bubble departure volume is decreased. The bubble shape is found to be in a good agreement with the prediction from Young-Laplace equation for given flow rates. The influence of nanoparticles on other detailed characteristics related to bubble growth inside, including the variation of bubble volume expansion rate, the radius of the curvature at the apex, the bubble height and bubble volume, is revealed. It is suggested that the variation of surface tensions and the resultant force balance at the triple line might be responsible for the modified dynamics of the triple line.

  10. Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats

    DEFF Research Database (Denmark)

    Hyldegaard, Ole; Kerem, Dikla; Melamed, Y

    2011-01-01

    Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing...... breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent...

  11. Storm in a "Teacup": a radio-quiet quasar with ~10kpc radio-emitting bubbles and extreme gas kinematics

    CERN Document Server

    Harrison, C M; Alexander, D M; Bauer, F E; Edge, A C; Hogan, M T; Mullaney, J R; Swinbank, A M

    2014-01-01

    We present multi-frequency (1-8 GHz) VLA data, combined with VIMOS IFU data and HST imaging, of a z=0.085 radio-quiet type 2 quasar (with L(1.4GHz)~5e23 W/Hz and L(AGN)~2e45 erg/s). Due to the morphology of its emission-line region, the target (J1430+1339) has been referred to as the Teacup AGN in the literature. We identify "bubbles" of radio emission that are extended ~10-12 kpc to both the east and west of the nucleus. The edge of the brighter eastern bubble is co-spatial with an arc of luminous ionized gas. We also show that the Teacup AGN hosts a compact radio structure, located ~0.8 kpc from the core position, at the base of the eastern bubble. This radio structure is co-spatial with an ionized outflow with an observed velocity of v=-760 km/s. This is likely to correspond to a jet, or possibly a quasar wind, interacting with the interstellar medium at this position. The large-scale radio bubbles appear to be inflated by the central AGN, which indicates that the AGN can also interact with the gas on >~10...

  12. Segregating gas from melt: an experimental study of the Ostwald ripening of vapor bubbles in magmas

    Science.gov (United States)

    Lautze, Nicole C.; Sisson, Thomas W.; Mangan, Margaret T.; Grove, Timothy L.

    2011-01-01

    Diffusive coarsening (Ostwald ripening) of H2O and H2O-CO2 bubbles in rhyolite and basaltic andesite melts was studied with elevated temperature–pressure experiments to investigate the rates and time spans over which vapor bubbles may enlarge and attain sufficient buoyancy to segregate in magmatic systems. Bubble growth and segregation are also considered in terms of classical steady-state and transient (non-steady-state) ripening theory. Experimental results are consistent with diffusive coarsening as the dominant mechanism of bubble growth. Ripening is faster in experiments saturated with pure H2O than in those with a CO2-rich mixed vapor probably due to faster diffusion of H2O than CO2 through the melt. None of the experimental series followed the time1/3 increase in mean bubble radius and time-1 decrease in bubble number density predicted by classical steady-state ripening theory. Instead, products are interpreted as resulting from transient regime ripening. Application of transient regime theory suggests that bubbly magmas may require from days to 100 years to reach steady-state ripening conditions. Experimental results, as well as theory for steady-state ripening of bubbles that are immobile or undergoing buoyant ascent, indicate that diffusive coarsening efficiently eliminates micron-sized bubbles and would produce mm-sized bubbles in 102–104 years in crustal magma bodies. Once bubbles attain mm-sizes, their calculated ascent rates are sufficient that they could transit multiple kilometers over hundreds to thousands of years through mafic and silicic melt, respectively. These results show that diffusive coarsening can facilitate transfer of volatiles through, and from, magmatic systems by creating bubbles sufficiently large for rapid ascent.

  13. A dual-scale turbulence model for gas-liquid bubbly flows☆

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Guan; Zhaoqi Li; Lijun Wang⁎; Xi Li; Youwei Cheng

    2015-01-01

    A dual-scale turbulence model is applied to simulate cocurrent upward gas–liquid bubbly flows and validated with available experimental data. In the model, liquid phase turbulence is split into shear-induced and bubble-induced turbulence. Single-phase standard k-εmodel is used to compute shear-induced turbulence and another transport equation is added to model bubble-induced turbulence. In the latter transport equation, energy loss due to interface drag is the production term, and the characteristic length of bubble-induced turbulence, simply the bubble diameter in this work, is introduced to model the dissipation term. The simulated results agree well with experimental data of the test cases and it is demonstrated that the proposed dual-scale turbulence model outperforms other models. Analysis of the predicted turbulence shows that the main part of turbulent kinetic en-ergy is the bubble-induced one while the shear-induced turbulent viscosity predominates within turbulent vis-cosity, especially at the pipe center. The underlying reason is the apparently different scales for the two kinds of turbulence production mechanisms:the shear-induced turbulence is on the scale of the whole pipe while the bubble-induced turbulence is on the scale of bubble diameter. Therefore, the model reflects the multi-scale phe-nomenon involved in gas–liquid bubbly flows.

  14. Dynamics of Single Hydrogen Bubbles at a Platinum Microelectrode.

    Science.gov (United States)

    Yang, Xuegeng; Karnbach, Franziska; Uhlemann, Margitta; Odenbach, Stefan; Eckert, Kerstin

    2015-07-28

    Bubble dynamics, including the formation, growth, and detachment, of single H2 bubbles was studied at a platinum microelectrode during the electrolysis of 1 M H2SO4 electrolyte. The bubbles were visualized through a microscope by a high-speed camera. Electrochemical measurements were conducted in parallel to measure the transient current. The periodic current oscillations, resulting from the periodic formation and detachment of single bubbles, allow the bubble lifetime and size to be predicted from the transient current. A comparison of the bubble volume calculated from the current and from the recorded bubble image shows a gas evolution efficiency increasing continuously with the growth of the bubble until it reaches 100%. Two different substrates, glass and epoxy, were used to embed the Pt wire. While nearly no difference was found with respect to the growth law for the bubble radius, the contact angle differs strongly for the two types of cell. Data provided for the contact point evolution further complete the image of single hydrogen bubble growth. Finally, the velocity field driven by the detached bubble was measured by means of PIV, and the effects of the convection on the subsequent bubble were evaluated.

  15. Voronoi analysis of bubbly flows via ultrafast X-ray tomographic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Yuk Man; Mueller, Karolin; Azizi, Salar; Schubert, Markus [Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Fluid Dynamics, Dresden (Germany)

    2016-03-15

    Although clustering of bubbles plays a significant role in bubble column reactors regarding the heat and mass transfer due to bubble-bubble and flow field interactions, it has yet to be fully understood. Contrary to flows in bubble columns, most literature studies on clustering report numerical and experimental results on dilute or micro-bubbly flows. In this paper, clustering of bubbles in a cylindrical bubble column of 100 mm diameter is experimentally investigated. Ultrafast X-ray tomographic imaging is used to obtain the bubble positions within a hybrid Eulerian framework. By means of Voronoi analysis, the clustering behavior of bubbles is investigated. Experiments are performed with different superficial gas velocities, where Voronoi diagrams are constructed at several column heights. From the PDFs of the Voronoi diagrams, it is shown that the bubble structuring in terms of Voronoi cell volumes develops slower than the bubble size distribution. The latter reaches a steady state earlier with increasing column height. The measured PDFs are compared with the PDF of randomly distributed points, which showed that the amount of bubbles as part of clusters (Voronoi cells < V/ anti V{sub cluster}) as well as bubbles as part of voids (Voronoi cells > V/ anti V{sub void}) increases with the superficial gas velocity. It is found that all experiments have an approximate cluster limit V/ anti V{sub cluster} of 0.63, while the void limit V/ anti V{sub void} varies between 1.5 and 3.0. (orig.)

  16. Sampling small volumes of ambient ammonia using a miniaturized gas sampler.

    Science.gov (United States)

    Timmer, Björn; Olthuis, Wouter; van den Berg, Albert

    2004-06-01

    The development of a gas sampler for a miniaturized ambient ammonia detector is described. A micromachined channel system is realized in glass and silicon using powder blasting and anodic bonding. The analyte gas is directly mixed with purified water, dissolving the ammonia that will dissociate into ammonium ions. Carrier gas bubbles are subsequently removed from the liquid stream through a venting hole sealed with a microporous water repellent PTFE membrane. A flow restrictor is placed at the outlet of the sampler to create a small overpressure underneath the membrane, enabling the gas to leave through the membrane. Experiments with a gas flow of 1 ml min(-1), containing ammonia concentrations ranging from 9.4 ppm to 0.6 ppm in a nitrogen carrier flow have been carried out, at a water flow of 20 microl min(-1). The ammonium concentration in the sample solution is measured with an electrolyte conductivity detector. The measured values correspond with the concentration calculated from the initial ammonia concentration in the analyte gas, the fifty times concentration enhancement due to the gas-liquid volume difference and the theoretical dissociation equilibrium as a function of the resulting pH.

  17. Proteomics of juvenile senegal sole (Solea senegalensis) affected by gas bubble disease in hyperoxygenated ponds.

    Science.gov (United States)

    Salas-Leiton, E; Cánovas-Conesa, B; Zerolo, R; López-Barea, J; Cañavate, J P; Alhama, J

    2009-01-01

    Solea senegalensis is a commercial flat fish traditionally farmed in earth ponds in coastal wetlands that might also become important to more intensive aquaculture. Gas bubble disease (GBD) is a potential risk for outdoor fish farming, particularly in certain periods of the year, related to improper management leading to macroalgae blooms. Physical-chemical conditions inducing hyperoxia, including radiation, temperature, and high levels of dissolved oxygen, have been monitored in fish affected by GBD together with observed symptoms. Exophthalmia, subcutaneous emphysemas, obstruction of gill lamellae, hemorrhages, and anomalous swimming were the main effects of oxygen supersaturation. A proteomic study was carried out for the first time under aquaculture conditions and protein expression changes are described for fish that were subject to hyperoxic conditions. Proteins identified in gill of GBD-affected fish are related to oxidative alteration of cytoskeleton structure/function (beta-tubulin, beta-actin), motility (light myosin chain, alpha-tropomyosin), or regulatory pathways (calmodulin, Raf kinase inhibitor protein), reflecting the central role of gill in oxygen exchange. Hepatic proteins identified are related to protein oxidative damages (beta-globin, FABPs), protection from oxidative stress (DCXR, GNMT), and inflammatory response (C3), in agreement with the predominant metabolic role of liver. Comparison of protein expression patterns and protein identification are suggested as potentially specific hyperoxia biomarkers that would facilitate prevention of GBD outbreaks.

  18. Three-phase gas-liquid-solid foaming bubble reactors and self-lubricated transport of bitumen froth

    Science.gov (United States)

    Mata, Clara E.

    Two distinct topics in multi-phase flow of interest of the oil industry are considered in this thesis. Studies of three-phase gas-liquid-solid foaming bubble reactors and self-lubricated transport of bitumen froth are reported. Applications of foams and foaming are found in many industrial processes such as flotation of minerals, enhanced oil recovery, drilling in oil reservoirs, and refining processes. However the physics of foaming and defoaming are not fully understood. Foams trap gas and are not desirable in some processes such as oil refining. Previously, it has been found that foaming may be strongly suppressed in a cold slit bubble reactor by fluidizing hydrophilic particles in the bubbly mixture below the foam. In this work, we fluidized hydrophobic and hydrophilic versions of two different sands in a cold slit foaming bubble reactor. We found that the hydrophobic sands suppress the foam substantially better than their hydrophilic counterparts. To study the capacity of foams to carry particles, we built a new slit foaming bubble reactor, which can be continuously fed with solid particles. Global gas, liquid, and solid holdups were measured for given gas and liquid velocities and solid flow rates. This research provides the fundamental ground work for the identification of flow types in a slit three-phase foaming bubble reactor with continuous injection of particles. Bitumen froth is produced from the oil sands of Athabasca, Canada. When transported in a pipeline, water present in the froth is released in regions of high shear (at the pipe wall). This results in a lubricating layer of water that allows bitumen froth pumping at greatly reduced pressures and hence the potential for savings in pumping energy consumption. Experimental results establishing the features of this self lubrication phenomenon are presented. The pressure gradient of lubricated flows closely follow the empirical law of Blasius for turbulent pipe flow with a constant of proportionality

  19. Bubble evolution and properties in homogeneous nucleation simulations.

    Science.gov (United States)

    Angélil, Raymond; Diemand, Jürg; Tanaka, Kyoko K; Tanaka, Hidekazu

    2014-12-01

    We analyze the properties of naturally formed nanobubbles in Lennard-Jones molecular dynamics simulations of liquid-to-vapor nucleation in the boiling and the cavitation regimes. The large computational volumes provide a realistic environment at unchanging average temperature and liquid pressure, which allows us to accurately measure properties of bubbles from their inception as stable, critically sized bubbles, to their continued growth into the constant speed regime. Bubble gas densities are up to 50% lower than the equilibrium vapor densities at the liquid temperature, yet quite close to the gas equilibrium density at the lower gas temperatures measured in the simulations: The latent heat of transformation results in bubble gas temperatures up to 25% below those of the surrounding bulk liquid. In the case of rapid bubble growth-typical for the cavitation regime-compression of the liquid outside the bubble leads to local temperature increases of up to 5%, likely significant enough to alter the surface tension as well as the local viscosity. The liquid-vapor bubble interface is thinner than expected from planar coexistence simulations by up to 50%. Bubbles near the critical size are extremely nonspherical, yet they quickly become spherical as they grow. The Rayleigh-Plesset description of bubble-growth gives good agreement in the cavitation regime.

  20. Monodisperse, submicrometer droplets via condensation of microfluidic-generated gas bubbles.

    Science.gov (United States)

    Seo, Minseok; Matsuura, Naomi

    2012-09-10

    Microfluidics (MFs) can produce monodisperse droplets with precise size control. However, the synthesis of monodisperse droplets much smaller than the minimum feature size of the microfluidic device (MFD) remains challenging, thus limiting the production of submicrometer droplets. To overcome the minimum micrometer-scale droplet sizes that can be generated using typical MFDs, the droplet material is heated above its boiling point (bp), and then MFs is used to produce monodisperse micrometer-scale bubbles (MBs) that are easily formed in the size regime where standard MFDs have excellent size control. After MBs are formed, they are cooled, condensing into dramatically smaller droplets that are beyond the size limit achievable using the original MFD, with a size decrease corresponding to the density difference between the gas and liquid phases of the droplet material. Herein, it is shown experimentally that monodisperse, submicrometer droplets of predictable sizes can be condensed from a monodisperse population of MBs as generated by MFs. Using perfluoropentane (PFP) as a representative solvent due to its low bp (29.2 °C), it is demonstrated that monodisperse PFP MBs can be produced at MFD temperatures >3.6 °C above the bp of PFP over a wide range of sizes (i.e., diameters from 2 to 200 μm). Independent of initial size, the generated MBs shrink rapidly in size from about 3 to 0 °C above the bp of PFP, corresponding to a phase change from gas to liquid, after which they shrink more slowly to form fully condensed droplets with diameters 5.0 ± 0.1 times smaller than the initial size of the MBs, even in the submicrometer size regime. This new method is versatile and flexible, and may be applied to any type of low-bp solvent for the manufacture of different submicrometer droplets for which precisely controlled dimensions are required.

  1. Thermodynamics of the low density excluded volume hadron gas

    CERN Document Server

    Zalewski, Kacper

    2015-01-01

    We discuss the influence of the excluded volume of hadrons on macroscopic variables and thermal parameters of the hadron gas at finite temperature and chemical potential in the low density approximation. Based solely on elementary thermodynamics we show that when the excluded volume grows at constant temperature, pressure, and number of particles, the overall volume increases just as much as the excluded volume, while the entropy and energy remain unchanged. The growth of the chemical potentials is equal to the work needed to create the respective excluded volumes. Consequently, the bulk density functions of a gas with excluded volume are expressed by the corresponding variables in a system of point particles with the shifted chemical potentials. Our results are fully consistent with the previous findings obtained upon applications of more advanced methods of statistical physics. A validity limit for the low density approximation is derived and discussed in the context of the hadron gas created in heavy ion c...

  2. Bubble diagnostics

    Science.gov (United States)

    Visuri, Steven R.; Mammini, Beth M.; Da Silva, Luiz B.; Celliers, Peter M.

    2003-01-01

    The present invention is intended as a means of diagnosing the presence of a gas bubble and incorporating the information into a feedback system for opto-acoustic thrombolysis. In opto-acoustic thrombolysis, pulsed laser radiation at ultrasonic frequencies is delivered intraluminally down an optical fiber and directed toward a thrombus or otherwise occluded vessel. Dissolution of the occlusion is therefore mediated through ultrasonic action of propagating pressure or shock waves. A vapor bubble in the fluid surrounding the occlusion may form as a result of laser irradiation. This vapor bubble may be used to directly disrupt the occlusion or as a means of producing a pressure wave. It is desirable to detect the formation and follow the lifetime of the vapor bubble. Knowledge of the bubble formation and lifetime yields critical information as to the maximum size of the bubble, density of the absorbed radiation, and properties of the absorbing material. This information can then be used in a feedback system to alter the irradiation conditions.

  3. Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

    Science.gov (United States)

    Nikolovska, Aneta; Sahling, Heiko; Bohrmann, Gerhard

    2008-10-01

    Detailed acoustic investigation of bubble streams rising from the seafloor were conducted during R/V Meteor cruise M72/3a at a deep submarine hydrocarbon seep environment. The area is located offshore Georgia (eastern part of the Black Sea) at a water depth between 840 m and 870 m. The sediment echosounder Parasound DS-3/P70 was used for detecting bubbles in the water column that causes strong backscatter in the echographs ("flares"). Employing the swath echsounder Kongsberg EM710 flares in the water column were mapped along the entire swath width of approximately 1000 m at high spatial resolution. The exact location of the flares could be extracted manually. Subsequently, the horizontally looking sonar Kongsberg digital telemetry MS1000 mounted on a remotely operated vehicle (ROV) was utilized to quantify the flux of bubbles. A model was developed that is based on the principle of finding the "acoustic mass" in order to quantify the bubble flux at various seeps. The acoustic approach from the backscatter data of the ROV sonar resulted in bubble fluxes in the range of 0.01 to 5.5 L/min (corresponding to 0.037 to 20.5 mol CH4/min) at in situ conditions (˜850 m water depth, ˜9°C). Independent flux estimations using a funnel-shaped device showed that the acoustic model consistently produced lower values but the offset is less than 12%. Furthermore, the deviation decreased with increasing flux rates. A field of bubble streams was scanned three times from different directions in order to reveal the reproducibility of the method. Flux estimations yielded consistent fluxes of about 2 l/min (7.4 mol CH4/min) with variations of less than 10%. Although gas emissions have been found at many sites at the seafloor in a range of geological settings, the amount of escaping gas is still largely unknown. With this study presenting a novel method of quantifying bubble fluxes employing a horizontally looking sonar system, it is intended to contribute to the global effort of better

  4. The role of particle-particle interactions in bubbling gas-fluidized beds of Geldart A particles: A discrete particle study

    NARCIS (Netherlands)

    Wang, Junwu; Hoef, van der M.A.; Kuipers, J.A.M.

    2009-01-01

    Discrete particle simulations are by now well established as an effective tool to study the mechanics of complex gas-solid flows in gas-fluidized beds. In this study, a state-of-the-art discrete particle model is used to explore the role of particle-particle interactions in bubbling gas-fluidized be

  5. Self-assembly of PbS hollow sphere quantum dots via gas-bubble technique for early cancer diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Mozafari, Masoud, E-mail: masoud.mozafari@okstate.edu [Helmerich Advanced Technology Research Center, School of Material Science and Engineering, Oklahoma State University, OK 74106 (United States); Biomaterials Group, Faculty of Biomedical Engineering (Center of Excellence), Amirkabir University of Technology, P.O Box 15875-4413, Tehran (Iran, Islamic Republic of); Moztarzadeh, Fathollah [Biomaterials Group, Faculty of Biomedical Engineering (Center of Excellence), Amirkabir University of Technology, P.O Box 15875-4413, Tehran (Iran, Islamic Republic of); Seifalian, Alexander M. [Centre for Nanotechnology and Regenerative Medicine, UCL Division of Surgery and Interventional Science, University College London, London (United Kingdom); Royal Free Hampstead NHS Trust Hospital, London (United Kingdom); Tayebi, Lobat [Helmerich Advanced Technology Research Center, School of Material Science and Engineering, Oklahoma State University, OK 74106 (United States)

    2013-01-15

    Quantum dots (QDs) with their unique optical properties have attracted widespread interest in cancer diagnosis and therapy. Due to their ability to absorb and emit light very efficiently, lead sulfide (PbS) hollow spheres with nanometer-to-micrometer dimensions having tailored structural, optical, and surface properties represent an important class of QDs that are potentially useful for early cancer detection. In this study, PbS hollow sphere QDs have been successfully synthesized using a template-free and green method. The formation of hollow structures was explained by a gas-liquid interface aggregation mechanism, in which the formation of SO{sub 2} gas bubbles plays a key role. The synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analyzer (EDX), photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). The results demonstrate that the PbS hollow spheres possess good optical quality with strong luminescence properties, which indicate their capabilities for the simultaneous detection of multiple cancer biomarkers in blood assays and cancer tissue biopsies. - Graphical abstract: The hollow structures were formed by gas-liquid interface aggregation mechanism, in which the formation of SO{sub 2} gas bubbles played a key role. When the SO{sub 2} gas bubbles generated in the liquid phase, they created numerous gas-liquid interfaces inside the solution phase. Then, the gas-liquid interfaces served as the nucleation or agglomeration centers for the PbS NCs. In addition, the PbS hollow sphere QDs possess strong optical properties, which indicate their capabilities for cancer diagnosis and therapy. Highlights: Black-Right-Pointing-Pointer Large quantities of SO{sub 2} bubbles produced in the reaction system serve as the aggregation centers. Black-Right-Pointing-Pointer After the initial nucleation, monomers would grow into NCs, which have a

  6. Nanosecond Discharge in Bubbled Liquid n-Heptane: Effects of Gas Composition and Water Addition

    KAUST Repository

    Hamdan, Ahmad

    2016-08-30

    Recently, an aqueous discharge reactor was developed to facilitate reformation of liquid fuels by in-liquid plasma. To gain a microscopic understanding of the physical elements behind this aqueous reactor, we investigate nanosecond discharges in liquid n-heptane with single and double gaseous bubbles in the gap between electrodes. We introduce discharge probability (DP) to characterize the stochastic nature of the discharges, and we investigate the dependence of DP on the gap distance, applied voltage, gaseous bubble composition, and the water content in n-heptane/distilled-water emulsified mixtures. Propagation of a streamer through the bubbles indicates no discharges in the liquids. DP is controlled by the properties of the gaseous bubble rather than by the composition of the liquid mixture in the gap with a single bubble; meanwhile, DP is determined by the dielectric permittivity of the liquid mixture in the gap with double bubbles, results that are supported by static electric field simulations. We found that a physical mechanism of increasing DP is caused by an interaction between bubbles and an importance of the dielectric permittivity of a liquid mixture on the local enhancement of field intensity. We also discuss detailed physical characteristics, such as plasma lifetime and electron density within the discharge channel, by estimating from measured emissions with a gated-intensified charge-coupled device and by using spectroscopic images, respectively. © 1973-2012 IEEE.

  7. North American Natural Gas Markets. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    1989-02-01

    This report summarizes die research by an Energy Modeling Forum working group on the evolution of the North American natural gas markets between now and 2010. The group`s findings are based partly on the results of a set of economic models of the natural gas industry that were run for four scenarios representing significantly different conditions: two oil price scenarios (upper and lower), a smaller total US resource base (low US resource case), and increased potential gas demand for electric generation (high US demand case). Several issues, such as the direction of regulatory policy and the size of the gas resource base, were analyzed separately without the use of models.

  8. A new method for measuring concentration of a fluorescent tracer in bubbly gas-liquid flows

    Science.gov (United States)

    Moghaddas, J. S.; Trägårdh, C.; Kovacs, T.; Östergren, K.

    2002-06-01

    A new experimental model, the two-tracer method (TTM), based on the planar laser-induced fluorescence technique (PLIF), is presented for the measurement of the local concentration of a fluorescent tracer in the liquid phase of a bubbly two-phase system. Light scattering and shading effects due to the bubbles were compensated for using the new model. The TTM results were found to give more accurate predictions of the local concentration than the normal PLIF method in a bubbly two-phase system.

  9. Coal liquefaction and gas conversion: Proceedings. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-31

    Volume I contains papers presented at the following sessions: AR-Coal Liquefaction; Gas to Liquids; and Direct Liquefaction. Selected papers have been processed separately for inclusion in the Energy Science and Technology Database.

  10. Small-bubble transport and splitting dynamics in a symmetric bifurcation

    KAUST Repository

    Qamar, Adnan

    2017-06-28

    Simulations of small bubbles traveling through symmetric bifurcations are conducted to garner information pertinent to gas embolotherapy, a potential cancer treatment. Gas embolotherapy procedures use intra-arterial bubbles to occlude tumor blood supply. As bubbles pass through bifurcations in the blood stream nonhomogeneous splitting and undesirable bioeffects may occur. To aid development of gas embolotherapy techniques, a volume of fluid method is used to model the splitting process of gas bubbles passing through artery and arteriole bifurcations. The model reproduces the variety of splitting behaviors observed experimentally, including the bubble reversal phenomenon. Splitting homogeneity and maximum shear stress along the vessel walls is predicted over a variety of physical parameters. Small bubbles, having initial length less than twice the vessel diameter, were found unlikely to split in the presence of gravitational asymmetry. Maximum shear stresses were found to decrease exponentially with increasing Reynolds number. Vortex-induced shearing near the bifurcation is identified as a possible mechanism for endothelial cell damage.

  11. North American Natural Gas Markets: Selected technical studies. Volume 3

    Energy Technology Data Exchange (ETDEWEB)

    Huntington, H.G.; Schuler, G.E. [eds.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  12. Computed Tomography Colonography Technique: The Role of Intracolonic Gas Volume

    Directory of Open Access Journals (Sweden)

    Patrick D. McLaughlin

    2013-01-01

    Full Text Available Introduction. Poor distention decreases the sensitivity and specificity of CTC. The total volume of gas administered will vary according to many factors. We aim to determine the relationship between the volume of retained gas at the time of image acquisition and colonic distention and specifically the presence of collapsed bowel segments at CTC. Materials and Methods. All patients who underwent CTC over a 12-month period at a single institution were included in the study. Colonic luminal distention was objectively scored by 2 radiologists using an established 4-point scale. Quantitative analysis of the volume of retained gas at the time of image acquisition was conducted using the threshold 3D region growing function of OsiriX. Results. 108 patients were included for volumetric analysis. Mean retained gas volume was 3.3 L. 35% (38/108 of patients had at least one collapsed colonic segment. Significantly lower gas volumes were observed in the patients with collapsed colonic segments when compared with those with fully distended colons 2.6 L versus 3.5 L (P=0.031. Retained volumes were significantly higher for the 78% of patients with ileocecal reflux at 3.4 L versus 2.6 L without ileocecal reflux (P=0.014. Conclusion. Estimation of intraluminal gas volume at CTC is feasible using image segmentation and thresholding tools. An average of 3.5 L of retained gas was found in diagnostically adequate CTC studies with significantly lower mean gas volume observed in patients with collapsed colonic segments.

  13. Propagation of shock waves in dilute bubbly liquids. 4. Comparison between theory and experiment for a uniform bubbly mixture

    Energy Technology Data Exchange (ETDEWEB)

    Kameda, Masaharu; Shimaura, Naoto; Higashino, Fumio [Tokyo Univ. of Agriculture and Technology, Fuchu, Tokyo (Japan); Matsumoto, Yoichiro

    1997-07-01

    Transient shock wave phenomena in a liquid containing noncondensable gas bubbles are studied experimentally and numerically. In order to obtain a uniform spatial distribution of bubbles experimentally, an upwardly directed bubbly flow, whose initial gas volume fraction is 0.2%, is generated in a shock tube. The liquid used is silicone oil. Nitrogen, argon, and SF{sub 6} gas bubbles are tested to show the thermal effects of the bubble interior. The transient pressure profiles determined in the experiments for the upwardly bubbly flow agree well quantitatively with those obtained by numerical calculation using a uniform spatial distribution of bubbles. Since the thermal diffusivity of SF{sub 6} is much lower than that of nitrogen and argon, the damping on the radial oscillation of the SF{sub 6} bubble is mainly due to the compressibility of the liquid. Thus, the radial motion of the bubble should be estimated by solving an equation in which the liquid compressibility is taken into account. (author)

  14. Acute and Chronic Outcomes of Gas-Bubble Disease in a Colony of African Clawed Frogs (Xenopus laevis).

    Science.gov (United States)

    Tsai, Julia Y; Felt, Stephen A; Bouley, Donna M; Green, Sherril L

    2017-02-01

    Gas-bubble disease occurs in aquatic species that are exposed to water that is supersaturated with gases. In February 2007, municipal water supersaturated with gas was inadvertently pumped into the vivarium's aquatic housing systems and affected approximately 450 adult female Xenopus laevis. The inflow of supersaturated water was stopped immediately, the holding tanks aggressively aerated, and all experimental manipulations and feeding ceased. Within the first 6 h after the event, morbidity approached 90%, and mortality reached 3.5%. Acutely affected frogs showed clinical signs of gas-bubble disease: buoyancy problems, micro- and macroscopic bubbles in the foot webbing, hyperemia in foot webbing and leg skin, and loss of the mucous slime coat. All of the frogs that died or were euthanized had areas of mesenteric infarction, which resulted in intestinal epithelial necrosis and degeneration of the muscular tunic. Over the subsequent 2 wk, as gas saturation levels returned to normal, the clinical symptoms resolved completely in the remaining frogs. However, 3 mo later, 85% of them failed to lay eggs or produce oocytes, and the remaining 15% produced oocytes of low number and poor quality, yielding cytosolic extracts with poor to no enzymatic activity. Histology of the egg mass from a single 2- to 3-y-old frog at 3 mo after disease resolution revealed irregularly shaped oocytes, few large mature oocytes, and numerous small, degenerating oocytes. At 6 mo after the incident, the remaining frogs continued to fail to produce eggs of sufficient quantity or quality after hormonal priming. The researchers consequently opted to cull the remainder of the colony and repopulate with new frogs.

  15. Acoustic monitoring of co-seismic changes in gas bubble rupture rate in a hydrothermal reservoir: field evaluation of a possible precursor and mechanism for remote seismic triggering

    Science.gov (United States)

    Crews, J. B.

    2015-12-01

    Remotely triggered seismicity is a phenomenon in which an earthquake at one location triggers others over distances up to thousands of kilometers. The mechanism by which low-amplitude dynamic oscillations of the confining stress can produce such an effect, often after a time delay of minutes-to-days, is unclear, but a concentration of remotely triggered seismic events in carbon-dioxide-rich volcanic and geothermal regions suggests that an increase in pore fluid pressure associated with the nucleation and growth of carbon-dioxide gas bubbles may reduce the effective stress in critically loaded geologic faults. While this hypothesis has been tested in bench-scale laboratory experiments, field detection of seismically initiated gas bubble growth in groundwater may provide further evidence for this remote triggering mechanism. In the present study, a hydrophone continuously records the acoustic power spectrum in CH-10B, a hydrothermal well located in Long Valley Caldera, California - a site that is susceptible to remotely seismic triggering. This well exhibits co-seismic changes in water level in response to near and distant earthquakes, including every magnitude-six or greater at any location on Earth. Exploiting the inverse relationship between gas bubble radius and the peak acoustic frequency emitted when a gas bubble ruptures, this investigation seeks to detect changes in the acoustic power spectrum arising from a shift in the size-distribution or count rate of rupturing gas bubbles, coincident with a distant earthquake. By resolving the timing and intensity of the onset of a change in gas bubble rupture rate after the passage of seismic wave from a distant source, it may be possible to establish the extent to which seismically initiated gas bubble growth contributes to co-seismic borehole water level response, pore fluid pressure perturbations, and the onset of remotely triggered seismicity.

  16. A modelling and experimental study of the bubble trajectory in a non-Newtonian crystal suspension

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, N M S [Process Engineering and Light Metals (PELM) Centre, Faculty of Sciences, Engineering and Health, CQUniversity, Rockhampton, QLD 4702 (Australia); Khan, M M K; Rasul, M G, E-mail: m.rasul@cqu.edu.a [School of Engineering and Built Environment, Faculty of Sciences, Engineering and Health, CQUniversity, Rockhampton, QLD 4702 (Australia)

    2010-12-15

    This paper presents an experimental and computational study of air bubbles rising in a massecuite-equivalent non-Newtonian crystal suspension. The bubble trajectory inside the stagnant liquid of a 0.05% xanthan gum crystal suspension was investigated and modelled using the computational fluid dynamics (CFD) model to gain an insight into the bubble flow characteristics. The CFD code FLUENT was used for numerical simulation, and the bubble trajectory calculations were performed through a volume of fluid (VOF) model. The influences of the Reynolds number (Re), the Weber number (We) and the bubble aspect ratio (E) on the bubble trajectory are discussed. The conditions for the bubbles' path oscillations are identified. The experimental results showed that the path instability for the crystal suspension was less rapid than in water. The trajectory analysis indicated that 5.76 mm diameter bubbles followed a zigzag motion in the crystal suspension. Conversely, the smaller bubbles (5.76 mm) followed a path of least horizontal movement and larger bubbles (21.21 mm) produced more spiral motion within the crystal suspension. Path instability occurred for bubbles of 15.63 and 21.21 mm diameter, and they induced both zigzag and spiral trajectories within the crystal suspension. At low Re and We, smaller bubbles (5.76 mm) produced a zigzag trajectory, whereas larger bubbles (15.63 and 21.21 mm) showed both zigzag and spiral trajectories at intermediate and moderately high Re and We in the crystal suspension. The simulation results illustrated that a repeating pattern of swirling vortices was created for smaller bubbles due to the unstable wake and unsteady flow of these bubbles. This is the cause of the smaller bubbles moving in a zigzag way. Larger bubbles showed two counter-rotating trailing vortices at the back of the bubble. These vortices induced a velocity component to the gas-liquid interface and caused a deformation. Hence, the larger bubbles produced a path

  17. Determination of turnover and cushion gas volume of a prospected gas storage reservoir under uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Gubik, A. [RAG-AG Wien (Austria); Baffoe, J.; Schulze-Riegert, R. [SPT Group GmbH, Hamburg (Germany)

    2013-08-01

    Gas storages define a key contribution for building a reliable gas supply chain from production to consumers. In a competitive gas market with short reaction times to seasonal and other gas injection and extraction requirements, gas storages also receive a strong focus on availability and precise prediction estimates for future operation scenarios. Reservoir management workflows are increasingly built on reservoir simulation support for optimizing production schemes and estimating the impact of subsurface uncertainties on field development scenarios. Simulation models for gas storages are calibrated to geological data and accurate reproduction of historical production data are defined as a prerequisite for reliable production and performance forecasts. The underlying model validation process is called history matching, which potentially generates alternative simulation models due to prevailing geological uncertainties. In the past, a single basecase reference model was used to predict production capacities of a gas storage. The working gas volume was precisely defined over a contracted plateau delivery and the required cushion gas volume maintains the reservoir pressure during the operation. Cushion and working gas Volume are strongly dependent on reservoir parameters. In this work an existing depleted gas reservoir and the operation target as a gas storage is described. Key input data to the reservoir model description and simulation is reviewed including production history and geological uncertainties based on large well spacing, limited core and well data and a limited seismic resolution. Target delivery scenarios of the prospected gas storage are evaluated under uncertainty. As one key objective, optimal working gas and cushion gas volumes are described in a probabilistic context reflecting geological uncertainties. Several work steps are defined and included in an integrated workflow design. Equiprobable geological models are generated and evaluated based on

  18. The Behaviour of Gas Bubble during Rest Period of Pulse-Activated Electrolysis Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Vilasmongkolchai Thanet

    2016-01-01

    Full Text Available The pulse-activated electrolyzer has been developed and used for several years. With the capability of enhancing the efficiency of an electrolytic process and easy operation, this technique becomes an interesting process for hydrogen production. Unfortunately during electrolytic reaction, the creation of bubbles becomes a reaction inhibitor and consumes energy. This paper aims to study the proper rest period that gives the bubble free rise-off the solution without additional bubble created. The mathematical method and acoustic emission method were used for investigation of bubble’s rising velocity. The result shows that the variation of rest period on pulse-activated makes production efficiency enhanced. For the practicality of use and set control parameters, duty cycle and frequency were demonstrated instead of rest period.

  19. Tribonucleation of bubbles

    CERN Document Server

    Wildeman, Sander; Sun, Chao; Lohse, Detlef; Prosperetti, Andrea

    2016-01-01

    We report on the nucleation of bubbles on solids that are gently rubbed against each other in a liquid. The phenomenon is found to depend strongly on the material and roughness of the solid surfaces. For a given surface, temperature, and gas content, a trail of growing bubbles is observed if the rubbing force and velocity exceed a certain threshold. Direct observation through a transparent solid shows that each bubble in the trail results from the early coalescence of several microscopic bubbles, themselves detaching from microscopic gas pockets forming between the solids. From a detailed study of the wear tracks, with atomic force and scanning electron microscopy imaging, we conclude that these microscopic gas pockets originate from a local fracturing of the surface asperities, possibly enhanced by chemical reactions at the freshly created surfaces. Our findings will be useful either for preventing undesired bubble formation or, on the contrary, for "writing with bubbles," i.e., creating controlled patterns ...

  20. Synchronous observation of rising soluble bubble through quiescent solution

    Institute of Scientific and Technical Information of China (English)

    Yifu ZHANG; Shuai TIAN; Weizhong LI; Yongchen SONG

    2009-01-01

    An experimental method using computer image processing technology (CIPT) was proposed to observe and investigate the velocity, deformation, heat and mass transfer, etc. of a rising soluble gas (CO2) bubble through a quiescent hot water. A model was set up to describe the behavior of the bubble in a visual experi-mental system in which a high-speed camera rose instantaneously with the movement of the bubble. A series of trajectory videos about the bubble were recorded by a computer linked to the camera. The trajectory, volume changes and rate of mass transfer of the bubble were obtained by the CIPT. It is found that the single bubble follows a rolling trajectory at the initial stage when there is mass transfer. With the volume decreasing, the disturbed behavior of the bubble becomes tempered. When the rising velocity of the bubble reaches the maximum, the velocity is nearly at a constant. The experimental and analysis results show that this method is useful for the research on the mass transfer and the movement of rising bubbles in liquid.

  1. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubble...

  2. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubbles...

  3. Distributed secondary gas injection via a fractal injector: a nature-inspired approach to improving conversion in fluidized bed reactors

    NARCIS (Netherlands)

    Christensen, D.O.

    2008-01-01

    The conversion in bubbling fluidized bed reactors is suppressed because the interphase mass transfer and gas-solid contact in bubbling fluidized bed reactors are often poor. Most of the gas is present in the form of bubbles, which have low surface-to-volume ratios and are nearly devoid of catalyst

  4. Enhanced recovery of unconventional gas. Executive summary. Volume I (of 3 volumes)

    Energy Technology Data Exchange (ETDEWEB)

    Kuuskraa, V. A.; Brashear, J. P.; Doscher, T. M.; Elkins, L. E.

    1978-10-01

    R and D efforts in enhanced gas recovery of near-conventional and unconventional gas sources are needed in order to augment domestic supplies. Unconventional gas sources could provide 200 to 220 Tcf of additional gas supply, if a combination of economic incentives and publicly sponsored R and D is used, and as much as 2 to 8 Tcf could be delivered per year by 1990. This volume comprises three parts discussing the public policy issues, proposed research strategy in enhanced gas recovery, and methodology. 14 figures. (DLC)

  5. Gas Density and the Volume Schmidt Law for Spiral Galaxies

    CERN Document Server

    Abramova, O V

    2007-01-01

    The thickness of the equilibrium isothermal gaseous layers and their volume densities \\rho_{gas}(R) in the disc midplane are calculated for 7 spiral galaxies (including our Galaxy) in the frame of self-consistent axisymmetric model. Local velocity dispersions of stellar discs were assumed to be close to marginal values necessary for the discs to be in a stable equilibrium state. Under this condition the stellar discs of at least 5 of 7 galaxies reveal a flaring. Their volume densities decrease with R faster than \\rho_{gas}, and, as a result, the gas dominates by the density at the disc periphery. Comparison of the azimuthally averaged star formation rate SFR with the gas density shows that there is no universal Schmidt law SFR \\rho_{gas}^n, common to all galaxies. Nevertheless, SFR in different galaxies reveals better correlation with the volume gas density than with the column one. Parameter n in the Schmidt law SFR \\rho_{gas}^n, formally calculated by the least square method, lies within 0.8-2.4 range and i...

  6. Observations of the collapses and rebounds of millimeter-sized lithotripsy bubbles.

    Science.gov (United States)

    Kreider, Wayne; Crum, Lawrence A; Bailey, Michael R; Sapozhnikov, Oleg A

    2011-11-01

    Bubbles excited by lithotripter shock waves undergo a prolonged growth followed by an inertial collapse and rebounds. In addition to the relevance for clinical lithotripsy treatments, such bubbles can be used to study the mechanics of inertial collapses. In particular, both phase change and diffusion among vapor and noncondensable gas molecules inside the bubble are known to alter the collapse dynamics of individual bubbles. Accordingly, the role of heat and mass transport during inertial collapses is explored by experimentally observing the collapses and rebounds of lithotripsy bubbles for water temperatures ranging from 20 to 60 °C and dissolved gas concentrations from 10 to 85% of saturation. Bubble responses were characterized through high-speed photography and acoustic measurements that identified the timing of individual bubble collapses. Maximum bubble diameters before and after collapse were estimated and the corresponding ratio of volumes was used to estimate the fraction of energy retained by the bubble through collapse. The rebounds demonstrated statistically significant dependencies on both dissolved gas concentration and temperature. In many observations, liquid jets indicating asymmetric bubble collapses were visible. Bubble rebounds were sensitive to these asymmetries primarily for water conditions corresponding to the most dissipative collapses.

  7. Does nitrogen gas bubbled through a low density polymer gel dosimeter solution affect the polymerization process?

    Directory of Open Access Journals (Sweden)

    Daryoush Shahbazi-Gahrouei

    2015-01-01

    Conclusion: It appeared that reactions between gelatin-free radicals and monomers, due to an increase in the gel temperature during rotation in the household mixer, led to a higher R 2 -background response. In the second type of gel, it seemed that the collapse of the nitrogen bubbles was the main factor that affected the R 2 -responses.

  8. Determination of the Accommodation Coefficient Using Vapor/gas Bubble Dynamics in an Acoustic Field

    Science.gov (United States)

    Gumerov, Nail A.; Hsiao, Chao-Tsung; Goumilevski, Alexei G.; Allen, Jeff (Technical Monitor)

    2001-01-01

    Nonequilibrium liquid/vapor phase transformations can occur in superheated or subcooled liquids in fast processes such as in evaporation in a vacuum. The rate at which such a phase transformation occurs depends on the "condensation" or "accommodation" coefficient, Beta, which is a property of the interface. Existing measurement techniques for Beta are complex and expensive. The development of a relatively inexpensive and reliable technique for measurement of Beta for a wide range of substances and temperatures is of great practical importance. The dynamics of a bubble in an acoustic field strongly depends on the value of Beta. It is known that near the saturation temperature, small vapor bubbles grow under the action of an acoustic field due to "rectified heat transfer." This finding can be used as the basis for an effective measurement technique of Beta. We developed a theory of vapor bubble behavior in an isotropic acoustic wave and in a plane standing acoustic wave. A numerical code was developed which enables simulation of a variety of experimental situations and accurately takes into account slowly evolving temperature. A parametric study showed that the measurement of Beta can be made over a broad range of frequencies and bubble sizes. We found several interesting regimes and conditions which can be efficiently used for measurements of Beta. Measurements of Beta can be performed in both reduced and normal gravity environments.

  9. The effect of a micro bubble dispersed gas phase on hydrogen isotope transport in liquid metals under nuclear irradiation

    CERN Document Server

    Fradera, Jorge

    2013-01-01

    The present work intend to be a first step towards the understanding and quantification of the hydrogen isotope complex phenomena in liquid metals for nuclear technology. Liquid metals under nuclear irradiation in,e.g., breeding blankets of a nuclear fusion reactor would generate tritium which is to be extracted and recirculated as fuel. At the same time that tritium is bred, helium is also generated and may precipitate in the form of nano bubbles. Other liquid metal systems of a nuclear reactor involve hydrogen isotope absorption processes, e.g., tritium extraction system. Hence, hydrogen isotope absorption into gas bubbles modelling and control may have a capital importance regarding design, operation and safety. Here general models for hydrogen isotopes transport in liquid metal and absorption into gas phase, that do not depend on the mass transfer limiting regime, are exposed and implemented in OpenFOAMR CFD tool for 0D to 3D simulations. Results for a 0D case show the impact of a He dispersed phase of na...

  10. Nitrogen-gas bubbling during the cultivation of Clostridium tetani produces a higher yield of tetanus toxin for the preparation of its toxoid.

    Science.gov (United States)

    De Luca, M M; Abeiro, H D; Bernagozzi, J A; Basualdo, J A

    1997-01-01

    We investigated the effect of exposing cultures of Clostridium tetani to nitrogen (N2) gas on the recovery of tetanus toxin to be processed for the preparation of its toxoid. N2 was bubbled through nine 10-liter cultures during the growth of the bacteria, while nine parallel control incubations were maintained without bubbling. We found that treatment of the C. tetani anaerobes with an inert gas in this manner during cultivation produced a highly significant increase in the yield of tetanus toxin from them in comparison with the standard procedure.

  11. Binary coalescence of gas bubbles in the presence of a non-ionic surfactant.

    Science.gov (United States)

    Duerr-Auster, N; Gunde, R; Mäder, R; Windhab, Erich J

    2009-05-15

    The coalescence behavior of air bubbles in a dilute aqueous surfactant solution of a polyglycerol fatty acid ester (PGE), a commercial non-ionic surfactant, is investigated in a binary coalescence experiment. The focus is on the influence of the ionic strength of the solution on the rate of coalescence. Results are compared with the adsorption kinetics and surface shear/dilatational rheological properties of the surfactant. Experiments show that the coalescence frequency is significantly lower at low ionic strength, and that bubble stability increases with increasing aging time. Stabilization occurs via surfactant adsorption and a resulting electrostatic and/or steric repulsive force. The electrostatic force presumably originates from small amounts of anionic fatty acid soaps, which are residues from the industrial synthesis. The steric force can be related to the adsorption of visco-elastic layers of PGE at the air-water interface.

  12. Well-posed Euler model of shock-induced two-phase flow in bubbly liquid

    Science.gov (United States)

    Tukhvatullina, R. R.; Frolov, S. M.

    2017-07-01

    A well-posed mathematical model of non-isothermal two-phase two-velocity flow of bubbly liquid is proposed. The model is based on the two-phase Euler equations with the introduction of an additional pressure at the gas bubble surface, which ensures the well-posedness of the Cauchy problem for a system of governing equations with homogeneous initial conditions, and the Rayleigh-Plesset equation for radial pulsations of gas bubbles. The applicability conditions of the model are formulated. The model is validated by comparing one-dimensional calculations of shock wave propagation in liquids with gas bubbles with a gas volume fraction of 0.005-0.3 with experimental data. The model is shown to provide satisfactory results for the shock propagation velocity, pressure profiles, and the shock-induced motion of the bubbly liquid column.

  13. Reliability of gas holdup measurements using the differential pressure method in a cyclone-static micro-bubble flotation column

    Institute of Scientific and Technical Information of China (English)

    Xia Wencheng; Yang Jianguo; Wang Yuling

    2011-01-01

    Gas holdup iS one of the Key parameters in flotation process.Gas holclup as measured by a differential pressure method was investigated and the relative errors compared to the average gas holdup from the volume expansion method.The errors were used to establish optimum measurement positions.The results show that the measurement position should be in the middle of the column and in the region half way from the center to the wall (the half-radius).The gas holdup along the axial direction is lower at the bottom and higher at the top of the floatation column.The gas holdup along the radial direction is lower near the wall and higher near the center of the flotation column.The average gas holdup measurement can be replaced bv regional gas holdup values.

  14. A New Method for the Measurement of Gas Holdup in Solid-Suspended Bubble Columns

    OpenAIRE

    "宮原, 敏郎; ミヤハラ, トシロウ"; Toshiro, "Miyahara

    1996-01-01

    A method for the measurement for gas holdup in gas-liquid-solid multiphase devices is developed. The method depends on measurements of hydrostatic pressuress in the three-phase dispersion followed by interruption of gas flow and solids and liquid holdups without gas flow.

  15. Gas content of a two-phase layer containing gas and a melt of K/sub 2/O-V/sub 2/O/sub 8/ averaged by volume and its foam formation in a reaction-regeneration cycle

    Energy Technology Data Exchange (ETDEWEB)

    Fazleev, M.P.; Chekhov, O.S.; Ermakov, E.A.

    1985-06-20

    This paper discusses the results of an investigation of the gas content averaged over the volume, hydrodynamic programs, and foaming in the K/sub 2/O-V/sub 2/O/sub 5/ melt plus gas system, which is used as a catalyst in several thermocatalytic processes. The experimental setup is described and a comparison of literature data on the gas content of different gas-liquid systems under comparable conditions is presented. The authors were able to determine the boundaries of the hydrodynamic modes in a bubbling reactor and derive equations for the calculation of the gas content. It was found that the gas content of the melt increased when V/sub 2/O/sub 5/ was reduced to V/sub 2/O/sub 4/ in the reaction portion of the reaction-regeneration cycle. Regeneration of the melt restores the value of gas content to its original level.

  16. Effects of Ar or O2 Gas Bubbling for Shape, Size, and Composition Changes in Silver-Gold Alloy Nanoparticles Prepared from Galvanic Replacement Reaction

    Directory of Open Access Journals (Sweden)

    Md. Jahangir Alam

    2013-01-01

    Full Text Available The galvanic replacement reaction between silver nanostructures and AuCl4- solution has recently been demonstrated as a versatile method for generating metal nanostructures with hollow interiors. Here we describe the results of a systematic study detailing the morphological, structural, compositional, and spectral changes involved in such a heterogeneous reaction on the nanoscale. Effects of Ar or O2 gas bubbling for the formation of Ag-Au alloy nanoparticles by the galvanic replacement between spherical Ag nanoparticles and AuCl4- especially were studied in ethylene glycol (EG at 150°C. The shape, size, and composition changes occur rapidly under O2 bubbling in comparison with those under Ar bubbling. The major product after 60 min heating under Ar gas bubbling was perforated Ag-Au alloy particles formed by the replacement reaction and the minor product was ribbon-type particles produced from splitting off some perforated particles. On the other hand, the major product after 60 min heating under O2 gas bubbling was ribbon-type particles. In addition, small spherical Ag particles are produced. They are formed through rereduction of Ag+ ions released from the replacement reaction and oxidative etching of Ag nanoparticles by O2/Cl− in EG.

  17. Particle Dispersion Behaviors of Dense Gas-Particle Flows in Bubble Fluidized Bed

    OpenAIRE

    Xue Liu; Guohui Li; Sihao Lv

    2013-01-01

    An Euler-Euler two-fluid model incorporating a developed momentum transfer empirical coefficient is developed to study the particle dispersion behaviors of dense gas-particle flows in gas-fluidization reactor. In this model, the four-way couplings among gas-particles, particle-gas, and particle-particle collisions are fully considered based on kinetic theory of granular flows and an improved smooth continuous drag coefficient is utilized. Gas turbulent flow is solved by large eddy simulation....

  18. Influence of infection with Renibacterium salmoninarum on susceptibility of juvenile spring chinook salmon to gas bubble trauma

    Science.gov (United States)

    Weiland, L.K.; Mesa, M.G.; Maule, A.G.

    1999-01-01

    During experiments in our laboratory to assess the progression and severity of gas bubble trauma (GBT) in juvenile spring chinook salmon Oncorhynchus tshawytscha, we had the opportunity to assess the influence of Renibacterium salmoninarum (Rs), the causative agent of bacterial kidney disease, on the susceptibility of salmon to GBT. We exposed fish with an established infection of Rs to 120% total dissolved gas (TDG) for 96 h and monitored severity of GBT signs in the fins and gills, Rs infection level in kidneys by using an enzyme-linked immunosorbent assay (ELISA), and mortality. Mortality occurred rapidly after exposure to 120% TDG, with a LT20 (time necessary to kill 20% of the population) of about 37 h, which is at a minimum about 16% earlier than other bioassays we have conducted using fish that had no apparent signs of disease. Fish that died early (from 31 to 36 h and from 49 to 52 h) had significantly higher infection levels (mean ?? SE ELISA absorbance = 1.532 ?? 0.108) than fish that survived for 96h (mean ?? SE ELISA absorbance = 0.828 ?? 0.137). Fish that died early also had a significantly greater number of gill filaments occluded with bubbles than those that survived 96 h. Conversely, fish that survived for 96 h had a significantly higher median fin severity ranking than those that died early. Our results indicate that fish with moderate to high levels of Rs infection are more vulnerable to the effects of dissolved gas supersaturation (DGS) and die sooner than fish with lower levels of Rs infection. However, there is a substantial amount of individual variation in susceptibility to the apparent cumulative effects of DGS and Rs infection. Collectively, our findings have important implications to programs designed to monitor the prevalence and severity of GBT in juvenile salmonids in areas like the Columbia River basin and perhaps elsewhere.

  19. 30 CFR 203.73 - How do suspension volumes apply to natural gas?

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false How do suspension volumes apply to natural gas... suspension volumes apply to natural gas? You must measure natural gas production under the royalty-suspension volume as follows: 5.62 thousand cubic feet of natural gas, measured in accordance with 30 CFR part...

  20. 含不凝性气体的蒸汽气泡凝结过程研究%Study on Condensation Process of Vapor Bubble Containing Noncondensable Gas

    Institute of Scientific and Technical Information of China (English)

    唐继国; 阎昌琪; 孙立成; 侯晓凡

    2015-01-01

    A visualized investigation was performed to study the condensation and collapse processes of vapor bubbles at high liquid subcooling with a high‐speed video camera (Fastcam SA5) .Experiment results show that a vapor bubble will collapse to many microbubbles rapidly when the initial volumetric fraction of noncondensable gas in the bubble ,x0 ,is less than 2.5% .Instead ,a large bubble will split into just several tiny bubbles when x0 is between 2.5% and 7.5% . Further , x0 increases exceeding 7.5% ,the bubble surface will be very stable ,and no collapse or fragmentation occurs . The noncondensable gas in a vapor bubble reduces the condensation at the bubble surface ,which weakens the inertial shock of the liquid on the surface and makes the bubble more stable . This may elucidate that the presence of noncondensable gas will inhibit the bubble collapse in microbubble emission boiling and deteriorate the heat transfer performance consequently .%利用高速摄像仪对高过冷度下含不凝性气体的蒸汽气泡冷凝及破裂过程进行可视化研究,以分析不凝性气体对气泡微细化沸腾(MEB)过程的影响。实验结果表明:初始不凝性气体体积份额 x0小于2.5%时,气泡突然破碎成大量微小气泡;x0在2.5%~7.5%之间时,较大气泡只会分裂成数个小气泡;x0大于7.5%时,气泡界面非常稳定,不会发生破碎和分裂现象。此外,当蒸汽气泡中含有较多不凝性气体时,气泡凝结过程减弱,液体对气泡的惯性冲击减小,气泡不易破裂。由此可表明,在气泡微细化沸腾发生时,不凝性气体的存在会阻碍加热面上气泡的破碎,从而降低传热能力。

  1. INFLUENCE OF SODIUM GLUTAMATE, BUBBLING N2- GAS AND SUPERFICIAL AERATION ON TETANUS TOXIN PRODUCTION IN Clostridium tetani CULTURES

    Directory of Open Access Journals (Sweden)

    I. Gutiérrez

    2005-12-01

    Full Text Available The influence of sodium glutamate as a supplement to Latham Mueller medium, while using bubbling nitrogen flow as an anaerobic agent and superficial aeration as an inducer of cell lysis and as a mechanism for the haulage of gases in the fermentation processes was evaluated. Using the Clostridium tetani Massachusetts’s strain, several five (5 liter batch fermentations were carried out for tetanus toxin production under the following conditions: Latham Mueller medium, with or without sodium glutamate, nitrogen flow and superficial aeration. The results demonstrated that the addition of sodium glutamate (2.5 g/l, combined with a bubbling nitrogen flow (0.33 l/min and superficial aeration (0.33 l/min, produced a significant increase in cell concentrations, repressing the tetanus toxin formation; while the gas flow (nitrogen and superficial aeration without sodium glutamate improved the toxin production by approximately 49%, providing conditions for the following outcomes: a maximum toxin level of 73 Lf/ml; a toxin formation rate of 1844.0 Lf/l.h; and, an over-all productivity of 833.5 Lf/l.h.

  2. Bubbles in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Lin, Jun

    2015-01-01

    Strain-induced deformations in graphene are predicted to give rise to large pseudomagnetic fields. We examine theoretically the case of gas-inflated bubbles to determine whether signatures of such fields are present in the local density of states. Sharp-edged bubbles are found to induce Friedel...

  3. Single bubble sonoluminescence

    NARCIS (Netherlands)

    Brenner, Michael P.; Hilgenfeldt, Sascha; Lohse, Detlef

    2002-01-01

    Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing at collapse leads to light emission. Detailed experiments have demonstrated the unique properties of this system: the spectrum of the emitted light ten

  4. Single bubble sonoluminescence

    NARCIS (Netherlands)

    Brenner, Michael P.; Hilgenfeldt, Sascha; Lohse, Detlef

    2002-01-01

    Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing at collapse leads to light emission. Detailed experiments have demonstrated the unique properties of this system: the spectrum of the emitted light

  5. Scaling law for bubbles rising near vertical walls

    Science.gov (United States)

    Dabiri, Sadegh; Bhuvankar, Pramod

    2016-06-01

    This paper examines the rising motion of a layer of gas bubbles next to a vertical wall in a liquid in the presence of an upward flow parallel to the wall to help with the understanding of the fluid dynamics in a bubbly upflow in vertical channels. Only the region near the wall is simulated with an average pressure gradient applied to the domain that balances the weight of the liquid phase. The upward flow is created by the rising motion of the bubbles. The bubbles are kept near the wall by the lateral lift force acting on them as a result of rising in the shear layer near the wall. The rise velocity of the bubbles sliding on the wall and the average rise velocity of the liquid depend on three dimensionless parameters, Archimedes number, Ar, Eötvös number, Eo, and the average volume fraction of bubbles on the wall. In the limit of small Eo, bubbles are nearly spherical and the dependency on Eo becomes negligible. In this limit, the scaling of the liquid Reynolds number with Archimedes number and the void fraction is presented. A scaling argument is presented based on viscous dissipation analysis that matches the numerical findings. Viscous dissipation rates are found to be high in a thin film region between the bubble and the wall. A scaling of the viscous dissipation and steady state film thickness between the bubble and the wall with Archimedes number is presented.

  6. Bubble and drop interfaces

    CERN Document Server

    Miller

    2011-01-01

    The book aims at describing the most important experimental methods for characterizing liquid interfaces, such as drop profile analysis, bubble pressure and drop volume tensiometry, capillary pressure technique, and oscillating drops and bubbles. Besides the details of experimental set ups, also the underlying theoretical basis is presented in detail. In addition, a number of applications based on drops and bubbles is discussed, such as rising bubbles and the very complex process of flotation. Also wetting, characterized by the dynamics of advancing contact angles is discussed critically. Spec

  7. Resolution of D- and L-glucoses by chiral N-octyl-beta-D-glycoside-Cu(II) complex adsorbed at the gas/liquid interface of small bubbles

    NARCIS (Netherlands)

    Sakai, M.; Miyazawa, K.; Jitsumatsu, H.; Kamio, K.; Mitsuiki, S.; Toh, N.; Sugihara, G.; Norde, W.

    2010-01-01

    A new technique of the jet drop method (JDM) was applied to a chiral molecular discrimination of optically active D- or L-glucose (guest) by chiral N-octyl-beta-D-glycoside (O beta DG)-Cu(II) complex (host) at the gas/liquid interface of small bubbles. The discrimination of glucoses as the guests is

  8. Novel empirical correlations for estimation of bubble point pressure, saturated viscosity and gas solubility of crude oils

    Institute of Scientific and Technical Information of China (English)

    Ehsan Khamehchi; Fariborz Rashidi; Hanieh Rasouli; Amir Ebrahi-mian

    2009-01-01

    Knowledge of petroleum fluid properties is crucial for the study of reservoirs and their development. Estimation of reserves in an oil reservoir or determination of its performance and economics requires a good knowledge of the fluid physical properties. Bubble point pressure, gas solubility and viscosity of oils are the most important parameters in use for petroleum and chemical engineers. In this study a simple-to-use, straight-forward mathematical model was correlated on a set of 94 crude oil data. Three correlations were achieved based on an exponential regression, which were different from conventional empirical correlations, and were evaluated against 12 laboratory data other than those used for the regression. It is concluded that the new exponential equation is of higher precision and accuracy than the conventional correlations and is a more convenient mathematical formulation.

  9. A new efficient empirical correlation for filtrate flux in slurry bubble column reactor of a gas-to-liquid process

    Energy Technology Data Exchange (ETDEWEB)

    Hemmati, Mohammad Reza [Entekhab Petrochemical Co., Tehran (Iran, Islamic Republic of); Khodagholi, Mohammad Ali [Research Institute of Petroleum Industry, Tehran (Iran, Islamic Republic of)

    2015-12-15

    Gas to Liquid has recently become of great interest. In this technology slurry bubble column reactors are favored for many reasons. Separation of liquid wax from the slurry is still a major problem that may be done by internal or external filtration. A system of sintered metal candle filters are designed and operated to collect experimental data of internal filtration. Data for 4 and 8 micron filter elements with different pressure differences and kinematic viscosity were collected. Data analysis revealed that these data could be correlated as a simple function of time, pressure drop and kinematic viscosity. This new and efficient correlation shows excellent ability to reproduce original data at moderate filtration conditions, but it is less precious in severe conditions. It was understood that main reason for this behavior is different filtrate flux regimes through filter media pores, led to inability of a single correlation to fit both regimes properly.

  10. Growth of a Gas Bubble in a Supersaturated Liquid Under the Effect of Variant Cases of Surface Tension

    Science.gov (United States)

    Mohammadein, S. A.; Mohamed, K. G.

    In this paper, the growth of a gas bubble in a supersaturated liquid is discussed for a constant and variable cases of surface tension effect. The mathematical model is solved analytically by using the method of Plesset and Zwick18 after modified it. The growth process is affected by: diffusion coefficient D, Jacob number Ja, surface tension σ, adjustment factor b and void fraction ϕ0. The famous formula of Plesset and Zwick is produced as a special case of the results at some values of the adjustment factors. Moreover, for some values of the adjustment factors, good approximation is obtained when a comparison between our results and the result that produced by Hashemi et al., 9 who solved the problem with the method of combining variables.

  11. Research on the Conductivity-Based Detection Principles of Bubbles in Two-Phase Flows and the Design of a Bubble Sensor for CBM Wells

    Directory of Open Access Journals (Sweden)

    Chuan Wu

    2016-09-01

    Full Text Available The parameters of gas-liquid two-phase flow bubbles in field coalbed methane (CBM wells are of great significance for analyzing coalbed methane output, judging faults in CBM wells, and developing gas drainage and extraction processes, which stimulates an urgent need for detecting bubble parameters for CBM wells in the field. However, existing bubble detectors cannot meet the requirements of the working environments of CBM wells. Therefore, this paper reports findings on the principles of measuring the flow pattern, velocity, and volume of two-phase flow bubbles based on conductivity, from which a new bubble sensor was designed. The structural parameters and other parameters of the sensor were then computed, the “water film phenomenon” produced by the sensor was analyzed, and the appropriate materials for making the sensor were tested and selected. After the sensor was successfully devised, laboratory tests and field tests were performed, and the test results indicated that the sensor was highly reliable and could detect the flow patterns of two-phase flows, as well as the quantities, velocities, and volumes of bubbles. With a velocity measurement error of ±5% and a volume measurement error of ±7%, the sensor can meet the requirements of field use. Finally, the characteristics and deficiencies of the bubble sensor are summarized based on an analysis of the measurement errors and a comparison of existing bubble-measuring devices and the designed sensor.

  12. Research on the Conductivity-Based Detection Principles of Bubbles in Two-Phase Flows and the Design of a Bubble Sensor for CBM Wells.

    Science.gov (United States)

    Wu, Chuan; Wen, Guojun; Han, Lei; Wu, Xiaoming

    2016-09-17

    The parameters of gas-liquid two-phase flow bubbles in field coalbed methane (CBM) wells are of great significance for analyzing coalbed methane output, judging faults in CBM wells, and developing gas drainage and extraction processes, which stimulates an urgent need for detecting bubble parameters for CBM wells in the field. However, existing bubble detectors cannot meet the requirements of the working environments of CBM wells. Therefore, this paper reports findings on the principles of measuring the flow pattern, velocity, and volume of two-phase flow bubbles based on conductivity, from which a new bubble sensor was designed. The structural parameters and other parameters of the sensor were then computed, the "water film phenomenon" produced by the sensor was analyzed, and the appropriate materials for making the sensor were tested and selected. After the sensor was successfully devised, laboratory tests and field tests were performed, and the test results indicated that the sensor was highly reliable and could detect the flow patterns of two-phase flows, as well as the quantities, velocities, and volumes of bubbles. With a velocity measurement error of ±5% and a volume measurement error of ±7%, the sensor can meet the requirements of field use. Finally, the characteristics and deficiencies of the bubble sensor are summarized based on an analysis of the measurement errors and a comparison of existing bubble-measuring devices and the designed sensor.

  13. Dynamics of diffusive bubble growth and pressure recovery in a bubbly rhyolitic melt embedded in an elastic solid

    Science.gov (United States)

    Chouet, Bernard A.; Dawson, Phillip B.; Nakano, Masaru

    2006-01-01

    We present a model of gas exsolution and bubble expansion in a melt supersaturated in response to a sudden pressure drop. In our model, the melt contains a suspension of gas bubbles of identical sizes and is encased in a penny-shaped crack embedded in an elastic solid. The suspension is modeled as a three-dimensional lattice of spherical cells with slight overlap, where each elementary cell consists of a gas bubble surrounded by a shell of volatile-rich melt. The melt is then subjected to a step drop in pressure, which induces gas exsolution and bubble expansion, resulting in the compression of the melt and volumetric expansion of the crack. The dynamics of diffusion-driven bubble growth and volumetric crack expansion span 9 decades in time. The model demonstrates that the speed of the crack response depends strongly on volatile diffusivity in the melt and bubble number density and is markedly sensitive to the ratio of crack thickness to crack radius and initial bubble radius but is relatively insensitive to melt viscosity. The net drop in gas concentration in the melt after pressure recovery represents only a small fraction of the initial concentration prior to the drop, suggesting the melt may undergo numerous pressure transients before becoming significantly depleted of gases. The magnitude of pressure and volume recovery in the crack depends sensitively on the size of the input-pressure transient, becoming relatively larger for smaller-size transients in a melt containing bubbles with initial radii less than 10-5 m. Amplification of the input transient may be large enough to disrupt the crack wall and induce brittle failure in the rock matrix surrounding the crack. Our results provide additional basis for the interpretation of volume changes in the magma conduit under Popocatépetl Volcano during Vulcanian degassing bursts in its eruptive activity in April–May 2000.

  14. An introduction to finite volumes for gas dynamics

    CERN Document Server

    Dubois, François

    2011-01-01

    We propose an elementary introduction to the finite volume method in the context of gas dynamics conservation laws. Our approach is founded on the advection equation, the exact integration of the associated Cauchy problem, and the so-called upwind scheme in one space dimension. It is then extended in three directions: hyperbolic linear systems and particularily the system of acoustics, gas dynamics with the help of the Roe matrix and two space dimensions by following the approach proposed by Van Leer. A special emphasis on boundary conditions is proposed all along the text.

  15. Review of scattering and extinction cross-sections, damping factors, and resonance frequencies of a spherical gas bubble

    NARCIS (Netherlands)

    Ainslie, M.A.; Leighton, T.G.

    2011-01-01

    Perhaps the most familiar concepts when discussing acoustic scattering by bubbles are the resonance frequency for bubble pulsation, the bubbles' damping, and their scattering and extinction cross-sections, all of which are used routinely in oceanography, sonochemistry, and biomedicine. The apparent

  16. You see what you know … gas bubbles in the inferior vena cava, an unusual presentation of necrotizing soft tissue infection.

    Science.gov (United States)

    Winter, Thomas C; Rudolf, Lou; Sommers, Daniel N

    2015-06-01

    Gas detected within the systemic circulation as an unexpected finding is a very rare phenomenon. A case of multiple bubbles within the inferior vena cava detected incidentally during a sonogram requested to assess for portal vein thrombosis is presented. These were eventually determined to be sequelae of a fatal, clinically silent necrotizing soft tissue infection. The differential diagnosis for gas within the inferior vena cava is reviewed, and teaching points that may help future patients are presented.

  17. Simulation of exchanges of multiple gases in bubbles in the body.

    Science.gov (United States)

    Burkard, M E; Van Liew, H D

    1994-02-01

    This communication introduces a system of equations, for numerical solution, which simulates the generation, growth, and decay of bubbles. The system is an advance over previous works because it allows for simultaneous diffusion of any number of gases. Our purpose for developing the system is to gain insight into the bubbles that occur in the body in decompression sickness (DCS). We validate the calculation system by matching observed data of DCS bubbles and of large subcutaneous gas pockets in rats. We demonstrate how a temporary supersaturation and bubble formation can occur without change of ambient pressure when there is a change in the inert gas being breathed. With exposures to hypobaric environments, such as when astronauts work in space, simulations show that O2, CO2, and water vapor add appreciably to volume of bubbles and affect the diffusion of inert gas.

  18. Review of Current Literature and Research on Gas Supersaturation and Gas Bubble Trauma: Special Publication Number 1, 1986.

    Energy Technology Data Exchange (ETDEWEB)

    Colt, John; Bouck, Gerald R.; Fidler, Larry

    1986-12-01

    This report presents recently published information and on-going research on the various areas of gas supersaturation. Growing interest in the effects of chronic gas supersaturation on aquatic animals has been due primarily to heavy mortality of salmonid species under hatchery conditions. Extensive examination of affected animals has failed to consistently identify pathogenic organisms. Water quality sampling has shown that chronic levels of gas supersaturation are commonly present during a significant period of the year. Small marine fish larvae are significantly more sensitive to gas supersaturation than salmonids. Present water quality criteria for gas supersaturation are not adequate for the protection of either salmonids under chronic exposure or marine fish larvae, especially in aquaria or hatcheries. To increase communication between interested parties in the field of gas supersaturation research and control, addresses and telephone numbers of all people responding to the questionnaire are included. 102 refs.

  19. LOFT reflood as a function of accumulator initial gas volume

    Energy Technology Data Exchange (ETDEWEB)

    Rhodes, H.F.

    1978-06-01

    The effect of the initial gas volume in the LOFT accumulators on the time to start of core reflood, after a LOCA, has been studied. The bases of the calculations are the data used and results presented in the Safety Analysis Report, Rev.1, August 1977, and the data in the RELAP and TOODEE2 program input and output listings. The results of this study show that an initial nitrogen volume of 12 cu ft, or more (at 600 psig initial pressure), would cause start of core reflood in time to prevent the cladding temperature from reaching 2200/sup 0/F. The 12 cu ft initial volume will expand from 600 psig, initial pressure, to about 10 psig (containment pressure shortly after start of LOCA is approximately 8 psig) when all ECC liquid has been expelled from the accumulator. This pressure margin is considered too small; the ECC flowrate will be zero before the accumulator is empty.

  20. Argonne Bubble Experiment Thermal Model Development II

    Energy Technology Data Exchange (ETDEWEB)

    Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-01

    This report describes the continuation of the work reported in “Argonne Bubble Experiment Thermal Model Development”. The experiment was performed at Argonne National Laboratory (ANL) in 2014. A rastered 35 MeV electron beam deposited power in a solution of uranyl sulfate, generating heat and radiolytic gas bubbles. Irradiations were performed at three beam power levels, 6, 12 and 15 kW. Solution temperatures were measured by thermocouples, and gas bubble behavior was observed. This report will describe the Computational Fluid Dynamics (CFD) model that was developed to calculate the temperatures and gas volume fractions in the solution vessel during the irradiations. The previous report described an initial analysis performed on a geometry that had not been updated to reflect the as-built solution vessel. Here, the as-built geometry is used. Monte-Carlo N-Particle (MCNP) calculations were performed on the updated geometry, and these results were used to define the power deposition profile for the CFD analyses, which were performed using Fluent, Ver. 16.2. CFD analyses were performed for the 12 and 15 kW irradiations, and further improvements to the model were incorporated, including the consideration of power deposition in nearby vessel components, gas mixture composition, and bubble size distribution. The temperature results of the CFD calculations are compared to experimental measurements.

  1. Granular dynamics simulation of segregation phenomena in bubbling gas-fluidised beds

    NARCIS (Netherlands)

    Hoomans, B.P.B.; Kuipers, J.A.M.; Swaaij, van W.P.M.

    2000-01-01

    A hard-sphere discrete particle model of a gas-fluidised bed was used in order to simulate segregation phenomena in systems consisting of particles of different sizes. In the model, the gas-phase hydrodynamics is described by the spatially averaged Navier¿Stokes equations for two-phase flow. For eac

  2. Gas Hold-Up, Mixing Time and Circulation Time in Internal Loop Airlift Bubble Column

    Directory of Open Access Journals (Sweden)

    Ali Abdul Rahman–Al Ezzi

    2014-01-01

    Full Text Available The effects of superficial gas in the riser (Vgr and liquid phase properties on the gas hold-up(ɛg , mixing time (Tm and circulation time (TC were studied in 8 liter internal air lift loop reactor (down comer-to-riser crosssectional area ratio = 0.249. Air was used as a gas phase. Water and four aqueous solutions of 10% concentration methanol, ethanol, (were used to simulate the behavior of non-coalescing organic liquids 50% glycerol and 2% Carboxy Methyl Cellulose (CMC were used to simulate the behavior of coalescing viscous liquids. Polyethylene-non-porous-solid particles with a concentration of (50 Kg/m3 were used as solid phase. Superficial gas velocity varied from 0.01 m/s to 0.1 m/s and air dispersed into the center of the draught tube by using a porous gas distributor. The results showed that (εg increased with increasing gas velocity and coalescence inhibition of liquid, while Tm and Tc decrease with increasing gas velocity. It was found that increasing liquid viscosity and coalescence reduces (εg but increases (Tm and (Tc. The gas holdup was correlated with dimensionless groups and independent parameter with correlation coefficient is 0.967, the following correlation is obtained.

  3. Effect of pore size on gas resistance of nanofiber membrane by the bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Shen Jing

    2015-01-01

    Full Text Available This paper explores the influence of pore size on gas resistance by comparing micron non-woven and nanofiber membrane. The result shows that membrane with a higher filtration and lower gas resistance can be received by controlling the pore size of nanofiber membrane.

  4. Passive acoustic records of two vigorous bubble-plume methane seeps on the Oregon continental margin

    Science.gov (United States)

    Dziak, R. P.; Matsumoto, H.; Merle, S. G.; Embley, R. W.; Baumberger, T.; Hammond, S. R.

    2016-12-01

    We present preliminary analysis of the acoustic records of two bubble-plume methane seeps recorded by an autonomous hydrophone deployed during the E/V Nautilus expedition (NA072) in June 2016. The goal of the NA072 expedition was to use the Simrad 302 as a survey tool to map bubble plumes at a regional scale along the Oregon and northern California margins, followed by in situ investigation of bubble-plume sites using the ROV Hercules. The exploration carried out during NA072 resulted in the discovery of hundreds of new individual methane seep sites in water depths ranging from 125 to 1725 m depth. A Greenridge Acousonde 3B™ hydrophone was deployed via ROV within two vigorous bubble-plume sites. Despite persistent ship and ROV propeller noise, the acoustic signature of the bubble-plume can be seen in the hydrophone record as a broadband (0.5 - 4.5 kHz) series of short duration ( 0.2-0.5 msec) pulses that occur in clusters of dozens of pulses lasting 2-3 secs. Previous studies of the passive acoustics of seep bubble-plumes indicate sound is generated during bubble formation, where detachment of the gas bubble from the end of a tube or conduit causes the bubble to oscillate, producing sound. The peak frequency f (the zeroth oscillatory mode) and the bubble equivalent spherical radius r for a given pressure P are: f = (2πr)-1 [(3γP/ρ)]1/2 where γ is the ratio of gas specific heat at constant pressure to constant volume and ρ is the water density (Leifer and Tang, 2006). Thus the frequency of a bubble's oscillation is proportional to the bubble's volume, and therefore it may be possible to use our acoustic data to obtain an estimate of the volume of methane being released at these seafloor plume sites.

  5. Characterization of nano-bubbles as an oxygen carrier for in-situ bioremediation of organic pollutants in the subsurface

    Science.gov (United States)

    KIM, E.; Jung, J.; Kang, S.; Choi, Y.

    2016-12-01

    In-situ bioremediation using bubbles as an oxygen carrier has shown its applicability for aerobic biodegradation of organic pollutants in the subsurface. By recent progresses, generation of nano-sized bubbles is possible, which have enhanced oxygen transfer efficiencies due to their high interfacial area and stability. We are developing an in-situ bioremediation technique using nano-bubbles as an oxygen carrier. In this study, nano-bubbles were characterized for their size and oxygen supply capacity. Nano-bubbles were generated with pure oxygen and pure helium gas. The stable nano-bubbles suspended in water were sonicated to induce the bubbles to coalesce, making them to rise and be released out of the water. By removing the bubbles, the water volume was decreased by 0.006%. The gas released from the bubble suspension was collected to measure the amount of gas in the nano-bubbles. For sparingly soluble helium gas 17.9 mL/L was released from the bubble suspension, while for oxygen 46.2 mL/L was collected. For the oxygen nano-bubble suspension, it is likely that the release of dissolved oxygen (DO) contributed to the collected gas volume. After removing the oxygen nano-bubbles, 36.0 mg/L of DO was still present in water. Altogether, the oxygen nano-bubble suspension was estimated to have 66.2 mg/L of oxygen in a dissolved form and 25.6 mg/L as nano-bubbles. A high DO level in the water was possible because of their large Laplace pressure difference across the fluid interface. Applying Young-Laplace equation and ideal gas law, the bubble diameter was estimated to be approximately 10 nm, having an internal pressure of 323 atm. Considering the saturation DO of 8.26 mg/L for water in equilibrium with the atmosphere, the total oxygen content of 91.8 mg/L in the nano-bubble suspension suggests its great potential as an oxygen carrier. Studies are underway to verify the enhanced aerobic biodegradation of organic pollutants in soils by injecting nano-bubble suspensions.

  6. Removal of NO from flue gas by aqueous chlorine-dioxide scrubbing solution in a lab-scale bubbling reactor

    Energy Technology Data Exchange (ETDEWEB)

    Deshwal, Bal Raj [Department of Chemistry, A.I.J.H.M. College, Rohtak 124001, Haryana (India); Jin, Dong Seop; Lee, Si Hyun; Moon, Seung Hyun [Korea Institute of Energy Research, Daejon 305 600 (Korea, Republic of); Jung, Jong Hyeon [Department of Environmental Engineering, Sorabol College, Kyungbuk - 780 711 (Korea, Republic of); Lee, Hyung Keun [Korea Institute of Energy Research, Daejon 305 600 (Korea, Republic of)], E-mail: hklee@kier.re.kr

    2008-02-11

    The present study attempts to clean up nitric oxide from the simulated flue gas using aqueous chlorine-dioxide solution in the bubbling reactor. Chlorine-dioxide is generated by chloride-chlorate process. Experiments are carried out to examine the effect of various operating variables like input NO concentration, presence of SO{sub 2}, pH of the solution and NaCl feeding rate on the NO{sub x} removal efficiency at 45 deg. C. Complete oxidation of nitric oxide into nitrogen dioxide occurred on passing sufficient ClO{sub 2} gas into the scrubbing solution. NO is finally converted into nitrate and ClO{sub 2} is reduced into chloride ions. A plausible reaction mechanism concerning NO{sub x} removal by ClO{sub 2} is suggested. DeNO{sub x} efficiency increased slightly with the increasing input NO concentration. The presence of SO{sub 2} improved the NO{sub 2} absorption but pH of solution showed marginal effect on NO{sub 2} absorption. NO{sub x} removal mechanism changed when medium of solution changed from acidic to alkaline. A constant NO{sub x} removal efficiency of about 60% has been achieved in the wide pH range of 3-11 under optimized conditions.

  7. Gas back-mixing studies in membrane assisted bubbling fluidized beds

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; van Sint Annaland, M.; Kuipers, J.A.M.

    2007-01-01

    Fluidized beds employing fine powders are finding increased application in the chemical and petrochemical industry because of their excellent mass and heat transfer characteristics. However, in fluidized bed chemical reactors axial gas back mixing can strongly decrease the conversion and

  8. Study on bubbly flow behavior in natural circulation reactor by thermal-hydraulic simulation tests with SF6-Gas and ethanol liquid

    Science.gov (United States)

    Kondo, Yoshiyuki; Suga, Keishi; Hibi, Koki; Okazaki, Toshihiko; Komeno, Toshihiro; Kunugi, Tomoaki; Serizawa, Akimi; Yoneda, Kimitoshi; Arai, Takahiro

    2009-02-01

    An advanced experimental technique has been developed to simulate two-phase flow behavior in a light water reactor (LWR). The technique applies three kinds of methods; (1) use of sulfur-hexafluoride (SF6) gas and ethanol (C2H5OH) liquid at atmospheric temperature and a pressure less than 1.0MPa, where the fluid properties are similar to steam-water ones in the LWR, (2) generation of bubble with a sintering tube, which simulates bubble generation on heated surface in the LWR, (3) measurement of detailed bubble distribution data with a bi-optical probe (BOP), (4) and measurement of liquid velocities with the tracer liquid. This experimental technique provides easy visualization of flows by using a large scale experimental apparatus, which gives three-dimensional flows, and measurement of detailed spatial distributions of two-phase flow. With this technique, we have carried out experiments simulating two-phase flow behavior in a single-channel geometry, a multi-rod-bundle one, and a horizontal-tube-bundle one on a typical natural circulation reactor system. Those experiments have clarified a) a flow regime map in a rod bundle on the transient region between bubbly and churn flow, b) three-dimensional flow behaviour in rod-bundles where inter-subassembly cross-flow occurs, c) bubble-separation behavior with consideration of reactor internal structures. The data have given analysis models for the natural circulation reactor design with good extrapolation.

  9. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 15: GAS-ASSISTED GLYCOL PUMPS

    Science.gov (United States)

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  10. Hydrodynamic models for slurry bubble column reactors

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D. [IIT Center, Chicago, IL (United States)

    1995-12-31

    The objective of this investigation is to convert a {open_quotes}learning gas-solid-liquid{close_quotes} fluidization model into a predictive design model. This model is capable of predicting local gas, liquid and solids hold-ups and the basic flow regimes: the uniform bubbling, the industrially practical churn-turbulent (bubble coalescence) and the slugging regimes. Current reactor models incorrectly assume that the gas and the particle hold-ups (volume fractions) are uniform in the reactor. They must be given in terms of empirical correlations determined under conditions that radically differ from reactor operation. In the proposed hydrodynamic approach these hold-ups are computed from separate phase momentum balances. Furthermore, the kinetic theory approach computes the high slurry viscosities from collisions of the catalyst particles. Thus particle rheology is not an input into the model.

  11. Fifth DOE symposium on enhanced oil and gas recovery and improved drilling technology. Volume 3. Gas and drilling

    Energy Technology Data Exchange (ETDEWEB)

    Linville, B. [ed.

    1979-01-01

    Volume 3 contains papers from the sessions on natural gas supporting research, western gas sands project, drilling technology, and environmental effects. Individuals were processed for inclusion in the Energy Data Base.

  12. Science Bubbles

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Pedersen, David Budtz

    2013-01-01

    Much like the trade and trait sof bubbles in financial markets,similar bubbles appear on the science market. When economic bubbles burst, the drop in prices causes the crash of unsustainable investments leading to an investor confidence crisis possibly followed by a financial panic. But when...... bubbles appear in science, truth and reliability are the first victims. This paper explores how fashions in research funding and research management may turn science into something like a bubble economy....

  13. Gas-liquid mass transfer coefficient of methane in bubble column reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jaewon; Ha, Kyoung-Su; Lee, Jinwon; Kim, Choongik [Sogang University, Seoul (Korea, Republic of); Yasin, Muhammad; Park, Shinyoung; Chang, In Seop [Gwangju Institute of Science and Technology (GIST), Gwangju (Korea, Republic of); Lee, Eun Yeol [Kyung Hee University, Yongin (Korea, Republic of)

    2015-06-15

    Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k{sub L}a). The feasibility of the new reactor was demonstrated by measuring k{sub L}a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k{sub L}a value of 102.9 h{sup -1} was obtained.

  14. Influence of inoculum density and aeration volume on biomass and bioactive compound production in bulb-type bubble bioreactor cultures of Eleutherococcus koreanum Nakai.

    Science.gov (United States)

    Lee, Eun-Jung; Moh, Sang-Hyun; Paek, Kee-Yoeup

    2011-07-01

    This study deals with the effects of initial inoculum density and aeration volume on biomass and bioactive compound production in adventitious roots of Eleutherococcus koreanum Nakai in bulb-type bubble bioreactors (3-L capacity). While the fresh and dry weights of the roots increased with increasing inoculum density, the highest percentage dry weight and accumulation of total target compounds (eleutheroside B and E, chlorogenic acid, total phenolics, and flavonoids) were noted at an inoculum density of 5.0 g L(-1). Poor aeration volume (0.05 vvm) stunted root growth, and high aeration volume (0.4 vvm) caused physiological disorders. Moreover, an inoculum density of 5.0 g L(-1) and an aeration volume of 0.1 vvm resulted in the highest concentration of total target compounds and least root death. Such optimization of culture conditions will be beneficial for the large-scale production of E. koreanum biomass and bioactive compounds.

  15. Physics of bubble oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Lauterborn, Werner; Kurz, Thomas [Third Physical Institute, University of Goettingen (Germany)

    2010-10-01

    Bubbles in liquids, soft and squeezy objects made of gas and vapour, yet so strong as to destroy any material and so mysterious as at times turning into tiny light bulbs, are the topic of the present report. Bubbles respond to pressure forces and reveal their full potential when periodically driven by sound waves. The basic equations for nonlinear bubble oscillation in sound fields are given, together with a survey of typical solutions. A bubble in a liquid can be considered as a representative example from nonlinear dynamical systems theory with its resonances, multiple attractors with their basins, bifurcations to chaos and not yet fully describable behaviour due to infinite complexity. Three stability conditions are treated for stable trapping of bubbles in standing sound fields: positional, spherical and diffusional stability. Chemical reactions may become important in that respect, when reacting gases fill the bubble, but the chemistry of bubbles is just touched upon and is beyond the scope of the present report. Bubble collapse, the runaway shrinking of a bubble, is presented in its current state of knowledge. Pressures and temperatures that are reached at this occasion are discussed, as well as the light emission in the form of short flashes. Aspherical bubble collapse, as for instance enforced by boundaries nearby, mitigates most of the phenomena encountered in spherical collapse, but introduces a new effect: jet formation, the self-piercing of a bubble with a high velocity liquid jet. Examples of this phenomenon are given from light induced bubbles. Two oscillating bubbles attract or repel each other, depending on their oscillations and their distance. Upon approaching, attraction may change to repulsion and vice versa. When being close, they also shoot self-piercing jets at each other. Systems of bubbles are treated as they appear after shock wave passage through a liquid and with their branched filaments that they attain in standing sound fields. The N-bubble

  16. Numerical investigation of shock induced bubble collapse in water

    Science.gov (United States)

    Apazidis, N.

    2016-04-01

    A semi-conservative, stable, interphase-capturing numerical scheme for shock propagation in heterogeneous systems is applied to the problem of shock propagation in liquid-gas systems. The scheme is based on the volume-fraction formulation of the equations of motion for liquid and gas phases with separate equations of state. The semi-conservative formulation of the governing equations ensures the absence of spurious pressure oscillations at the material interphases between liquid and gas. Interaction of a planar shock in water with a single spherical bubble as well as twin adjacent bubbles is investigated. Several stages of the interaction process are considered, including focusing of the transmitted shock within the deformed bubble, creation of a water-hammer shock as well as generation of high-speed liquid jet in the later stages of the process.

  17. Comparison of induced damage, range, reflection, and sputtering yield between amorphous, bcc crystalline, and bubble-containing tungsten materials under hydrogen isotope and noble gas plasma irradiations

    Science.gov (United States)

    Saito, Seiki; Nakamura, Hiroaki; Tokitani, Masayuki

    2017-01-01

    Binary-collision-approximation simulation of hydrogen isotope (i.e., hydrogen, deuterium, and tritium) and noble gas (i.e., helium, neon, and argon) injections into tungsten materials is performed. Three tungsten structures (i.e., amorphous, bcc crystalline, and helium bubble-containing structures) are prepared as target materials. Then, the trajectories of incident atoms, the distribution of recoil atoms, the penetration depth range of incident atoms, the sputtering yield, and the reflection rate are carefully investigated for these target materials.

  18. An energy-efficient process for decomposing perfluorooctanoic and perfluorooctane sulfonic acids using dc plasmas generated within gas bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Yasuoka, K; Sasaki, K; Hayashi, R, E-mail: yasuoka@ee.titech.ac.jp [Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, Ookayama, Tokyo (Japan)

    2011-06-15

    Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are environmentally harmful and persistent substances. Their decomposition was investigated using dc plasmas generated within small gas bubbles in a solution. The plasma characteristics including discharge voltage, voltage drop in the liquid, plasma shape and the emission spectrum were examined with different gases. The decomposition rate and energy efficiency were evaluated by measuring the concentration of fluoride and sulfate ions released from PFOA/PFOS molecules. The concentration of fluoride ions and energy efficiency in the treatment of a PFOS solution were 17.7 mg l{sup -1} (54.8% of the initial amount of fluorine atoms) and 26 mg kWh{sup -1}, respectively, after 240 min of operation. The addition of scavengers of hydroxyl radicals and hydrated electrons showed little effect on the decomposition. The decomposition processes were analyzed with an assumption that positive species reacted with PFOA/PFOS molecules at the boundary of the plasma-solution surface. This type of plasma showed a much higher decomposition energy efficiency compared with energy efficiencies reported in other studies.

  19. 30 CFR 250.1163 - How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and...

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false How must I measure gas flaring or venting... SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1163 How must I measure gas flaring or venting volumes and liquid...

  20. Use of an ultrasonic reflectance technique to examine bubble size changes in dough

    Science.gov (United States)

    Strybulevych, A.; Leroy, V.; Shum, A. L.; Koksel, H. F.; Scanlon, M. G.; Page, J. H.

    2012-12-01

    Bread quality largely depends on the manner in which bubbles are created and manipulated in the dough during processing. We have developed an ultrasonic reflectance technique to monitor bubbles in dough, even at high volume fractions, where near the bubble resonances it is difficult to make measurements using transmission techniques. A broadband transducer centred at 3.5 MHz in a normal incidence wave reflection set-up is used to measure longitudinal velocity and attenuation from acoustic impedance measurements. The technique is illustrated by examining changes in bubbles in dough due to two very different physical effects. In dough made without yeast, a peak in attenuation due to bubble resonance is observed at approximately 2 MHz. This peak diminishes rapidly and shifts to lower frequencies, indicative of Ostwald ripening of bubbles within the dough. The second effect involves the growth of bubble sizes due to gas generated by yeast during fermentation. This process is experimentally challenging to investigate with ultrasound because of very high attenuation. The reflectance technique allows the changes of the velocity and attenuation during fermentation to be measured as a function of frequency and time, indicating bubble growth effects that can be monitored even at high volume fractions of bubbles.

  1. Numerical study of spike characteristics due to the motions of a non-spherical rebounding bubble

    Institute of Scientific and Technical Information of China (English)

    王加夏; 宗智; 孙雷; 李章锐; 姜明佐

    2016-01-01

    The boundary integral method (BIM) is used to simulate the 3-D gas bubble, generated within the two bubble pulsation periods in proximity to a free surface in an inviscid, incompressible and irrotational flow. The present method is well validated by comparing the calculated shapes of the bubble and the free surface with both the experimental results and the numerical ones obtained by the Axisymmetric BIM code. The expansion, the collapse of the gas bubble and the further evolution of the rebounding non-spherical bubble are simulated. The various variation patterns of the free surface spike and the bubble centroid for different standoff distances, the buoyancy parameters and the strength parameters are obtained to reveal the nonlinear interaction between the bubble and the free surface. The amplitude of the second maximum bubble volume and the four typical patterns of the bubble jet and the free surface spike are examined in the context of the standoff distance. The large buoyancy is used to elevate the spray dome rather than the free surface spike.

  2. A simple parameterization for the rising velocity of bubbles in a liquid pool

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Hoon [Dept. of Environmental Engineering, Sunchon National University, Suncheon (Korea, Republic of); Park, Chang Hwan; Lee, Jin Yong; Lee, Byung Chul [FNC Technology, Co., Ltd., Yongin (Korea, Republic of)

    2017-06-15

    The determination of the shape and rising velocity of gas bubbles in a liquid pool is of great importance in analyzing the radioactive aerosol emissions from nuclear power plant accidents in terms of the fission product release rate and the pool scrubbing efficiency of radioactive aerosols. This article suggests a simple parameterization for the gas bubble rising velocity as a function of the volume-equivalent bubble diameter; this parameterization does not require prior knowledge of bubble shape. This is more convenient than previously suggested parameterizations because it is given as a single explicit formula. It is also shown that a bubble shape diagram, which is very similar to the Grace's diagram, can be easily generated using the parameterization suggested in this article. Furthermore, the boundaries among the three bubble shape regimes in the E{sub o}–R{sub e} plane and the condition for the bypass of the spheroidal regime can be delineated directly from the parameterization formula. Therefore, the parameterization suggested in this article appears to be useful not only in easily determining the bubble rising velocity (e.g., in postulated severe accident analysis codes) but also in understanding the trend of bubble shape change due to bubble growth.

  3. Gas-bubble snap-off under pressure driven flow in constricted noncircular capillaries

    Energy Technology Data Exchange (ETDEWEB)

    Kovscek, A.R.; Radke, C.J.

    1996-04-01

    A model for snap-off of a gas thread in a constricted cornered pore is developed. The time for wetting liquid to accumulate at a pore throat into an unstable collar is examined, as for the resulting pore-spanning lens to be displaced from the pore so that snap-off is the time may repeat. A comer-flow hydrodynamic analysis for the accumulation rate of wetting liquid due to both gradients in interfacial curvature and in applied liquid-phase pressure reveals that wetting-phase pressure gradients significantly increase the frequency of liquid accumulation for snap-off as compared to liquid rearrangement driven only by differences in pore-wall curvature. For moderate and large pressure gradients, the frequency of accumulation increases linearly with pressure gradient because of the increased rate of wetting liquid flow along pore comers. Pore topology is important to the theory, for pores with relatively small throats connected to large bodies demonstrate excellent ability to snapoff gas threads even when the initial capillary pressure is high or equivalently when the liquid saturation is low. A macroscopic momentum balance across the lens resulting from snap-off reveals that lens displacement rates are not linear with the imposed pressure drop. Instead, the frequency of lens displacement scales with powers between 0.5 and 0.6 for pores with dimensionless constriction radii between 0.15 and 0.40. Statistical percolation arguments are employed to form a generation rate expression and connect pore-level foam generation events to macroscopic pressure gradients in porous media. The rate of foam generation by capillary snap-off increases linearly with the liquid-phase pressure gradient and according to a power-law relationship with respect to the imposed gas-phase pressure gradient.

  4. Phase distribution in horizontal gas-liquid two-phase bubbly flow

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    An investigation on phase distribution in air-water two-phaseflow in horizontal circular channel was conducted by using the double-sensor resistivity probe. The variations of phase distribution with variations ofgas and liquid volumetric fluxes were analyzed and the present data werecompared with some of other researcher's data and existing models. It wasfound there exists more complicated phase distribution pattern in horizontalflow system than in vertical flow. The radial local void fraction profilesare similar at the same measurement angle with various gas and liquid flowrates. However, an asymmetric profile can be observed at a given slice ofthe pipe cross-section.

  5. Safe Reduction of Blood Volume in the Blood Gas Laboratory.

    Science.gov (United States)

    Jensen, Phillip R; Markewitz, Boaz A

    2016-11-01

    Phlebotomy is a significant cause of iatrogenic anemia in the critical care environment. It is estimated that one-third of all transfusions of packed red blood cells in intensive care units (ICU) result from phlebotomy. The aims of this study were to determine if utilizing the 1mL blood gas syringe for an adult population would impact the rate at which specimens were acceptable for testing and result reporting based on lab specimen rejection criteria; and to compare blood utilization between the 2 different syringes. This study was conducted in 1 of the adult ICUs at the University of Utah Hospital. Over a baseline period a standard adult 3 mL blood gas syringe was utilized. Subsequently the standard adult syringe was replaced by a 1 mL syringe produced by the same manufacturer with the same heparin concentration. The change to the 1 mL syringe had no effect on specimen integrity in regards to laboratory's ability to process the specimen. With use of the 1 mL syringe there was a 60% reduction in the volume of blood drawn compared with the baseline period. Standardizing the 1 mL syringe for Blood Gas Laboratory tests will reduce patient blood loss without appreciably affecting specimen rejection relative to current rates. © American Society for Clinical Pathology, 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Bubble stimulation efficiency of dinoflagellate bioluminescence.

    Science.gov (United States)

    Deane, Grant B; Stokes, M Dale; Latz, Michael I

    2016-02-01

    Dinoflagellate bioluminescence, a common source of bioluminescence in coastal waters, is stimulated by flow agitation. Although bubbles are anecdotally known to be stimulatory, the process has never been experimentally investigated. This study quantified the flash response of the bioluminescent dinoflagellate Lingulodinium polyedrum to stimulation by bubbles rising through still seawater. Cells were stimulated by isolated bubbles of 0.3-3 mm radii rising at their terminal velocity, and also by bubble clouds containing bubbles of 0.06-10 mm radii for different air flow rates. Stimulation efficiency, the proportion of cells producing a flash within the volume of water swept out by a rising bubble, decreased with decreasing bubble radius for radii less than approximately 1 mm. Bubbles smaller than a critical radius in the range 0.275-0.325 mm did not stimulate a flash response. The fraction of cells stimulated by bubble clouds was proportional to the volume of air in the bubble cloud, with lower stimulation levels observed for clouds with smaller bubbles. An empirical model for bubble cloud stimulation based on the isolated bubble observations successfully reproduced the observed stimulation by bubble clouds for low air flow rates. High air flow rates stimulated more light emission than expected, presumably because of additional fluid shear stress associated with collective buoyancy effects generated by the high air fraction bubble cloud. These results are relevant to bioluminescence stimulation by bubbles in two-phase flows, such as in ship wakes, breaking waves, and sparged bioreactors.

  7. ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS0745-191

    CERN Document Server

    Russell, H R; Fabian, A C; Nulsen, P E J; Edge, A C; Combes, F; Murray, N W; Parrish, I J; Salome, P; Sanders, J S; Baum, S A; Donahue, M; Main, R A; O'Connell, R W; O'Dea, C P; Oonk, J B R; Tremblay, G; Vantyghem, A N; Voit, G M

    2016-01-01

    We present ALMA observations of the CO(1-0) and CO(3-2) line emission tracing filaments of cold molecular gas in the central galaxy of the cluster PKS0745-191. The total molecular gas mass of 4.6 +/- 0.3 x 10^9 solar masses, assuming a Galactic X_{CO} factor, is divided roughly equally between three filaments each extending radially 3-5 kpc from the galaxy centre. The emission peak is located in the SE filament roughly 1 arcsec (2 kpc) from the nucleus. The velocities of the molecular clouds in the filaments are low, lying within +/-100 km/s of the galaxy's systemic velocity. Their FWHMs are less than 150 km/s, which is significantly below the stellar velocity dispersion. Although the molecular mass of each filament is comparable to a rich spiral galaxy, such low velocities show that the filaments are transient and the clouds would disperse on <10^7 yr timescales unless supported, likely by the indirect effect of magnetic fields. The velocity structure is inconsistent with a merger origin or gravitational ...

  8. Bubble Content in Air/Hydro System--Part 1:Measurement of Bubble Content

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The mechanism of bubble formation in air/hydro systems is investigated. Results presented in this paper include further insight into the mechanism of bubble formation and the measurement of bubble content. The regularity of bubble transport in the system is found, with an idea for a new method for separating gas from oil. The method has been verified experimentally with favorable results.

  9. Mesoscale Benchmark Demonstration Problem 1: Mesoscale Simulations of Intra-granular Fission Gas Bubbles in UO2 under Post-irradiation Thermal Annealing

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yulan; Hu, Shenyang Y.; Montgomery, Robert; Gao, Fei; Sun, Xin; Tonks, Michael; Biner, Bullent; Millet, Paul; Tikare, Veena; Radhakrishnan, Balasubramaniam; Andersson , David

    2012-04-11

    A study was conducted to evaluate the capabilities of different numerical methods used to represent microstructure behavior at the mesoscale for irradiated material using an idealized benchmark problem. The purpose of the mesoscale benchmark problem was to provide a common basis to assess several mesoscale methods with the objective of identifying the strengths and areas of improvement in the predictive modeling of microstructure evolution. In this work, mesoscale models (phase-field, Potts, and kinetic Monte Carlo) developed by PNNL, INL, SNL, and ORNL were used to calculate the evolution kinetics of intra-granular fission gas bubbles in UO2 fuel under post-irradiation thermal annealing conditions. The benchmark problem was constructed to include important microstructural evolution mechanisms on the kinetics of intra-granular fission gas bubble behavior such as the atomic diffusion of Xe atoms, U vacancies, and O vacancies, the effect of vacancy capture and emission from defects, and the elastic interaction of non-equilibrium gas bubbles. An idealized set of assumptions was imposed on the benchmark problem to simplify the mechanisms considered. The capability and numerical efficiency of different models are compared against selected experimental and simulation results. These comparisons find that the phase-field methods, by the nature of the free energy formulation, are able to represent a larger subset of the mechanisms influencing the intra-granular bubble growth and coarsening mechanisms in the idealized benchmark problem as compared to the Potts and kinetic Monte Carlo methods. It is recognized that the mesoscale benchmark problem as formulated does not specifically highlight the strengths of the discrete particle modeling used in the Potts and kinetic Monte Carlo methods. Future efforts are recommended to construct increasingly more complex mesoscale benchmark problems to further verify and validate the predictive capabilities of the mesoscale modeling

  10. Evolution of the buoyant bubbles in M87

    CERN Document Server

    Churazov, E; Kaiser, C R; Böhringer, H; Forman, W R

    2000-01-01

    The morphology of the X-ray and radio emitting features in the central 50 kpc region around the galaxy M87 strongly suggests that buoyant bubbles of cosmic rays (inflated by an earlier nuclear active phase of the galaxy) are slowly rising through the cooling gas. In the absence of strong surface tension, an intrinsic property of initially spherical bubbles is their transformation into tori as they rise through an external medium. Such structures can be identified in the radio images of the halo of M87. During their rise the bubbles uplift relatively cool X-ray emitting ambient gas from the central regions of the cooling flow to larger distances. This gas is colder than the ambient gas and has a higher volume emissivity. As a result, rising "radio" bubbles may be trailed by elongated X-ray features as indeed is observed in M87. We performed simple hydrodynamical simulations in order to qualitatively illustrate the evolution of the buoyant bubbles in the M87 environment.

  11. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  12. Vortex Simulation of the Bubbly Flow around a Hydrofoil

    Directory of Open Access Journals (Sweden)

    Tomomi Uchiyama

    2007-01-01

    Full Text Available This study is concerned with the two-dimensional simulation for an air-water bubbly flow around a hydrofoil. The vortex method, proposed by the authors for gas-liquid two-phase free turbulent flow in a prior paper, is applied for the simulation. The liquid vorticity field is discrerized by vortex elements, and the behavior of vortex element and the bubble motion are simultaneously computed by the Lagrangian approach. The effect of bubble motion on the liquid flow is taken into account through the change in the strength of vortex element. The bubbly flow around a hydrofoil of NACA4412 with a chord length 100 mm is simulated. The Reynolds number is 2.5×105, the bubble diameter is 1 mm, and the volumetric flow ratio of bubble to whole fluid is 0.048. It is confirmed that the simulated distributions of air volume fraction and pressure agree well with the trend of the measurement and that the effect of angle of attack on the flow is favorably analyzed. These demonstrate that the vortex method is applicable to the bubbly flow analysis around a hydrofoil.

  13. Bubble coalescence

    NARCIS (Netherlands)

    Orvalho, Sandra; Ruzicka, Marek C.; Olivieri, Giuseppe; Marzocchella, Antonio

    2015-01-01

    The goal of this study is to present new experimental data on the effect of the bubble approach velocity and liquid viscosity on pairwise bubble coalescence. Measurements were performed to investigate the dynamics of bubble coalescence under well-defined laboratory conditions. Air and pure

  14. Bubble-included chocolate: relating structure with sensory response.

    Science.gov (United States)

    Haedelt, J; Beckett, S T; Niranjan, K

    2007-04-01

    Bubbles impart a very unique texture, chew, and mouth-feel to foods. However, little is known about the relationship between structure of such products and consumer response in terms of mouth-feel and eating experience. The objective of this article is to investigate the sensory properties of 4 types of bubble-containing chocolates, produced by using different gases: carbon dioxide, nitrogen, nitrous oxide, and argon. The structure of these chocolates were characterized in terms of (1) gas hold-up values determined by density measurements and (2) bubble size distribution which was measured by undertaking an image analysis of X-ray microtomograph sections. Bubble size distributions were obtained by measuring bubble volumes after reconstructing 3D images from the tomographic sections. A sensory study was undertaken by a nonexpert panel of 20 panelists and their responses were analyzed using qualitative descriptive analysis (QDA). The results show that chocolates made from the 4 gases could be divided into 2 groups on the basis of bubble volume and gas hold-up: the samples produced using carbon dioxide and nitrous oxide had a distinctly higher gas hold-up containing larger bubbles in comparison with those produced using argon and nitrogen. The sensory study also demonstrated that chocolates made with the latter were perceived to be harder, less aerated, slow to melt in the mouth, and having a higher overall flavor intensity. These products were further found to be creamier than the chocolates made by using carbon dioxide and nitrous oxide; the latter sample also showed a higher intensity of cocoa flavor.

  15. Investigation of Bubble-Slag Layer Behaviors with Hybrid Eulerian-Lagrangian Modeling and Large Eddy Simulation

    Science.gov (United States)

    Li, Linmin; Li, Baokuan

    2016-08-01

    In ladle metallurgy, bubble-liquid interaction leads to complex phase structures. Gas bubble behavior, as well as the induced slag layer behavior, plays a significant role in the refining process and the steel quality. In the present work, a mathematical model using the large eddy simulation (LES) is developed to investigate the bubble transport and slag layer behavior in a water model of an argon-stirred ladle. The Eulerian volume of fluid model is adopted to track the liquid steel-slag-air free surfaces while the Lagrangian discrete phase model is used for tracking and handling the dynamics of discrete bubbles. The bubble coalescence is considered using O'Rourke's algorithm to solve the bubble diameter redistribution and bubbles are removed after leaving the air-liquid interface. The turbulent liquid flow that is induced by bubble-liquid interaction is solved by LES. The slag layer fluactuation, slag droplet entrainment and spout eye open-close phenomenon are well revealed. The bubble diameter distribution and the spout eye size are compared with the experiment. The results show that the hybrid Eulerian-Lagrangian-LES model provides a valid modeling framework to predict the unsteady gas bubble-slag layer coupled behaviors.

  16. Electrowetting of a soap bubble

    CERN Document Server

    Arscott, Steve

    2013-01-01

    A proof-of-concept demonstration of the electrowetting-on-dielectric of a sessile soap bubble is reported here. The bubbles are generated using a commercial soap bubble mixture - the surfaces are composed of highly doped, commercial silicon wafers covered with nanometre thick films of Teflon. Voltages less than 40V are sufficient to observe the modification of the bubble shape and the apparent bubble contact angle. Such observations open the way to inter alia the possibility of bubble-transport, as opposed to droplet-transport, in fluidic microsystems (e.g. laboratory-on-a-chip) - the potential gains in terms of volume, speed and surface/volume ratio are non-negligible.

  17. THREE-FIBER OPTICAL PROBE FOR STUDYING FLUIDIZED GAS-SOLID BEDS IN BUBBLING REGIME

    Directory of Open Access Journals (Sweden)

    ERICK REYES-VERA

    2011-01-01

    Full Text Available En este trabajo se muestra el desarrollo de una sonda con tres fi bras ópticas para estudiar el comportamiento de la burbuja en lechos gas-sólido fl uidizados burbujeantes. Su estructura compacta permite minimizar las perturbaciones inducidas al campo del fl ujo, lográndose resultados más exactos frentes a otros tipos de sonda. Los lechos fl uidizados burbujeantes son ampliamente usados en procesos petroquímicos, metalúrgicos y en termoeléctricas. El comportamiento de la burbuja es uno de los parámetros más importantes para la simulación y diseño de reactores termoeléctricos, dado que se relaciona con los saltos de fase, la interacción entre las fases sólida y gaseosa del lecho y el comportamiento de la transferencia de masa. Conocer tanto la velocidad como el tamaño de burbuja, ayudan a caracterizar estos sistemas, llevando un mejor diseño de reactores a gran escala.

  18. Propagation of shock waves in dilute bubbly liquids. 4th Report. Comparison between theory and experiment for a uniform bubbly mixture; Kihoryuchu ni okeru shogekiha no denpa. 4. Kin`itsu kiho bunpuji no jikken to riron tono hikaku

    Energy Technology Data Exchange (ETDEWEB)

    Kameda, M.; Shimaura, N.; Higashino, F. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Faculty of Technology; Matsumoto, Y. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering

    1997-07-25

    Transient shock wave phenomena in a liquid containing non-condensable gas bubbles are studied experimentally and numerically. In order to obtain a uniform spatial distribution of bubbles experimentally, an upwardly directed bubbly flow, whose initial gas volume fraction is 0.2%, is generated in a shock tube. The liquid used is silicone oil. Nitrogen, argon, and SF6 gas bubbles are tested to show the thermal effects of the bubble interior. The transient pressure profiles determined in the experiments for the upwardly bubbly flow agree well quantitatively with those obtained by numerical calculation using a uniform spatial distribution of bubbles. Since the thermal diffusivity of SF6 is much lower than that of nitrogen and argon, the damping on the radial oscillation of the SF6 bubble is mainly due to the compressibility of the liquid. Thus, the radial motion of the bubble should be estimated by solving an equation in which the liquid compressibility is taken into account. 12 refs., 10 figs.

  19. Preparation and crystallization of hollow α-Fe{sub 2}O{sub 3} microspheres following the gas-bubble template method

    Energy Technology Data Exchange (ETDEWEB)

    Valladares, L. de los Santos, E-mail: ld301@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); León Félix, L. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Laboratory of Magnetic Characterization, Instituto de Física, Universidade de Brasília, DF 70910-900, Brasilia (Brazil); Espinoza Suarez, S.M.; Bustamante Dominguez, A.G. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Mitrelias, T.; Holmes, S. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); Moreno, N.O. [Departamento de Física, Universidade Federal de Sergipe, 49100-000, Sao Cristóvao, Sergipe (Brazil); Albino Aguiar, J. [Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife (Brazil); Barnes, C.H.W. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom)

    2016-02-01

    In this work we report the formation of hollow α-Fe{sub 2}O{sub 3} (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO{sub 3}){sub 3}.9H{sub 2}O and citric acid in water by sol–gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250–400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented. - Highlights: • Formation of hollow hematite microspheres by the gas-bubble template method. • This technique does not require hard templates or special conditions of atmosphere. • Annealing promotes the transition magnetite to maghemite to hematite. • Crystallization of the hematite shells increase with annealing temperature.

  20. Imaging air volume fraction in sea ice using non-destructive X-ray tomography

    Science.gov (United States)

    Crabeck, Odile; Galley, Ryan; Delille, Bruno; Else, Brent; Geilfus, Nicolas-Xavier; Lemes, Marcos; Des Roches, Mathieu; Francus, Pierre; Tison, Jean-Louis; Rysgaard, Søren

    2016-05-01

    Although the presence of a gas phase in sea ice creates the potential for gas exchange with the atmosphere, the distribution of gas bubbles and transport of gases within the sea ice are still poorly understood. Currently no straightforward technique exists to measure the vertical distribution of air volume fraction in sea ice. Here, we present a new fast and non-destructive X-ray computed tomography technique to quantify the air volume fraction and produce separate images of air volume inclusions in sea ice. The technique was performed on relatively thin (4-22 cm) sea ice collected from an experimental ice tank. While most of the internal layers showed air volume fractions bubblesbubbles (1 mm bubbles (Ø > 5 mm). While micro bubbles were the most abundant type of gas bubbles, most of the air porosity observed resulted from the presence of large and macro bubbles. The ice texture (granular and columnar) as well as the permeability state of ice are important factors controlling the air volume fraction. The technique developed is suited for studies related to gas transport and bubble migration.

  1. Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models

    National Research Council Canada - National Science Library

    Warzinski, Robert P; Lynn, Ronald; Haljasmaa, Igor; Leifer, Ira; Shaffer, Frank; Anderson, Brian J; Levine, Jonathan S

    2014-01-01

    Predicting the fate of subsea hydrocarbon gases escaping into seawater is complicated by potential formation of hydrate on rising bubbles that can enhance their survival in the water column, allowing...

  2. Bubble rupture in bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Chen Rouxi

    2015-01-01

    Full Text Available 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.

  3. Bubbles trapped in a fluidized bed: Trajectories and contact area

    Science.gov (United States)

    Poryles, Raphaël; Vidal, Valérie; Varas, Germán

    2016-03-01

    This work investigates the dynamics of bubbles in a confined, immersed granular layer submitted to an ascending gas flow. In the stationary regime, a central fluidized zone of parabolic shape is observed, and the bubbles follow different dynamics: either the bubbles are initially formed outside the fluidized zone and do not exhibit any significant motion over the experimental time or they are located inside the fluidized bed, where they are entrained downwards and are, finally, captured by the central air channel. The dependence of the air volume trapped inside the fluidized zone, the bubble size, and the three-phase contact area on the gas injection flow rate and grain diameter are quantified. We find that the volume fraction of air trapped inside the fluidized region is roughly constant and of the order of 2%-3% when the gas flow rate and the grain size are varied. Contrary to intuition, the gas-liquid-solid contact area, normalized by the air injected into the system, decreases when the flow rate is increased, which may have significant importance in industrial applications.

  4. Numerical simulaion of dynamics of a gas bubble in liquid near a rigid wall during its growth and collapse

    Science.gov (United States)

    Ilgamov, M. A.; Kosolapova, L. A.; Malakhov, V. G.

    2016-11-01

    A numerical technique of calculating the dynamics of a cavitation bubble near a plane rigid wall is presented. The bubble at its collapse can become toroidal. The liquid is assumed inviscid and incompressible, its flow being potential. The bubble surface movement is determined by the Euler method, the normal component of the liquid velocity on the bubble surface is found by the boundary element method. The technique also includes an algorithm for calculating the velocity and pressure fields in the liquid. The convergence of the numerical solution with refining the temporal and spatial steps is demonstrated. The results of the present technique are compared with some known numerical and experimental data by other authors, their satisfactory agreement is found. To illustrate the capabilities of the present technique the process of growth and collapse of a bubble in water near a wall is considered. The liquid pressure contours in the stage of the bubble collapse are given and the radial liquid pressure profiles on the wall and at a small distance from the wall where the liquid pressure is maximum are shown.

  5. STORM IN A {sup T}EACUP{sup :} A RADIO-QUIET QUASAR WITH ≈10 kpc RADIO-EMITTING BUBBLES AND EXTREME GAS KINEMATICS

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, C. M.; Thomson, A. P.; Alexander, D. M.; Edge, A. C.; Hogan, M. T.; Swinbank, A. M. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Bauer, F. E. [Instituto de Astrofísica, Facultad de Física, Pontifica Universidad Católica de Chile, 306, Santiago 22 (Chile); Mullaney, J. R., E-mail: c.m.harrison@mail.com [Department of Physics and Astronomy, University of Sheffield, Sheffield S7 3RH (United Kingdom)

    2015-02-10

    We present multi-frequency (1-8 GHz) Very Large Array data, combined with VIsible MultiObject Spectrograph integral field unit data and Hubble Space Telescope imaging, of a z = 0.085 radio-quiet type 2 quasar (with L {sub 1.4} {sub GHz} ≈ 5 × 10{sup 23} W Hz{sup –1} and L {sub AGN} ≈ 2 × 10{sup 45} erg s{sup –1}). Due to the morphology of its emission-line region, the target (J1430+1339) has been referred to as the ''Teacup'' active galactic nucleus (AGN) in the literature. We identify ''bubbles'' of radio emission that are extended ≈10-12 kpc to both the east and west of the nucleus. The edge of the brighter eastern bubble is co-spatial with an arc of luminous ionized gas. We also show that the ''Teacup'' AGN hosts a compact radio structure, located ≈0.8 kpc from the core position, at the base of the eastern bubble. This radio structure is co-spatial with an ionized outflow with an observed velocity of v = –740 km s{sup –1}. This is likely to correspond to a jet, or possibly a quasar wind, interacting with the interstellar medium at this position. The large-scale radio bubbles appear to be inflated by the central AGN, which indicates that the AGN can also interact with the gas on ≳ 10 kpc scales. Our study highlights that even when a quasar is formally ''radio-quiet'' the radio emission can be extremely effective for observing the effects of AGN feedback.

  6. Storm in a "Teacup": A Radio-quiet Quasar with ≈10 kpc Radio-emitting Bubbles and Extreme Gas Kinematics

    Science.gov (United States)

    Harrison, C. M.; Thomson, A. P.; Alexander, D. M.; Bauer, F. E.; Edge, A. C.; Hogan, M. T.; Mullaney, J. R.; Swinbank, A. M.

    2015-02-01

    We present multi-frequency (1-8 GHz) Very Large Array data, combined with VIsible MultiObject Spectrograph integral field unit data and Hubble Space Telescope imaging, of a z = 0.085 radio-quiet type 2 quasar (with L 1.4 GHz ≈ 5 × 1023 W Hz-1 and L AGN ≈ 2 × 1045 erg s-1). Due to the morphology of its emission-line region, the target (J1430+1339) has been referred to as the "Teacup" active galactic nucleus (AGN) in the literature. We identify "bubbles" of radio emission that are extended ≈10-12 kpc to both the east and west of the nucleus. The edge of the brighter eastern bubble is co-spatial with an arc of luminous ionized gas. We also show that the "Teacup" AGN hosts a compact radio structure, located ≈0.8 kpc from the core position, at the base of the eastern bubble. This radio structure is co-spatial with an ionized outflow with an observed velocity of v = -740 km s-1. This is likely to correspond to a jet, or possibly a quasar wind, interacting with the interstellar medium at this position. The large-scale radio bubbles appear to be inflated by the central AGN, which indicates that the AGN can also interact with the gas on >~ 10 kpc scales. Our study highlights that even when a quasar is formally "radio-quiet" the radio emission can be extremely effective for observing the effects of AGN feedback.

  7. Slurry bubble column hydrodynamics

    Science.gov (United States)

    Rados, Novica

    Slurry bubble column reactors are presently used for a wide range of reactions in both chemical and biochemical industry. The successful design and scale up of slurry bubble column reactors require a complete understanding of multiphase fluid dynamics, i.e. phase mixing, heat and mass transport characteristics. The primary objective of this thesis is to improve presently limited understanding of the gas-liquid-solid slurry bubble column hydrodynamics. The effect of superficial gas velocity (8 to 45 cm/s), pressure (0.1 to 1.0 MPa) and solids loading (20 and 35 wt.%) on the time-averaged solids velocity and turbulent parameter profiles has been studied using Computer Automated Radioactive Particle Tracking (CARPT). To accomplish this, CARPT technique has been significantly improved for the measurements in highly attenuating systems, such as high pressure, high solids loading stainless steel slurry bubble column. At a similar set of operational conditions time-averaged gas and solids holdup profiles have been evaluated using the developed Computed Tomography (CT)/Overall gas holdup procedure. This procedure is based on the combination of the CT scans and the overall gas holdup measurements. The procedure assumes constant solids loading in the radial direction and axially invariant cross-sectionally averaged gas holdup. The obtained experimental holdup, velocity and turbulent parameters data are correlated and compared with the existing low superficial gas velocities and atmospheric pressure CARPT/CT gas-liquid and gas-liquid-solid slurry data. The obtained solids axial velocity radial profiles are compared with the predictions of the one dimensional (1-D) liquid/slurry recirculation phenomenological model. The obtained solids loading axial profiles are compared with the predictions of the Sedimentation and Dispersion Model (SDM). The overall gas holdup values, gas holdup radial profiles, solids loading axial profiles, solids axial velocity radial profiles and solids

  8. Hydrodynamics in a swarm of rising bubbles; Hydrodynamique d'un essaim de bulles en ascension

    Energy Technology Data Exchange (ETDEWEB)

    Riboux, G

    2007-04-15

    In many applications, bubbles are used to agitate a liquid in order to enhance mixing and transfer. This work is devoted to the study of the hydrodynamics in a stable bubble column. Experimentally, we have determined the properties of the velocity fluctuations inside and behind a homogeneous swarm of rising bubbles for different bubble sizes and gas volume fractions {alpha}: self-similarity in {alpha}{sup 0,4}, spectrum in k{sup -3} and integral length scale controlled by buoyancy. Numerically, we have reproduced these properties by means of large-scale simulations, the bubbles being modeled by volume-forces. This confirms that the dynamics is controlled by wake interactions. (author)

  9. Bubbles, microparticles, and neutrophil activation: changes with exercise level and breathing gas during open-water SCUBA diving.

    Science.gov (United States)

    Thom, Stephen R; Milovanova, Tatyana N; Bogush, Marina; Yang, Ming; Bhopale, Veena M; Pollock, Neal W; Ljubkovic, Marko; Denoble, Petar; Madden, Dennis; Lozo, Mislav; Dujic, Zeljko

    2013-05-15

    The study goal was to evaluate responses in humans following decompression from open-water SCUBA diving with the hypothesis that exertion underwater and use of a breathing mixture containing more oxygen and less nitrogen (enriched air nitrox) would alter annexin V-positive microparticle (MP) production and size changes and neutrophil activation, as well as their relationships to intravascular bubble formation. Twenty-four divers followed a uniform dive profile to 18 m of sea water breathing air or 22.5 m breathing 32% oxygen/68% nitrogen for 47 min, either swimming with moderately heavy exertion underwater or remaining stationary at depth. Blood was obtained pre- and at 15 and 120 min postdive. Intravascular bubbles were quantified by transthoracic echocardiography postdive at 20-min intervals for 2 h. There were no significant differences in maximum bubble scores among the dives. MP number increased 2.7-fold, on average, within 15 min after each dive; only the air-exertion dive resulted in a significant further increase to 5-fold over baseline at 2 h postdive. Neutrophil activation occurred after all dives. For the enriched air nitrox stationary at depth dive, but not for other conditions, the numbers of postdive annexin V-positive particles above 1 μm in diameter were correlated with intravascular bubble scores (correlation coefficients ∼0.9, P bubbles, MPs, platelet-neutrophil interactions, and neutrophil activation appear to exist, but more study is required to improve confidence in the associations.

  10. Bubble systems

    CERN Document Server

    Avdeev, Alexander A

    2016-01-01

    This monograph presents a systematic analysis of bubble system mathematics, using the mechanics of two-phase systems in non-equilibrium as the scope of analysis. The author introduces the thermodynamic foundations of bubble systems, ranging from the fundamental starting points to current research challenges. This book addresses a range of topics, including description methods of multi-phase systems, boundary and initial conditions as well as coupling requirements at the phase boundary. Moreover, it presents a detailed study of the basic problems of bubble dynamics in a liquid mass: growth (dynamically and thermally controlled), collapse, bubble pulsations, bubble rise and breakup. Special emphasis is placed on bubble dynamics in turbulent flows. The analysis results are used to write integral equations governing the rate of vapor generation (condensation) in non-equilibrium flows, thus creating a basis for solving a number of practical problems. This book is the first to present a comprehensive theory of boil...

  11. Radiation from Large Gas Volumes and Heat Exchange in Steam Boiler Furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Makarov, A. N., E-mail: tgtu-kafedra-ese@mail.ru [Tver State Technical University (Russian Federation)

    2015-09-15

    Radiation from large cylindrical gas volumes is studied as a means of simulating the flare in steam boiler furnaces. Calculations of heat exchange in a furnace by the zonal method and by simulation of the flare with cylindrical gas volumes are described. The latter method is more accurate and yields more reliable information on heat transfer processes taking place in furnaces.

  12. No-migration variance petition: Draft. Volume 4, Appendices DIF, GAS, GCR (Volume 1)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-05-31

    The Department of Energy is responsible for the disposition of transuranic (TRU) waste generated by national defense-related activities. Approximately 2.6 million cubic feet of the se waste have been generated and are stored at various facilities across the country. The Waste Isolation Pilot Plant (WIPP), was sited and constructed to meet stringent disposal requirements. In order to permanently dispose of TRU waste, the DOE has elected to petition the US EPA for a variance from the Land Disposal Restrictions of RCRA. This document fulfills the reporting requirements for the petition. This report is volume 4 of the petition which presents details about the transport characteristics across drum filter vents and polymer bags; gas generation reactions and rates during long-term WIPP operation; and geological characterization of the WIPP site.

  13. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    KAUST Repository

    Sharma, Ashish

    2016-09-08

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface. © 2016 IOP Publishing Ltd.

  14. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    Science.gov (United States)

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L.; Cha, Min Suk

    2016-10-01

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface.

  15. Bubble Size Distributions in Coastal Seas

    NARCIS (Netherlands)

    Leeuw, G. de; Cohen, L.H.

    1995-01-01

    Bubble size distributions have been measured with an optical system that is based on imaging of a small sample volume with a CCD camera system, and processing of the images to obtain the size of individual bubbles in the diameter range from 30 to lOOO^m. This bubble measuring system is deployed from

  16. Bubble Size Distribution in a Vibrating Bubble Column

    Science.gov (United States)

    Mohagheghian, Shahrouz; Wilson, Trevor; Valenzuela, Bret; Hinds, Tyler; Moseni, Kevin; Elbing, Brian

    2016-11-01

    While vibrating bubble columns have increased the mass transfer between phases, a universal scaling law remains elusive. Attempts to predict mass transfer rates in large industrial scale applications by extrapolating laboratory scale models have failed. In a stationary bubble column, mass transfer is a function of phase interfacial area (PIA), while PIA is determined based on the bubble size distribution (BSD). On the other hand, BSD is influenced by the injection characteristics and liquid phase dynamics and properties. Vibration modifies the BSD by impacting the gas and gas-liquid dynamics. This work uses a vibrating cylindrical bubble column to investigate the effect of gas injection and vibration characteristics on the BSD. The bubble column has a 10 cm diameter and was filled with water to a depth of 90 cm above the tip of the orifice tube injector. BSD was measured using high-speed imaging to determine the projected area of individual bubbles, which the nominal bubble diameter was then calculated assuming spherical bubbles. The BSD dependence on the distance from the injector, injector design (1.6 and 0.8 mm ID), air flow rates (0.5 to 5 lit/min), and vibration conditions (stationary and vibration conditions varying amplitude and frequency) will be presented. In addition to mean data, higher order statistics will also be provided.

  17. Bubble Size Control to Improve Oxygen-Based Bleaching: Characterization of Flow Regimes in Pulp-Water-Gas Three-Phase Flows

    Energy Technology Data Exchange (ETDEWEB)

    S.M. Ghiaasiaan and Seppo Karrila

    2006-03-20

    Flow characteristics of fibrous paper pulp-water-air slurries were investigated in a vertical circular column 1.8 m long, with 5.08 cm diameter. Flow structures, gas holdup (void fraction), and the geometric and population characteristics of gas bubbles were experimentally investigated, using visual observation, Gamma-ray densitometry, and flash X-ray photography. Five distinct flow regimes could be visually identified: dispersed bubbly, layered bubbly, plug, churn-turbulent, and slug. Flow regime maps were constructed, and the regime transition lines were found to be sensitive to consistency. The feasibility of using artificial neural networks (ANNs) for the identification of the flow regimes, using the statistical characteristics of pressure fluctuations measured by a single pressure sensor, was demonstrated. Local pressure fluctuations at a station were recorded with a minimally-intrusive transducer. Three-layer, feed-forward ANNs were designed that could identify the four major flow patterns (bubbly, plug, churn, and slug) well. The feasibility of a transportable artificial neural network (ANN) - based technique for the classification of flow regimes was also examined. Local pressures were recorded at three different locations using three independent but similar transducers. An ANN was designed, trained and successfully tested for the classification of the flow regimes using one of the normalized pressure signals (from Sensor 1). The ANN trained and tested for Sensor 1 predicted the flow regimes reasonably well when applied directly to the other two sensors, indicating a good deal of transportability. An ANN-based method was also developed, whereby the power spectrum density characteristics of other sensors were adjusted before they were used as input to the ANN that was based on Sensor 1 alone. The method improved the predictions. The gas-liquid interfacial surface area concentration was also measured in the study. The gas absorption technique was applied

  18. Effects of respiratory rate and tidal volume on gas exchange in total liquid ventilation.

    Science.gov (United States)

    Bull, Joseph L; Tredici, Stefano; Fujioka, Hideki; Komori, Eisaku; Grotberg, James B; Hirschl, Ronald B

    2009-01-01

    Using a rabbit model of total liquid ventilation (TLV), and in a corresponding theoretical model, we compared nine tidal volume-respiratory rate combinations to identify a ventilator strategy to maximize gas exchange, while avoiding choked flow, during TLV. Nine different ventilation strategies were tested in each animal (n = 12): low [LR = 2.5 breath/min (bpm)], medium (MR = 5 bpm), or high (HR = 7.5 bpm) respiratory rates were combined with a low (LV = 10 ml/kg), medium (MV = 15 ml/kg), or high (HV = 20 ml/kg) tidal volumes. Blood gases and partial pressures, perfluorocarbon gas content, and airway pressures were measured for each combination. Choked flow occurred in all high respiratory rate-high volume animals, 71% of high respiratory rate-medium volume (HRMV) animals, and 50% of medium respiratory rate-high volume (MRHV) animals but in no other combinations. Medium respiratory rate-medium volume (MRMV) resulted in the highest gas exchange of the combinations that did not induce choke. The HRMV and MRHV animals that did not choke had similar or higher gas exchange than MRMV. The theory predicted this behavior, along with spatial and temporal variations in alveolar gas partial pressures. Of the combinations that did not induce choked flow, MRMV provided the highest gas exchange. Alveolar gas transport is diffusion dominated and rapid during gas ventilation but is convection dominated and slow during TLV. Consequently, the usual alveolar gas equation is not applicable for TLV.

  19. Fine bubble generator and method

    Energy Technology Data Exchange (ETDEWEB)

    Bhagat, P.M.; Koros, R.M.

    1990-10-09

    This patent describes a method of forming fine gaseous bubbles in a liquid ambient. It comprises: forcing a gas through orifices located in the liquid ambient while simultaneously forcing a liquid through liquid orifices at a velocity sufficient to form jet streams of liquid, the liquid orifices being equal in number to the gas orifices and so oriented that each jet stream of liquid intersects the gas forced through each gas orifice and creates sufficient turbulence where the gas and jet stream of liquid intersect, whereby fine gaseous bubbles are formed.

  20. High order finite volume methods on wavelet-adapted grids with local time-stepping on multicore architectures for the simulation of shock-bubble interactions

    Science.gov (United States)

    Hejazialhosseini, Babak; Rossinelli, Diego; Bergdorf, Michael; Koumoutsakos, Petros

    2010-11-01

    We present a space-time adaptive solver for single- and multi-phase compressible flows that couples average interpolating wavelets with high-order finite volume schemes. The solver introduces the concept of wavelet blocks, handles large jumps in resolution and employs local time-stepping for efficient time integration. We demonstrate that the inherently sequential wavelet-based adaptivity can be implemented efficiently in multicore computer architectures using task-based parallelism and introducing the concept of wavelet blocks. We validate our computational method on a number of benchmark problems and we present simulations of shock-bubble interaction at different Mach numbers, demonstrating the accuracy and computational performance of the method.

  1. Experimental evidence for seismically initiated gas bubble nucleation and growth in groundwater as a mechanism for coseismic borehole water level rise and remotely triggered seismicity

    Science.gov (United States)

    Crews, Jackson B.; Cooper, Clay A.

    2014-09-01

    Changes in borehole water levels and remotely triggered seismicity occur in response to near and distant earthquakes at locations around the globe, but the mechanisms for these phenomena are not well understood. Experiments were conducted to show that seismically initiated gas bubble growth in groundwater can trigger a sustained increase in pore fluid pressure consistent in magnitude with observed coseismic borehole water level rise, constituting a physically plausible mechanism for remote triggering of secondary earthquakes through the reduction of effective stress in critically loaded geologic faults. A portion of the CO2 degassing from the Earth's crust dissolves in groundwater where seismic Rayleigh and P waves cause dilational strain, which can reduce pore fluid pressure to or below the bubble pressure, triggering CO2 gas bubble growth in the saturated zone, indicated by a spontaneous buildup of pore fluid pressure. Excess pore fluid pressure was measured in response to the application of 0.1-1.0 MPa, 0.01-0.30 Hz confining stress oscillations to a Berea sandstone core flooded with initially subsaturated aqueous CO2, under conditions representative of a confined aquifer. Confining stress oscillations equivalent to the dynamic stress of the 28 June 1992 Mw 7.3 Landers, California, earthquake Rayleigh wave as it traveled through the Long Valley caldera, and Parkfield, California, increased the pore fluid pressure in the Berea core by an average of 36 ± 15 cm and 23 ± 15 cm of equivalent freshwater head, respectively, in agreement with 41.8 cm and 34 cm rises recorded in wells at those locations.

  2. Effects of bubbly flow on bending moment acting on the shaft of a gas sparged vessel stirred by a Rushton turbine☆

    Institute of Scientific and Technical Information of China (English)

    Daien Shi; Ziqi Cai; Archie Eaglesham; Zhengming Gao

    2015-01-01

    The bending moment acting on the overhung shaft of a gas-sparged vessel stirred by a Rushton turbine, as one of the results of fluid and structure interactions in stirred vessels, was measured using a moment sensor equipped with digital telemetry. An analysis of the shaft bending moment amplitude shows that the amplitude distribution of the bending moment, which indicates the elasticity nature of shaft material against bending deformation, fol-lows the Weibull distribution. The trends of amplitude mean, standard deviation and peak deviation character-istics manifest an“S”shape versus gas flow. The“S”trend of the relative mean bending moment over gas flow rate, depending on the flow regime in gas–liquid stirred vessels, resulted from the competition among the non-uniformity of bubbly flow around the impeller, the formation of gas cavities behind the blades, and the gas direct impact on the impel er when gas is introduced. A further analysis of the bending moment power spectral density shows that the rather low frequency and speed frequency are evident. The low-frequency contribution to bend-ing moment fluctuation peaks in the complete dispersion regime.

  3. Bubbling at high flow rates in inviscid and viscous liquids (slags)

    Science.gov (United States)

    Engh, T. Abel; Nilmani, M.

    1988-02-01

    The behavior of gas discharging into melts at high velocities but still in the bubbling regime has been investigated in a laboratory modeling study for constant flow conditions. Air or helium was injected through a vertical tuyere into water, zinc-chloride, and aqueous glycerol solutions. High speed cinematography and pressure measurements in the tuyere have been carried out simultaneously. Pressure fluctuations at the injection point were monitored and correlated to the mode of bubble formation. The effects of high gas flow rates and high liquid viscosities have been examined in particular. Flow rates were employed up to 10-3 m3/s and viscosity to 0.5 Ns/m2. In order to attain a high gas momentum, the tuyere diameter was only 3 x 10-3 m. The experimental conditions and modeling liquids were chosen with special reference to the established practice of submerged gas injection to treat nonferrous slags. Such slags can be highly viscous. Bubble volume is smaller than that calculated from existing models such as those given by Davidson and Schüler10,11 due to the effect of gas momentum elongating the bubbles. On the other hand, viscosity tends to retard the bubble rise velocity, thus increasing volumes. To take elongation into account, a mathematical model is presented that assumes a prolate ellipsoidal shape of the bubbles. The unsteady potential flow equations for the liquid are solved for this case. Viscous effects are taken into account by noting that flow deviates from irrotational motion only in a thin boundary layer along the surface of the bubble. Thus, drag on the bubble can be obtained by calculating the viscous energy dissipation for potential flow past an ellipse. The time-dependent inertia coefficient for the ellipsoid is found by equating the vertical pressure increase inside and outside the bubble. This pressure change in the bubble is obtained by assuming that gas enters as a homogeneous jet and then calculating the stagnation pressure at the apex of

  4. Bubble, Bubble, Toil and Trouble.

    Science.gov (United States)

    Journal of Chemical Education, 2001

    2001-01-01

    Bubbles are a fun way to introduce the concepts of surface tension, intermolecular forces, and the use of surfactants. Presents two activities in which students add chemicals to liquid dishwashing detergent with water in order to create longer lasting bubbles. (ASK)

  5. VolumeExplorer: Roaming Large Volumes to Couple Visualization and Data Processing for Oil and Gas Exploration

    OpenAIRE

    2005-01-01

    http://ieeexplore.ieee.org/; In this paper, we present a volume roaming system dedicated to oil and gas exploration. Our system combines probe-based volume rendering with data processing and computing. The daily oil production and the estimation of the world proven-reserves directly affect the barrel price and have a strong impact on the economy. Among others, production and correct estimation are linked to the accuracy of the subsurface model used for predicting oil reservoirs shape and size...

  6. Droplets, Bubbles and Ultrasound Interactions.

    Science.gov (United States)

    Shpak, Oleksandr; Verweij, Martin; de Jong, Nico; Versluis, Michel

    2016-01-01

    The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to circulate within blood vessels. Perfluorocarbon liquid droplets can be a potential new generation of microbubble agents as ultrasound can trigger their conversion into gas bubbles. Prior to activation, they are at least five times smaller in diameter than the resulting bubbles. Together with the violent nature of the phase-transition, the droplets can be used for local drug delivery, embolotherapy, HIFU enhancement and tumor imaging. Here we explain the basics of bubble dynamics, described by the Rayleigh-Plesset equation, bubble resonance frequency, damping and quality factor. We show the elegant calculation of the above characteristics for the case of small amplitude oscillations by linearizing the equations. The effect and importance of a bubble coating and effective surface tension are also discussed. We give the main characteristics of the power spectrum of bubble oscillations. Preceding bubble dynamics, ultrasound propagation is introduced. We explain the speed of sound, nonlinearity and attenuation terms. We examine bubble ultrasound scattering and how it depends on the wave-shape of the incident wave. Finally, we introduce droplet interaction with ultrasound. We elucidate the ultrasound-focusing concept within a droplets sphere, droplet shaking due to media compressibility and droplet phase-conversion dynamics.

  7. First-order Description of the Mechanical Fracture Behavior of Fine-Grained Surficial Marine Sediments During Gas Bubble Growth

    Science.gov (United States)

    2010-01-01

    10 F04O29 BARRY ET AL.: BUBBLE GROWTH BY FRACTURE P04029 Figure 3. Map of field site. Canard, Nova Scotia, Canada. appears to approximate the...Bottinger. and T. Dahm (2005), Buoyancy-driven fracture ascent: Experiments in layered gelatine. J. Volcano!. Geotherm . Res., 144. 273-285. doi...Journal Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE First-order description of the mechanical fracture behavior of fine-grained

  8. Rise of an argon bubble in liquid steel in the presence of a transverse magnetic field

    Science.gov (United States)

    Jin, K.; Kumar, P.; Vanka, S. P.; Thomas, B. G.

    2016-09-01

    The rise of gaseous bubbles in viscous liquids is a fundamental problem in fluid physics, and it is also a common phenomenon in many industrial applications such as materials processing, food processing, and fusion reactor cooling. In this work, the motion of a single argon gas bubble rising in quiescent liquid steel under an external magnetic field is studied numerically using a Volume-of-Fluid method. To mitigate spurious velocities normally generated during numerical simulation of multiphase flows with large density differences, an improved algorithm for surface tension modeling, originally proposed by Wang and Tong ["Deformation and oscillations of a single gas bubble rising in a narrow vertical tube," Int. J. Therm. Sci. 47, 221-228 (2008)] is implemented, validated and used in the present computations. The governing equations are integrated by a second-order space and time accurate numerical scheme, and implemented on multiple Graphics Processing Units with high parallel efficiency. The motion and terminal velocities of the rising bubble under different magnetic fields are compared and a reduction in rise velocity is seen in cases with the magnetic field applied. The shape deformation and the path of the bubble are discussed. An elongation of the bubble along the field direction is seen, and the physics behind these phenomena is discussed. The wake structures behind the bubble are visualized and effects of the magnetic field on the wake structures are presented. A modified drag coefficient is obtained to include the additional resistance force caused by adding a transverse magnetic field.

  9. Seismically Initiated Carbon Dioxide Gas Bubble Growth in Groundwater: A Mechanism for Co-seismic Borehole Water Level Rise and Remotely Triggered Secondary Seismicity

    Science.gov (United States)

    Crews, Jackson B.

    Visualization experiments, core-scale laboratory experiments, and numerical simulations were conducted to examine the transient effect of dilational seismic wave propagation on pore fluid pressure in aquifers hosting groundwater that is near saturation with respect to dissolved carbon dioxide (CO2) gas. Groundwater can become charged with dissolved CO2 through contact with gas-phase CO2 in the Earth's crust derived from magma degasing, metamorphism, and biogenic processes. The propagation of dilational seismic waves (e.g., Rayleigh and p-waves) causes oscillation of the mean normal confining stress and pore fluid pressure. When the amplitude of the pore fluid pressure oscillation is large enough to drive the pore fluid pressure below the bubble pressure, an aqueous-to-gas-phase transition can occur in the pore space, which causes a buildup of pore fluid pressure and reduces the inter-granular effective stress under confined conditions. In visualization experiments conducted in a Hele-Shaw cell representing a smooth-walled, vertically oriented fracture, millisecond-scale pressure perturbations triggered bubble nucleation and growth lasting tens of seconds, with resulting pore fluid overpressure proportional to the magnitude of the pressure perturbation. In a Berea sandstone core flooded with initially under-saturated aqueous CO2 under conditions representative of a confined aquifer, rapid reductions in confining stress triggered transient pore pressure rise up to 0.7 MPa (100 psi) overpressure on a timescale of ~10 hours. The rate of pore pressure buildup in the first 100 seconds was proportional to the saturation with respect to dissolved CO 2 at the pore pressure minimum. Sinusoidal confining stress oscillations on a Berea sandstone core produced excess pore fluid pressure after the oscillations were terminated. Confining stress oscillations in the 0.1-0.4 MPa (15-60 psi) amplitude range and 0.05-0.30 Hz frequency band increased the pore fluid pressure by 13-60 cm

  10. 鼓泡塔中水合物法分离混合气体的数值模拟%Numerical Simulation of Separating Gas Mixtures via Hydrate Formation in Bubble Column

    Institute of Scientific and Technical Information of China (English)

    罗艳托; 朱建华; 陈光进

    2007-01-01

    To develop a new technique for separating gas mixtures via hydrate formation, a set of medium-sized experimental bubble column reactor equipment was constructed.On the basis of the structure parameters of the experimental bubble column reactor, assuming that the liquid phase was in the axial dispersion regime and the gas phase was in the plug flow regime, in the presence of hydrate promoter tetrahydrofuran (THF), the rate of hydrogen enrichment for CH4+H2 gas mixtures at different operational conditions (such as temperature, pressure, concentration of gas components, gas flow rate, liquid flow rate) were simulated.The heat product of the hydrate reaction and its axial distribution under different operational conditions were also calculated.The results would be helpful not only to setting and optimizing operation conditions and design of multi-refrigeration equipment, but also to hydrate separation technique industrialization.

  11. The study of volume ultrasonic waves propagation in the gas-containing iron ore pulp.

    Science.gov (United States)

    Morkun, V; Morkun, N; Pikilnyak, A

    2015-02-01

    The results of research of the volume ultrasonic waves propagation in the gas-containing iron ore slurry using ultrasonic phased array technology is presented. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. First measurements of gas output from bubbling pools in a mud volcano at the periphery of Mt Etna (Italy): methodologies and implications for monitoring purposes

    Science.gov (United States)

    Federico, Cinzia; Giudice, Gaetano; Liuzzo, Marco; Pedone, Maria; Cosenza, Paolo; Riccobono, Giuseppe

    2014-05-01

    Gases and brines emitted in the southern sector of Mt Etna from mofettes, mud pools and mud volcanoes come from an hydrothermal reservoir hosted within the clayey formations of the sedimentary basement (Chiodini et al., 1996). The gas emitted consists mainly of CO2, with CH4, N2 and He as minor species. CO2 and He stable isotopes indicate a clear magmatic origin for these gases, and their compositional changes during either eruptive or rest periods closely parallel that of crater fumaroles (Paonita et al., 2012). Altough these manifestations are the most significant CO2 emitters outside the crater area, their mass output has never been measured. We present the first measurements of gas flux from several bubbling mud pools in a mud volcano located in the village of Paternò (Lon 14.89° Lat 37.57°), in the southern flank of the volcano. We performed gas measurements using a home-made apparatus, able to capture all the bubbles over an area of 0.4 m2. Over an area of about 7000 m2, we measured the flow rate of every single bubbling pool, providing that it had a minimum flux rate of 0.5 l/min. The maximum measured flow rate for a single pool was 15 l/min. A preliminary estimate of the total CO2 output over the whole mud volcano is in the order of few t/d. At the same time, we measured the chemical composition of emitted gases in various pools, characterised by different gas flow rates, to calculate the output of CO2 and verify the effect of eventual chemical fractionation processes upon gas chemistry. During the same campaign of direct measurements, we also used a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) for measurement of volcanic CO2 path-integrated concentrations along cross-sections of the atmospheric plumes in the area. The GasFinder was set as to measure CO2 concentrations at 1 Hz rate. During the field campaigns, the position of the GasFinder unit was sequentially moved so as to scan the plumes from different viewing directions and

  13. Exploring Bubbles

    Science.gov (United States)

    O'Geary, Melissa A.

    Bubbles provide an enjoyable and festive medium through which to teach many concepts within the science topics of light, color, chemistry, force, air pressure, electricity, buoyancy, floating, density, among many others. In order to determine the nature of children's engagement within a museum setting and the learning opportunities of playing with bubbles, I went to a children's interactive museum located in a metropolitan city in the Northeastern part of the United States.

  14. Antigravitating bubbles

    CERN Document Server

    Barnaveli, A T; Barnaveli, Andro; Gogberashvili, Merab

    1995-01-01

    We investigate the gravitational behavior of spherical domain walls (bubbles) arising during the phase transitions in the early Universe. In the thin-wall approximation we show the existence of the new solution of Einstein equations with negative gravitational mass of bubbles and the reversed direction of time flow on the shell. This walls exhibit gravitational repulsion just as the planar walls are assumed to do. The equilibrium radius and critical mass of such objects are found for realistic models.

  15. Free volume and gas permeation in ion-exchanged forms of the Nafion® membrane

    Science.gov (United States)

    Mohamed, Hamdy F. M.; Kobayashi, Y.; Kuroda, C. S.; Ohira, A.

    2010-04-01

    Variations of free volume and gas permeability of the Nafion® membrane upon ion-exchange of H+ with Cs+ or Pt2+ was studied as a function of temperature. Free volume was quantified using the positron annihilation lifetime technique. Our results showed that the free volume (VFV,Ps) of the dried membrane is enlarged by thermal expansion. It was found that the ion-exchange significantly expands the free volume and at the same time decreases the permeabilities of O2 and H2. Good linear correlations between the logarithm of permeabilities of O2 and H2 at different temperatures and 1/VFV,Ps for the ion-exchanged forms of Nafion® in the dried state suggest an important role played by the free volume in gas permeation. Considerable downward deviation of the correlations for the ion-exchanged ionomers from the H+-form suggested the importance of polymer stiffening in gas permeation.

  16. Theoretical test of Jarzynski's equality for reversible volume-switching processes of an ideal gas system.

    Science.gov (United States)

    Sung, Jaeyoung

    2007-07-01

    We present an exact theoretical test of Jarzynski's equality (JE) for reversible volume-switching processes of an ideal gas system. The exact analysis shows that the prediction of JE for the free energy difference is the same as the work done on the gas system during the reversible process that is dependent on the shape of path of the reversible volume-switching process.

  17. Squeezing through: capsule or bubble?

    CERN Document Server

    Dawson, Geoffrey

    2013-01-01

    In this fluid dynamics video, we compare the deformation of two flexible particles as they propagate through a sudden constriction of a liquid filled channel under constant-flux flow: a gas bubble, and a capsule formed by encapsulating a liquid droplet in a cross-linked polymeric membrane. Both bubble and capsule adopt highly contorted configurations as they squeeze through the constriction, exhibit broadly similar features over a wide range of flow rates, and rupture for sufficiently high flow rates. However, at flow rates prior to rupture, certain features of the deformation allow bubble and capsule to be distinguished: bubbles exhibit a tip-streaming singularity associated with critical thinning of the rear of the bubble, while the capsule membrane wrinkles under large compressive stresses induced by the constriction.

  18. Growing bubbles rising in line

    Directory of Open Access Journals (Sweden)

    John F. Harper

    2001-01-01

    Full Text Available Over many years the author and others have given theories for bubbles rising in line in a liquid. Theory has usually suggested that the bubbles will tend towards a stable distance apart, but experiments have often showed them pairing off and sometimes coalescing. However, existing theory seems not to deal adequately with the case of bubbles growing as they rise, which they do if the liquid is boiling, or is a supersaturated solution of a gas, or simply because the pressure decreases with height. That omission is now addressed, for spherical bubbles rising at high Reynolds numbers. As the flow is then nearly irrotational, Lagrange's equations can be used with Rayleigh's dissipation function. The theory also works for bubbles shrinking as they rise because they dissolve.

  19. Enhanced recovery of unconventional gas. The methodology--Volume III (of 3 volumes)

    Energy Technology Data Exchange (ETDEWEB)

    Kuuskraa, V. A.; Brashear, J. P.; Doscher, T. M.; Elkins, L. E.

    1979-02-01

    The methodology is described in chapters on the analytic approach, estimated natural gas production, recovery from tight gas sands, recovery from Devonian shales, recovery from coal seams, and recovery from geopressured aquifers. (JRD)

  20. Shell correction energy for bubble nuclei

    CERN Document Server

    Yu, Y; Magierski, P; Bulgac, Aurel; Magierski, Piotr

    2000-01-01

    The positioning of a bubble inside a many fermion system does not affect the volume, surface or curvature terms in the liquid drop expansion of the total energy. Besides possible Coulomb effects, the only other contribution to the ground state energy of such a system arises from shell effects. We show that the potential energy surface is a rather shallow function of the displacement of the bubble from the center and in most cases the preferential position of a bubble is off center. Systems with bubbles are expected to have bands of extremely low lying collective states, corresponding to various bubble displacements.

  1. Robust acoustic wave manipulation of bubbly liquids

    Energy Technology Data Exchange (ETDEWEB)

    Gumerov, N. A., E-mail: gumerov@umiacs.umd.edu [Institute for Advanced Computer Studies, University of Maryland, College Park, Maryland 20742 (United States); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Akhatov, I. S. [Center for Design, Manufacturing and Materials, Skolkovo Institute of Science and Technology, Moscow 143026 (Russian Federation); Ohl, C.-D. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Sametov, S. P. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Khazimullin, M. V. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Institute of Molecule and Crystal Physics, Ufa Research Center of Russian Academy of Sciences, Ufa 450054 (Russian Federation); Gonzalez-Avila, S. R. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2016-03-28

    Experiments with water–air bubbly liquids when exposed to acoustic fields of frequency ∼100 kHz and intensity below the cavitation threshold demonstrate that bubbles ∼30 μm in diameter can be “pushed” away from acoustic sources by acoustic radiation independently from the direction of gravity. This manifests formation and propagation of acoustically induced transparency waves (waves of the bubble volume fraction). In fact, this is a collective effect of bubbles, which can be described by a mathematical model of bubble self-organization in acoustic fields that matches well with our experiments.

  2. Lidar signature from bubbles in the sea.

    Science.gov (United States)

    Churnside, James H

    2010-04-12

    The lidar signature from a collection of bubbles is proportional to the volume backscatter coefficient at a scattering angle of 180 degrees . This quantity, calculated using a combination of geometric optics and diffraction, is proportional to the void fraction of the bubbles in the water for any bubble size distribution. The constant of proportionality is 233 m(-1) sr(-1)for clean bubbles, slightly less for bubbles coated with a thin layer of organic material, and as large as 1445 m(-1) sr(-1) for a thick coating of protein.

  3. Industrial Fuel Gas Demonstration Plant Program. Volume 1. Demonstration plant environmental analysis (Deliverable No. 27)

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Robert W.; Swift, Richard J.; Krause, Arthur J.; Berkey, Edgar

    1979-08-01

    This environmental report describes the proposed action to construct, test and operate a coal gasification demonstration plant in Memphis, Tennessee, under the co-sponsorship of the Memphis Light, Gas and Water Division (MLGW) and the US Department of Energy (DOE). This document is Volume I of a three-volume Environmental Report. Volume I consists of the Summary, Introduction and the Description of the Proposed Action. Volume II consists of the Description of the Existing Environment. Volume III contains the Environmental Impacts of the Proposed Action, Mitigating Measures and Alternatives to the Proposed Action.

  4. Industrial Fuel Gas Demonstration Plant Program. Volume III. Demonstration plant environmental analysis (Deliverable No. 27)

    Energy Technology Data Exchange (ETDEWEB)

    1979-08-01

    An Environmental Report on the Memphis Light, Gas and Water Division Industrial Fuel Demonstration Plant was prepared for submission to the US Department of Energy under Contract ET-77-C-01-2582. This document is Volume III of a three-volume Environmental Report. Volume I consists of the Summary, Introduction and the Description of the Proposed Action. Volume II consists of the Description of the Existing Environment. Volume III contains the Environmental Impacts of the Proposed Action, Mitigating Measures and Alternatives to the Proposed Action.

  5. Coal liquefaction and gas conversion: Proceedings. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-31

    Volume II contains papers presented at the following sessions: Indirect Liquefaction (oxygenated fuels); and Indirect Liquefaction (Fischer-Tropsch technology). Selected papers have been processed separately for inclusion in the Energy Science and Technology Database.

  6. Thermodynamic property of gases in the sonoluminescing bubble

    Institute of Scientific and Technical Information of China (English)

    AN Yu; LI Guiqin; ZHOU Tieying

    2001-01-01

    With the theory of statistical physics dealing with chemical reaction (the law of mass action), the different thermodynamic property of noble gases (mono-atomic gases) in a small bubble and diatomic gases in a small bubble semi-quantitatively are analyzed. As bubbles of the mono-atomic and the diatomic gases are compressed, shock waves are produced in both bubbles. Though shock wave leads to sharp increase of pressure and temperature of gases in the bubble, diatomic gas will excitated vibrations and dissociate themselves to mono-atomic gas,these processes will consume many accumulated heat energy and block the further increase of the temperature. Therefore, compare with the mono-atomic gases in the bubble, there will be no enough charged particles ionized to flash for diatomic gases in the bubble, this may be the reason why a bubble of diatomic gases has no single bubble sonoluminescence while a bubble of noble gases has.

  7. Fuel Gas Demonstration Plant Program. Volume I. Demonstration plant

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    The objective of this project is for Babcock Contractors Inc. (BCI) to provide process designs, and gasifier retort design for a fuel gas demonstration plant for Erie Mining Company at Hoyt Lake, Minnesota. The fuel gas produced will be used to supplement natural gas and fuel oil for iron ore pellet induration. The fuel gas demonstration plant will consist of five stirred, two-stage fixed-bed gasifier retorts capable of handling caking and non-caking coals, and provisions for the installation of a sixth retort. The process and unit design has been based on operation with caking coals; however, the retorts have been designed for easy conversion to handle non-caking coals. The demonstration unit has been designed to provide for expansion to a commercial plant (described in Commercial Plant Package) in an economical manner.

  8. Interface tracking simulations of bubbly flows in PWR relevant geometries

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Jun, E-mail: jfang3@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Rasquin, Michel, E-mail: michel.rasquin@colorado.edu [Aerospace Engineering Department, University of Colorado, Boulder, CO 80309 (United States); Bolotnov, Igor A., E-mail: igor_bolotnov@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States)

    2017-02-15

    Highlights: • Simulations were performed for turbulent bubbly flows in PWR subchannel geometry. • Liquid turbulence is fully resolved by direct numerical simulation approach. • Bubble behavior is captured using level-set interface tracking method. • Time-averaged single- and two-phase turbulent flow statistical quantities are obtained. - Abstract: The advances in high performance computing (HPC) have allowed direct numerical simulation (DNS) approach coupled with interface tracking methods (ITM) to perform high fidelity simulations of turbulent bubbly flows in various complex geometries. In this work, we have chosen the geometry of the pressurized water reactor (PWR) core subchannel to perform a set of interface tracking simulations (ITS) with fully resolved liquid turbulence. The presented research utilizes a massively parallel finite-element based code, PHASTA, for the subchannel geometry simulations of bubbly flow turbulence. The main objective for this research is to demonstrate the ITS capabilities in gaining new insight into bubble/turbulence interactions and assisting the development of improved closure laws for multiphase computational fluid dynamics (M-CFD). Both single- and two-phase turbulent flows were studied within a single PWR subchannel. The analysis of numerical results includes the mean gas and liquid velocity profiles, void fraction distribution and turbulent kinetic energy profiles. Two sets of flow rates and bubble sizes were used in the simulations. The chosen flow rates corresponded to the Reynolds numbers of 29,079 and 80,775 based on channel hydraulic diameter (D{sub h}) and mean velocity. The finite element unstructured grids utilized for these simulations include 53.8 million and 1.11 billion elements, respectively. This has allowed to fully resolve all the turbulence scales and the deformable interfaces of individual bubbles. For the two-phase flow simulations, a 1% bubble volume fraction was used which resulted in 17 bubbles in

  9. [Inspection of gas cylinders in storage at TA-54, Area L]. Volume 1, Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-06-23

    ERC sampled, analyzed, and recontainerized when necessary gas cylinders containing various chemicals in storage at Los Alamos TA-54 Area L. A vapor containment structure was erected. A total of 179 cylinders was processed; 39 were repackaged; and 55 were decommissioned. This report summarizes the operation; this is Volume 1 of five volumes.

  10. EVALUATION OF VAPOR EQUILIBRATION AND IMPACT OF PURGE VOLUME ON SOIL-GAS SAMPLING RESULTS

    Science.gov (United States)

    Sequential sampling was utilized at the Raymark Superfund site to evaluate attainment of vapor equilibration and the impact of purge volume on soil-gas sample results. A simple mass-balance equation indicates that removal of three to five internal volumes of a sample system shou...

  11. ECONOMETRIC MODELING OF THE DYNAMICS OF VOLUMES HYDROCARBONS OF SMALL OIL AND GAS ENTERPRISES

    Directory of Open Access Journals (Sweden)

    GORLOV A.V.

    2015-01-01

    Full Text Available In this paper investigates the principles of functioning of small oil and gas enterprises of Russia. The basic characteristics and socio-economic tasks performed by the small oil and gas enterprises. Made correlation and regression analysis, a result of which the pair correlation coefficients between the indicator of development of small oil and gas enterprises (volumes hydrocarbons and the factors that characterize the work environment of their operation; built regressions, describing the process of development of small oil and gas enterprises. With a view to forecasting the development of small oil and gas enterprises built production function of Cobb-Douglas and selected econometric model, has good predictive properties. Made predictive calculations dynamics of volumes hydrocarbons of small oil and gas enterprises on formulating scenarios for the planning period (2015-2016 years.

  12. Bubble Dynamics and Resulting Noise from Traveling Bubble Cavitation.

    Science.gov (United States)

    1982-04-13

    has resulted in models which aqree well with bubble dynamics recorded by high speed film . Chahine, et. al. (23) incorporated asymmetric bubble...recording on the tape soundtrack . 3.8 Measurement of Gas Nuclei in Water The role of nuclei density and size in cavitation inception has been the subject...interference between the coherent background and the particle-diffracted radiation exooses photographic film in the far-field of the nuclei. This

  13. Liquefied natural gas as a transportation fuel for heavy-duty trucks: Volume I

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    This document contains Volume 1 of a three-volume manual designed for use with a 2- to 3-day liquefied natural gas (LNG) training course. Transportation and off-road agricultural, mining, construction, and industrial applications are discussed. This volume provides a brief introduction to the physics and chemistry of LNG; an overview of several ongoing LNG projects, economic considerations, LNG fuel station technology, LNG vehicles, and a summary of federal government programs that encourage conversion to LNG.

  14. Doughnut-shaped soap bubbles

    Science.gov (United States)

    Préve, Deison; Saa, Alberto

    2015-10-01

    Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L . It is well known that the sphere is the solution for V =L3/6 π2 , and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for V <α L3/6 π2 , with α ≈0.21 , such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but is rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V <α L3/6 π2 cannot be stable and should not exist in foams, for instance.

  15. A Laboratory Experiment To Measure Henry's Law Constants of Volatile Organic Compounds with a Bubble Column and a Gas Chromatography Flame Ionization Detector (GC-FID)

    Science.gov (United States)

    Lee, Shan-Hu; Mukherjee, Souptik; Brewer, Brittany; Ryan, Raphael; Yu, Huan; Gangoda, Mahinda

    2013-01-01

    An undergraduate laboratory experiment is described to measure Henry's law constants of organic compounds using a bubble column and gas chromatography flame ionization detector (GC-FID). This experiment is designed for upper-division undergraduate laboratory courses and can be implemented in conjunction with physical chemistry, analytical…

  16. A Laboratory Experiment To Measure Henry's Law Constants of Volatile Organic Compounds with a Bubble Column and a Gas Chromatography Flame Ionization Detector (GC-FID)

    Science.gov (United States)

    Lee, Shan-Hu; Mukherjee, Souptik; Brewer, Brittany; Ryan, Raphael; Yu, Huan; Gangoda, Mahinda

    2013-01-01

    An undergraduate laboratory experiment is described to measure Henry's law constants of organic compounds using a bubble column and gas chromatography flame ionization detector (GC-FID). This experiment is designed for upper-division undergraduate laboratory courses and can be implemented in conjunction with physical chemistry, analytical…

  17. In situ rheology and gas volume in Hanford double-shell waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, C.W.; Alzheimer, J.M.; Brewster, M.E.; Chen, G.; Reid, H.C.; Shepard, C.L.; Terrones, G. [Pacific Northwest National Lab., Richland, WA (United States); Mendoza, R.E. [Westinghouse Hanford Co., Richland, WA (United States)

    1996-09-01

    This report is a detailed characterization of gas retention and release in 6 Hanford DS waste tanks. The results came from the ball rheometer and void fraction instrument in (flammable gas watch list) tanks SY-101, SY-103, AW-101, AN-103, AN-104, and AN-105 are presented. Instrument operation and derivation of data reduction methods are presented. Gas retention and release information is summarized for each tank and includes tank fill history and instrumentation, waste configuration, gas release, void fraction distribution, gas volumes, rheology, and photographs of the waste column from extruded core samples. Potential peak burn pressure is computed as a function of gas release fraction to portray the `hazard signature` of each tank. It is shown that two tanks remain well below the maximum allowable pressure, even if the entire gas content were released and ignited, and that none of the others present a hazard with their present gas release behavior.

  18. Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity

    Directory of Open Access Journals (Sweden)

    Muntazim Munir Khan

    2015-05-01

    Full Text Available High free-volume copolymers were prepared via polycondensation with 2,3,5,6,-tetrafluoroterephthalonitrile (TFTPN in which a portion of the 3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI of PIM-1 was replaced with dibutyl anthracene maleimide (4bIII. An investigation of free volume using positron annihilation lifetime spectroscopy (PALS, and gas permeation measurements was carried out for the thin film composite copolymer membranes and compared to PIM-1. The average free volume hole size and the gas permeance of the copolymer membranes increased with decreasing TTSBI content in the copolymer.

  19. Interactions of the Infrared bubble N4 with the surroundings

    CERN Document Server

    Liu, Hong-Li; Wu, Yuefang; Yuan, Jing-Hua; Liu, Tie; Dubner, G; Paron, S; Ortega, M E; Molinari, Sergio; Huang, Maohai; Zavagno, Annie; Samal, Manash R; Huang, Ya-Fang; Zhang, Si-Ju

    2016-01-01

    The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with HII regions have been considered to be a good sample to investigate triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the HII region G11.898+0.747, analyzing its interaction with the surroundings and star formation histories therein, aiming at determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a wide wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 $\\times10^{22}$ cm$^{-2}$, mean volume density of about 4.4 $\\times10^{4}$ cm$^{-3}$, and a mean mass of 320 $M_{\\odot}$. In addition, from PAH emission seen at 8 $\\mu$m, ...

  20. The search for the origin of the Local Bubble redivivus

    CERN Document Server

    Fuchs, B; D'Avillez, M A; Dettbarn, C; Flynn, C

    2006-01-01

    We present a new unbiased search and analysis of all B stars in the solar neighbourhood (within a volume of 400 pc diameter) using the Arivel data base to track down the remains of the OB associations, which hosted the supernovae responsible for the Local Bubble in the interstellar gas. We find after careful dereddening and by comparison with theoretical isochrones, that besides the Upper Scorpius the Upper Centaurus Lupus and Lower Centaurus Crux subgroups are the youngest stellar associations in the solar neighbourhood with ages of 20 to 30 Myr, in agreement with previous work. In search for the ``smoking gun'' of the origin of the Local Bubble, we have traced the paths of the associations back into the past and found that they entered the present bubble region 10 to 15 Myr ago. We argue that the Local Bubble began to form then and estimate that 14 to 20 supernovae have gone off since. It is shown that the implied energy input is sufficient to excavate a bubble of the presently observed size.

  1. Bubbles Outside the Plume During the LUMINY Wind-Wave Experiment

    NARCIS (Netherlands)

    Leeuw, G. de; Leifer, I.

    2002-01-01

    Since many bubble-mediated processes are size dependent, it is often necessary to characterize the bubble distribution over the full size spectrum. For example, in regards to bubble-mediated gas transfer, small bubbles are important for insoluble gases like helium, while large bubbles are important

  2. Rapid estimate of solid volume in large tuff cores using a gas pycnometer

    Energy Technology Data Exchange (ETDEWEB)

    Thies, C. [ed.; Geddis, A.M.; Guzman, A.G. [and others

    1996-09-01

    A thermally insulated, rigid-volume gas pycnometer system has been developed. The pycnometer chambers have been machined from solid PVC cylinders. Two chambers confine dry high-purity helium at different pressures. A thick-walled design ensures minimal heat exchange with the surrounding environment and a constant volume system, while expansion takes place between the chambers. The internal energy of the gas is assumed constant over the expansion. The ideal gas law is used to estimate the volume of solid material sealed in one of the chambers. Temperature is monitored continuously and incorporated into the calculation of solid volume. Temperature variation between measurements is less than 0.1{degrees}C. The data are used to compute grain density for oven-dried Apache Leap tuff core samples. The measured volume of solid and the sample bulk volume are used to estimate porosity and bulk density. Intrinsic permeability was estimated from the porosity and measured pore surface area and is compared to in-situ measurements by the air permeability method. The gas pycnometer accommodates large core samples (0.25 m length x 0.11 m diameter) and can measure solid volume greater than 2.20 cm{sup 3} with less than 1% error.

  3. Stable tridimensional bubble clusters in multi-bubble sonoluminescence (MBSL).

    Science.gov (United States)

    Rosselló, J M; Dellavale, D; Bonetto, F J

    2015-01-01

    In the present work, stable clusters made of multiple sonoluminescent bubbles are experimentally and theoretically studied. Argon bubbles were acoustically generated and trapped using bi-frequency driving within a cylindrical chamber filled with a sulfuric acid aqueous solution (SA85w/w). The intensity of the acoustic pressure field was strong enough to sustain, during several minutes, a large number of positionally and spatially fixed (without pseudo-orbits) sonoluminescent bubbles over an ellipsoidally-shaped tridimensional array. The dimensions of the ellipsoids were studied as a function of the amplitude of the applied low-frequency acoustic pressure (PAc(LF)) and the static pressure in the fluid (P0). In order to explain the size and shape of the bubble clusters, we performed a series of numerical simulations of the hydrodynamic forces acting over the bubbles. In both cases the observed experimental behavior was in excellent agreement with the numerical results. The simulations revealed that the positionally stable region, mainly determined by the null primary Bjerknes force (F→Bj), is defined as the outer perimeter of an axisymmetric ellipsoidal cluster centered in the acoustic field antinode. The role of the high-frequency component of the pressure field and the influence of the secondary Bjerknes force are discussed. We also investigate the effect of a change in the concentration of dissolved gas on the positional and spatial instabilities through the cluster dimensions. The experimental and numerical results presented in this paper are potentially useful for further understanding and modeling numerous current research topics regarding multi-bubble phenomena, e.g. forces acting on the bubbles in multi-frequency acoustic fields, transient acoustic cavitation, bubble interactions, structure formation processes, atomic and molecular emissions of equal bubbles and nonlinear or unsteady acoustic pressure fields in bubbly media.

  4. Heterocoagulation of hydrophobic particle and bubble during microflotation

    NARCIS (Netherlands)

    Mishchuk, N.A.; Koopal, L.K.; Dukhin, S.S.

    2002-01-01

    The laws of the interaction between a gas bubble and a hydrophobic solid particle were studied. The range of the system parameters that can ensure the heterocoagulation of the particle and the bubble was determined.

  5. Heterocoagulation of hydrophobic particle and bubble during microflotation

    NARCIS (Netherlands)

    Mishchuk, N.A.; Koopal, L.K.; Dukhin, S.S.

    2002-01-01

    The laws of the interaction between a gas bubble and a hydrophobic solid particle were studied. The range of the system parameters that can ensure the heterocoagulation of the particle and the bubble was determined.

  6. Theoretical and experimental analysis of a multiphase screw pump, handling gas-liquid mixtures with very high gas volume fractions

    Energy Technology Data Exchange (ETDEWEB)

    Raebiger, K. [LEISTRITZ Pumpen GmbH, Nuremberg (Germany); Faculty of Advanced Technology, University of Glamorgan, Pontypridd, Wales (United Kingdom); Maksoud, T.M.A.; Ward, J. [Faculty of Advanced Technology, University of Glamorgan, Pontypridd, Wales (United Kingdom); Hausmann, G. [Department of Mechanical Engineering and Building Services Engineering, University of Applied Sciences, Nuremberg (Germany)

    2008-09-15

    In the investigation of the pumping behaviour of multiphase screw pumps, handling gas-liquid mixtures with very high gas volume fractions, theoretical and experimental analyses were performed. A new theoretical screw pump model was developed, which calculates the time-dependent conditions inside the several chambers of a screw pump as well as the exchange of mass and energy between these chambers. By means of the performed experimental analysis, the screw pump model was verified, especially at very high gas volume fractions from 90% to 99%. The experiments, which were conducted with the reference fluids water and air, can be divided mainly into the determination of the steady state pumping behaviour on the one hand and into the analysis of selected transient operating conditions on the other hand, whereas the visualisation of the leakage flows through the circumferential gaps was rounded off the experimental analysis. (author)

  7. Bubbling Threat

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The shift of China’s monetary policy stance from "moderately loose" to "prudent" in 2011 indicates curbing inflation and asset bubbles have become the Central Government’s top priority. But is China’s bubble problem short-term or long-term? Is it only monetary or related to economic structure? Is it the cause of China’s economic imbalance or the result? And what kind of deep-rooted problems in the macro economy does it reflect? All these questions call for deep thought,said Zhang Monan,a

  8. Cosmological HII Bubble Growth During Reionization

    CERN Document Server

    Shin, Min-Su; Cen, Renyue

    2007-01-01

    We present general properties of ionized hydrogen (HII) bubbles and their growth based on a state-of-the-art large-scale (100 Mpc/h) cosmological radiative transfer simulation. The simulation resolves all halos with atomic cooling at the relevant redshifts and simultaneously performs radiative transfer and dynamical evolution of structure formation. Our major conclusions include: (1) for significant HII bubbles, the number distribution is peaked at a volume of ~ 0.6 Mpc^3/h^3 at all redshifts. But, at z 10 even the largest HII bubbles have a balanced ionizing photon contribution from Pop II and Pop III stars, while at z < 8 Pop II stars start to dominate the overall ionizing photon production for large bubbles, although Pop III stars continue to make a non-negligible contribution. (6) The relationship between halo number density and bubble size is complicated but a strong correlation is found between halo number density and bubble size for for large bubbles.

  9. Thermocapillary simulation of single bubble dynamics in zero gravity

    Science.gov (United States)

    Alhendal, Yousuf; Turan, Ali; Hollingsworth, Peter

    2013-07-01

    The lack of significant buoyancy effects in zero gravity conditions poses an issue with fluid transfer in a stagnant liquid. In this paper bubble movement in a stagnant liquid is analysed and presented numerically using a computational fluid dynamics (CFD) approach. The governing continuum conservation equations for two phase flow are solved using the commercial software package Ansys-Fluent v.13 and the Volume of Fluid (VOF) method is used to track the liquid/gas interface in 2D and 3D domains. The simulation results are in reasonable agreement with the earlier experimental observations, the VOF algorithm is found to be a valuable tool for studying the phenomena of gas-liquid interaction. The flow is driven via Marangoni influence induced by the temperature difference which in turn drives the bubble from the cold to the hot region. A range of thermal Reynolds (ReT) and Marangoni numbers (MaT) are selected for the numerical simulations, specifically ReT=13-658 and MaT=214-10,721 respectively. The results indicate that the inherent velocity of bubbles decreases with an increase of the Marangoni number, a result that is line with the results of previous space experiments (Kang et al., 2008) [1]. An expression for predicting the scaled velocity of bubble has been derived based on the data obtained in the present numerical study. Some three-dimensional simulations are also performed to compare and examine the results with two-dimensional simulations.

  10. NUMERICAL SIMULATION OF SPHERICAL, CYLINDRICAL AND AXIAL BUBBLE CLOUDS COLLAPSE

    Institute of Scientific and Technical Information of China (English)

    MAHDI Miralam; EBRAHIMI Reza; SHAMS Mehrzad

    2012-01-01

    The nonlinear dynamics of a spherical,cylindrical and axial cloud of cavitation bubbles were numerically simulated in order to learn more about the physical phenomena occurring in the cloud cavitation.The simulations employed the fully nonlinear continuum mixture equations coupled with the Gilmore equation for the dynamics of bubbles by considering the compressibility of liquid.A set of the Navier-Stokes equations was solved for the gas inside a spherical bubble,considering heat transfer through the gas inside the bubble and the liquid layer.The flow field around the cylindrical and axial cloud was obtained by solving the Navier-Stokes equations using a finite volume method and a dynamic layering mesh scheme.The calculated strength of shock wave in the liquid around the cloud was of the order of 1 × 106 Pa and the propagation of this shock wave lasted for 10 μs.The conducted investigations illustrate that the shock wave propagates before the cloud has completely collapsed.A good agreement with experimental data was observed.

  11. Deep Panuke offshore gas development project summary : volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-11-15

    This project summary is the first of 5 documents intended to comprise a development plan application for approval of the Deep Panuke Offshore Gas Development. EnCana Corporation plans to produce gas from the completion of 4 existing wells and 1 new production well feeding a central production facility sized for a peak sales gas throughput of 8.5 x 10{sup 6} m{sup 3}/day. The project was designed to meet the significant and growing demand for natural gas for markets in Canada and the United States. The development phase of the project is expected to continue until 2010. Following the commissioning of the project facilities, project life is expected to be in the range of 8 to 17.5 years. The project summary included details of EnCana Corporation's development strategy as well as a detailed description of the project. Project principles and management principles were outlined. Environmental assessment methodologies were presented, as well as details of the potential environmental and socio-economic effects of the project. A project schedule was provided, as well as a regulatory overview. Project components and activities included development drilling; subsea equipment; a mobile offshore processing unit (MOPU); offshore pipelines; and onshore pipeline and facilities. Environmental, health and safety management plans were provided, as well as details of public and Aboriginal consultation processes. It was concluded that the project is not likely to have significant adverse environmental or socio-economic impacts. The results of the economic opportunities and impacts analysis conducted for the project indicated that the project will have a positive impact on the communities of the province of Nova Scotia and Canada. 4 tabs., 3 figs.

  12. Numerical Simulation of Turbulent Bubbly Flow in a Vertical Square Duct

    Science.gov (United States)

    Vanka, Pratap; Kumar, Purushotam; Jin, Kai

    2016-11-01

    We numerically investigate the dynamics of a large number of gas bubbles in a turbulent liquid flow in a confined vertical square duct, a problem of interest to many industrial equipment. The fluid flow is simulated by Direct Numerical Simulations and the motions of the bubbles are resolved by an accurate Volume of Fluid (VOF) technique. The flow is considered periodic in the streamwise direction with an imposed pressure gradient. The surface tension force is incorporated through a Sharp Surface Force (SSF) method that is observed to generate only very small spurious velocities at the interface. The algorithm has been programmed on a multiple-GPU computer in a data parallel mode. The turbulence driven secondary flows are first ensured to agree with previous DNS/LES by other researchers. A very fine grid with 192 x 192 x 768 control volumes is used to resolve the liquid flow as well as 864 bubbles using 12 grid points across each bubble in all directions. The computations are carried out to 1.5 million time steps. It is seen that the bubbles preferentially migrate to walls, starting from a uniform layout. We present instantaneous and time mean velocities, turbulence statistics and compare them with unladen flow as well as with a bubbly flow in a planar channel.

  13. Leverage bubble

    Science.gov (United States)

    Yan, Wanfeng; Woodard, Ryan; Sornette, Didier

    2012-01-01

    Leverage is strongly related to liquidity in a market and lack of liquidity is considered a cause and/or consequence of the recent financial crisis. A repurchase agreement is a financial instrument where a security is sold simultaneously with an agreement to buy it back at a later date. Repurchase agreement (repo) market size is a very important element in calculating the overall leverage in a financial market. Therefore, studying the behavior of repo market size can help to understand a process that can contribute to the birth of a financial crisis. We hypothesize that herding behavior among large investors led to massive over-leveraging through the use of repos, resulting in a bubble (built up over the previous years) and subsequent crash in this market in early 2008. We use the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles and behavioral finance to study the dynamics of the repo market that led to the crash. The JLS model qualifies a bubble by the presence of characteristic patterns in the price dynamics, called log-periodic power law (LPPL) behavior. We show that there was significant LPPL behavior in the market before that crash and that the predicted range of times predicted by the model for the end of the bubble is consistent with the observations.

  14. Bubbles Rising Through a Soft Granular Material

    Science.gov (United States)

    Le Mestre, Robin; MacMinn, Chris; Lee, Sungyon

    2016-11-01

    Bubble migration through a soft granular material involves a strong coupling between the bubble dynamics and the deformation of the material. This is relevant to a variety of natural processes such as gas venting from sediments and gas exsolution from magma. Here, we study this process experimentally by injecting air bubbles into a quasi-2D packing of soft hydrogel beads and measuring the size, speed, and morphology of the bubbles as they rise due to buoyancy. Whereas previous work has focused on deformation resisted by intergranular friction, we focus on the previously inaccessible regime of deformation resisted by elasticity. At low confining stress, the bubbles are irregular and rounded, migrating via local rearrangement. At high confining stress, the bubbles become unstable and branched, migrating via pathway opening. The authors thank The Royal Society for support (International Exchanges Ref IE150885).

  15. Importance of evaluation of uncertainties on the measurement of natural gas and petroleum volumes; Importancia da avaliacao das incertezas na medicao dos volumes de petroleo e gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Silva Filho, Jose Alberto Pinheiro da; Oliveira, Thiago Barra Vidal de; Mata, Josaphat Dias da [PETROBRAS, Rio de Janeiro, RJ (Brazil)], Emails: jose.pinheiro@petrobras.com.br, thiagovidal@petrobras.com.br, josaphat@petrobras.com.br; Val, Luiz Gustavo do [Instituto de Qualidade e Metrologia (IQM), Rio de Janeiro, RJ (Brazil)], E-mail: gdoval.iqm@petrobras.com.br

    2009-07-01

    The measurement is considered as the 'cash register' of the enterprises, increasing the accuracy and the exigence at each step when come close to the delivery points, where the 0.1 % of differences are discussed. The work presents the approach used in the evaluation of measurement uncertainties in the volumes obtained of petroleum and natural gas at the processes of production in Brazil, and in the international level as well.

  16. Binary Schemes of Vapor Bubble Growth

    Science.gov (United States)

    Zudin, Yu. B.

    2015-05-01

    A problem on spherically symmetric growth of a vapor bubble in an infi nite volume of a uniformly superheated liquid is considered. A description of the limiting schemes of bubble growth is presented. A binary inertial-thermal bubble growth scheme characterized by such specifi c features as the "three quarters" growth law and the effect of "pressure blocking" in a vapor phase is considered.

  17. Shock propagation in polydisperse bubbly flows

    OpenAIRE

    Ando, Keita; Colonius, Tim; Brennen, Christopher E.

    2009-01-01

    The effect of distributed bubble size on shock propagation in homogeneous bubbly liquids is computed using a continuum two-phase model. An ensemble-averaging technique is employed to derive the statistically averaged equations and a finite-volume method is used to solve the model equations. The bubble dynamics are incorporated using a Rayleigh-Plesset-type equation which includes the effects of heat transfer, liquid viscosity and compressibility. For the case of monodispe...

  18. The effects of bubble-bubble interactions on pressures and temperatures produced by bubbles collapsing near a rigid surface

    Science.gov (United States)

    Alahyari Beig, Shahaboddin; Johnsen, Eric

    2016-11-01

    Cavitation occurs in a wide range of hydraulic applications, and one of its most important consequences is structural damage to neighboring surfaces following repeated bubble collapse. A number of studies have been conducted to predict the pressures produced by the collapse of a single bubble. However, the collapse of multiple bubbles is known to lead to enhanced collapse pressures. In this study, we quantify the effects of bubble-bubble interactions on the bubble dynamics and pressures/temperatures produced by the collapse of a pair of bubbles near a rigid surface. For this purpose, we use an in-house, high-order accurate shock- and interface-capturing method to solve the 3D compressible Navier-Stokes equations for gas/liquid flows. The non-spherical bubble dynamics are investigated and the subsequent pressure and temperature fields are characterized based on the relevant parameters entering the problem: stand-off distance, geometrical configuation, collapse strength. We demonstrate that bubble-bubble interactions amplify/reduce pressures and temperatures produced at the collapse, and increase the non-sphericity of the bubbles and the collapse time, depending on the flow parameters.

  19. Digital volume imaging of the PEFC gas diffusion layer

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory; Mukherjee, Partha [ORNL; Shim, Eunkyoung [NC ST

    2010-01-01

    The gas diffusion layer (GDL) plays a key role in the overall performance/durability of a polymer electrolyte fuel cell (PEFC). Of profound importance, especially in the context of water management and flooding phenomena, is the influence of the underlying pore morphology and wetting characteristics Of the GDL microstructure. In this article, we present the digital volumetric imaging (DVI) technique in order to generate the 3-D carbon paper GDL microstructure. The internal pore structure and the local microstructural variations in terms of fiber alignment and fiber/binder distributions are investigated using the several 3-D thin sections of the sample obtained from DVI.

  20. Energy spectra in bubbly turbulence

    CERN Document Server

    Prakash, Vivek N; Ramos, Fabio Ernesto Mancilla; Tagawa, Yoshiyuki; Lohse, Detlef; Sun, Chao

    2013-01-01

    We conduct experiments in a turbulent bubbly flow to study the unknown nature of the transition between the classical -5/3 energy spectrum scaling for a single-phase turbulent flow and the -3 scaling for a swarm of bubbles rising in a quiescent liquid and of bubble-dominated turbulence. The bubblance parameter, b, which measures the ratio of the bubble-induced kinetic energy to the kinetic energy induced by the turbulent liquid fluctuations before bubble injection, is used to characterise the bubbly flow. We vary b from $b = \\infty$ (pseudo-turbulence) to b = 0 (single-phase flow) over 2-3 orders of magnitude: ~O(0.01, 0.1, 5) to study its effect on the turbulent energy spectrum and liquid velocity fluctuations. The experiments are conducted in a multi-phase turbulent water tunnel with air bubbles of diameters 2-4 mm and 3-5 mm. An active-grid is used to generate nearly homogeneous and isotropic turbulence in the liquid flow. The liquid speeds and gas void fractions are varied to achieve the above mentioned b...

  1. Population Balance Modeling of Polydispersed Bubbly Flow in Continuous-Casting Using Multiple-Size-Group Approach

    Science.gov (United States)

    Liu, Zhongqiu; Li, Linmin; Qi, Fengsheng; Li, Baokuan; Jiang, Maofa; Tsukihashi, Fumitaka

    2015-02-01

    A population balance model based on the multiple-size-group (MUSIG) approach has been developed to investigate the polydispersed bubbly flow inside the slab continuous-casting mold and bubble behavior including volume fraction, breakup, coalescence, and size distribution. The Eulerian-Eulerian approach is used to describe the equations of motion of the two-phase flow. All the non-drag forces (lift force, virtual mass force, wall lubrication force, and turbulent dispersion force) and drag force are incorporated in this model. Sato and Sekiguchi model is used to account for the bubble-induced turbulence. Luo and Svendsen model and Prince and Blanch model are used to describe the bubbles breakup and coalescence behavior, respectively. A 1/4th water model of the slab continuous-casting mold was applied to investigate the distribution and size of bubbles by injecting air through a circumferential inlet chamber which was made of the specially-coated samples of mullite porous brick, which is used for the actual upper nozzle. Against experimental data, numerical results showed good agreement for the gas volume fraction and local bubble Sauter mean diameter. The bubble Sauter mean diameter in the upper recirculation zone decreases with increasing water flow rate and increases with increasing gas flow rate. The distribution of bubble Sauter mean diameter along the width direction of the upper mold increases first, and then gradually decreases from the SEN to the narrow wall. Close agreements between the predictions and measurements demonstrate the capability of the MUSIG model in modeling bubbly flow inside the continuous-casting mold.

  2. Doughnut-shaped soap bubbles

    CERN Document Server

    Preve, Deison

    2015-01-01

    Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume $V$ and with a fixed equatorial perimeter $L$. It is well known that the sphere is the solution for $V=L^3/6\\pi^2$, and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for $V<\\alpha L^3/6\\pi^2$, with $\\alpha\\approx 0.21$, such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtainin...

  3. Effect of Bubbles and Silica Dissolution on Melter Feed Rheology during Conversion to Glass

    Energy Technology Data Exchange (ETDEWEB)

    Marcial, Jose; Chun, Jaehun; Hrma, Pavel R.; Schweiger, Michael J.

    2014-10-21

    As the nuclear waste glass melter feed is converted to molten glass, the feed becomes a continuous glass-forming melt where dissolving refractory constituents are suspended together with numerous gas bubbles. Knowledge of mechanical properties of the reacting melter feed is crucial for understanding the feed-to-glass conversion as it occurs during melting. We studied the melter feed viscosity during heating and correlated it with volume fractions of dissolving quartz particles and gas phase. The measurements were performed with a rotating spindle rheometer on the melter feed heated at 5 K/min, starting at several different temperatures. The effects of undissolved quartz particles, gas bubbles, and compositional inhomogeneity on the melter feed viscosity were determined by fitting a linear relationship between log viscosity and volume fractions of suspended phases.

  4. Degradation of perfluoro compounds and f{sup -} recovery in water using discharge plasmas generated within gas bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Yasuoka, K.; Sasaki, K.; Hayashi, R.; Kosugi, A.; Takeuchi, N. [Tokyo Inst. of Technology, Tokyo (Japan). Dept. of Electrical and Electronic Engineering

    2010-07-01

    The widespread use of perfluorocarbons (PFCs) has raised environmental concerns because of their chemical stability and the toxicity of long-chain PFCs. Since PFCs such as perfluorooctanoic acid (PFOA) or perfluorooctanesulfonic acid (PFOS) cannot be decomposed by advanced oxidation technologies utilizing OH radicals, other methods have been tested to decompose their strong C-F bonds. Recent studies have shown that direct plasma-water interaction can easily decompose such persistent substances in water. A DC plasma generated within oxygen bubbles in water showed a higher decomposition rate and efficiency than pulsed plasmas. During decomposition, fluorine ions were generated in the solution. The recovery of fluorine from PFOA in water was tested by combining the PFOA decomposition process and calcium precipitation method. The recovery of fluorine is important due to the increasing price of fluorite. The PFC decomposing rate and efficiency were evaluated by measuring the fluorine ions generated in the solution. The decomposing rate for PFOA was slightly higher than that for PFOS. The direct plasma interaction to the solution surfaces appeared to enhance the degradation of PFOA/PFOS. 10 refs., 1 tab., 9 figs.

  5. 气泡尺寸对曝气池内气液两相流数值模拟的影响%Influence of the bubble size on numerical simulation of the gas-liquid flow in aeration tanks

    Institute of Scientific and Technical Information of China (English)

    肖柏青; 张法星; 戎贵文

    2012-01-01

    In order to explore the influence of bubble size on numerical simulation of gas-liquid two-phase flow in aeration tanks, a mathematical model for two-phase flow in aeration tanks was established using large-eddy simulation and Eulerian-Lagrangian approach. Based on the measured bubble size distribution produced by a commonly used membrane diffuser in model experiments, three kinds of bubble size set schemes in numerical simulation were designed. The effect of the different set schemes on the calculation of the flow velocity and gas holdup was studied. Bubble size had a great influence on the flow field in aeration tanks, and had little effect on the gas holdup distribution in most regions except the vicinity of the gas holdup peak; the input of bubble size using multiple size groups instead of a single group improved the prediction of two-phase flow in aeration tanks; when single bubble size was used, it should be as close to the average bubble diameter as possible.%为探索在曝气池气液两相流数值模拟中气泡尺寸对两相流流动特性的影响,采用大涡模拟和欧拉—拉格朗日方法建立了曝气池两相流数学模型.基于模型实验得到的工程上常用的微孔曝气盘的气泡尺寸分布,在数值模拟中设定了3种气泡尺寸分布方案,比较了不同的气泡尺寸设定方案对计算曝气池内水流流速和气含率等参数的影响.结果表明,气泡尺寸对水流流场具有较大的影响,而对气含率分布的影响在大部分区域不明显,只在气含率峰值附近影响较显著;使用多组气泡尺寸的设定方案可以提高计算结果的准确性,采用单组气泡尺寸时应尽量使其接近平均气泡直径.

  6. Bubble Drag Reduction Requires Large Bubbles

    Science.gov (United States)

    Verschoof, Ruben A.; van der Veen, Roeland C. A.; Sun, Chao; Lohse, Detlef

    2016-09-01

    In the maritime industry, the injection of air bubbles into the turbulent boundary layer under the ship hull is seen as one of the most promising techniques to reduce the overall fuel consumption. However, the exact mechanism behind bubble drag reduction is unknown. Here we show that bubble drag reduction in turbulent flow dramatically depends on the bubble size. By adding minute concentrations (6 ppm) of the surfactant Triton X-100 into otherwise completely unchanged strongly turbulent Taylor-Couette flow containing bubbles, we dramatically reduce the drag reduction from more than 40% to about 4%, corresponding to the trivial effect of the bubbles on the density and viscosity of the liquid. The reason for this striking behavior is that the addition of surfactants prevents bubble coalescence, leading to much smaller bubbles. Our result demonstrates that bubble deformability is crucial for bubble drag reduction in turbulent flow and opens the door for an optimization of the process.

  7. Bubble drag reduction requires large bubbles

    CERN Document Server

    Verschoof, Ruben A; Sun, Chao; Lohse, Detlef

    2016-01-01

    In the maritime industry, the injection of air bubbles into the turbulent boundary layer under the ship hull is seen as one of the most promising techniques to reduce the overall fuel consumption. However, the exact mechanism behind bubble drag reduction is unknown. Here we show that bubble drag reduction in turbulent flow dramatically depends on the bubble size. By adding minute concentrations (6 ppm) of the surfactant Triton X-100 into otherwise completely unchanged strongly turbulent Taylor-Couette flow containing bubbles, we dramatically reduce the drag reduction from more than 40% to about 4%, corresponding to the trivial effect of the bubbles on the density and viscosity of the liquid. The reason for this striking behavior is that the addition of surfactants prevents bubble coalescence, leading to much smaller bubbles. Our result demonstrates that bubble deformability is crucial for bubble drag reduction in turbulent flow and opens the door for an optimization of the process.

  8. A Ten Billion Solar Mass Outflow of Molecular Gas Launched by Radio Bubbles in the Abell 1835 Brightest Cluster Galaxy

    CERN Document Server

    McNamara, B R; Nulsen, P E J; Edge, A C; Murray, N W; Main, R A; Vantyghem, A N; Combes, F; Fabian, A C; Salome, P; Kirkpatrick, C C; Baum, S A; Bregman, J N; Donahue, M; Egami, E; Hamer, S; O'Dea, C P; Oonk, J B R; Tremblay, G; Voit, G M

    2013-01-01

    We report ALMA Early Science observations of the Abell 1835 brightest cluster galaxy (BCG) in the CO (3-2) and CO (1-0) emission lines. We detect 5E10 solar masses of molecular gas within 10 kpc of the BCG. Its velocity width of ~130 km/s FWHM is too narrow to be supported by dynamical pressure. The gas may instead be supported in a rotating, turbulent disk oriented nearly face-on. The disk is forming stars at a rate of 100-180 solar masses per year. Roughly 1E10 solar masses of molecular gas is projected 3-10 kpc to the north-west and to the east of the nucleus with line of sight velocities lying between -250 km/s to +480 km/s with respect to the systemic velocity. Although inflow cannot be ruled out, the rising velocity gradient with radius is consistent with a broad, bipolar outflow driven by radio jets or buoyantly rising X-ray cavities. The molecular outflow may be associated with an outflow of hot gas in Abell 1835 seen on larger scales. Molecular gas is flowing out of the BCG at a rate of approximately...

  9. FEASTING BLACK HOLE BLOWS BUBBLES

    Science.gov (United States)

    2002-01-01

    A monstrous black hole's rude table manners include blowing huge bubbles of hot gas into space. At least, that's the gustatory practice followed by the supermassive black hole residing in the hub of the nearby galaxy NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC 4438 is in the Virgo Cluster, 50 million light-years from Earth. These NASA Hubble Space Telescope images of the galaxy's central region clearly show one of the bubbles rising from a dark band of dust. The other bubble, emanating from below the dust band, is barely visible, appearing as dim red blobs in the close-up picture of the galaxy's hub (the colorful picture at right). The background image represents a wider view of the galaxy, with the central region defined by the white box. These extremely hot bubbles are caused by the black hole's voracious eating habits. The eating machine is engorging itself with a banquet of material swirling around it in an accretion disk (the white region below the bright bubble). Some of this material is spewed from the disk in opposite directions. Acting like high-powered garden hoses, these twin jets of matter sweep out material in their paths. The jets eventually slam into a wall of dense, slow-moving gas, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The bubbles will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this bubble-blowing phase is a short-lived event. The bubble is much brighter on one side of the galaxy's center because the jet smashed into a denser amount of gas. The brighter bubble is 800 light-years tall and 800 light-years across. The observations are being presented June 5 at the American Astronomical Society meeting in Rochester, N.Y. Both pictures were taken March 24, 1999 with the Wide Field and Planetary Camera 2. False colors were used to enhance the details of the bubbles. The red regions in the picture denote the hot gas

  10. A Radiative Transfer Modeling Methodology in Gas-Liquid Multiphase Flow Simulations

    Directory of Open Access Journals (Sweden)

    Gautham Krishnamoorthy

    2014-01-01

    Full Text Available A methodology for performing radiative transfer calculations in computational fluid dynamic simulations of gas-liquid multiphase flows is presented. By considering an externally irradiated bubble column photoreactor as our model system, the bubble scattering coefficients were determined through add-on functions by employing as inputs the bubble volume fractions, number densities, and the fractional contribution of each bubble size to the bubble volume from four different multiphase modeling options. The scattering coefficient profiles resulting from the models were significantly different from one another and aligned closely with their predicted gas-phase volume fraction distributions. The impacts of the multiphase modeling option, initial bubble diameter, and gas flow rates on the radiation distribution patterns within the reactor were also examined. An increase in air inlet velocities resulted in an increase in the fraction of larger sized bubbles and their contribution to the scattering coefficient. However, the initial bubble sizes were found to have the strongest impact on the radiation field.

  11. Blowing bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Casteel, K.

    1999-04-01

    The article, based on a series of interviews with column flotation equipment suppliers, reviews and comments on the progress of bubble generator design. Developments mentioned include the Air/Water sparger from Cominco, the SparJet and SlamJet from CPT, the CISA sparger from Sevala CISA, Microcel flotation columns from Birtley Engineering, Flotaire column flotation cells from LMC International, and the Variable Gap Sparger from MinnovEX. 1 fig., 2 photo.

  12. Interaction of cavitation bubbles on a wall

    NARCIS (Netherlands)

    Bremond, Nicolas; Arora, Manish; Dammer, Stephan M.; Lohse, Detlef

    2006-01-01

    We report experimental and numerical investigations on the dynamics of the cavitation of bubbles on a solid surface and the interaction between them with the help of controlled cavitation nuclei: hemispherical bubbles are nucleated from hydrophobic microcavities that act as gas traps when the substr

  13. Compressible gas gills of diving insects: measurements and models.

    Science.gov (United States)

    Matthews, Philip G D; Seymour, Roger S

    2010-05-01

    Many diving insects collect a bubble of air from the surface to supply their oxygen requirements while submerged. It has been theorised that these air bubbles may also act as compressible gas gills, as the low oxygen partial pressure P(O(2))within the bubble caused by the insect's respiration creates a gradient capable of driving the diffusion of oxygen from the water into the bubble. Under these conditions nitrogen diffuses in the opposite direction, resulting in a situation where the volume of the bubble is continually shrinking while oxygen is obtained. This study measures changes in volume and P(O(2)) within the gas gills held by a tethered water bug, Agraptocorixa eurynome. Both gill volume and P(O(2)) drop rapidly at the beginning of a dive, but eventually the P(O(2)) reaches an apparently stable level while volume continually declines at a slower rate. Active ventilation of the gill is crucial to maintaining oxygen uptake. These measurements are used to calculate oxygen flux into the gas gill and the oxygen consumption rate V(O(2)) of the bug. The effectiveness of a gas gill as a respiratory organ is also demonstrated by determining the critical P(O(2)) of the water bug and comparing this with measured gas gill P(O(2)) and calculated V(O(2)) .

  14. Hot-gas cleanup system model development. Volume I. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ushimaru, K.; Bennett, A.; Bekowies, P.J.

    1982-11-01

    This two-volume report summarizes the state of the art in performance modeling of advanced high-temperature, high-pressure (HTHP) gas cleanup devices. Volume I contains the culmination of the research effort carried over the past 12 months and is a summary of research achievements. Volume II is the user's manual for the computer programs developed under the present research project. In this volume, Section 2 presents background information on pressurized, fluidized-bed combustion concepts, a description of the role of the advanced gas cleanup systems, and a list of advanced gas cleanup systems that are currently in development under DOE sponsorship. Section 3 describes the methodology for the software architecture that forms the basis of the well-disciplined and structured computer programs developed under the present project. Section 4 reviews the fundamental theories that are important in analyzing the cleanup performance of HTHP gas filters. Section 5 discusses the effect of alkali agents in HTHP gas cleanup. Section 6 evaluates the advanced HTHP gas cleanup models based on their mathematical integrity, availability of supporting data, and the likelihood of commercialization. As a result of the evaluation procedure detailed in Section 6, five performance models were chosen to be incorporated into the overall system simulation code, ASPEN. These five models (the electrocyclone, ceramic bag filter, moving granular bed filter, electrostatic granular bed filter, and electrostatic precipitator) are described in Section 7. The method of cost projection for these five models is discussed in Section 8. The supporting data and validation of the computer codes are presented in Section 9, and finally the conclusions and recommendations for the HTHP gas cleanup system model development are given in Section 10. 72 references, 19 figures, 25 tables.

  15. Bubble burst as jamming phase transition

    CERN Document Server

    Nishinari, Katsuhiro; Saito, Yukiko Umeno; Watanabe, Tsutomu

    2010-01-01

    Recently research on bubble and its burst attract much interest of researchers in various field such as economics and physics. Economists have been regarding bubble as a disorder in prices. However, this research strategy has overlooked an importance of the volume of transactions. In this paper, we have proposed a bubble burst model by focusing the transactions incorporating a traffic model that represents spontaneous traffic jam. We find that the phenomenon of bubble burst shares many similar properties with traffic jam formation by comparing data taken from US housing market. Our result suggests that the transaction could be a driving force of bursting phenomenon.

  16. Gas permeation measurement under defined humidity via constant volume/variable pressure method

    KAUST Repository

    Jan Roman, Pauls

    2012-02-01

    Many industrial gas separations in which membrane processes are feasible entail high water vapour contents, as in CO 2-separation from flue gas in carbon capture and storage (CCS), or in biogas/natural gas processing. Studying the effect of water vapour on gas permeability through polymeric membranes is essential for materials design and optimization of these membrane applications. In particular, for amine-based CO 2 selective facilitated transport membranes, water vapour is necessary for carrier-complex formation (Matsuyama et al., 1996; Deng and Hägg, 2010; Liu et al., 2008; Shishatskiy et al., 2010) [1-4]. But also conventional polymeric membrane materials can vary their permeation behaviour due to water-induced swelling (Potreck, 2009) [5]. Here we describe a simple approach to gas permeability measurement in the presence of water vapour, in the form of a modified constant volume/variable pressure method (pressure increase method). © 2011 Elsevier B.V.

  17. Mechanisms of single bubble cleaning.

    Science.gov (United States)

    Reuter, Fabian; Mettin, Robert

    2016-03-01

    The dynamics of collapsing bubbles close to a flat solid is investigated with respect to its potential for removal of surface attached particles. Individual bubbles are created by nanosecond Nd:YAG laser pulses focused into water close to glass plates contaminated with melamine resin micro-particles. The bubble dynamics is analysed by means of synchronous high-speed recordings. Due to the close solid boundary, the bubble collapses with the well-known liquid jet phenomenon. Subsequent microscopic inspection of the substrates reveals circular areas clean of particles after a single bubble generation and collapse event. The detailed bubble dynamics, as well as the cleaned area size, is characterised by the non-dimensional bubble stand-off γ=d/Rmax, with d: laser focus distance to the solid boundary, and Rmax: maximum bubble radius before collapse. We observe a maximum of clean area at γ≈0.7, a roughly linear decay of the cleaned circle radius for increasing γ, and no cleaning for γ>3.5. As the main mechanism for particle removal, rapid flows at the boundary are identified. Three different cleaning regimes are discussed in relation to γ: (I) For large stand-off, 1.8substrate and remove particles without significant contact of the gas phase. (II) For small distances, γsubstrate are driven by the jet impact with its subsequent radial spreading, and by the liquid following the motion of the collapsing and rebounding bubble wall. Both flows remove particles. Their relative timing, which depends sensitively on the exact γ, appears to determine the extension of the area with forces large enough to cause particle detachment. (III) At intermediate stand-off, 1.1substrate, but acts with cleaning mechanisms similar to an effective small γ collapse: particles are removed by the jet flow and the flow induced by the bubble wall oscillation. Furthermore, the observations reveal that the extent of direct bubble gas phase contact to the solid is partially smaller than the

  18. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 13: CHEMICAL INJECTION PUMPS

    Science.gov (United States)

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  19. Modelling dynamic liquid-gas systems: Extensions to the volume-of-fluid solver

    CSIR Research Space (South Africa)

    Heyns, Johan A

    2013-06-01

    Full Text Available This study presents the extension of the volume-of-fluid solver, interFoam, for improved accuracy and efficiency when modelling dynamic liquid-gas systems. Examples of these include the transportation of liquids, such as in the case of fuel carried...

  20. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 12: PNEUMATIC DEVICES

    Science.gov (United States)

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  1. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 11: COMPRESSOR DRIVER EXHAUST

    Science.gov (United States)

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  2. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 7: BLOW AND PURGE ACTIVITIES

    Science.gov (United States)

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  3. Bubble Growth in Lunar Basalts

    Science.gov (United States)

    Zhang, Y.

    2009-05-01

    Although Moon is usually said to be volatile-"free", lunar basalts are often vesicular with mm-size bubbles. The vesicular nature of the lunar basalts suggests that they contained some initial gas concentration. A recent publication estimated volatile concentrations in lunar basalts (Saal et al. 2008). This report investigates bubble growth on Moon and compares with that on Earth. Under conditions relevant to lunar basalts, bubble growth in a finite melt shell (i.e., growth of multiple regularly-spaced bubbles) is calculated following Proussevitch and Sahagian (1998) and Liu and Zhang (2000). Initial H2O content of 700 ppm (Saal et al. 2008) or lower is used and the effect of other volatiles (such as carbon dioxide, halogens, and sulfur) is ignored. H2O solubility at low pressures (Liu et al. 2005), concentration-dependent diffusivity in basalt (Zhang and Stolper 1991), and lunar basalt viscosity (Murase and McBirney 1970) are used. Because lunar atmospheric pressure is essentially zero, the confining pressure on bubbles is completely supplied by the overlying magma. Due to low H2O content in lunar basaltic melt (700 ppm H2O corresponds to a saturation pressure of 75 kPa), H2O bubbles only grow in the upper 16 m of a basalt flow or lake. A depth of 20 mm corresponds to a confining pressure of 100 Pa. Hence, vesicular lunar rocks come from very shallow depth. Some findings from the modeling are as follows. (a) Due to low confining pressure as well as low viscosity, even though volatile concentration is very low, bubble growth rate is extremely high, much higher than typical bubble growth rates in terrestrial melts. Hence, mm-size bubbles in lunar basalts are not strange. (b) Because the pertinent pressures are so low, bubble pressure due to surface tension plays a main role in lunar bubble growth, contrary to terrestrial cases. (c) Time scale to reach equilibrium bubble size increases as the confining pressure increases. References: (1) Liu Y, Zhang YX (2000) Earth

  4. Model documentation Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-26

    The Natural Gas Transmission and Distribution Model (NGTDM) of the National Energy Modeling System is developed and maintained by the Energy Information Administration (EIA), Office of Integrated Analysis and Forecasting. This report documents the archived version of the NGTDM that was used to produce the natural gas forecasts presented in the Annual Energy Outlook 1996, (DOE/EIA-0383(96)). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic approach, and provides detail on the methodology employed. Previously this report represented Volume I of a two-volume set. Volume II reported on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.

  5. Mechanism of bubble detachment from vibrating walls

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongjun; Park, Jun Kwon, E-mail: junkeun@postech.ac.kr; Kang, Kwan Hyoung [Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of); Kang, In Seok [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of)

    2013-11-15

    We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.

  6. The effect of dissolve gas concentration in the initial growth stage of multi cavitation bubbles. Differences between vacuum degassing and ultrasound degassing.

    Science.gov (United States)

    Yanagida, Hirotaka

    2008-04-01

    The sonochemical luminescence intensity from luminol was measured at a sampling rate of several kilohertz. This was noted at three different periods: first, the latent period in which no light emission occurs at all; second, the increased emission period from the start of light emission to the time when a steady state is reached; and third, the steady state period in which light emission occurs at the steady state value. When irradiated with ultrasound of different intensities, the times of the latent period and increased emission period are shorter for higher ultrasound intensities. To know how the dissolved oxygen content is involved in early-stage cavitation growth, an experiment was conducted using solutions with varying dissolved oxygen contents from 100% to 37%. For dissolved air content of 50% or less, it was found that the latent period was 30 times longer in a saturated condition. It was also found that the increased emission period was 10 times longer. However, the emission intensity in the steady state did not change at all even when the initial dissolved gas concentration of the sample was changed. From this, it was found that the reuse of collapsed bubbles takes place efficiently in the steady state. Dissolved oxygen was reduced by the use of a vacuum pump and by the degassing action of ultrasound, and it was discovered that the behavior of transient emission differed for the two ways of degassing.

  7. THE VISCOUS TO BRITTLE TRANSITION IN CRYSTAL- AND BUBBLE-BEARING MAGMAS

    Directory of Open Access Journals (Sweden)

    Mattia ePistone

    2015-11-01

    Full Text Available The transition from viscous to brittle behaviour in magmas plays a decisive role in determining the style of volcanic eruptions. While this transition has been determined for one- or two-phase systems, it remains poorly constrained for natural magmas containing silicic melt, crystals, and gas bubbles. Here we present new experimental results on shear-induced fracturing of three-phase magmas obtained at high-temperature (673-1023 K and high-pressure (200 MPa conditions over a wide range of strain-rates (5·10-6 s-1 to 4·10-3 s-1. During the experiments bubbles are deformed (i.e. capillary number are in excess of 1 enough to coalesce and generate a porous network that potentially leads to outgassing. A physical relationship is proposed that quantifies the critical stress required for magmas to fail as a function of both crystal (0.24 to 0.65 and bubble volume fractions (0.09 to 0.12. The presented results demonstrate efficient outgassing for low crystal fraction ( 0.44 promote gas bubble entrapment and inhibit outgassing. The failure of bubble-free, crystal-bearing systems is enhanced by the presence of bubbles that lower the critical failure stress in a regime of efficient outgassing, while the failure stress is increased if bubbles remain trapped within the crystal framework. These contrasting behaviours have direct impact on the style of volcanic eruptions. During magma ascent, efficient outgassing reduces the potential for an explosive eruption and favours brittle behaviour, contributing to maintain low overpressures in an active volcanic system resulting in effusion or rheological flow blockage of magma at depth. Conversely, magmas with high crystallinity experience limited loss of exsolved gas, permitting the achievement of larger overpressures prior to a potential sudden transition to brittle behaviour, which could result in an explosive volcanic eruption.

  8. Manipulating bubbles with secondary Bjerknes forces

    Energy Technology Data Exchange (ETDEWEB)

    Lanoy, Maxime [Institut Langevin, ESPCI ParisTech, CNRS (UMR 7587), PSL Research University, 1 rue Jussieu, 75005 Paris (France); Laboratoire Matière et Systèmes Complexes, Université Paris-Diderot, CNRS (UMR 7057), 10 rue Alice Domon et Léonie Duquet, 75013 Paris (France); Derec, Caroline; Leroy, Valentin [Laboratoire Matière et Systèmes Complexes, Université Paris-Diderot, CNRS (UMR 7057), 10 rue Alice Domon et Léonie Duquet, 75013 Paris (France); Tourin, Arnaud [Institut Langevin, ESPCI ParisTech, CNRS (UMR 7587), PSL Research University, 1 rue Jussieu, 75005 Paris (France)

    2015-11-23

    Gas bubbles in a sound field are submitted to a radiative force, known as the secondary Bjerknes force. We propose an original experimental setup that allows us to investigate in detail this force between two bubbles, as a function of the sonication frequency, as well as the bubbles radii and distance. We report the observation of both attractive and, more interestingly, repulsive Bjerknes force, when the two bubbles are driven in antiphase. Our experiments show the importance of taking multiple scatterings into account, which leads to a strong acoustic coupling of the bubbles when their radii are similar. Our setup demonstrates the accuracy of secondary Bjerknes forces for attracting or repealing a bubble, and could lead to new acoustic tools for noncontact manipulation in microfluidic devices.

  9. Armoring confined bubbles in concentrated colloidal suspensions

    Science.gov (United States)

    Yu, Yingxian; Khodaparast, Sepideh; Stone, Howard

    2016-11-01

    Encapsulation of a bubble with microparticles is known to significantly improve the stability of the bubble. This phenomenon has recently gained increasing attention due to its application in a variety of technologies such as foam stabilization, drug encapsulation and colloidosomes. Nevertheless, the production of such colloidal armored bubble with controlled size and particle coverage ratio is still a great challenge industrially. We study the coating process of a long air bubble by microparticles in a circular tube filled with a concentrated microparticles colloidal suspension. As the bubble proceeds in the suspension of particles, a monolayer of micro-particles forms on the interface of the bubble, which eventually results in a fully armored bubble. We investigate the phenomenon that triggers and controls the evolution of the particle accumulation on the bubble interface. Moreover, we examine the effects of the mean flow velocity, the size of the colloids and concentration of the suspension on the dynamics of the armored bubble. The results of this study can potentially be applied to production of particle-encapsulated bubbles, surface-cleaning techniques, and gas-assisted injection molding.

  10. Bioinspired bubble design for particle generation.

    Science.gov (United States)

    Gunduz, Oguzhan; Ahmad, Zeeshan; Stride, Eleanor; Tamerler, Candan; Edirisinghe, Mohan

    2012-02-07

    In this study, we devise a method to generate homogeneous particles from a bubble suspension, with the capability to control loading and the structure of bubbles. Ideally, a process such as this would occur at the interface between daughter bubble formation (instant) and gaseous diffusion (gradual). Interestingly, the budding mechanism in micro-organisms is one that demonstrates features of the desired phenomena (although at a much slower rate), as viruses can eject and evolve structures from their membranes. With these natural concepts, a bubble's surface can also be made to serve as a platform for particle generation, which transfers significant elements from the initial bubble coating to the newly generated structures. Here, we illustrate this by preparing coated bubbles (approx. 150 µm in diameter) using a hydrophobic polymer, which may be comparable to naturally occurring bubble coatings (e.g. organic matter forming part of bubble coatings in the sea), and dye (which can demonstrate entrapment of smaller quantities of a desired moiety) and then observe particle generation (approx. 500 nm). The process, which may be driven by a polymerosome-forming mechanism, also illustrates how additional uniform sub-micrometre-scale structures may form from a bubble's surface, which may have also previously been attributed to gas diffusion. In addition, such methods of particle formation from a bubble structure, the incorporation of chemical or biological media via an in situ process and subsequent release technologies have several areas of interest across the broad scientific community.

  11. Neutron Imaging study of bubble behaviors in Nanofluid Through Engineered Orifices

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Seok Bin; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Kim, Tae Joo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Most studies focused on the change of surface parameters through deposited nanoparticles, while Vafaei and Wen firstly discussed modification of bubble dynamics by dispersed nanoparticles in fluid as well as deposited ones. The boiling mechanism, as an effective heat transfer mode, includes bubble generation, growth, departure, and coalescence. Therefore the change of bubble dynamics can lead to the change of boiling heat transfer condition. That is, not only surface characteristics but the dispersed nanoparticles would be the essential parameters of boiling mechanism in terms of bubble dynamics. For advanced visualization of opaque fluids, the neutron imaging technique is introduced. In the present study, the bubble dynamics in nanofluid through engineered orifices was studied. The main parameters of engineered orifices are size and geometry. Photographic analysis of bubble departure frequency and averaged bubble departure volume provides as follows: With increasing orifice diameter, averaged bubble departure volume increases, while bubble departure frequency decreases. The results are attributed to enhanced capillary force by increasing contact perimeter. Averaged bubble departure volume and bubble departure frequency remain similar for three different types of orifices. But edges of the triangle and square orifice produce small bubbles which interrupts bubble generation. The converged triple contact line due to the edge may be a reason for the emerged baby bubbles. Nanofluid shows less averaged bubble departure volume and higher bubble departure frequency. Considering little change in physical properties of the fluid, interaction between bubble interface and nanoparticles may be in charge of the results.

  12. Molecular dynamics study of helium bubble pressure in titanium

    Institute of Scientific and Technical Information of China (English)

    Zhang Bao-Ling; Wang Jun; Hou Qing

    2011-01-01

    In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics (MD) method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble pressure and helium/vacancy ratio; then the dependences of the helium bubble pressure on the bubble radius at different temperatures are studied. It is shown that the product of the bubble pressure and the radius is approximately a constant, a result justifying the pressure-radius relation predicted by thermodynamics-based theory for gas bubble. Furthermore, a state equation of the helium bubble is established based on the MD calculations. Comparison between the results obtained by the state equation and corresponding experimental data shows that the state equation can describe reasonably the state of helium bubble and thus could be used for Monte Carlo simulations of the evolution of helium bubble in metals.

  13. Dynamics of Fe-Ni Bubbles in Young Supernova Remnants

    CERN Document Server

    Blondin, J M; Reynolds, S P

    2001-01-01

    Observations of core-collapse supernovae (SNe) have revealed the presence of extensive mixing of radioactive material in SN ejecta. The mixing of radioactive material, mostly freshly synthesized Ni, is not complete, which leads to a two-phase SN ejecta structure. The low-density phase consists of Fe bubbles, created by the energy input from radioactive Co and Ni, surrounded by compressed high-density metal-rich ejecta. We report on the theoretical investigation of supernova remnant (SNR) dynamics with the two-phase SN ejecta. We first present 3-dimensional hydrodynamic simulations of a single Fe bubble immersed in an outer ejecta envelope, and compare the results with previous work on shock-cloud interactions. We then consider randomly distributed Fe bubbles with an average volume filling fraction of 1/2. We find that the presence of Fe bubbles leads to vigorous turbulence and mixing of Fe with other heavy elements and with the ambient normal-abundance gas. The turbulent energy can be an order of magnitude la...

  14. Two-dimensional investigation of forced bubble oscillation under microgravity

    Institute of Scientific and Technical Information of China (English)

    HONG Ruoyu; Masahiro KAWAJI

    2003-01-01

    Recent referential studies of fluid interfaces subjected to small vibration under microgravity conditions are reviewed. An experimental investigation was carried out aboard the American Space Shuttle Discovery. Two-dimensional (2-D) modeling and simulation were conducted to further understand the experimental results. The oscillation of a bubble in fluid under surface tension is governed by the incompressible Navier-Stokes equations. The SIMPLEC algorithm was used to solve the partial differential equations on an Eulerian mesh in a 2-D coordinate. Free surfaces were represented with the volume of fluid (VOF) obtained by solving a kinematic equation. Surface tension was modeled via a continuous surface force (CSF) algorithm that ensures robustness and accuracy. A new surface reconstruction scheme, alternative phase integration (API) scheme, was adopted to solve the kinematic equation, and was compared with referential schemes. Numerical computations were conducted to simulate the transient behavior of an oscillating gas bubble in mineral oil under different conditions. The bubble positions and shapes under different external vibrations were obtained numerically. The computed bubble oscillation amplitudes were compared with experimental data.

  15. Temperature measurements in cavitation bubbles

    Science.gov (United States)

    Coutier-Delgosha, Olivier

    2016-11-01

    Cavitation is usually a nearly isothermal process in the liquid phase, but in some specific flow conditions like hot water or cryogenic fluids, significant temperature variations are detected. In addition, a large temperature increase happens inside the cavitation bubbles at the very end of their collapse, due to the fast compression of the gas at the bubble core, which is almost adiabatic. This process is of primary interest in various biomedical and pharmaceutical applications, where the mechanisms of bubble collapse plays a major role. To investigate the amplitude and the spatial distribution of these temperature variations inside and outside the cavitation bubbles, a system based on cold wires has been developed. They have been tested in a configuration of a single bubble obtained by submitting a small air bubble to a large amplitude pressure wave. Some promising results have been obtained after the initial validation tests. This work is funded by the Office of Naval Research Global under Grant N62909-16-1-2116, Dr. Salahuddin Ahmed & Ki-Han Kim program managers.

  16. The effects of different syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin

    Science.gov (United States)

    Küme, Tuncay; Şişman, Ali Rıza; Solak, Ahmet; Tuğlu, Birsen; Çinkooğlu, Burcu; Çoker, Canan

    2012-01-01

    Introductıon: We evaluated the effect of different syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin. Materials and methods: In this multi-step experimental study, percent dilution ratios (PDRs) and final heparin concentrations (FHCs) were calculated by gravimetric method for determining the effect of syringe volume (1, 2, 5 and 10 mL), needle size (20, 21, 22, 25 and 26 G) and sample volume (0.5, 1, 2, 5 and 10 mL). The effect of different PDRs and FHCs on blood gas and electrolyte parameters were determined. The erroneous results from nonstandardized sampling were evaluated according to RiliBAK’s TEa. Results: The increase of PDRs and FHCs was associated with the decrease of syringe volume, the increase of needle size and the decrease of sample volume: from 2.0% and 100 IU/mL in 10 mL-syringe to 7.0% and 351 IU/mL in 1 mL-syringe; from 4.9% and 245 IU/mL in 26G to 7.6% and 380 IU/mL in 20 G with combined 1 mL syringe; from 2.0% and 100 IU/mL in full-filled sample to 34% and 1675 IU/mL in 0.5 mL suctioned sample into 10 mL-syringe. There was no statistical difference in pH; but the percent decreasing in pCO2, K+, iCa2+, iMg2+; the percent increasing in pO2 and Na+ were statistical significance compared to samples full-filled in syringes. The all changes in pH and pO2 were acceptable; but the changes in pCO2, Na+, K+ and iCa2+ were unacceptable according to TEa limits except fullfilled-syringes. Conclusions: The changes in PDRs and FHCs due nonstandardized sampling in syringe washed with liquid heparin give rise to erroneous test results for pCO2 and electrolytes. PMID:22838185

  17. Electrolysis Bubbles Make Waterflow Visible

    Science.gov (United States)

    Schultz, Donald F.

    1990-01-01

    Technique for visualization of three-dimensional flow uses tiny tracer bubbles of hydrogen and oxygen made by electrolysis of water. Strobe-light photography used to capture flow patterns, yielding permanent record that is measured to obtain velocities of particles. Used to measure simulated mixing turbulence in proposed gas-turbine combustor and also used in other water-table flow tests.

  18. Three-dimensional simulations of a rising bubble in a self-rewetting fluid

    Science.gov (United States)

    Premlata, Amarnath; Tripathi, Manoj; Sahu, Kirti; Karapetsas, George; Sefiane, Khellil; Matar, Omar

    2015-11-01

    The motion of a gas bubble in a square channel with linearly increasing temperature in the vertical direction is investigated via 3D numerical simulations. The channel contains a so-called ``self-rewetting'' fluid whose surface tension exhibits a parabolic dependence on temperature with a well-defined minimum. An open-source finite-volume fluid flow solver, Gerris, is used with a dynamic adaptive grid refinement technique, based on the vorticity magnitude and position of the interface. We find that in self-rewetting fluids, the buoyancy-induced upward motion of the bubble is retarded by a thermocapillary-driven flow, which occurs as the bubble crosses the location at which the surface tension is minimum. The bubble then migrates downwards when thermocapillarity exceeds buoyancy. In its downward path, the bubble encounters regions of horizontal temperature gradients, which lead to bubble motion towards one of the channel walls. These phenomena are observed at sufficiently small Bond numbers and have no analogue for fluids whose surface tension decreases linearly with temperature. The mechanisms underlying these phenomena are elucidated by considering how the surface tension dependence on temperature affects the thermocapillary stresses in the flow. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  19. Bubble Pinch-Off in a Rotating Flow

    DEFF Research Database (Denmark)

    Bergmann, Raymond; Andersen, Anders Peter; van der Meer, Devaraj

    2009-01-01

    We create air bubbles at the tip of a "bathtub vortex" which reaches to a finite depth. The bathtub vortex is formed by letting water drain through a small hole at the bottom of a rotating cylindrical container. The tip of the needlelike surface dip is unstable at high rotation rates and releases...... bubbles which are carried down by the flow. Using high-speed imaging we find that the minimal neck radius of the unstable tip decreases in time as a power law with an exponent close to 1/3. This exponent was found by Gordillo et al. [Phys. Rev. Lett. 95, 194501 (2005)] to govern gas flow driven pinch......-off, and indeed we find that the volume oscillations of the tip creates a considerable air flow through the neck. We argue that the Bernoulli pressure reduction caused by this air flow can become sufficient to overcome the centrifugal forces and cause the final pinch-off....

  20. Circulation in gas-slurry column reactors

    Energy Technology Data Exchange (ETDEWEB)

    Clark, N.; Kuhlman, J.; Celik, I.; Gross, R.; Nebiolo, E.; Wang, Yi-Zun.

    1990-08-15

    Circulation in bubble columns, such as those used in fischer-tropsch synthesis, detracts from their performance in that gas is carried on average more rapidly through the column, and the residence time distribution of the gas in the column is widened. Both of these factors influence mass-transfer operations in bubble columns. Circulation prediction and measurement has been undertaken using probes, one-dimensional models, laser Doppler velocimetry, and numerical modeling. Local void fraction was measured using resistance probes and a newly developed approach to determining air/water threshold voltage for the probe. A tall column of eight inch diameter was constructed of Plexiglas and the distributor plate was manufactured to distribute air evenly through the base of the column. Data were gathered throughout the volume at three different gas throughputs. Bubble velocities proved difficult to measure using twin probes with cross-correlation because of radial bubble movement. A series of three-dimensional mean and RMS bubble and liquid velocity measurements were also obtained for a turbulent flow in a laboratory model of a bubble column. These measurements have been made using a three-component laser Doppler velocimeter (LDV), to determine velocity distributions non-intrusively. Finally, the gas-liquid flow inside a vertically situated circular isothermal column reactor was simulated numerically. 74 refs., 170 figs., 5 tabs.

  1. Free volumes and gas transport in polymers: amine-modified epoxy resins as a case study.

    Science.gov (United States)

    Patil, Pushkar N; Roilo, David; Brusa, Roberto S; Miotello, Antonio; Aghion, Stefano; Ferragut, Rafael; Checchetto, Riccardo

    2016-02-07

    The CO2 transport process was studied in a series of amine-modified epoxy resins having different cross-linking densities but the same chemical environment for the penetrant molecules. Positron Annihilation Lifetime Spectroscopy (PALS) was used to monitor the free volume structure of the samples and experimentally evaluate their fractional free volume fh(T) and its temperature evolution. The analysis of the free volume hole size distribution showed that all the holes have a size large enough to accommodate the penetrant molecules at temperatures T above the glass transition temperature Tg. The measured gas diffusion constants at T > Tg have been reproduced in the framework of the free volume theory of diffusion using a novel procedure based on the use of fh(T) as an input experimental parameter.

  2. Development of Parametric Mass and Volume Models for an Aerospace SOFC/Gas Turbine Hybrid System

    Science.gov (United States)

    Tornabene, Robert; Wang, Xiao-yen; Steffen, Christopher J., Jr.; Freeh, Joshua E.

    2005-01-01

    In aerospace power systems, mass and volume are key considerations to produce a viable design. The utilization of fuel cells is being studied for a commercial aircraft electrical power unit. Based on preliminary analyses, a SOFC/gas turbine system may be a potential solution. This paper describes the parametric mass and volume models that are used to assess an aerospace hybrid system design. The design tool utilizes input from the thermodynamic system model and produces component sizing, performance, and mass estimates. The software is designed such that the thermodynamic model is linked to the mass and volume model to provide immediate feedback during the design process. It allows for automating an optimization process that accounts for mass and volume in its figure of merit. Each component in the system is modeled with a combination of theoretical and empirical approaches. A description of the assumptions and design analyses is presented.

  3. A method for measurement of the bubble formation threshold in biological liquids.

    Science.gov (United States)

    Bjorno, L; Kornum, L O; Krag, P; Nielsen, C H; Paulev, P E

    1977-06-01

    Liquid under pressure is saturated with a given gas, such as argon, nitrogen, or air, by circulation through a column of gas exchangers. A sample of the gas-saturated liquid is isolated in a test chamber, the volume of which can be increased by means of a moving piston. The piston motion is cyclical with a variable frequency. Pressure in the test chamber is measured by means of a capacitive pressure pick-up. When the volume increase of the gas-saturated liquid in the test chamber is compensated for by the development of gas phase bubbles, the pressure decrease will stop; the recording device will show a pressure plateau, or a dip in the pressure-time course, depending on the velocity of the growth of the bubbles. Bubble formation threshold was independent of the frequency of the piston movement within frequency limits from 1 Hz down to 10(-3) Hz. Most experiements were carried out at a single frequency of 0.5 Hz. This new method appears to have advantages over previous ones.

  4. Sensitivity of a bubble growth to the cheese material properties during ripening

    Science.gov (United States)

    Fokoua, G.; Grenier, D.; Lucas, T.

    2016-10-01

    In this study, a model of transport phenomena describes a single bubble growth in semi-hard cheese. Carbon dioxide production, its transport to the bubble interface, equilibrium laws and mechanics were coupled. Semi-hard cheese mainly behaves as elastic when loads are quickly applied to a piece of cheese like during chewing (few seconds). However, when slowly loaded with increasing gas pressure during ripening in warm room, the mechanical cheese behavior can be simply modelled as a viscous material (Grenier et al. [9]). It is true, as long as viscosity remains low compared to the rate of gas production. This paper investigates a wider range of viscosity (from core η = 6.32 × 107 Pa.s to rind η = 2.88 × 108 Pa.s) than that used in previous studies. FEM simulations have shown that higher viscosities encountered close to the rind of a cheese block can partly explain the increase in gas pressure within bubbles from the core to the rind (up to 3.4 kPa). These results confirm that mechanics does not really control the evolution of bubble volume in cheese. However, mechanics can explain greater pressure observed close to the rind even if gas production is lower than at core.

  5. Two-Phase Flow in Packed Columns and Generation of Bubbly Suspensions for Chemical Processing in Space

    Science.gov (United States)

    Motil, Brian J.; Green, R. D.; Nahra, H. K.; Sridhar, K. R.

    2000-01-01

    For long-duration space missions, the life support and In-Situ Resource Utilization (ISRU) systems necessary to lower the mass and volume of consumables carried from Earth will require more sophisticated chemical processing technologies involving gas-liquid two-phase flows. This paper discusses some preliminary two-phase flow work in packed columns and generation of bubbly suspensions, two types of flow systems that can exist in a number of chemical processing devices. The experimental hardware for a co-current flow, packed column operated in two ground-based low gravity facilities (two-second drop tower and KC- 135 low-gravity aircraft) is described. The preliminary results of this experimental work are discussed. The flow regimes observed and the conditions under which these flow regimes occur are compared with the available co-current packed column experimental work performed in normal gravity. For bubbly suspensions, the experimental hardware for generation of uniformly sized bubbles in Couette flow in microgravity conditions is described. Experimental work was performed on a number of bubbler designs, and the capillary bubble tube was found to produce the most consistent size bubbles. Low air flow rates and low Couette flow produce consistent 2-3 mm bubbles, the size of interest for the "Behavior of Rapidly Sheared Bubbly Suspension" flight experiment. Finally the mass transfer implications of these two-phase flows is qualitatively discussed.

  6. Quantitative measurement of regional lung gas volume by synchrotron radiation computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Monfraix, Sylvie [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble (France); Bayat, Sam [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble (France); Porra, Liisa [Department of Physical Sciences, University of Helsinki, POB 64, FIN-00014 Helsinki (Finland); Berruyer, Gilles [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble (France); Nemoz, Christian [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble (France); Thomlinson, William [Canadian Light Source, 101 Perimeter Road, Saskatoon, SK S7N 0X4 (Canada); Suortti, Pekka [Department of Physical Sciences, University of Helsinki, POB 64, FIN-00014 Helsinki (Finland); Sovijaervi, Anssi R A [Department of Clinical Physiology and Nuclear Medicine, Helsinki University Central Hospital, POB 340, FIN-00029 HUS, Helsinki (Finland)

    2005-01-07

    The aim of this study was to assess the feasibility of a novel respiration-gated spiral synchrotron radiation computed tomography (SRCT) technique for direct quantification of absolute regional lung volumes, using stable xenon (Xe) gas as an inhaled indicator. Spiral SRCT with K-edge subtraction using two monochromatic x-ray beams was used to visualize and directly quantify inhaled Xe concentrations and airspace volumes in three-dimensional (3D) reconstructed lung images. Volume measurements were validated using a hollow Xe-filled phantom. Spiral images spanning 49 mm in lung height were acquired following 60 breaths of an 80% Xe-20% O{sub 2} gas mixture, in two anaesthetized and mechanically ventilated rabbits at baseline and after histamine aerosol inhalation. Volumetric images of 20 mm lung sections were obtained at functional residual capacity (FRC) and at end-inspiration. 3D images showed large patchy filling defects in peripheral airways and alveoli following histamine provocation. Local specific lung compliance was calculated based on FRC/end-inspiration images in normal lung. This study demonstrates spiral SRCT as a new technique for direct determination of regional lung volume, offering possibilities for non-invasive investigation of regional lung function and mechanics, with a uniquely high spatial resolution. An example of non-uniform volume distribution in rabbit lung following histamine inhalation is presented.

  7. Hot and Dense Hadron Gas (HG): A New Excluded-volume approach

    CERN Document Server

    Tiwari, S K

    2013-01-01

    We formulate a thermodynamically consistent equation of state (EOS), based on excluded-volume approach, for a hot, dense hadron gas (HG). We calculate various thermodynamical quantities of HG and various hadron ratios and compare our model results with the results of other excluded-volume models and experimental data. We also calculate various transport coefficients such as $\\eta/s$ etc. and compare them with other HG model results. Furthermore, we test the validity of our model in getting the rapidity spectra of various hadrons and the effect of flow on them is investigated by matching our predictions with the experimental data.

  8. Gas content of Gladys McCall reservoir brine

    Energy Technology Data Exchange (ETDEWEB)

    Hayden, C.G.; Randolph, P.L.

    1987-05-29

    On October 8, 1983, after the first full day of production from Sand No.8 in the Gladys McCall well, samples of separator gas and separator brine were collected for laboratory P-V-T (pressure, volume, temperature) studies. Recombination of amounts of these samples based upon measured rates at the time of sample collection, and at reservoir temperature (290 F), revealed a bubble point pressure of 9200 psia. This is substantially below the reported reservoir pressure of 12,783 psia. The gas content of the recombined fluids was 30.19 SCF of dry gas/STB of brine. In contrast, laboratory studies indicate that 35.84 SCF of pure methane would dissolve in each STB of 95,000 mg/L sodium chloride brine. These results indicate that the reservoir brine was not saturated with natural gas. By early April, 1987, production of roughly 25 million barrels of brine had reduced calculated flowing bottomhole pressure to about 6600 psia at a brine rate of 22,000 STB/D. If the skin factor(s) were as high as 20, flowing pressure drop across the skin would still be only about 500 psi. Thus, some portion of the reservoir volume was believed to have been drawn down to below the bubble point deduced from the laboratory recombination of separator samples. When the pressure in a geopressured geothermal reservoir is reduced to below the bubble point pressure for solution gas, gas is exsolved from the brine flowing through the pores in the reservoir rock. This exsolved gas is trapped in the reservoir until the fractional gas saturation of pore volume becomes large enough for gas flow to commence through a continuous gas-filled channel. At the same time, the gas/brine ratio becomes smaller and the chemistry of the remaining solution gas changes for the brine from which gas is exsolved. A careful search was made for the changes in gas/brine ratio or solution gas chemistry that would accompany pressure dropping below the bubble point pressure. Changes of about the same magnitude as the scatter in

  9. Controllable Generation of a Submillimeter Single Bubble in Molten Metal Using a Low-Pressure Macrosized Cavity

    Science.gov (United States)

    Konovalenko, Alexander; Sköld, Per; Kudinov, Pavel; Bechta, Sevostian; Grishchenko, Dmitry

    2017-04-01

    We develop a method for generation of a single gas bubble in a pool of molten metal. The method can be useful for applications and research studies where a controllable generation of a single submillimeter bubble in opaque hot liquid is required. The method resolves difficulties with bubble detachment from the orifice, wettability issues, capillary channel and orifice surfaces degradation due to contact with corrosive hot liquid, etc. The macrosized, 5- to 50-mm3 cavity is drilled in the solid part of the pool. Flushing the cavity with gas, vacuuming it to low pressure, as well as sealing and consequent remelting cause cavity implosion due to a few orders in magnitude pressure difference between the cavity and the molten pool. We experimentally demonstrate a controllable production of single bubbles ranging from a few milliliters down to submillimeter size. The uncertainties in size and bubble release timing are estimated and compared with experimental observations for bubbles ranging within 0.16 to 4 mm in equivalent-volume sphere diameter. Our results are obtained in heavy liquid metals such as Wood's and Lead-Bismuth eutectics at 353 K to 423 K (80 °C to 150 °C).

  10. Controllable Generation of a Submillimeter Single Bubble in Molten Metal Using a Low-Pressure Macrosized Cavity

    Science.gov (United States)

    Konovalenko, Alexander; Sköld, Per; Kudinov, Pavel; Bechta, Sevostian; Grishchenko, Dmitry

    2017-01-01

    We develop a method for generation of a single gas bubble in a pool of molten metal. The method can be useful for applications and research studies where a controllable generation of a single submillimeter bubble in opaque hot liquid is required. The method resolves difficulties with bubble detachment from the orifice, wettability issues, capillary channel and orifice surfaces degradation due to contact with corrosive hot liquid, etc. The macrosized, 5- to 50-mm3 cavity is drilled in the solid part of the pool. Flushing the cavity with gas, vacuuming it to low pressure, as well as sealing and consequent remelting cause cavity implosion due to a few orders in magnitude pressure difference between the cavity and the molten pool. We experimentally demonstrate a controllable production of single bubbles ranging from a few milliliters down to submillimeter size. The uncertainties in size and bubble release timing are estimated and compared with experimental observations for bubbles ranging within 0.16 to 4 mm in equivalent-volume sphere diameter. Our results are obtained in heavy liquid metals such as Wood's and Lead-Bismuth eutectics at 353 K to 423 K (80 °C to 150 °C).

  11. 球状泡群内气泡的耦合振动∗%Coupled oscillation of bubbles in a spherical bubble cluster

    Institute of Scientific and Technical Information of China (English)

    王成会; 莫润阳; 胡静; 陈时

    2015-01-01

    The pressure wave emitted by a pulsating bubble affects the motions of other bubbles, so in an acoustic field bubbles are in a state of coupled oscillation. In this paper, a cluster with cavitation bubbles inside is considered, and a mathematical model is developed to describe the dynamics of the bubbles of the same radius inside a spherical cluster when the effects of coupled oscillation are included. Based on this new model, the nonlinear acoustic response of cavitation bubbles is analyzed numerically. Comparison of our model with those in the literature, shows that bubbles are suppressed heavily. Because of the coupled oscillations of bubbles, the motions of a bubble are affected by more constraints in the system, which cause the decrease of natural frequency of the bubbles. The nonlinear acoustical response of bubbles is improved by the coupled oscillation in a bubble cluster. With the rise in number density of the cluster, the suppression of bubble oscillation is enhanced. For a cluster of 1 mm radius, when the bubble number is below 500, the change of bubble number may cause a sharp decrease of maximum radial displacement of the bubbles. In cavitation region, there are bubble clusters and large-sized bubble, and the moving large bubble can absorb small bubbles from the surface of bubble cluster, so the bubble numbers inside a cluster varies with time, which may change the acoustic response of coupled oscillating bubbles. The increase of the liquid static pressure can suppress the oscillation of bubbles too, and there is a sensitive region (1–2 atm) that affects remarkably the acoustical response of bubbles. Driving ultrasound can affect the motion of bubble greatly. The range of cavitation bubble size is narrowed when the wave frequency increases. The bubbles whose initial radii are close to 5 µm are easy to be activated by ultrasound under given acoustic conditions, i.e. sizes of bubble cluster, surrounding liquid and inner gas. The cluster oscillation of

  12. Influence of bubble size, diffuser width, and flow rate on the integral behavior of bubble plumes

    Science.gov (United States)

    Fraga, Bruño.; Stoesser, Thorsten

    2016-06-01

    A large-eddy simulation based Eulerian-Lagrangian model is employed to quantify the impact of bubble size, diffuser diameter, and gas flow rate on integral properties of bubble plumes, such as the plume's width, centerline velocity, and mass flux. Calculated quantities are compared with experimental data and integral model predictions. Furthermore, the LES data were used to assess the behavior of the entrainment coefficient, the momentum amplification factor, and the bubble-to-momentum spread ratio. It is found that bubble plumes with constant bubble size and smaller diameter behave in accordance with integral plume models. Plumes comprising larger and non-uniform bubble sizes appear to deviate from past observations and model predictions. In multi-diameter bubble plumes, a bubble self-organisation takes place, i.e., small bubbles cluster in the center of the plume whilst large bubbles are found at the periphery of the plume. Multi-diameter bubble plumes also feature a greater entrainment rate than single-size bubble plumes, as well as a higher spread ratio and lower turbulent momentum rate. Once the plume is fully established, the size of the diffuser does not appear to affect integral properties of bubble plumes. However, plume development is affected by the diffuser width, as larger release areas lead to a delayed asymptotic behavior of the plume and consequently to a lower entrainment and higher spread ratio. Finally, the effect of the gas flow rate on the integral plume is studied and is deemed very relevant with regards to most integral plume properties and coefficients. This effect is already fairly well described by integral plume models.

  13. Shock-induced collapse of a bubble inside a deformable vessel.

    Science.gov (United States)

    Coralic, Vedran; Colonius, Tim

    2013-07-01

    Shockwave lithotripsy repeatedly focuses shockwaves on kidney stones to induce their fracture, partially through cavitation erosion. A typical side effect of the procedure is hemorrhage, which is potentially the result of the growth and collapse of bubbles inside blood vessels. To identify the mechanisms by which shock-induced collapse could lead to the onset of injury, we study an idealized problem involving a preexisting bubble in a deformable vessel. We utilize a high-order accurate, shock- and interface-capturing, finite-volume scheme and simulate the three-dimensional shock-induced collapse of an air bubble immersed in a cylindrical water column which is embedded in a gelatin/water mixture. The mixture is a soft tissue simulant, 10% gelatin by weight, and is modeled by the stiffened gas equation of state. The bubble dynamics of this model configuration are characterized by the collapse of the bubble and its subsequent jetting in the direction of the propagation of the shockwave. The vessel wall, which is defined by the material interface between the water and gelatin/water mixture, is invaginated by the collapse and distended by the impact of the jet. The present results show that the highest measured pressures and deformations occur when the volumetric confinement of the bubble is strongest, the bubble is nearest the vessel wall and/or the angle of incidence of the shockwave reduces the distance between the jet tip and the nearest vessel surface. For a particular case considered, the 40 MPa shockwave utilized in this study to collapse the bubble generated a vessel wall pressure of almost 450 MPa and produced both an invagination and distention of nearly 50% of the initial vessel radius on a (10) ns timescale. These results are indicative of the significant potential of shock-induced collapse to contribute to the injury of blood vessels in shockwave lithotripsy.

  14. Hydrodynamic models for slurry bubble column reactors. Seventh technical progress report, January--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D.

    1996-04-01

    The objective of this investigation is to convert our ``learning gas solid-liquid`` fluidization model into a predictive design model. The IIT hydrodynamic model computes the phase velocities and the volume fractions of gas, liquid and particulate phase. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. A hydrodynamic model for multiphase flows, based on the principles of mass, momentum and energy conservation for each phase, was developed and applied to model gas-liquid, gas-liquid-solid fluidization and gas-solid-solid separation. To simulate the industrial slurry bubble column reactors, a computer program based on the hydrodynamic model was written with modules for chemical reactions (e.g. the synthesis of methanol), phase changes and heat exchangers. In the simulations of gas-liquid two phases flow system, the gas hold-ups, computed with a variety of operating conditions such as temperature, pressure, gas and liquid velocities, agree well with the measurements obtained at Air Products` pilot plant. The hydrodynamic model has more flexible features than the previous empirical correlations in predicting the gas hold-up of gas-liquid two-phase flow systems. In the simulations of gas-liquid-solid bubble column reactors with and without slurry circulation, the code computes volume fractions, temperatures and velocity distributions for the gas, the liquid and the solid phases, as well as concentration distributions for the species (CO, H{sub 2}, CH{sub 3}0H, ... ), after startup from a certain initial state. A kinetic theory approach is used to compute a solid viscosity due to particle collisions. Solid motion and gas-liquid-solid mixing are observed on a color PCSHOW movie made from computed time series data. The steady state and time average catalyst concentration profiles, the slurry height and the rates of methanol production agree well with the measurements obtained at an Air Products` pilot plant.

  15. Data Pre-Processing Method to Remove Interference of Gas Bubbles and Cell Clusters During Anaerobic and Aerobic Yeast Fermentations in a Stirred Tank Bioreactor

    Science.gov (United States)

    Princz, S.; Wenzel, U.; Miller, R.; Hessling, M.

    2014-11-01

    One aerobic and four anaerobic batch fermentations of the yeast Saccharomyces cerevisiae were conducted in a stirred bioreactor and monitored inline by NIR spectroscopy and a transflectance dip probe. From the acquired NIR spectra, chemometric partial least squares regression (PLSR) models for predicting biomass, glucose and ethanol were constructed. The spectra were directly measured in the fermentation broth and successfully inspected for adulteration using our novel data pre-processing method. These adulterations manifested as strong fluctuations in the shape and offset of the absorption spectra. They resulted from cells, cell clusters, or gas bubbles intercepting the optical path of the dip probe. In the proposed data pre-processing method, adulterated signals are removed by passing the time-scanned non-averaged spectra through two filter algorithms with a 5% quantile cutoff. The filtered spectra containing meaningful data are then averaged. A second step checks whether the whole time scan is analyzable. If true, the average is calculated and used to prepare the PLSR models. This new method distinctly improved the prediction results. To dissociate possible correlations between analyte concentrations, such as glucose and ethanol, the feeding analytes were alternately supplied at different concentrations (spiking) at the end of the four anaerobic fermentations. This procedure yielded low-error (anaerobic) PLSR models for predicting analyte concentrations of 0.31 g/l for biomass, 3.41 g/l for glucose, and 2.17 g/l for ethanol. The maximum concentrations were 14 g/l biomass, 167 g/l glucose, and 80 g/l ethanol. Data from the aerobic fermentation, carried out under high agitation and high aeration, were incorporated to realize combined PLSR models, which have not been previously reported to our knowledge.

  16. Gas Breakthrough Pressure (GBP through Claystones: Correlation with FIB/SEM Imaging of the Pore Volume

    Directory of Open Access Journals (Sweden)

    Song Yang

    2016-07-01

    Full Text Available This contribution uses six claystone samples imaged by FIB/SEM (Focused Ion Beam/Scanning Electron Microscopy, within micrometric volumes located in the clay matrix; their 3D connected pore network is identified down to 17-22 nm pore size. All samples are gently dried to minimize damage, and several are impregnated with Poly(Methyl MethAcrylate (PMMA resin to avoid further damage during FIB/SEM observations. Three pore volumes out of six are connected between two parallel end surfaces through crack-like pores; two are not connected between any two parallel end surfaces; only one sample has a connected pore network distinct from cracks. By assuming varied pathways for gas to migrate by capillarity through the connected pore volumes (either by taking the shortest path, or through the largest path, or through the most frequent pore size, or by simulating the ingress of a non wetting fluid, we determine the Gas Breakthrough Pressure (GBP through the initially fully liquid saturated claystone, from these micrometric volumes. The scale change (from the micrometric to the macroscopic scale is assumed possible without changing the GBP value, and clay/water interactions are not accounted for. By comparison with GBP values measured in the laboratory on centimetric-sized claystone samples, it is concluded that breakthrough occurs most probably by capillary digitation; micro-cracks are the most probable pathways for gas, so that gas does not progress in a homogeneous manner through the claystone, as standard macroscopic finite element models would represent it. For intact claystone, predictions based on the capillary ingress of a non wetting fluid provide a GBP value ranging between 7-14 MPa.

  17. Fama on Bubbles

    DEFF Research Database (Denmark)

    Engsted, Tom

    2016-01-01

    While Eugene Fama has repeatedly expressed his discontent with the notion of an “irrational bubble,” he has never publicly expressed his opinion on “rational bubbles.” On empirical grounds Fama rejects bubbles by referring to the lack of reliable evidence that price declines are predictable. Howe...... component in stock market valuation ratios, consistent with a rational bubble....

  18. Measurements of the fluctuating liquid velocity of a bidisperse suspension of bubbles rising in a vertical channel

    Science.gov (United States)

    Serrano, Juan Carlos; Mendez, Santos; Zenit, Roberto

    2009-11-01

    Experiments were performed in a vertical channel to study the behaviour of a bidisperse suspension of bubbles. Bubbles were produced using capillaries of two distinct inner diameters. The capillaries are small enough to generate bubbles in the range of 1 to 6 mm in diameter. Using water and water-glycerin mixtures, the vertical component of the fluctuating liquid velocity was obtained using a flying hot wire anemometer technique. The system is characterized by the dimensionless Reynolds and Weber numbers in the range of 22gas volume fraction ranges between 0.5% and 6%. The measurements were obtained for three ratios R of gas volume fraction: R = 1/3, 1 and 3, where R=αlarge/αsmall% . The results show that the flow agitation, characterized by the liquid velocity variance increases with bubble concentration. We also found that the variance, normalized with the mean bubble velocity squared, Tf% =Uf^^'2/Ub^2, increased as the Reynolds number decreased. Bidisperse flows, in general, show larger values of fluctuation.

  19. Numerical Simulations of Inclusion Behavior in Gas-Stirred Ladles

    Science.gov (United States)

    Lou, Wentao; Zhu, Miaoyong

    2013-06-01

    A computation fluid dynamics-population balance model (CFD-PBM) coupled model has been proposed to investigate the bubbly plume flow and inclusion behavior including growth, size distribution, and removal in gas-stirred ladles, and some new and important phenomena and mechanisms were presented. For the bubbly plume flow, a modified k- ɛ model with extra source terms to account for the bubble-induced turbulence was adopted to model the turbulence, and the bubble turbulent dispersion force was taken into account to predict gas volume fraction distribution in the turbulent gas-stirred system. For inclusion behavior, the phenomena of inclusions turbulent random motion, bubbles wake, and slag eye forming on the molten steel surface were considered. In addition, the multiple mechanisms both that promote inclusion growth due to inclusion-inclusion collision caused by turbulent random motion, shear rate in turbulent eddy, and difference inclusion Stokes velocities, and the mechanisms that promote inclusion removal due to bubble-inclusion turbulence random collision, bubble-inclusion turbulent shear collision, bubble-inclusion buoyancy collision, inclusion own floatation near slag-metal interface, bubble wake capture, and wall adhesion were investigated. The importance of different mechanisms and total inclusion removal ratio under different conditions, and the distribution of inclusion number densities in ladle, were discussed and clarified. The results show that at a low gas flow rate, the inclusion growth is mainly attributed to both turbulent shear collision and Stokes collision, which is notably affected by the Stokes collision efficiency, and the inclusion removal is mainly attributed to the bubble-inclusion buoyancy collision and inclusion own floatation near slag-metal interface. At a higher gas flow rate, the inclusions appear as turbulence random motion in bubbly plume zone, and both the inclusion-inclusion and inclusion-bubble turbulent random collisions become

  20. Cavitation inception from bubble nuclei

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2015-01-01

    , and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model......The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years...

  1. Numerical Simulations of Liquid-Gas-Solid Three-Phase Flows in Microgravity

    Directory of Open Access Journals (Sweden)

    Xinyu Zhang

    2012-03-01

    Full Text Available Three-phase liquid-gas-solid flows under microgravity condition are studied. An Eulerian-Lagrangian computational model was developed and used in the simulations. In this approach, the liquid flow was modeled by a volume-averaged system of governing equations, whereas motions of particles and bubbles were evaluated using the Lagrangian trajectory analysis procedure. It was assumed that the bubbles remained spherical, and their shape variations were neglected. The bubble-liquid, particle-liquid and bubbl-particle two-way interactions were accounted for in the analysis. The discrete phase equations used included drag, lift, buoyancy, and virtual mass forces. Particle-particle interactions and bubble-bubble interactions were accounted for by the hard sphere model. Bubble coalescence was also included in the model. The transient flow characteristics of the three-phase flow were studied; and the effects of gravity, inlet bubble size and g-jitter acceleration on variation of flow characteristics were discussed. The low gravity simulations showed that most bubbles are aggregated in the inlet region. Also, under microgravity condition, bubble transient time is much longer than that in normal gravity. As a result, the Sauter mean bubble diameter, which is proportional to the transient time of the bubble, becomes rather large, reaching to more than 9 mm. The bubble plume in microgravity exhibits a plug type flow behavior. After the bubble plume reaches the free surface, particle volume fraction increases along the height of the column. The particles are mainly located outside the bubble plume, with very few particles being retained in the plume. In contrast to the normal gravity condition, the three phases in the column are poorly mixed under microgravity conditions. The velocities of the three phases were also found to be of the same order. Bubble size significantly affects the characteristics of the three-phase flows under microgravity conditions. For

  2. Effect of Water Vapour to Temperature Inside Sonoluminescing Bubble

    Institute of Scientific and Technical Information of China (English)

    安宇; 谢崇国; 应崇福

    2003-01-01

    Using the model based on the homo-pressure approximation, we explain why the maximum temperature is sensitive to the ambient temperature in the single bubble sonoluminescence. The numerical simulation shows that the maximum temperature inside a sonoluminescing bubble depends on how much water vapour evaporates or coagulates at the bubble wall during the bubble shrinking to its minimum size. While the amount of water vapour inside the bubble at the initial and the final state of the compression depends on the saturated water vapour pressure which is sensitive to the ambient temperature. The lower the saturated vapour pressure is, the higher the maximum temperature is. This may lead to more general conclusion that those liquids with lower saturated vapour pressure are more favourable for the single bubble sonoluminescence. We also compare those bubbles with different noble gases, the result shows that the maximum temperatures in the different gas bubbles are almost the same for those with the same ambient temperature.

  3. Reduction of total lung capacity in obese men: comparison of total intrathoracic and gas volumes.

    Science.gov (United States)

    Watson, R A; Pride, N B; Thomas, E Louise; Fitzpatrick, J; Durighel, G; McCarthy, J; Morin, S X; Ind, P W; Bell, J D

    2010-06-01

    Restriction of total lung capacity (TLC) is found in some obese subjects, but the mechanism is unclear. Two hypotheses are as follows: 1) increased abdominal volume prevents full descent of the diaphragm; and 2) increased intrathoracic fat reduces space for full lung expansion. We have measured total intrathoracic volume at full inflation using magnetic resonance imaging (MRI) in 14 asymptomatic obese men [mean age 52 yr, body mass index (BMI) 35-45 kg/m2] and 7 control men (mean age 50 yr, BMI 22-27 kg/m2). MRI volumes were compared with gas volumes at TLC. All measurements were made with subjects supine. Obese men had smaller functional residual capacity (FRC) and FRC-to-TLC ratio than control men. There was a 12% predicted difference in mean TLC between obese (84% predicted) and control men (96% predicted). In contrast, differences in total intrathoracic volume (MRI) at full inflation were only 4% predicted TLC (obese 116% predicted TLC, control 120% predicted TLC), because mediastinal volume was larger in obese than in control [heart and major vessels (obese 1.10 liter, control 0.87 liter, P=0.016) and intrathoracic fat (obese 0.68 liter, control 0.23 liter, P80% predicted (ON) was 26% predicted TLC. Mediastinal volume was similar in OR (1.84 liter) and ON (1.73 liter), but total intrathoracic volume was 19% predicted TLC smaller in OR than in ON. We conclude that the major factor restricting TLC in some obese men was reduced thoracic expansion at full inflation.

  4. INTERACTIONS OF THE INFRARED BUBBLE N4 WITH ITS SURROUNDINGS

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hong-Li; Li, Jin-Zeng; Yuan, Jing-Hua; Huang, Maohai; Huang, Ya-Fang; Zhang, Si-Ju [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Wu, Yuefang [Department of Astronomy, Peking University, 100871 Beijing (China); Liu, Tie [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Dubner, G.; Paron, S.; Ortega, M. E. [1Instituto de Astronomía y Física del Espacio (IAFE, CONICET-UBA), CC 67, Suc. 28, 1428 Buenos Aires (Argentina); Molinari, Sergio [Istituto di Astrofisica e Planetologia Spaziali—IAPS, Istituto Nazionale di Astrofisica—INAF, via Fosso del Cavaliere 100, I-00133 Roma (Italy); Zavagno, Annie; Samal, Manash R., E-mail: hlliu@nao.cas.cn [Aix Marseille Universit, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France)

    2016-02-10

    The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with H ii regions have been considered to be good samples for investigating triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the H ii region G11.898+0.747, analyzing its interaction with its surroundings and star formation histories therein, with the aim of determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a wide wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 × 10{sup 22} cm{sup −2}, mean volume density of about 4.4 × 10{sup 4} cm{sup −3}, and a mean mass of 320 M{sub ⊙}. In addition, from PAH emission seen at 8 μm, free–free emission detected at 20 cm, and a probability density function in special regions, we could identify clear signatures of the influence of the H ii region on the surroundings. There are hints of star formation, though further investigation is required to demonstrate that N4 is the triggering source.

  5. Oscillation of large air bubble cloud

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Y.Y.; Kim, H.Y.; Park, J.K. [Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of)

    2001-07-01

    The behavior of a large air bubble cloud, which is generated by the air discharged from a perforated sparger, is analyzed by solving Rayleigh-Plesset equation, energy equations and energy balance equation. The equations are solved by Runge-Kutta integration and MacCormack finite difference method. Initial conditions such as driving pressure, air volume, and void fraction strongly affect the bubble pressure amplitude and oscillation frequency. The pool temperature has a strong effect on the oscillation frequency and a negligible effect on the pressure amplitude. The polytropic constant during the compression and expansion processes of individual bubbles ranges from 1.0 to 1.4, which may be attributed to the fact that small bubbles oscillated in frequencies different from their resonance. The temperature of the bubble cloud rapidly approaches the ambient temperature, as is expected from the polytropic constants being between 1.0 and 1.4. (authors)

  6. Shape measurement of bubble in a liquid metal

    Science.gov (United States)

    Saito, Y.; Shen, X.; Mishima, K.; Matsubayashi, M.

    2009-06-01

    Dynamic behavior of a two-phase bubble, i.e. a steam bubble containing a droplet evaporating in the bubble, in the molten alloy was clearly visualized using high-frame-rate neutron radiography. In relation to some direct contact heat exchanger design with molten lead-bismuth (Pb-Bi), experiments have been done at JRR-3M of JAEA (Japan Atomic Energy Agency) with water droplets evaporating in a stable thermally stratified Newton's alloy pool. The instantaneous shape and size of the bubble has been iteratively estimated from the void fraction distributions and total void volume by assuming a symmetrical bubble shape.

  7. Sonoluminescence and the probability of isothermal bubble collapse

    Institute of Scientific and Technical Information of China (English)

    ThomasVPrevenslik

    1997-01-01

    Computations of air bubble collapse dynamics usually neglect thermal conduction.but recent computations show about a 3-fold reduction in bubble gas temperature if thermal conduction is included.However,an isothermal collapse at ambient temperature is even more likely because the air molecuses collide with and stick to the bubble walls during bubble expansion and are not available for compression heating during collapse.The probability of isothermal collapse is shown to depend on the mean free path of the air molecules moving through the H2O vapor molecules within the bullbe during bubble expansion and is sensitive to the lowering of ambinet temperature to the freezing point.

  8. EOS simulation and GRNN modeling of the constant volume depletion behavior of gas condensate reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Elsharkawy, A.M.; Foda, S.G. [Kuwait University, Safat (Kuwait). Petroleum Engineering Dept.

    1998-03-01

    Currently, two approaches are being used to predict the changes in retrograde gas condensate composition and estimate the pressure depletion behavior of gas condensate reservoirs. The first approach uses the equation of states whereas the second uses empirical correlations. Equations of states (EOS) are poor predictive tools for complex hydrocarbon systems. The EOS needs adjustment against phase behavior data of reservoir fluid of known composition. The empirical correlation does not involve numerous numerical computations but their accuracy is limited. This study presents two general regression neural network (GRNN) models. The first model, GRNNM1, is developed to predict dew point pressure and gas compressibility at dew point using initial composition of numerous samples while the second model, GRNNM2, is developed to predict the changes in well stream effluent composition at any stages of pressure depletion. GRNNM2 can also be used to determine the initial reservoir fluid composition using dew point pressure, gas compressibility at dew point, and reservoir temperature. These models are based on analysis of 142 sample of laboratory studies of constant volume depletion (CVD) for gas condensate systems forming a total of 1082 depletion stages. The database represents a wide range of gas condensate systems obtained worldwide. The performance of the GRNN models has been compared to simulation results of the equation of state. The study shows that the proposed general regression neural network models are accurate, valid, and reliable. These models can be used to forecast CVD data needed for many reservoir engineering calculations in case laboratory data is unavailable. The GRNN models save computer time involved in EOS calculations. The study also show that once these models are properly trained they can be used to cut expenses of frequent sampling and laborious experimental CVD tests required for gas condensate reservoirs. 55 refs., 13 figs., 6 tabs.

  9. Numerical modeling of oscillating Taylor bubbles

    Directory of Open Access Journals (Sweden)

    S. Ambrose

    2016-01-01

    Full Text Available In this study, computational fluid dynamics (CFD modeling is used to simulate Taylor bubbles rising in vertical pipes. Experiments indicate that in large diameter (0.29 m pipes for an air–water system, the bubbles can rise in a oscillatory manner, depending on the method of air injection. The CFD models are able to capture this oscillatory behavior because the air phase is modeled as a compressible ideal gas. Insights into the flow field ahead and behind the bubble during contraction and expansion are shown. For a bubble with an initial pressure equal to the hydrostatic pressure at its nose, no oscillations are seen in the bubble as it rises. If the initial pressure in the bubble is set less than or greater than the hydrostatic pressure then the length of the bubble oscillates with an amplitude that depends on the magnitude of the initial bubble pressure relative to the hydrostatic pressure. The frequency of the oscillations is inversely proportional to the square root of the head of water above the bubble and so the frequency increases as the bubble approaches the water surface. The predicted frequency also depends inversely on the square root of the average bubble length, in agreement with experimental observations and an analytical model that is also presented. In this model, a viscous damping term due to the presence of a Stokes boundary layer for the oscillating cases is introduced for the first time and used to assess the effect on the oscillations of increasing the liquid viscosity by several orders of magnitude.

  10. Prediction of forage intake using in vitro gas production methods: Comparison of multiphase fermentation kinetics measured in an automated gas test, and combined gas volume and substrate degradability measurements in a manual syringe system

    NARCIS (Netherlands)

    Blümmel, M.; Cone, J.W.; Gelder, van A.H.; Nshalai, I.; Umunna, N.N.; Makkar, H.P.S.; Becker, K.

    2005-01-01

    This study investigated two approaches to in vitro analysis of gas production data, being a three phase model with long (¿72 h) incubation times, to obtain kinetics and asymptotic values of gas production, and combination of gas volume measurements with residue determinations after a relatively shor

  11. Treating network junctions in finite volume solution of transient gas flow models

    Science.gov (United States)

    Bermúdez, Alfredo; López, Xián; Vázquez-Cendón, M. Elena

    2017-09-01

    A finite volume scheme for the numerical solution of a non-isothermal non-adiabatic compressible flow model for gas transportation networks on non-flat topography is introduced. Unlike standard Euler equations, the model takes into account wall friction, variable height and heat transfer between the pipe and the environment which are source terms. The case of one single pipe was considered in a previous reference by the authors, [8], where a finite volume method with upwind discretization of the flux and source terms has been proposed in order to get a well-balanced scheme. The main goal of the present paper is to go a step further by considering a network of pipes. The main issue is the treatment of junctions for which container-like 2D finite volumes are introduced. The couplings between pipes (1D) and containers (2D) are carefully described and the conservation properties are analyzed. Numerical tests including real gas networks are solved showing the performance of the proposed methodology.

  12. RESOLVE Survey Photometry and Volume-limited Calibration of the Photometric Gas Fractions Technique

    CERN Document Server

    Eckert, Kathleen D; Stark, David V; Moffett, Amanda J; Norris, Mark A; Snyder, Elaine M; Hoversten, Erik A

    2015-01-01

    We present custom-processed UV, optical, and near-IR photometry for the RESOLVE survey, a volume-limited census of stellar, gas, and dynamical mass within two subvolumes of the nearby universe (RESOLVE-A and -B), complete down to baryonic mass ~10^9.1-9.3 Msun. In contrast to standard pipeline photometry (e.g., SDSS), our photometry uses optimal background subtraction, avoids suppressing color gradients, and includes systematic errors. With these improvements, we measure brighter magnitudes, larger radii, bluer colors, and a real increase in scatter around the red sequence. Combining stellar masses from our photometry with the RESOLVE-A HI mass census, we create volume-limited calibrations of the photometric gas fractions (PGF) technique, which predicts gas-to-stellar mass ratios (G/S) from galaxy colors and optional additional parameters. We analyze G/S-color residuals vs. potential third parameters, finding that axial ratio is the best independent and physically meaningful third parameter. We define a "modi...

  13. A new method for the measurement of meteorite bulk volume via ideal gas pycnometry

    Science.gov (United States)

    Li, Shijie; Wang, Shijie; Li, Xiongyao; Li, Yang; Liu, Shen; Coulson, Ian M.

    2012-10-01

    To date, of the many techniques used to measure the bulk volume of meteorites, only three methods (Archimedean bead method, 3-D laser imaging and X-ray microtomography) can be considered as nondestructive or noncontaminating. The bead method can show large, random errors for sample sizes of smaller than 5 cm3. In contrast, 3-D laser imaging is a high-accuracy method even when measuring the bulk volumes of small meteorites. This method is both costly and time consuming, however, and meteorites of a certain shape may lead to some uncertainties in the analysis. The method of X-ray microtomography suffers from the same problems as 3-D laser imaging. This study outlines a new method of high-accuracy, nondestructive and noncontaminating measurement of the bulk volume of meteorite samples. In order to measure the bulk volume of a meteorite, one must measure the total volume of the balloon vacuum packaged meteorite and the volume of balloon that had been used to enclose the meteorite using ideal gas pycnometry. The difference between the two determined volumes is the bulk volume of the meteorite. Through the measurement of zero porosity metal spheres and tempered glass fragments, our results indicate that for a sample which has a volume of between 0.5 and 2 cm3, the relative error of the measurement is less than ±0.6%. Furthermore, this error will be even smaller (less than ±0.1%) if the determined sample size is larger than 2 cm3. The precision of this method shows some volume dependence. For samples smaller than 1 cm3, the standard deviations are less than ±0.328%, and these values will fall to less than ±0.052% for samples larger than 2 cm3. The porosities of nine fragments of Jilin, GaoGuenie, Zaoyang and Zhaodong meteorites have been measured using our vacuum packaging-pycnometry method, with determined average porosities of Jilin, GaoGuenie, Zaoyang and Zhaodong of 9.0307%, 2.9277%, 17.5437% and 5.9748%, respectively. These values agree well with the porosities

  14. A new estimate of the volume and distribution of gas hydrate in the northern Gulf of Mexico

    Science.gov (United States)

    Majumdar, U.; Cook, A.

    2016-12-01

    In spite of the wealth of information gained over the last several decades about gas hydrate in the northern Gulf of Mexico, there is still considerable uncertainty about the distribution and volume of gas hydrate. In our assessment we build a dataset of basin-wide gas hydrate distribution and thickness, as appraised from publicly available petroleum industry well logs within the gas hydrate stability zone (HSZ), and subsequently develop a Monte Carlo to determine the volumetric estimate of gas hydrate using the dataset. We evaluate the presence of gas hydrate from electrical resistivity well logs, and categorized possible reservoir type (either sand or clay) based on the gamma ray response and resistivity curve characteristics. Out of the 798 wells with resistivity well log data within the HSZ we analyzed, we found evidence of gas hydrate in 124 wells. In this research we present a new stochastic estimate of the gas hydrate volume in the northern Gulf of Mexico guided by our well log dataset. For our Monte Carlo simulation, we divided our assessment area of 200,000 km2 into 1 km2 grid cells. Our volume assessment model incorporates variables unique to our well log dataset such as the likelihood of gas hydrate occurrence, fraction of the HSZ occupied by gas hydrate, reservoir type, and gas hydrate saturation depending on the reservoir, in each grid cell, in addition to other basic variables such as HSZ thickness and porosity. Preliminary results from our model suggests that the total volume of gas at standard temperature and pressure in gas hydrate in the northern Gulf of Mexico is in the range of 430 trillion cubic feet (TCF) to 730 TCF, with a mean volume of 585 TCF. While the reservoir distribution from our well log dataset found gas hydrate in sand reservoirs in 30 wells out of the 124 wells with evidence of gas hydrate ( 24%), we find sand reservoirs contain over half of the total volume of gas hydrate in the Gulf of Mexico, as a result of the relatively high

  15. Stability of bubbles in a linear elastic medium: Implications for bubble growth in marine sediments

    Science.gov (United States)

    Algar, C. K.; Boudreau, B. P.

    2010-09-01

    Methane bubbles in muddy fine-grained sediments grow initially through a process of elastic expansion, punctuated by discrete fracture events (LEFM-growth). The ability of the surrounding sediments to support a stress and actively resist expansion can, under conditions of low gas production or high sediment toughness, result in the cessation of growth and the presence of stable bubbles. Thus, it is possible for a bubble to stop growing despite the presence of a source in the sediments that continues to produce gas. This contrasts with growth of bubbles in a fluid medium, which cannot support a stress and so will continue to grow as long as a surrounding source provides gas. This "no-growth" condition is the result of the coupling between gas supply (methane production or supersaturation) and the sediment mechanics. Here we quantify this condition and present a criterion for the switch between no-growth and the LEFM growth regimes. We apply this theory to the sediments of Eckernförde Bay, in the Kiel Bight, Germany, and despite the absence of measurements for the key sediment mechanical properties, we can provide a qualitative explanation for the sizes and shapes of the observed bubble population with depth in the sediment. We also show how the release of hydrostatic pressure can stimulate growth, by pushing otherwise stable bubbles into the LEFM growth regime. This could provide a mechanism for the release of bubbles during periods of low water, such as during low tide or wave events.

  16. Bubbles in live-stranded dolphins.

    Science.gov (United States)

    Dennison, S; Moore, M J; Fahlman, A; Moore, K; Sharp, S; Harry, C T; Hoppe, J; Niemeyer, M; Lentell, B; Wells, R S

    2012-04-07

    Bubbles in supersaturated tissues and blood occur in beaked whales stranded near sonar exercises, and post-mortem in dolphins bycaught at depth and then hauled to the surface. To evaluate live dolphins for bubbles, liver, kidneys, eyes and blubber-muscle interface of live-stranded and capture-release dolphins were scanned with B-mode ultrasound. Gas was identified in kidneys of 21 of 22 live-stranded dolphins and in the hepatic portal vasculature of 2 of 22. Nine then died or were euthanized and bubble presence corroborated by computer tomography and necropsy, 13 were released of which all but two did not re-strand. Bubbles were not detected in 20 live wild dolphins examined during health assessments in shallow water. Off-gassing of supersaturated blood and tissues was the most probable origin for the gas bubbles. In contrast to marine mammals repeatedly diving in the wild, stranded animals are unable to recompress by diving, and thus may retain bubbles. Since the majority of beached dolphins released did not re-strand it also suggests that minor bubble formation is tolerated and will not lead to clinically significant decompression sickness.

  17. Numerical investigation of bubble nonlinear dynamics characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Jie, E-mail: shijie@hrbeu.edu.cn; Yang, Desen; Shi, Shengguo; Hu, Bo [Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001 (China); College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang, Haoyang; Jiang, Wei [College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001 (China)

    2015-10-28

    The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.

  18. Simulation of dynamic behavior in bubbling fluidization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Both the behavior of bubbles in the distributor with several orifices and the sensitive dependence of bubbling fluidization on initial condition have been simulated by particle-motion-resolved discrete model in which the gas flow is obtained by solving the Navier-Stokes equation including two-phase interaction, and the motion of solid phase is obtained by decomposing the motion of each particle into collision process and suspension process. Compared with the pseudo-fluid models and previous discrete models, this model is authentic and can be widely used for simulating bubbling fluidization.

  19. Screening of liquids for thermocapillary bubble movement

    Science.gov (United States)

    Wilcox, W. R.; Subramanian, R. S.; Papazian, J. M.; Smith, H. D.; Mattox, D. M.

    1979-01-01

    Ground-based methods for pretesting qualitatively the thermocapillary movement of gas bubbles in a liquid to be used in space processing are discussed. Theoretical considerations are shown to require the use of a thin, enclosed, horizontal liquid film in order that the bubbles move faster than the bulk convection of the liquid, with insulating boundaries to prevent the onset of instabilities. Experimental realizations of horizontal cells in which to test the thermocapillary movement of bubbles in sheets of molten glass heated from below and organic melts in tubes heated from both ends are briefly described and the results of experiments are indicated.

  20. Gravity Wave Generation by Largescale Bubbles

    Science.gov (United States)

    Brandenburg, A.

    The response of an isothermal atmosphere to small disturbances in entropy is studied taking compressible effects fully into account. The method of Green's functions is applied to solve the linearized hydrodynamic equations by Fourier transformation. A bubble may be created by perturbing the entropy within a finite volume. At first Lamb waves will be then emitted radially and the bubble undergoes a series of Brunt-Väisälä oscillations.