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Sample records for gas bubbles rising

  1. Liquid jet pumped by rising gas bubbles

    NASA Technical Reports Server (NTRS)

    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.

  2. Liquid jet pumped by rising gas bubbles

    NASA Technical Reports Server (NTRS)

    Hussain, N. A.; Siegel, R.

    1975-01-01

    From observations of a stream of gas bubbles rising through a liquid, a two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. The 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 arise 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.

  3. Liquid jet pumped by rising gas bubbles

    NASA Technical Reports Server (NTRS)

    Hussain, N. A.; Siegel, R.

    1975-01-01

    From observations of a stream of gas bubbles rising through a liquid, a two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. The 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 arise 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.

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

    SciTech Connect

    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.

  5. Behavior of bubbles in glassmelts. III - Dissolution and growth of a rising bubble containing a single gas

    NASA Technical Reports Server (NTRS)

    Onorato, P. I. K.; Weinberg, M. C.; Uhlmann, D. R.

    1981-01-01

    Finite difference solutions of the mass transport equations governing the dissolution (growth) of a rising gas bubble, containing a single gas, in a glassmelt were obtained. These solutions were compared with those obtained from an approximate procedure for a range of the controlling parameters. Applications were made to describe various aspects of O2 and CO2 gas-bubble behavior in a soda-lime-silicate melt.

  6. Behavior of bubbles in glassmelts. III - Dissolution and growth of a rising bubble containing a single gas

    NASA Technical Reports Server (NTRS)

    Onorato, P. I. K.; Weinberg, M. C.; Uhlmann, D. R.

    1981-01-01

    Finite difference solutions of the mass transport equations governing the dissolution (growth) of a rising gas bubble, containing a single gas, in a glassmelt were obtained. These solutions were compared with those obtained from an approximate procedure for a range of the controlling parameters. Applications were made to describe various aspects of O2 and CO2 gas-bubble behavior in a soda-lime-silicate melt.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Instability of two rising bubbles

    NASA Astrophysics Data System (ADS)

    Galper, Alexander; Miloh, Touvia

    1999-11-01

    We consider the stability of two rising ideal gas spherical bubbles subject of an intrinsic dynamics. The dynamics is prescribed or governed by the Rayleigh-Plesset equation adjusted for the pressure field induced by the other bubble in the center of each. Hence, each bubble exhibits linear (nonlinear) oscillations about a stable equilibrium. In order to treat the Liapunov stability problem of bubbles spatial motion we develop the corresponding Hamiltonian formalism. Thus, we find that the oscillations can stabilize the side-by-side and one-below-the-other bubbles translation. These types of translation are known to be asymptotically stable (unstable) for the motion of a pair of purely spherical rigid bubbles. The stabilization phenomenon depends on the frequency and phase difference in the bubbles fast oscillations. The ``rigid'' bubbles theory of the motion is known to have certain discrepancies with the relevant experiments. In order to remove them it is proposed to account for the vorticity wake behind each bubble. Nevertheless, we are able to explain the experiments remaining within the potential framework. Finally, we consider the case of chaotic pulsations. The motion of the two bubbles can also inherit a chaotic character. It results, in turn, in a certain strange attractor for the spatial motion of a pair.

  9. Visualization of gas-liquid mass transfer and wake structure of rising bubbles using pH-sensitive PLIF

    NASA Astrophysics Data System (ADS)

    Stöhr, M.; Schanze, J.; Khalili, A.

    2009-07-01

    A planar laser-induced fluorescence (PLIF) technique for visualizing gas-liquid mass transfer and wake structure of rising gas bubbles is described. The method uses an aqueous solution of the pH-sensitive dye Naphthofluorescein and CO2 as a tracer gas. It features a high spatial resolution and frame rates of up to 500 Hz, providing the ability to capture cinematographic image sequences. By steering the laser beam with a set of two programmable scanning mirrors, sequences of three-dimensional LIF images can be recorded. The technique is applied to freely rising bubbles with diameters between 0.5 and 5 mm, which perform rectilinear, oscillatory or irregular motions. The resulting PLIF image sequences reveal the evolution of characteristic patterns in the near and far wake of the bubbles and prove the potential of the technique to provide new and detailed insights into the spatio-temporal dynamics of mass transfer of rising gas bubbles. The image sequences further allow the estimation of bubble size and rise velocity. The analysis of bubble rise velocities in the Naphthofluorescein solution indicates that surfactant-contaminated conditions are encountered.

  10. ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745-191

    NASA Astrophysics Data System (ADS)

    Russell, H. R.; McNamara, B. R.; Fabian, A. C.; Nulsen, P. E. J.; Edge, A. C.; Combes, F.; Murray, N. W.; Parrish, I. J.; Salomé, 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.

    2016-05-01

    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 PKS 0745-191. The total molecular gas mass of 4.6± 0.3× 109 M_{⊙}, assuming a Galactic XCO 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 ˜ 1 arcsec (2 kpc) from the nucleus. The velocities of the molecular clouds in the filaments are low, lying within ± 100 { km s^{-1}} of the galaxy's systemic velocity. Their full width at half-maximum (FWHM) are less than 150 { km s^{-1},} 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 < 107 yr time-scales unless supported, likely by the indirect effect of magnetic fields. The velocity structure is inconsistent with a merger origin or gravitational free-fall of cooling gas in this massive central galaxy. If the molecular clouds originated in gas cooling even a few kpc from their current locations their velocities would exceed those observed. Instead, the projection of the N and SE filaments underneath X-ray cavities suggests they formed in the updraft behind bubbles buoyantly rising through the cluster atmosphere. Direct uplift of the dense gas by the radio bubbles appears to require an implausibly high coupling efficiency. The filaments are coincident with low temperature X-ray gas, bright optical line emission and dust lanes indicating that the molecular gas could have formed from lifted warmer gas that cooled in situ.

  11. Velocity of a freely rising gas bubble in a soda-lime silicate glass melt

    NASA Technical Reports Server (NTRS)

    Hornyak, E. J.; Weinberg, M. C.

    1984-01-01

    A comparison is conducted between measured velocities for the buoyant rise of single bubbles of varying size and composition, in a soda-lime silicate glass melt, with the steady state velocities predicted by the Stokes and Hadamard-Rybczynski formulas. In all cases, the data are noted to fit the Hadamard-Rybczynski expression for steady state rise speed considerably better than the Stokes formula.

  12. Velocity of a freely rising gas bubble in a soda-lime silicate glass melt

    NASA Technical Reports Server (NTRS)

    Hornyak, E. J.; Weinberg, M. C.

    1984-01-01

    A comparison is conducted between measured velocities for the buoyant rise of single bubbles of varying size and composition, in a soda-lime silicate glass melt, with the steady state velocities predicted by the Stokes and Hadamard-Rybczynski formulas. In all cases, the data are noted to fit the Hadamard-Rybczynski expression for steady state rise speed considerably better than the Stokes formula.

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

    NASA Astrophysics Data System (ADS)

    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 (<10) we find [ hboxFr = frac{9.494times 10^{-3}}{({1+{6197}/hboxEo^{2.561}})^{0.5793}}R^{1.026}.] The flat region for high buoyancy Reynolds number and sloped region for low buoyancy Reynolds number is separated by a transition region (10 {<} R {<} 200) which we describe by fitting the data to a logistic dose curve. Repeated application of logistic dose curves leads to a composition of rational fractions of rational fractions of power laws. This leads to the following universal correlation: [ hboxFr = L[{R;A,B,C,G}] equiv frac{A}{({1+({{R}/{B}})^C})^G} ] where [ A = L[hboxEo;a,b,c,d],quad B = L[hboxEo;e,f,g,h],quad C = L[hboxEo;i,j,k,l],quad G = m/C ] and the parameters (a, b,...,l) are begin{eqnarray*} &&hspace*{-5pt}a hspace*{-0.8pt} {=} hspace*{-0.8pt} 0.34;quad bhspace*{-0.8pt} {=} hspace*{-0.8pt} 14.793;quad chspace*{-0.8pt} {=} hspace*{-0.6pt}{-}3.06;quad dhspace*{-0.6pt} {=} hspace*{-0.6pt}0.58;quad ehspace*{-0.6pt} {=} hspace*{-0.6pt} 31.08;quad fhspace*{-0.6pt} {=} hspace*{-0.6pt}29.868;quad ghspace*{-0.6pt} { =} hspace*{-0.6pt}{ -}1

  14. Bubbles Rising Through a Soft Granular Material

    NASA Astrophysics Data System (ADS)

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

    PubMed

    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.

  16. Formation and influence of the dynamic adsorption layer on kinetics of the rising bubble collisions with solution/gas and solution/solid interfaces.

    PubMed

    Zawala, J; Kosior, D; Malysa, K

    2015-08-01

    The DAL (dynamic adsorption layer) formation, that is, the establishment of uneven distribution of adsorption coverage over the rising bubble surface, with significantly diminished coverage at the upstream pole, is the factor of crucial importance for the bubble motion parameters and kinetic of the bubble collisions with various interfaces. The DAL presence can influence the stability of the thin liquid films formed by the colliding bubble at solution/gas and solution solid interfaces. The purpose of this paper is to critically review the existing state of art regarding the influence of the DAL formation and existence on the bubble motion parameters as well as kinetics of coalescence at free solution surface and three phase contact (TPC) formation at solid/liquid interfaces of different hydrophilic/hydrophobic properties. Despite the fact that up to now there is no direct experimental evidence showing DAL existence, it is documented by experimental data showing clear correlation between bubble local velocity variations and shape pulsations as well as lifetimes of the liquid film formed by the colliding bubble at gas/liquid and gas/solid interfaces. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Gas bubble detector

    NASA Technical Reports Server (NTRS)

    Mount, Bruce E. (Inventor); Burchfield, David E. (Inventor); Hagey, John M. (Inventor)

    1995-01-01

    A gas bubble detector having a modulated IR source focused through a bandpass filter onto a venturi, formed in a sample tube, to illuminate the venturi with modulated filtered IR to detect the presence of gas bubbles as small as 0.01 cm or about 0.004 in diameter in liquid flowing through the venturi. Means are provided to determine the size of any detected bubble and to provide an alarm in the absence of liquid in the sample tube.

  18. Arrested Bubble Rise in a Narrow Tube

    NASA Astrophysics Data System (ADS)

    Lamstaes, Catherine; Eggers, Jens

    2017-05-01

    If a long air bubble is placed inside a vertical tube closed at the top it can rise by displacing the fluid above it. However, Bretherton found that if the tube radius, R, is smaller than a critical value Rc=0.918 ℓ _c, where ℓ _c=√{γ /ρ g} is the capillary length, there is no solution corresponding to steady rise. Experimentally, the bubble rise appears to have stopped altogether. Here we explain this observation by studying the unsteady bubble motion for Rbubble and the tube goes to zero in limit of large t like t^{-4/5}, leading to a rapid slow-down of the bubble's mean speed U ∝ t^{-2}. As a result, the total bubble rise in infinite time remains very small, giving the appearance of arrested motion.

  19. Scaling law for bubbles rising near vertical walls

    NASA Astrophysics Data System (ADS)

    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.

  20. Seismically Initiated Carbon Dioxide Gas Bubble Growth in Groundwater: A Mechanism for Co-seismic Borehole Water Level Rise and Remotely Triggered Secondary Seismicity

    NASA Astrophysics Data System (ADS)

    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

  1. Initial rise of bubbles in cohesive sediments by a process of viscoelastic fracture

    NASA Astrophysics Data System (ADS)

    Algar, C. K.; Boudreau, B. P.; Barry, M. A.

    2011-04-01

    An understanding of the mechanics of bubble rise in sediments is essential because of the role of bubbles in releasing methane to the atmosphere and the formation and melting of gas hydrates. Past models to describe and predict the rise of other buoyant geological bodies through a surrounding solid (e.g., magmas and hydrofractures) appear not to be applicable to bubbles in soft sediments, and this paper presents a new model for gas bubble rise in soft, fine-grained, cohesive sediments. Bubbles in such sediments are essentially "dry" (little if any free water) and grow through a process of elastic expansion and fracture that can be described using the principles of linear elastic fracture mechanics, which assume the existence of a spectrum of flaws within the sediment fabric. By extending this theory, we predict that bubbles initially rise by preferential propagation of a fracture in a (sub) vertical direction. We present a criterion for initial bubble rise. Once rise is initiated, the speed of rise is controlled by the viscoelastic response of the sediments to stress. Using this new bubble rise model, we estimate rise velocities to be of the order of centimeters per second. We again show that capillary pressure plays no substantive role in controlling bubble growth or rise.

  2. Bubble Rise and Break-Up in Volcanic Conduits

    NASA Astrophysics Data System (ADS)

    Soldati, A.; Cashman, K. V.; Rust, A.; Rosi, M.

    2013-12-01

    The continual passive degassing occurring at open-vent mafic volcanoes is often punctuated by bursts of active degassing. The latter are generally thought to be the result of slug flow: large, conduit-filling bubbles periodically rising up the feeder conduit and bursting at the magma-air interface. Existing models of volcanic degassing systems make the simplifying assumption that the conduit is cylindrical; however, while this may be true at shallow levels, a flaring probably connects it to a dyke-like geometry at depth. The overall goal of this research is to assess the influence of conduit geometry on the speed and stability of bubbles rising in open-vent systems, and ultimately to devise a model to infer conduit shape from emerging bubbles size. In order to do that an analogue experimental approach was used. All of the experiments were two-phase (melt+volatiles); the analogue materials of choice were golden syrup-water mixtures ranging in viscosity from 10-1 to 104 Pa*s and air. Two experimental apparatuses were used: a bi-dimensional and a tri-dimensional one. The bi-dimensional set-up is a cell made of two flat transparent PVC plates (44x23cm) 10mm or 5mm apart (the front one having a hole at the bottom permitting bubble injection) containing a variety of parallelepipeds apt to outline different plumbing system geometries. The tri-dimensional one consists of a cylindrical tube (r=1,5cm; l=7cm) allowing bubble injection through the bottom rubber tap and terminating into a square tank (l=22cm). Results indicate that conduit geometry directly controls the slug rise velocity and the surrounding liquid descending speed, which in turn control the slug stability. Small enough bubbles simply deform as they go through the flaring, while bigger ones split into two daughter bubbles. A regime diagram has been constructed, illustrating the bubble break-up threshold dependence on the flare geometry and initial slug size, the two main controlling factors. The phenomenon of

  3. A computational study of the dynamic motion of a bubble rising in Carreau model fluids

    NASA Astrophysics Data System (ADS)

    Ohta, Mitsuhiro; Yoshida, Yutaka; Sussman, Mark

    2010-04-01

    We present the results of three-dimensional direct numerical simulations of the dynamic motion of a gas bubble rising in Carreau model fluids. The simulations are carried out by a coupled level-set/volume-of-fluid (CLSVOF) method, which combines some of the advantages of the volume-of-fluid (VOF) method with the level-set (LS) method. In our study, it is shown that the motion of a rising gas bubble largely depends on the Carreau model parameters, n and B (n, the slope of decreasing viscosity and B, time constant). Both the model parameters, n and B, have considerable influence on the bubble rise motion. Using numerical analysis, we can understand in detail the bubble morphology for non-Newtonian two-phase flow systems. We also discuss bubble rise motion in shear-thinning fluids in terms of the effective viscosity, ηeff, the effective Reynolds number, Reeff and the effective Morton number, Meff.

  4. Rising motion of a bubble layer near a vertical wall

    NASA Astrophysics Data System (ADS)

    Dabiri, Sadegh; Bhuvankar, Pramod

    2015-11-01

    Bubbly flows in vertical pipes and channels form a wall-peak distribution of bubbles under certain conditions. The dynamics of the bubbles near the wall is different than in an unbounded liquid. Here we report the rising motion of bubbles in a liquid near a vertical wall. In a simulation of a bubbly flow in a periodic domain with a vertical wall on one side, an average pressure gradient is 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 a shear flow which is in turn generated by rising motion of bubbles. The rise velocity of the bubbles on the wall and the average rise velocity of the liquid depend on three dimensionless parameters, Archimedes number, Eotvos number, and the average volume fraction of bubbles near 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.

  5. The shape of bubbles rising near the nozzle exit in molten metal baths

    NASA Astrophysics Data System (ADS)

    Iguchi, Manabu; Nakatani, Tadatoshi; Tokunaga, Hirohiko

    1997-06-01

    A previously developed multineedle electroresistivity probe was used to investigate the shape of bubbles generated at the exit of a central single-hole bottom nozzle in molten Wood’s metal and mercury baths. This probe is capable of detecting the vertical cross section of rising bubbles. The shape of bubbles just after the detachment from the nozzle exit was correlated as a function of a modified Reynolds number and a modified Weber number. Furthermore, the relations between the shape of bubbles and the radial distributions of bubble characteristics specified by gas holdup, bubble frequency, etc. were derived. As a result, it is possible to predict the shape of the bubbles by measuring the bubble characteristics with a conventional two-needle electroresistivity probe.

  6. Numerical simulation of superheated vapor bubble rising in stagnant liquid

    NASA Astrophysics Data System (ADS)

    Samkhaniani, N.; Ansari, M. R.

    2017-09-01

    In present study, the rising of superheated vapor bubble in saturated liquid is simulated using volume of fluid method in OpenFOAM cfd package. The surface tension between vapor-liquid phases is considered using continuous surface force method. In order to reduce spurious current near interface, Lafaurie smoothing filter is applied to improve curvature calculation. Phase change is considered using Tanasawa mass transfer model. The variation of saturation temperature in vapor bubble with local pressure is considered with simplified Clausius-Clapeyron relation. The couple velocity-pressure equation is solved using PISO algorithm. The numerical model is validated with: (1) isothermal bubble rising and (2) one-dimensional horizontal film condensation. Then, the shape and life time history of single superheated vapor bubble are investigated. The present numerical study shows vapor bubble in saturated liquid undergoes boiling and condensation. It indicates bubble life time is nearly linear proportional with bubble size and superheat temperature.

  7. Experimental study on wake structure of single rising clean bubble

    NASA Astrophysics Data System (ADS)

    Sato, Ayaka; Takedomi, Yuta; Shirota, Minori; Sanada, Toshiyuki; Watanabe, Masao

    2007-11-01

    Wake structure of clean bubble rising in quiescent silicone oil solution of photochromic dye is experimentally studied. A single bubble is generated, immediately after UV sheet light illuminates the part of the liquid just above the bubble generation nozzle in order to activate photochromic dye. Once the bubble passes across the colored part of the liquid, the bubble is accompanied by some portion of activated dye tracers; hence the flow structure in the rear of the single rising bubble is visualized. We capture stereo images of both wake structure and bubble motion. We study how wake structure changes with the increase in bubble size. We observe the stable axisymmetric wake structure, which is called `standing eddy' when bubble size is relatively small, and then wake structure becomes unstable and starts to oscillate with the increase in bubble size. With further increase in bubble size, a pair of streamwise vortices, which is called `double thread', is observed. We discuss in detail this transition from the steady wake to unsteady wake structure, especially double thread wake development and hairpin vortices shedding, in relation to the transition from rectilinear to spiral or zigzag bubble motions.

  8. On the deformation of gas bubbles in liquids

    NASA Astrophysics Data System (ADS)

    Legendre, Dominique; Zenit, Roberto; Velez-Cordero, J. Rodrigo

    2012-04-01

    We consider the deformation of gas bubbles rising in different liquids over a wide range of Morton numbers, from O(10-11) to O(1), and bubble diameters. We have collected data from the literature and performed new experiments for relatively large Morton numbers. A simple expression is proposed to describe the evolution of the bubble deformation, which is consistent with the analytical solution of Moore ["The rise of a gas bubble in a viscous liquid," J. Fluid Mech. 6, 113 (1959)]. It appears that deformation can be predicted correctly by considering the Morton and Weber numbers. The variation of the bubble interfacial area is also analyzed; this quantity is very important for the case of bubbly flow modeling but has not been measured directly to date.

  9. Etiology of gas bubble disease

    SciTech Connect

    Bouck, G.R.

    1980-11-01

    Gas bubble disease is a noninfectious, physically induced process caused by uncompensated hyperbaric pressure of total dissolved gases. When pressure compensation is inadequate, dissolved gases may form emboli (in blood) and emphysema (in tissues). The resulting abnormal physical presence of gases can block blood vessels (hemostasis) or tear tissues, and may result in death. Population mortality is generally skewed, in that the median time to death occurs well before the average time to death. Judged from mortality curves, three stages occur in gas bubble disease: (1) a period of gas pressure equilibrium, nonlethal cavitation, and increasing morbidity; (2) a period of rapid and heavy mortality; and (3) a period of protracted survival, despite lesions, and dysfunction that eventually terminates in total mortality. Safe limits for gas supersaturation depend on species tolerance and on factors that differ among hatcheries and rivers, between continuous and intermittent exposures, and across ranges of temperature and salinity.

  10. Rise of an argon bubble in liquid steel in the presence of a transverse magnetic field

    NASA Astrophysics Data System (ADS)

    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.

  11. From Rising Bubble to RNA/DNA and Bacteria

    NASA Astrophysics Data System (ADS)

    Marks, Roman; Cieszyńska, Agata; Wereszka, Marzena; Borkowski, Wojciech

    2017-04-01

    In this study we have focused on the movement of rising bubbles in a salty water body. Experiments reviled that free buoyancy movement of bubbles forces displacement of ions, located on the outer side of the bubble wall curvatures. During the short moment of bubble passage, all ions in the vicinity of rising bubble, are separated into anions that are gathered on the bubble upper half sphere and cations that slip along the bottom concave half-sphere of a bubble and develop a sub-bubble vortex. The principle of ions separation bases on the differences in displacement resistance. In this way, relatively heavier and larger, thus more resistant to displacement anions are gathered on the rising bubble upper half sphere, while smaller and lighter cations are assembled on the bottom half sphere and within the sub-bubble vortex. The acceleration of motion generates antiparallel rotary of bi-ionic domains, what implies that anions rotate in clockwise (CW) and cationic in counter-clockwise (CCW) direction. Then, both rotational systems may undergo splicing and extreme condensing by bi-pirouette narrowing of rotary. It is suggested that such double helix motion of bi-ionic domains creates RNA/DNA molecules. Finally, when the bubble reaches the water surface it burst and the preprocessed RNA/DNA matter is ejected into the droplets. Since that stage, droplet is suspended in positively charged troposphere, thus the cationic domain is located in the droplet center, whilst negative ions are attracted to configure the outer areola. According to above, the present study implies that the rising bubbles in salty waters may incept synergistic processing of matter resulting in its rotational/spherical organization that led to assembly of RNA/DNA molecules and bacteria cells.

  12. Rise of Air Bubbles in Aircraft Lubricating Oils

    NASA Technical Reports Server (NTRS)

    Robinson, J. V.

    1950-01-01

    Lubricating and antifoaming additives in aircraft lubricating oils may impede the escape of small bubbles from the oil by forming shells of liquid with a quasi-solid or gel structure around the bubbles. The rates of rise of small air bubbles, up to 2 millimeters in diameter, were measured at room temperature in an undoped oil, in the same oil containing foam inhibitors, and in an oil containing lubricating additives. The apparent diameter of the air bubbles was measured visually through an ocular micrometer on a traveling telescope. The bubbles in the undoped oil obeyed Stokes' Law, the rate of rise being proportional to the square of the apparent diameter and inversely proportional to the viscosity of the oil. The bubbles in the oils containing lubricating additives or foam inhibitors rose more slowly than the rate predicted by Stokes 1 Law from the apparent diameter, and the rate of rise decreased as the length of path the bubbles traveled increased. A method is derived to calculate the thickness of the liquid shell which would have to move with the bubbles in the doped oils to account for the abnoi'I!l8.lly slow velocity. The maximum thickness of this shell, calculated from the velocities observed, was equal to the bubble radius.

  13. Freon bubble rise measurements in a vertical rectangular duct

    SciTech Connect

    Vassallo, P.F.; Symolon, P.D.; Moore, W.E.; Trabold, T.A.

    1995-12-01

    Isolated bubble rise experiments provide data on bubble drag as a function of size and fluid properties. This data is useful in obtaining drag models for higher void fraction bubbly flows. Previous experiments (Haberman and Morton, 1953) have shown that the purity of the fluid affects the bubble rise velocity, and therefore the drag coefficient. For contaminated systems, impurities collecting at the liquid-vapor interface increase the effective viscous drag and decrease the rise velocity. In the current experimental work, Freon-114 is used to simulate high temperature environments. Freon is chosen as the modeling fluid because it boils at a lower temperature, and may be scaled appropriately. However, if the purity of the Freon test liquid is unknown, using it to model high temperature environments may lead to inaccurate results. The purpose of the bubble rise experiment is then (1) to identify the purity of the Freon test liquid, and (2) understand the bubble drag mechanism for single bubbles as a building block for multiple bubble drag models.

  14. Gas-rise velocities during kicks

    SciTech Connect

    White, D.B. )

    1991-12-01

    This paper reports on experiments to examine gas migration rates in drilling muds that were performed in a 15-m-long, 200-mm-ID inclinable flow loop where air injection simulates gas entry during a kick. These tests were conducted using a xanthum gum (a common polymer used in drilling fluids) solution to simulate drilling muds as the liquid phase and air as the gas phase. This work represents a significant extension of existing correlations for gas/liquid flows in large pipe diameters with non- Newtonian fluids. Bubbles rise faster in drilling muds than in water despite the increased viscosity. This surprising result is caused by the change in the flow regime, with large slug-type bubbles forming at lower void fractions. The gas velocity is independent of void fraction, thus simplifying flow modeling. Results show that a gas influx will rise faster in a well than previously believed. This has major implications for kick simulation, with gas arriving at the surface earlier than would be expected and the gas outflow rate being higher than would have been predicted. A model of the two-phase gas flow in drilling mud, including the results of this work, has been incorporated into the joint Schlumberger Cambridge Research (SCR)/BP Intl. kick model.

  15. Two initially spherical bubbles rising in quiescent liquid

    NASA Astrophysics Data System (ADS)

    Tripathi, Manoj Kumar; Premlata, A. R.; Sahu, Kirti Chandra; Govindarajan, Rama

    2017-07-01

    A pair of bubbles starting from rest and rising side-by-side in a liquid have been shown earlier to display spherical and ellipsoidal shapes. In contrast to earlier computational studies on the two-dimensional dynamics of a pair of bubbles, we study the fully three-dimensional motion of the bubbles in the inertial regime. We reveal the destabilizing nature of the interaction between the wakes of the bubbles, which causes them to rise in an oscillatory path. Such three-dimensionality sets in earlier in time than for a single bubble and also at a lower inertia. The interaction leads to a mirror symmetry in the trajectories of the two bubbles, which persists for some time even in the high-inertia regime where each path is chaotic. The effect of the inertia and initial separation on the mirror symmetry of the path, the vortex shedding pattern, and the attraction and repulsion between the bubbles are examined. The bubble rise has been interestingly observed to be symmetrical about the plane perpendicular to the separation vector for all separation distances considered in the present study.

  16. A novel method of measuring electrophoretic mobility of gas bubbles.

    PubMed

    Najafi, Aref Seyyed; Drelich, Jaroslaw; Yeung, Anthony; Xu, Zhenghe; Masliyah, Jacob

    2007-04-15

    Accurate measurement of electrophoretic mobility for gas bubbles is a challenging task as it requires the creation of a desired number of very small air bubbles to ensure negligible rise velocities during the course of the measurement. Here, we report a simple and reliable method for generating stable dispersions of "nano-bubbles." Preparation of such dispersions relies on the nucleation of nano-bubbles in solutions supersaturated with gas. Electrophoretic mobility of these nano-bubbles is determined by the ZetaPALS technique (Brookhaven Instruments) using Uzgiris electrodes coated with palladium. The Smoluchowski limit is assumed in the calculation of zeta potentials. In regard to reproducibility and reliability, this novel method shows a clear advantage over other existing techniques of zeta potential measurement for bubbles.

  17. Gas Bubble Formation in Stagnant and Flowing Mercury

    SciTech Connect

    Wendel, Mark W; Abdou, Ashraf A; Riemer, Bernie; Felde, David K

    2007-01-01

    Investigations in the area of two-phase flow at the Oak Ridge National Laboratory's (ORNL) Spallation Neutron Source (SNS) facility are progressing. It is expected that the target vessel lifetime could be extended by introducing gas into the liquid mercury target. As part of an effort to validate the two-phase computational fluid dynamics (CFD) model, simulations and experiments of gas injection in stagnant and flowing mercury have been completed. The volume of fluid (VOF) method as implemented in ANSYS-CFX, was used to simulate the unsteady two-phase flow of gas injection into stagnant mercury. Bubbles produced at the upwards-oriented vertical gas injector were measured with proton radiography at the Los Alamos Neutron Science Center. The comparison of the CFD results to the radiographic images shows good agreement for bubble sizes and shapes at various stages of the bubble growth, detachment, and gravitational rise. Although several gas flows were measured, this paper focuses on the case with a gas flow rate of 8 cc/min through the 100-micron-diameter injector needle. The acoustic waves emitted due to the detachment of the bubble and during subsequent bubble oscillations were recorded with a microphone, providing a precise measurement of the bubble sizes. As the mercury flow rate increases, the drag force causes earlier bubble detachment and therefore smaller bubbles.

  18. Correlation of bubble rise velocity and volume

    SciTech Connect

    Burge, C.

    1991-01-01

    This project was conducted at Westinghouse's Savannah River Laboratories (SRL). The goal of SRL is to make certain that the modifications on the reactor are safe for those working at the plant as well as the general public. One of the steps needed to insure safety is the knowledge of the occurrences that result from a plenum pipe breakage. When a plenum pipe breaks, two things occur: air is sucked into the pipe and is trapped in the cooling water; and water used to cool the fuel rods is lost. As a result of these occurrences, the water is slowed down by both the loss in water pressure and the upward force of air bubbles pushing against the downward force of the water. The project required the conducting of tests to find the bubble velocity in an annular ribbed pipe filled with stagnant water. This document discusses the methodology and results of this testing.

  19. Correlation of bubble rise velocity and volume

    SciTech Connect

    Burge, C.

    1991-12-31

    This project was conducted at Westinghouse`s Savannah River Laboratories (SRL). The goal of SRL is to make certain that the modifications on the reactor are safe for those working at the plant as well as the general public. One of the steps needed to insure safety is the knowledge of the occurrences that result from a plenum pipe breakage. When a plenum pipe breaks, two things occur: air is sucked into the pipe and is trapped in the cooling water; and water used to cool the fuel rods is lost. As a result of these occurrences, the water is slowed down by both the loss in water pressure and the upward force of air bubbles pushing against the downward force of the water. The project required the conducting of tests to find the bubble velocity in an annular ribbed pipe filled with stagnant water. This document discusses the methodology and results of this testing.

  20. Exploring the mechanisms of rising bubbles in marine biofouling prevention

    NASA Astrophysics Data System (ADS)

    Menesses, Mark; Belden, Jesse; Dickenson, Natasha; Bird, James

    2015-11-01

    Fluid motion, such as flow past a ship, is known to inhibit the growth of marine biofouling. Bubbles rising along a submerged structure also exhibit this behavior, which is typically attributed to buoyancy induced flow. However, the bubble interface may also have a direct influence on inhibiting growth that is independent of the surrounding flow. Here we aim to decouple these two mechanisms through a combination of field and laboratory experiments. In this study, a wall jet and a stream of bubbles are used to create two flows near a submerged solid surface where biofouling occurs. The flow structure characteristics were recorded using PIV. This experimental analysis allows for us to compare the efficacy of each flow relative to its flow parameters. Exploration of the mechanisms at play in the prevention of biofouling by use of rising bubbles provides a foundation to predict and optimize this antifouling technique under various conditions.

  1. Gas separation and bubble behavior at a woven screen

    NASA Astrophysics Data System (ADS)

    Conrath, Michael; Dreyer, Michael E.

    trapped bubble volumes, liquid flow rates and flow-induced compression, ii) typical breakthrough of a trapped bubble at rising liquid flow rate and iii) steady gas supply in steady liquid flow. It shows that our model can explain the experimental observations. One of the interesting findings for the dynamic bubble point is that hydraulic losses in the rest of the circuit will shift the breakthrough of gas to higher liquid flow rates.

  2. Mechanics of gas-vapor bubbles

    NASA Astrophysics Data System (ADS)

    Hao, Yue; Zhang, Yuhang; Prosperetti, Andrea

    2017-03-01

    Most bubbles contain a mixture of vapor and incondensible gases. While the limit cases of pure vapor and pure gas bubbles are well studied, much less is known about the more realistic case of a mixture. The bubble contents continuously change due to the combined effects of evaporation and condensation and of gas diffusion in the liquid and in the bubble. This paper presents a model for this situation and illustrates by means of examples several physical processes that can occur: a bubble undergoing a temporary pressure reduction, which makes the liquid temporarily superheated; a bubble subjected to a burst of sound; and a bubble continuously growing by rectified diffusion of heat in the presence of an incondensible gas.

  3. A numerical simulation of flows around a deformable gas bubble

    NASA Astrophysics Data System (ADS)

    Sugano, Minoru; Ishii, Ryuji; Morioka, Shigeki

    1991-12-01

    A numerical simulation of flows around a (deformable) gas bubble rising through an incompressible viscous fluid was carried out on a supercomputer Fujitsu VP2600 at Data Processing Center of Kyoto University. The solution algorithm is a modified Marker And Cell (MAC) method. For the grid generation, an orthogonal mapping proposed by Ryskin and Leal was applied. it is assumed that the shape of the bubble and the flow field are axisymmetric.

  4. Evolution of energy in flow driven by rising bubbles.

    PubMed

    Mazzitelli, Irene M; Lohse, Detlef

    2009-06-01

    We investigate by direct numerical simulations the flow that rising bubbles cause in an originally quiescent fluid. We employ the Eulerian-Lagrangian method with two-way coupling and periodic boundary conditions. In order to be able to treat up to 288000 bubbles, the following approximations and simplifications had to be introduced, as done before, e.g., by Climent and Magnaudet, Phys. Rev. Lett. 82, 4827 (1999). (i) The bubbles were treated as point particles, thus (ii) disregarding the near-field interactions among them, and (iii) effective force models for the lift and the drag forces were used. In particular, the lift coefficient was assumed to be 1/2, independent of the bubble Reynolds number and the local flow field. The results suggest that large-scale motions are generated, owing to an inverse energy cascade from the small to the large scales. However, as the Taylor-Reynolds number is only in the range of 1, the corresponding scaling of the energy spectrum with an exponent of -5/3 cannot develop over a pronounced range. In the long term, the property of local energy transfer, characteristic of real turbulence, is lost and the input of energy equals the viscous dissipation at all scales. Due to the lack of strong vortices, the bubbles spread rather uniformly in the flow. The mechanism for uniform spreading is as follows. Rising bubbles induce a velocity field behind them that acts on the following bubbles. Owing to the shear, those bubbles experience a lift force, which makes them spread to the left or right, thus preventing the formation of vertical bubble clusters and therefore of efficient forcing. Indeed, when the lift is artificially put to zero in the simulations, the flow is forced much more efficiently and a more pronounced energy that accumulation at large scales (due to the inverse energy cascade) is achieved.

  5. Finger evolution of a gas bubble driven by atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Shiu, Jia-Hau; Chu, Hong-Yu

    2016-12-01

    We report the generation and evolution of a finger-shaped bubble in liquid by dielectric discharge setup. The spherical gas bubble is deformed into a finger-shaped bubble after the ignition of plasma. The presence of the filamentary discharge in the bubble not only provides the local heating to the bubble, it also changes the distribution of the electric field in the bubble and the bubble mutually provides the pathway to the discharge. The reduced surface tension on the liquid-gas interface due to the rise of temperature by plasma heating and the nonuniform electric field caused by the presence of filamentary discharge might induce the concave-shaped bubble. We also observe the formation of the quasi-two-dimensional bubble, which is generated from the bubble and attached on one side of the electrodes. It is found that the discharge induces the growth of the periodic fluctuations in the thin layer of gas.

  6. Rise of an argon bubble in liquid steel in the presence of a transverse magnetic field

    SciTech Connect

    Jin, K.; Kumar, P.; Vanka, S. P.; Thomas, B. G.

    2016-09-15

    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.

  7. Gas Bubble Growth in Muddy Sediments

    DTIC Science & Technology

    2016-06-07

    naval mines. Gas ebullition of methane is a major release mechanism to the atmosphere for this greenhouse gas. Thus, understanding bubble formation...3R2D∂C∂r r =R (2) where ρg is the density of the gas and D is the effective molecular diffusion coefficient in the porewater . The gas-bubble literature...produced acoustic signals and place limits of the flux of methane to the atmosphere . RELATED PROJECTS We are not formally cooperating with any

  8. Bubble-driven anodic gas in molten salt electrolytes

    NASA Astrophysics Data System (ADS)

    Osarinmwian, C.

    2017-03-01

    Herein online mass spectrometry is used to record real-time concentration curves of anodic gases released during the electrochemical oxidation of graphite anodes in molten CaCl2. The shape of these curves suggests that electrochemical oxidation is rate limited by the mass transport of oxidant ions to the anode surface. Anodic gas bubbles are formed and released from nucleation sites at this surface. Although the applied voltage is less than the decomposition voltage, an unexpectedly high release of Cl2 gas indicates continuous decomposition of molten CaCl2. The origin of experimentally observed anodic gas bubbling is explained using phase-field simulations of a rising gas bubble in molten CaCl2.

  9. Dynamics of an initially spherical bubble rising in quiescent liquid

    NASA Astrophysics Data System (ADS)

    Tripathi, Manoj Kumar; Sahu, Kirti Chandra; Govindarajan, Rama

    2015-02-01

    The beauty and complexity of the shapes and dynamics of bubbles rising in liquid have fascinated scientists for centuries. Here we perform simulations on an initially spherical bubble starting from rest. We report that the dynamics is fully three-dimensional, and provide a broad canvas of behaviour patterns. Our phase plot in the Galilei-Eötvös plane shows five distinct regimes with sharply defined boundaries. Two symmetry-loss regimes are found: one with minor asymmetry restricted to a flapping skirt; and another with marked shape evolution. A perfect correlation between large shape asymmetry and path instability is established. In regimes corresponding to peripheral breakup and toroid formation, the dynamics is unsteady. A new kind of breakup, into a bulb-shaped bubble and a few satellite drops is found at low Morton numbers. The findings are of fundamental and practical relevance. It is hoped that experimenters will be motivated to check our predictions.

  10. BUBBLE DYNAMICS AT GAS-EVOLVING ELECTRODES

    SciTech Connect

    Sides, Paul J.

    1980-12-01

    Nucleation of bubbles, their growth by diffusion of dissolved gas to the bubble surface and by coalescence, and their detachment from the electrode are all very fast phenomena; furthermore, electrolytically generated bubbles range in size from ten to a few hundred microns; therefore, magnification and high speed cinematography are required to observe bubbles and the phenomena of their growth on the electrode surface. Viewing the action from the front side (the surface on which the bubbles form) is complicated because the most important events occur close to the surface and are obscured by other bubbles passing between the camera and the electrode; therefore, oxygen was evolved on a transparent tin oxide "window" electrode and the events were viewed from the backside. The movies showed that coalescence of bubbles is very important for determining the size of bubbles and in the chain of transport processes; growth by diffusion and by coalescence proceeds in series and parallel; coalescing bubbles cause significant fluid motion close to the electrode; bubbles can leave and reattach; and bubbles evolve in a cycle of growth by diffusion and different modes of coalescence. An analytical solution for the primary potential and current distribution around a spherical bubble in contact with a plane electrode is presented. Zero at the contact point, the current density reaches only one percent of its undisturbed value at 30 percent of the radius from that point and goes through a shallow maximum two radii away. The solution obtained for spherical bubbles is shown to apply for the small bubbles of electrolytic processes. The incremental resistance in ohms caused by sparse arrays of bubbles is given by {Delta}R = 1.352 af/kS where f is the void fraction of gas in the bubble layer, a is the bubble layer thickness, k is the conductivity of gas free electrolyte, and S is the electrode area. A densely populated gas bubble layer on an electrode was modeled as a hexagonal array of

  11. Structure of nanoscale gas bubbles in metals

    SciTech Connect

    Caro, A. Schwen, D.; Martinez, E.

    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.

  12. Entrapment efficiencies of hydrodynamic boundary layers on rising bubbles.

    PubMed

    Mileva, Elena; Nikolov, Ljubomir

    2003-09-15

    Flotation and separation practice shows that fine hydrophilic solids are often drawn into the froth product. The occurrence of this unwanted event in the classical froth flotation has led to the idea of using it for the separation by size of ground materials. Thus, a method for the extraction of hydrophilic fines by foaming of a suspension was proposed. The aim of the present study is to relate this phenomenon to the residence time of the particles in the vicinities of the rising bubbles. Dynamic interactions of fine solids with rising bubbles cause perturbations in the background flow field. A procedure for the mathematical modeling of these disturbance effects is proposed. The initial idea is that the particles lag behind the background bubble-driven flows. A key point is the possibility of classifying fine entities according to a general criterion, containing only parameters of the outer flow. The basic result is that there exists a range of particle and bubble dimensions for which this entrapment is optimal. The proposed model investigation gives a concise explanation for the observed capture of fine solids in many flotation and separation processes.

  13. Evolution of bubble size distribution from gas blowout in shallow water

    NASA Astrophysics Data System (ADS)

    Zhao, Lin; Boufadel, Michel C.; Lee, Kenneth; King, Thomas; Loney, Norman; Geng, Xiaolong

    2016-03-01

    Gas is often emanated from the sea bed during a subsea oil and gas blowout. The size of a gas bubble changes due to gas dissolution in the ambient water and expansion as a result of a decrease in water pressure during the rise. It is important to understand the fate and transport of gas bubbles for the purpose of environmental and safety concerns. In this paper, we used the numerical model, VDROP-J to simulate gas formation in jet/plume upon release, and dissolution and expansion while bubble rising during a relatively shallow subsea gas blowout. The model predictions were an excellent match to the experimental data. Then a gas dissolution and expansion module was included in the VDROP-J model to predict the fate and transport of methane bubbles rising due to a blowout through a 0.10 m vertical orifice. The numerical results indicated that gas bubbles would increase the mixing energy in released jets, especially at small distances and large distances from the orifice. This means that models that predict the bubble size distribution (BSD) should account for this additional mixing energy. It was also found that only bubbles of certain sizes would reach the water surfaces; small bubbles dissolve fast in the water column, while the size of the large bubbles decreases. This resulted in a BSD that was bimodal near the orifice, and then became unimodal.

  14. A global stability approach to wake and path instabilities of nearly oblate spheroidal rising bubbles

    NASA Astrophysics Data System (ADS)

    Cano-Lozano, José Carlos; Tchoufag, Joël; Magnaudet, Jacques; Martínez-Bazán, Carlos

    2016-01-01

    A global Linear Stability Analysis (LSA) of the three-dimensional flow past a nearly oblate spheroidal gas bubble rising in still liquid is carried out, considering the actual bubble shape and terminal velocity obtained for various sets of Galilei (Ga) and Bond (Bo) numbers in axisymmetric numerical simulations. Hence, this study extends the stability analysis approach of Tchoufag et al. ["Linear stability and sensitivity of the flow past a fixed oblate spheroidal bubble," Phys. Fluids 25, 054108 (2013) and "Linear instability of the path of a freely rising spheroidal bubble," J. Fluid Mech. 751, R4 (2014)] (which considered perfectly spheroidal bubbles with an arbitrary aspect ratio) to the case of bubbles with a realistic fore-aft asymmetric shape (i.e., a flatter front and a more rounded rear). The critical curve separating stable and unstable regimes for the straight vertical path is obtained both in the (Ga,Bo) and the (Re,χ) planes, where Re is the bubble Reynolds number and χ its aspect ratio (i.e., the major-to-minor axes length ratio). This provides new insight into the effect of the shape asymmetry on the wake instability of bubbles held fixed in a uniform stream and on the path instability of freely rising bubbles, respectively. For the range of Ga and Bo explored here, we find that the flow past a bubble with a realistic shape is generally more stable than that past a perfectly spheroidal bubble with the same aspect ratio. This study also provides the first critical curve for the onset of path instability that can be compared with experimental observations. The tendencies revealed by this critical curve agree well with those displayed by available data. The quantitative agreement is excellent for O(1) Bond numbers. However, owing to two simplifying assumptions used in the LSA scheme, namely, the steadiness of the base state and the uncoupling between the bubble shape and the flow disturbances, quantitative discrepancies (up to 20%-30%) with

  15. Gas transfer in a bubbly wake flow

    NASA Astrophysics Data System (ADS)

    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.

  16. Advances in the Rising Bubble Technique for discharge measurement

    NASA Astrophysics Data System (ADS)

    Hilgersom, Koen; Luxemburg, Willem; Willemsen, Geert; Bussmann, Luuk

    2014-05-01

    Already in the 19th century, d'Auria described a discharge measurement technique that applies floats to find the depth-integrated velocity (d'Auria, 1882). The basis of this technique was that the horizontal distance that the float travels on its way to the surface is the image of the integrated velocity profile over depth. Viol and Semenov (1964) improved this method by using air bubbles as floats, but still distances were measured manually until Sargent (1981) introduced a technique that could derive the distances from two photographs simultaneously taken from each side of the river bank. Recently, modern image processing techniques proved to further improve the applicability of the method (Hilgersom and Luxemburg, 2012). In the 2012 article, controlling and determining the rising velocity of an air bubble still appeared a major challenge for the application of this method. Ever since, laboratory experiments with different nozzle and tube sizes lead to advances in our self-made equipment enabling us to produce individual air bubbles with a more constant rising velocity. Also, we introduced an underwater camera to on-site determine the rising velocity, which is dependent on the water temperature and contamination, and therefore is site-specific. Camera measurements of the rising velocity proved successful in a laboratory and field setting, although some improvements to the setup are necessary to capture the air bubbles also at depths where little daylight penetrates. References D'Auria, L.: Velocity of streams; A new method to determine correctly the mean velocity of any perpendicular in rivers and canals, (The) American Engineers, 3, 1882. Hilgersom, K.P. and Luxemburg, W.M.J.: Technical Note: How image processing facilitates the rising bubble technique for discharge measurement, Hydrology and Earth System Sciences, 16(2), 345-356, 2012. Sargent, D.: Development of a viable method of stream flow measurement using the integrating float technique, Proceedings of

  17. Gas bubble dynamics in soft materials.

    PubMed

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

    2015-01-07

    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.

  18. Development and interactions of two inert gas bubbles during decompression.

    PubMed

    Jiang, Y; Homer, L D; Thalmann, E D

    1996-09-01

    A mathematical model has been developed to simulate the evolution of two inert gas bubbles in tissue. This is useful for understanding the dynamics of bubbles that presumably arise during decompression. It is assumed that they are spherical and that the tissue volume surrounding them is infinite. The total pressure in each bubble is determined by the barometric and metabolic gas pressures as well as the pressure due to surface tension. Bipolar coordinates are employed to determine the inert gas pressure distribution. Two coupled governing equations for bubble radii are then derived and solved numerically. The results demonstrate how bubble evolution is affected by the distance between bubbles and the initial bubble radii. The existence time and bubble surface flux of two equal-sized bubbles are calculated and compared with those of a single gas bubble model. The results indicate that when two bubbles are very close, it takes 20% more time for two bubbles to dissolve than for a single one, and the total surface flux of two bubbles is nearly 20% less than twice of a single bubble. When the center-to-center distance is 10 times of bubble radius, the effect of bubble interaction on bubble existence time and surface flux are about 6 and 9% changes, respectively. We conclude that if bubbles are not too small, the interactions among bubbles should be included in inert gas bubble models predicting bubble evolution.

  19. The hydrodynamics of bubble rise and impact with solid surfaces.

    PubMed

    Manica, Rogerio; Klaseboer, Evert; Chan, Derek Y C

    2016-09-01

    A bubble smaller than 1mm in radius rises along a straight path in water and attains a constant speed due to the balance between buoyancy and drag force. Depending on the purity of the system, within the two extreme limits of tangentially immobile or mobile boundary conditions at the air-water interface considerably different terminal speeds are possible. When such a bubble impacts on a horizontal solid surface and bounces, interesting physics can be observed. We study this physical phenomenon in terms of forces, which can be of colloidal, inertial, elastic, surface tension and viscous origins. Recent advances in high-speed photography allow for the observation of phenomena on the millisecond scale. Simultaneous use of such cameras to visualize both rise/deformation and the dynamics of the thin film drainage through interferometry are now possible. These experiments confirm that the drainage process obeys lubrication theory for the spectrum of micrometre to millimetre-sized bubbles that are covered in this review. We aim to bridge the colloidal perspective at low Reynolds numbers where surface forces are important to high Reynolds number fluid dynamics where the effect of the surrounding flow becomes important. A model that combines a force balance with lubrication theory allows for the quantitative comparison with experimental data under different conditions without any fitting parameter. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. On the bubble rise velocity of a continually released bubble chain in still water and with crossflow

    NASA Astrophysics Data System (ADS)

    Wang, Binbin; Socolofsky, Scott A.

    2015-10-01

    The rise velocities of in-chain bubbles continually released from a single orifice in still water with and without crossflow are investigated in a series of laboratory experiments for wobbling ellipsoidal bubbles with moderate Reynolds number. For the limiting case in still water, that is, crossflow velocity = 0, the theoretical turbulent wake model correctly predicts the in-chain bubble rise velocity. In this case, the bubble rise velocities VB are enhanced compared to the terminal velocities of the isolated bubbles V0 due to wake drafting and are scaled with flow rate Q and bubble diameter D. Here, we also derive an updated wake model with consideration of the superposition of multiple upstream bubble wakes, which removes the nonlinear behavior of the non-distant (i.e., local) wake model. For the cases with crossflow, the enhancement of the in-chain bubble rise velocity can be significantly reduced, and imaging of the experiments shows very organized paring and grouping trajectories of rising bubbles not observed in still water under different crossflow velocities. The in-chain bubble rise velocities in crossflow are described by two models. First, an empirical model is used to correct the still-water equation for the crossflow effect. In addition, a semi-theoretical model considering the turbulent wake flow and the crossflow influence is derived and used to develop a theoretical normalization of bubble rise velocity, crossflow velocity, and the released bubble flow rate. The theoretical model suggests there are two different regimes of bubble-bubble interaction, with strong interaction occurring for the non-dimensional crossflow velocity Uc + = π Uc 3 D 3 V 0 / ( 18 g β Q 2 ) less than 0.06 and weaker interaction occurring for Uc + greater than 0.06, where Uc is the crossflow velocity, g is the acceleration of gravity, and β is the mixing length coefficient.

  1. Combined experimental and theoretical investigation of the gas bubble motion in an acoustic field.

    PubMed

    Ma, Xiaojian; Xing, Tianyu; Huang, Biao; Li, Qiuhe; Yang, Yifei

    2018-01-01

    The objective of this paper is to apply the combined experimental and theoretical method to investigate the various behaviors of gas bubbles in an acoustic field. In the experiments, high-speed video and ultrasonic processor are used to capture the transient evolution of gas bubble patterns, as well as velocity profiles. In the theoretical analysis, the theories of primary and secondary Bjerknes forces and buoyancy force are introduced to accurately demonstrate the variations of bubble volume and motion. Results are presented for gas bubbles with the radius of 1.4mm under an acoustic field with a frequency of 18kHz, for three cases, namely single bubble rising in a quiescent liquid, acoustic single bubble oscillation and two bubbles coalescence conditions. The results show that the fragments around the single gas bubble presents the periodical behaviors, namely, splitting, attraction, and secondary splitting motion. The centroid of the single gas bubble almost oscillates without motion upwards or downwards, because of the equilibrium of the primary Bjerknes force caused by acoustic waves and the effect of the buoyancy force. For the two coalescing bubbles, the resultant of buoyancy, primary and secondary Bjerknes forces acting on two bubbles are same in magnitude, but in opposite direction, which indicates that two gas bubbles attract each other and and coalesce into one. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Numerical study of a Taylor bubble rising in stagnant liquids.

    PubMed

    Kang, Chang-Wei; Quan, Shaoping; Lou, Jing

    2010-06-01

    The dynamics of a Taylor bubble rising in stagnant liquids is numerically investigated using a front tracking coupled with finite difference method. Parametric studies on the dynamics of the rising Taylor bubble including the final shape, the Reynolds number (Re(T)), the Weber number (We(T)), the Froude number (Fr), the thin liquid film thickness (w/D), and the wake length (l(w)/D) are carried out. The effects of density ratio (η), viscosity ratio (λ), Eötvös number (Eo), and Archimedes number (Ar) are examined. The simulations demonstrate that the density ratio and the viscosity ratio under consideration have minimal effect on the dynamics of the Taylor bubble. Eötvös number and Archimedes number influence the elongation of the tail and the wake structures, where higher Eo and Ar result in longer wake. To explain the sudden extension of the tail, a Weber number (We(l)) based on local curvature and velocity is evaluated and a critical We(l) is detected around unity. The onset of flow separation at the wake occurs in between Ar=2×10(3) and Ar=1×10(4), which corresponds to Re(T) between 13.39 and 32.55. Archimedes number also drastically affects the final shape of Taylor bubble, the terminal velocity, the thickness of thin liquid film, as well as the wall shear stress. It is found that w/D=0.32 Ar(-0.1).

  3. Experimental Study on Rising Velocity of Different Nitrogen Bubbles in of Circular Pipe

    NASA Astrophysics Data System (ADS)

    Zhang, Hua; Liu, Yiping; Wang, Jing

    2007-06-01

    Nitrogen bubble rising velocity in bottom of circular pipe has been studied by virtual experiment with high-speed camera. The obtained images are processed systematically. Based on Cole's and Mendelson's empirical formula of bubble rising velocity, fitting formula of nitrogen bubble rising velocity in bottom of circular pipe has been acquired through analyzing nitrogen bubble rising velocity. The treatment results of experimental data show that the rising velocity is related with the diameter of bubbles. And rising velocity of slug bubble is relative to L/D and change law is found. Through this experiment, we research rising velocity's change law, which is the spade work to study propagation mechanism of nitrogen slug bubble in circular pipe.

  4. Dynamics and acoustics of a spherical bubble rising under gravity in an inviscid liquid.

    PubMed

    Riccardi, Giorgio; De Bernardis, Enrico

    2016-09-01

    The rising motion and the acoustic emission of a pulsating spherical gas/vapour bubble in an isochoric, inviscid liquid are investigated. The motion is driven by the uniform and constant force field due to the gravity. The liquid is assumed at rest at the initial time. Unlike previous work on this subject, the mass of the bubble is not neglected, so that the bubble motion is accurately simulated also in the presence of large volume variations. After developing the relationships between the bubble motion to the liquid flow, a system of two nonlinear ordinary differential equations (ODEs) for the radius and the position of the center of mass of the bubble is written. The near-field pressure disturbance produced in the liquid by the bubble motion is evaluated by means of elliptic integrals and an efficient approximation of it free from these special functions is also used. The numerical integration of the ODE system allows one to evaluate the acoustic signal. This is carried out with the above mentioned approximation, and several features of it are demonstrated through the study of a sample flow.

  5. Inert gas bubbles in bcc Fe

    NASA Astrophysics Data System (ADS)

    Gai, Xiao; Smith, Roger; Kenny, S. D.

    2016-03-01

    The properties of inert gas bubbles in bcc Fe is examined using a combination of static energy minimisation, molecular dynamics and barrier searching methods with empirical potentials. Static energy minimisation techniques indicate that for small Ar and Xe bubbles, the preferred gas to vacancy ratio at 0 K is about 1:1 for Ar and varies between 0.5:1 and 0.9:1 for Xe. In contrast to interstitial He atoms and small He interstitial clusters, which are highly mobile in the lattice, Ar and Xe atoms prefer to occupy substitutional sites and any interstitials present in the lattice soon displace Fe atoms and become substitutional. If a pre-existing bubble is present then there is a capture radius around a bubble which extends up to the 6th neighbour position. Collision cascades can also enlarge an existing bubble by the capture of vacancies. Ar and Xe can diffuse through the lattice through vacancy driven mechanisms but with relatively high energy barriers of 1.8 and 2.0 eV respectively. This indicates that Ar and Xe bubbles are much harder to form than bubbles of He and that such gases produced in a nuclear reaction would more likely be dispersed at substitutional sites without the help of increased temperature or radiation-driven mechanisms.

  6. Numerical simulation on single Taylor bubble rising in LBE using moving particle method

    NASA Astrophysics Data System (ADS)

    Li, Xin; Tian, Wen X.; Chen, Rong H.; Su, Guang H.; Qiu, Sui Z.

    2013-07-01

    An improved meshless numerical method (MPS-MAFL) is utilized to simulate single Taylor bubble rising in liquid LBE to study its hydrodynamic characteristics. The computational region is a circular tube in which the liquid is described using discretized particles by un-uniform grid scheme. The gas-liquid interface was approximately treated as a free surface boundary and nonslip conditions are applied on tube wall. Several simulation results and corresponding analysis including Taylor bubble propagation procedure, pressure distribution, velocity profile around bubble nose and in the wake region as well as in the falling film are presented. Some experimental results and CFD numerical simulations from other previous researchers are compared with the present study as validation. The simulation results agree well with both theoretical analysis and experimental results, which demonstrate the reasonable selection of model as well as the accuracy and reliability of moving particle method.

  7. Ripples on a rising bubble through an immiscible two-liquid interface generate numerous micro droplets

    NASA Astrophysics Data System (ADS)

    Uemura, T.; Ueda, Y.; Iguchi, M.

    2010-11-01

    The mass transfer between immiscible two liquid phases can be greatly accelerated by bubbling gas through a reactor (Bird R. B., Stewart W. E. and Lightfoot E. N., Transport Phenomena, 2nd edition (John Wiley and Sons) 2002). Therefore, the physical phenomenon occurring during the passage of a rising bubble through an immiscible two-liquid interface is of particular interest. The passage of the bubble through the oil (upper phase)/water (lower phase) interface starts with an upward lifting of the interface, and the bubble attracts a column of the water phase upwards keeping a film of the water phase around itself. In the present study, a particular remark is given to the influence of different interface tensions retracting the water film, after the water film ruptured, which lays on the interface between air and silicone oil. Unlike the previous studies on the rupture of a single liquid film in a gas which is pulled due to the identical surface tension, this system can form concentric ripples on the outer interface of the water film (oil/water interface) around the bubble due to the weak interface tension. Then, numerous micro water droplets break out from the fully grown ripples.

  8. Hydrodynamic interaction of a pair of bubbles rising in a quiescent liquid.

    NASA Astrophysics Data System (ADS)

    Sanada, Toshiyuki

    2005-11-01

    Interaction effects on the motions of a pair of bubbles, which either rose in vertical line or side by side, in silicon oil pool were experimentally studied. A pair of bubbles rising in vertical line was generated by releasing bubbles successively from a single nozzle, while one rising side by side was generated, by releasing bubble simultaneously from a pair of horizontally placed orifices. Bubble diameter and liquid kinematic viscosity were taken as the experimental parameters. The motions of bubbles were recorded by a high-speed camera with 2000 fps. We observed that Reynolds number significantly affected the motions of a pair of bubbles rising both in vertical line and side by side. When a pair of bubbles rose in vertical line, the trailing bubble was attracted by the leading bubble wake, and then it collided with leading bubble, in the case of low Re, while a pair of bubbles kept a mutual equilibrium distance due to the balance between the leading bubble wake attractive force and potential repulsive force, in the case of intermediate Re. As Re further increased, the trailing bubble oscillated and then escaped from the vertical line. When a pair of bubbles rose side by side, they separated from each other as they rose in the case of low Re, while they attracted each other and then collided if the initial bubble horizontal distance was smaller than a critical value, in the case of large Re.

  9. Gas Bubble Growth in Muddy Sediments

    DTIC Science & Technology

    2000-09-30

    the ebullitive flux of methane, an important “greenhouse gas”, to the atmosphere. OBJECTIVES The immediate objective is a working model for the growth...OMB control number. 1. REPORT DATE SEP 2000 2. REPORT TYPE 3. DATES COVERED 00-00-2000 to 00-00-2000 4. TITLE AND SUBTITLE Gas Bubble Growth in...N is the porosity, D is the tortuosity-corrected diffusivity, cg is the concentration of gas in the bubble, S is the local rate of methanogenesis, R1

  10. Non-linear shape oscillations of rising drops and bubbles: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Lalanne, Benjamin; Abi Chebel, Nicolas; Vejražka, Jiří; Tanguy, Sébastien; Masbernat, Olivier; Risso, Frédéric

    2015-12-01

    This paper focuses on shape-oscillations of a gas bubble or a liquid drop rising in another liquid. The bubble/drop is initially attached to a capillary and is released by a sudden motion of that capillary, resulting in the rise of the bubble/drop along with the oscillations of its shape. Such experimental conditions make difficult the interpretation of the oscillation dynamics with regard to the standard linear theory of oscillation because (i) amplitude of deformation is large enough to induce nonlinearities, (ii) the rising motion may be coupled with the oscillation dynamics, and (iii) clean conditions without residual surfactants may not be achieved. These differences with the theory are addressed by comparing experimental observation with numerical simulation. Simulations are carried out using Level-Set and Ghost-Fluid methods with clean interfaces. The effect of the rising motion is investigated by performing simulations under different gravity conditions. Using a decomposition of the bubble/drop shape into a series of spherical harmonics, experimental and numerical time evolutions of their amplitudes are compared. Due to large oscillation amplitude, non-linear couplings between the modes are evidenced from both experimental and numerical signals; modes of lower frequency influence modes of higher frequency, whereas the reverse is not observed. Nevertheless, the dominant frequency and overall damping rate of the first five modes are in good agreement with the linear theory. Effect of the rising motion on the oscillations is globally negligible, provided the mean shape of the oscillation remains close to a sphere. In the drop case, despite the residual interface contamination evidenced by a reduction in the terminal velocity, the oscillation dynamics is shown to be unaltered compared to that of a clean drop.

  11. Mathematical model of gas bubble evolution in a straight tube.

    PubMed

    Halpern, D; Jiang, Y; Himm, J F

    1999-10-01

    Deep sea divers suffer from decompression sickness (DCS) when their rate of ascent to the surface is too rapid. When the ambient pressure drops, inert gas bubbles may form in blood vessels and tissues. The evolution of a gas bubble in a rigid tube filled with slowly moving fluid, intended to simulate a bubble in a blood vessel, is studied by solving a coupled system of fluid-flow and gas transport equations. The governing equations for the fluid motion are solved using two techniques: an analytical method appropriate for small nondeformable spherical bubbles, and the boundary element method for deformable bubbles of arbitrary size, given an applied steady flow rate. A steady convection-diffusion equation is then solved numerically to determine the concentration of gas. The bubble volume, or equivalently the gas mass inside the bubble for a constant bubble pressure, is adjusted over time according to the mass flux at the bubble surface. Using a quasi-steady approximation, the evolution of a gas bubble in a tube is obtained. Results show that convection increases the gas pressure gradient at the bubble surface, hence increasing the rate of bubble evolution. Comparing with the result for a single gas bubble in an infinite tissue, the rate of evolution in a tube is approximately twice as fast. Surface tension is also shown to have a significant effect. These findings may have important implications for our understanding of the mechanisms of inert gas bubbles in the circulation underlying decompression sickness.

  12. Increased pressure from rising bubbles as a mechanism for remotely triggered seismicity

    USGS Publications Warehouse

    Linde, A.T.; Sacks, I.S.; Johnston, M.J.S.; Hill, D.P.; Bilham, R.G.

    1994-01-01

    Aftershocks of large earthquakes tend to occur close to the main rupture zone, and can be used to constrain its dimensions. But following the 1992 Landers earthquake (magnitude M(w) = 7.3) in southern California, many aftershocks were reported in areas remote from the mainshock. Intriguingly, this remote seismicity occurred in small clusters near active volcanic and geothermal systems. For one of these clusters (Long Valley, about 400 km from the Landers earthquake), crustal deformation associated with the seismic activity was also monitored. Here we argue that advective overpressure provides a viable mechanism for remote seismicity triggered by the Landers earthquake. Both the deformation and seismicity data are consistent with pressure increases owing to gas bubbles rising slowly within a volume of magma. These bubbles may have been shaken loose during the passage of seismic waves generated by the mainshock.

  13. Terminal velocities of pure and hydrate coated CO 2 droplets and CH 4 bubbles rising in a simulated oceanic environment

    NASA Astrophysics Data System (ADS)

    Bigalke, N. K.; Enstad, L. I.; Rehder, G.; Alendal, G.

    2010-09-01

    Understanding the upward motion of CO 2 droplets or CH 4 bubbles in oceanic waters is prerequisite to predict the vertical distribution of the two most important greenhouse gases in the water column after these have been released from the seabed. One of the key parameters governing the fate of droplets or bubbles dissolving into the surrounding seawater as they rise, is the terminal velocity, uT. The latter is strongly influenced by the ability of both compounds to form skins of gas hydrate, if pressure and temperature satisfy thermodynamic framework conditions. Experimental efforts aiming to elucidate the rise properties of CO 2 droplets and CH 4 bubbles and specifically the influence of hydrate skins open the possibility to obtain a parameterization of uT applicable to both hydrate-coated and pure fluid particles of CH 4 and CO 2. With the present study, we report on experimentally determined terminal velocities of single CH 4 bubbles released to pressurized and temperature-regulated seawater. Hydrate skins were identified by high bubble sphericities and changed motion characteristics. Based on these experiments as well as published data on the rise of hydrate-coated and pure liquid CO 2 droplets and physical principles previously successfully used for clean bubbles near atmospheric pressures, a new parameterization of uT is proposed. Model predictions show a good agreement with the data base established from the laboratory-based measurements.

  14. Hydroacoustic detection and quantification of free gas -methane bubbles- in the ocean

    NASA Astrophysics Data System (ADS)

    Greinert, J.; Artemov, Y.; Gimpel, P.

    2003-04-01

    Extensive methane release as a free gas phase from cold vents is well known from deep (>2000m) and shallow (10s of meters) water depths. Supposedly, much more methane is transported into the water column by free gas than by dissolved gas, which is oxidized by anaerobic and aerobic processes and partly precipitated as carbonate. Rising gas bubbles are not affected by this 'filter' mechanisms. Because of the strength of the backscattered signal from gas bubbles in the water column, bubbles can be detected by single-beam or multi-beam echosounder systems. Thus, hydroacoustic systems with different frequencies can be used to 1) detect free gas in the water column, 2) map the distribution of active vent sites which release free gas, 3) monitor a possible periodicity in the release of bubbles induced by e.g. tides or currents, 4) quantify the gas volume and gas flux that is released in a local area or larger region. In the German research project LOTUS we use ship- mounted single-beam echosounders to map gas plumes (flares) and investigate their periodicity (Flare Imaging). Using specialized single-beam echosounder systems makes it possible to measure the bubble sizes and their distribution. In combination with the volume of the backscattering strength these measurements can be used to estimate the gas volume in a defined part of the water body. Though gas bubbles rise in the water column, they are - particularly methane - rapidly dissolved and thus become smaller. Their rising speed as well as their diminishing size can be determined, which helps to understand the dissolution behaviour of methane bubbles; they form a hydrate skin at distinct pressure and temperature conditions. For a detailed, long-term observation of active bubble-expulsing areas we developed a lander based 180 kHz multi beam system that 'looks' horizontally (GasQuant). The system records backscatter data from a 75° swath that covers an area of about 5300m2. Via calibration we can quantify the methane

  15. Gas Bubble Growth In Muddy Sediments

    DTIC Science & Technology

    2002-09-30

    1 Gas Bubble Growth In Muddy Sediments Bruce D . Johnson Department of Oceanography, Dalhousie University Halifax, Nova Scotia, Canada B3H 4J1 phone...that this information can be used to improve and test acoustic backscatter models for sediments and to better understand the ebullitive flux of...currently valid OMB control number. 1. REPORT DATE 30 SEP 2002 2. REPORT TYPE 3. DATES COVERED 00-00-2002 to 00-00-2002 4. TITLE AND SUBTITLE

  16. Gas Bubble Growth in Muddy Sediments

    DTIC Science & Technology

    2001-09-30

    1 Gas Bubble Growth In Muddy Sediments Bruce D . Johnson Department of Oceanography, Dalhousie University Halifax, Nova Scotia, Canada B3H 4J1 phone...that this information can be used to improve and test acoustic backscatter models for sediments and to better understand the ebullitive flux of...currently valid OMB control number. 1. REPORT DATE 30 SEP 2001 2. REPORT TYPE 3. DATES COVERED 00-00-2001 to 00-00-2001 4. TITLE AND SUBTITLE

  17. The effect of surfactants on path instability of a rising bubble

    NASA Astrophysics Data System (ADS)

    Tagawa, Yoshiyuki; Takagi, Shu; Matsumoto, Yoichiro

    2013-11-01

    We experimentally investigate the surfactant effect on path instability of an air bubble rising in quiescent water. An addition of surfactant varies the gas-water boundary condition from zero shear stress to non-zero shear stress. We report three main findings: firstly, while the drag force acting on the bubble increases with the surfactant concentration as expected, the lift force shows a non-monotonic behavior; secondly, the transient trajectory starting from helical to zigzag is observed, which has never been reported in the case of purified water; lastly, a bubble with the intermediate slip conditions between free-slip and no-slip show a helical motion for a broad range of the Reynolds number. Aforementioned results are rationalized by considering the adsorption-desorption kinetics of the surfactants on gas-water interface and the wake dynamics. Y.T. thanks for financial support from Grant-in-Aid for JSPS Fellows (20-10701). We also thank for Grant-in-Aid for Scientific Research (B) (21360079).

  18. Gas depletion through single gas bubble diffusive growth and its effect on subsequent bubbles

    NASA Astrophysics Data System (ADS)

    Moreno Soto, Alvaro; Prosperetti, Andrea; Lohse, Detlef; van der Meer, Devaraj; Physics of Fluid Group Collaboration; MCEC Netherlands CenterMultiscale Catalytic Energy Conversion Collaboration

    2016-11-01

    In weakly supersaturated mixtures, bubbles are known to grow quasi-statically as diffusion-driven mass transfer governs the process. In the final stage of the evolution, before detachment, there is an enhancement of mass transfer, which changes from diffusion to natural convection. Once the bubble detaches, it leaves behind a gas-depleted area. The diffusive mass transfer towards that region cannot compensate for the amount of gas which is taken away by the bubble. Consequently, the consecutive bubble will grow in an environment which contains less gas than for the previous one. This reduces the local supersaturation of the mixture around the nucleation site, leading to a reduced bubble growth rate. We present quantitative experimental data on this effect and the theoretical model for depletion during the bubble growth rate. This work was supported by the Netherlands Center for Multiscale Catalytic Energy Conversion (MCEC), an NWO Gravitation programme funded by the Ministry of Education, Culture and Science of the government of the Netherlands.

  19. A CFD-DEM study of single bubble formation in gas fluidization of spherical and non-spherical particles

    NASA Astrophysics Data System (ADS)

    Shrestha, Siddhartha; Zhou, Zongyan

    2017-06-01

    Bubble dynamics significantly affect the hydrodynamics of gas-solid fluidized bed since they influence the gas-solid mixing. In this study, simulations using CFD-DEM were carried out to characterize the bubble size and shape for a bubble formed at a single orifice in gas-solid fluidized bed. Impact of parameters such as jet velocity, orifice size and particle shape on bubble equivalent diameter and bubble aspect ratio were analysed and discussed. Bubble equivalent diameter was found to increase with increasing jet velocity, decreasing bed width to orifice width ratio, and particle shape deviating from spherical. The bubble shape illustrated by aspect ratio, was found to elongate more as it rise through the bed and then commence to expand horizontally after it was detached from the orifice. Aspect ratio was found to be closer to a circle for the bubble at higher jet velocity, lower orifice width to bed ratio and for non-spherical particles.

  20. Open system degassing, bubble rise and flow dynamics within volcanic conduits- an experimental approach

    NASA Astrophysics Data System (ADS)

    Pioli, L.; Azzopardi, B. J.; Bonadonna, C.; Marchetti, E.; Ripepe, M.

    2009-12-01

    Open conduit basaltic volcanoes are characterized by frequent eruptions, usually consisting in mild Strombolian and Hawaiian explosions, alternating years to months of quiescence periods, with degassing activity from the central conduit. Recent improvements of thermal, video, radar and acoustic monitoring techniques have provided new powerful tools for the study of degassing processes and made available geophysical and geochemical datasets for many central volcanoes, such as Stromboli, Etna (Italy), Kilauea (Hawaii), Villarrica (Chile). These studies revealed that degassing is an unsteady, often pulsatory process, characterized by fluctuations in both intensity and composition of the emitted gases. Unambiguous interpretation of monitoring data of surface activity in terms of conduit dynamics and flow processes is, however, not possible, due to partial knowledge of the physical processes controlling the dynamics of two-phase flows in magmas. We performed a series of experiments to gain further insights on the dynamics of the gas-bubble rise in magmas within a cylindrical conduit, their ability to segregate and coalesce and the effect of these processes on the degassing dynamics. The experiments consisted in generating fluxes at variable intensities of air through stagnant water or glucose syrup in a bubble column apparatus 6.5 m high and with a diameter of 24 cm diameter. Glucose syrup and water are Newtonian liquids with viscosity ranging from 2.4 to 204.0 Pa*s and from 1.7 to 0.2 10 -3 Pa*s respectively, depending on temperature. Air was inserted at the base of the column through a variable number (1 to 25) of 5mm-diameter nozzles reaching surficial gas velocities of up to 0.5 m/s. The activity of the bubble column was monitored through temperature, pressure, void fraction and acoustic measurements and filmed by a high-speed camera with maximum resolution of 800x600 pixels. Pressure fluctuations, vesicularity and acoustic signal were then analyzed and correlated

  1. Measurement of Averaged Liquid Velocity Field around Large Bubbles Rising in Stagnant Water in Round Pipe Using UVP

    NASA Astrophysics Data System (ADS)

    Minagawa, Hisato; Fukazawa, Tsuyoshi; Nakazawa, Yoshiyuki; Yamada, Satoshi; Shiomi, Yoichi

    An ultrasonic velocity profile monitor (UVP) measurement was performed to measure the average liquid velocity field around a large bubble rising in stagnant water in a round pipe of inner diameter D=54mm in order to obtain fundamental information for gas-liquid two-phase slug flows. Two ultrasonic transducers were set at different directions to obtain velocity vectors. The measured results are presented and compared with the results of some previous studies on the corresponding phenomena. In the liquid film near the bubble nose, the difference in bubble length does not affect the acceleration. The parameter z/D is more dominant than z itself, particularly when z/D is less than unity. In the wake region, a large ring vortex is recognized. The upward velocity at the pipe axis agrees well with previously predicted results. The effect of bubble length on the vortex length is also discussed.

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

    PubMed

    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.

  3. Shockwave-Gas bubble Interaction in Complex Configurations

    NASA Astrophysics Data System (ADS)

    Li, Fenfang; Arora, Manish; Ohl, Claus-Dieter

    2014-11-01

    Shockwave-gas bubble interaction is relevant in biomedical applications such as shock wave lithotripsy and histotripsy where cell rupture needs to be avoided or is advantageous, as well as in the mining industry for microbubble aerated explosive gels. Here we demonstrate an experimental technique to study this interaction in a well-controlled manner utilizing microfluidics and high-speed photography of up to 2 million frames per second. Micron-size gas bubbles are generated with a continuous wave laser beam modulated with a digital hologram, whereas the shockwave and an expanding cavitation bubble are created with a pulsed laser. Gas bubbles are known to generate fast jets when impacted by shockwaves and we observe jets of 125 m/s and more. Complex interactions are reported for geometric arrangements of up to 6 gas bubbles: cascaded and simultaneous collapse of gas bubbles, back reaction of the gas bubbles on the cavitation bubble, and the deflection of jets for neighbouring bubbles. Besides, we find secondary cavitation within the liquid film below the expanding cavitation bubble, which is likely due to trapped gas exposed to low pressures and high shear, i.e. a regime relevant for cavitation in lubricating films.

  4. Pseudo-Steady Diffusional Growth or Collapse of Bubbles Rising in Time Dependent Pressure Fields

    DTIC Science & Technology

    1990-03-13

    et al. [12], Ishikawa, et al. [13] and Payvar [14] to name a few. Brankovic, et al. collected data for air and carbon dioxide bubbles with a triple...hydrostatic pressure field. Payvar [141 examined the effects, both experimentally and analytically, of a rapid de- compression on bubble growth for C0 2...Furthermore, bubble experimental rise data have only been obtained for a static hydrostatic head, with the exception of Payvar [14], but that was for a

  5. How does gas pass? Bubble transport through sediments

    NASA Astrophysics Data System (ADS)

    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.

  6. Visualization of gas bubbles during cavitation in the nozzle

    NASA Astrophysics Data System (ADS)

    Jana, Jablonská; Milada, Kozubková

    2017-09-01

    The creation and extinction of bubbles is a very fast process that can be observed by a high-speed camera. The article deals with the visualization of gas bubbles and investigates the formation and collapse of cavitation bubbles in a convergent-divergent nozzle of a rectangular cross section. Measurement values are then used as boundary conditions for mathematical modeling. Comparison of the bubble velocities with the 3D mathematical model of the mixture flow (water - vapor - air) is performed.

  7. Morphology of Gas Bubbles in Mud: A Microcomputed Tomographic Evaluation

    DTIC Science & Technology

    2005-07-01

    valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYYI 2. REPORT TYPE 3. DATES COVERED (From - To) 01...oxidation of organic matter is ubiquitous in marine sediments [1,2] and when supersaturated produces gas bubbles. Ebullition of methane gas bubbles from...cycle [10]. Pressure changes during a tidal cycle have also been correlated with bubble migration/ ebullition [11]. The relationship between pressure

  8. 1300-m-high rising bubbles from mud volcanoes at 2080 m in the Black Sea: Hydroacoustic characteristics and temporal variability

    NASA Astrophysics Data System (ADS)

    Greinert, Jens; Artemov, Yuriy; Egorov, Viktor; De Batist, Marc; McGinnis, Daniel

    2006-04-01

    A mud volcano area in the deep waters (> 2000 m) of the Black Sea was studied by hydroacoustic measurements during several cruises between January 2002 and June 2004. Gas bubbles in the water column give strong backscatter signals and thus can be detected even in great water depths by echosounders as the 38 kHz EK500 scientific split-beam system that was used during the surveys. Because of their shape in echograms and to differentiate against geochemical plumes and real upwelling bubble-water plumes, we call these hydroacoustic manifestations of bubbles in the water column 'flares'. Digital recording and processing of the data allows a 3D visualization and data comparison over the entire observation period, without artefacts caused by changing system settings. During our surveys, we discovered bubble release from three separate mud volcanoes, Dvurechenskiy (DMV), Vodianitskiy (VMV) and the Nameless Seep Site (NSS), in about 2080 m water depth simultaneously. Bubble release was observed between 9 June 2003 and 5 June 2004. The most frequently surveyed, DMV, was found to be inactive during very intensive studies in January 2002. The first activity was observed on 27 June 2002, which finally ceased between 5 and 15 June 2004 after a period of continuously decreasing activity. This observed 2-yr bubble-release period at a mud volcano may give an indication for the duration of active periods. The absence of short-term variations (within days or hours) may indicate that the bubble release from the observed mud volcanoes does not undergo rapid changes. The recorded echograms show that bubbles rise about 1300 m high through the water column, to a final water depth of about 770 m, which is ˜75 m below the phase boundary of pure methane hydrate in the Black Sea. With a release depth from 2068 m and a detected rise height of 1300 m, the flare at VMV is among the deepest and highest reported so far, and gives evidence of highly extended bubble life times (up to 108 min) in

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  11. Measurement and Analysis of Gas Bubbles Near a Reference Electrode in Aqueous Solutions

    SciTech Connect

    Supathorn Phongikaroon; Steve Herrmann; Shelly Li; Michael Simpson

    2005-10-01

    Bubble size distributions (BSDs) near a reference electrode (RE) in aqueous glycerol solutions of an electrolyte NaCl have been investigated under various gas superficial velocities (U{sub S}). BSD and voltage reading of the solution were measured by using a high-speed digital camera and a pH/voltage meter, respectively. The results show that bubble size (b) increases with liquid viscosity ({mu}{sub c}) and U{sub S}. Self-similarity is seen and can be described by the log-normal form of the continuous number frequency distribution. The result shows that b controls the voltage reading in each solution. As b increases, the voltage increases because of gas bubbles interrupting their electrolyte paths in the solutions. An analysis of bubble rising velocity reveals that Stokes Law should be used cautiously to describe the system. The fundamental equation for bubble formation was developed via Newton's second law of motion and shown to be the function of three dimensionless groups--Weber number, Bond number, and Capillary number. After linking an electrochemical principle in the practical application, the result indicates that the critical bubble size is {approx}177 {micro}m. Further analysis suggests that there may be 3000 to 70,000 bubbles generated on the anode surface depending on the size of initial bubbles and provides the potential cause of the efficiency drop observed in the practical application.

  12. Methane rising from the Deep: Hydrates, Bubbles, Oil Spills, and Global Warming

    NASA Astrophysics Data System (ADS)

    Leifer, I.; Rehder, G. J.; Solomon, E. A.; Kastner, M.; Asper, V. L.; Joye, S. B.

    2011-12-01

    Elevated methane concentrations in near-surface waters and the atmosphere have been reported for seepage from depths of nearly 1 km at the Gulf of Mexico hydrate observatory (MC118), suggesting that for some methane sources, deepsea methane is not trapped and can contribute to atmospheric greenhouse gas budgets. Ebullition is key with important sensitivity to the formation of hydrate skins and oil coatings, high-pressure solubility, bubble size and bubble plume processes. Bubble ROV tracking studies showed survival to near thermocline depths. Studies with a numerical bubble propagation model demonstrated that consideration of structure I hydrate skins transported most methane only to mid-water column depths. Instead, consideration of structure II hydrates, which are stable to far shallower depths and appropriate for natural gas mixtures, allows bubbles to survive to far shallower depths. Moreover, model predictions of vertical methane and alkane profiles and bubble size evolution were in better agreement with observations after consideration of structure II hydrate properties as well as an improved implementation of plume properties, such as currents. These results demonstrate the importance of correctly incorporating bubble hydrate processes in efforts to predict the impact of deepsea seepage as well as to understand the fate of bubble-transported oil and methane from deepsea pipeline leaks and well blowouts. Application to the DWH spill demonstrated the importance of deepsea processes to the fate of spilled subsurface oil. Because several of these parameters vary temporally (bubble flux, currents, temperature), sensitivity studies indicate the importance of real-time monitoring data.

  13. Force Balance Model for Bubble Rise, Impact, and Bounce from Solid Surfaces.

    PubMed

    Manica, Rogerio; Klaseboer, Evert; Chan, Derek Y C

    2015-06-23

    A force balance model for the rise and impact of air bubbles in a liquid against rigid horizontal surfaces that takes into account effects of buoyancy and hydrodynamic drag forces, bubble deformation, inertia of the fluid via an added mass force, and a film force between the bubble and the rigid surface is proposed. Numerical solution of the governing equations for the position and velocity of the center of mass of the bubbles is compared against experimental data taken with ultraclean water. The boundary condition at the air-water interface is taken to be stress free, which is consistent for bubbles in clean water systems. Features that are compared include bubble terminal velocity, bubbles accelerating from rest to terminal speed, and bubbles impacting and bouncing off different solid surfaces for bubbles that have already or are yet to attain terminal speed. Excellent agreement between theory and experiments indicates that the forces included in the model constitute the main physical ingredients to describe the bouncing phenomenon.

  14. Shape Oscillations of Gas Bubbles With Newtonian Interfacial Rheological Properties

    NASA Technical Reports Server (NTRS)

    Nadim, Ali

    1996-01-01

    The oscillation frequency and damping rate for small-amplitude axisymmetric shape modes of a gas bubble in an ideal liquid are obtained, in the limit when the bubble interface possesses Newtonian interfacial rheology with constant surface shear and dilatational viscosities. Such results permit the latter surface properties to be measured by analyzing experimental data on frequency shift and damping rate of specific shape modes of suspended bubbles in the presence of surfactants.

  15. Measurement Of Gas Bubbles In Mercury Using Proton Radiography

    SciTech Connect

    Riemer, Bernie; Bingham, Philip R; Mariam, Fesseha G; Merrill, Frank E

    2007-01-01

    An experiment using proton radiography on a small mercury loop for testing gas bubble injection was conducted at the Los Alamos Neutron Science Center (LANSCE) in December 2006. Small gas bubble injection is one of the approaches under development to reduce cavitation damage in the U.S. Spallation Neutron Source mercury target vessel. Several hundred radiograph images were obtained as the test loop was operated over range of conditions that included two jet type bubble generators, two needle type bubble generators, various mercury flow speeds and gas injection rates, and use of helium, argon and xenon. This paper will describe the analysis of the radiograph images and present the obtained bubble measurement data.

  16. Pulsed Electrical Discharge in a Gas Bubble in Water

    NASA Astrophysics Data System (ADS)

    Schaefer, Erica; Gershman, Sophia; Mozgina, Oksana

    2005-10-01

    This experiment is an investigation of the electrical and optical characteristics of a pulsed electrical discharge ignited in a gas bubble in water in a needle-to-plane electrode geometry. Argon or oxygen gas is fed through a platinum hypodermic needle that serves as the high voltage electrode. The gas filled bubble forms at the high voltage electrode with the tip of the needle inside the bubble. The discharge in the gas bubble in water is produced by applying 5 -- 15 kV, microsecond long rectangular pulses between the electrodes submerged in water. The voltage across the electrodes and the current are measured as functions of time. Electrical measurements suggest a discharge ignited in the bubble (composed of the bubbled gas and water vapor) without breakdown of the entire water filled electrode gap. Time-resolved optical emission measurements are taken in the areas of the spectrum corresponding to the main reactive species produced in the discharge, e.g. OH 309 nm, Ar 750 nm, and O 777 nm emissions using optical filters. The discharge properties are investigated as a function of the applied voltage, the distance between the electrodes, the gas in the bubble (Ar or O2). Work supported by the US Army, Picatinny Arsenal, NJ and the US DOE (Contract number DE-AC02-76CH03073).

  17. Three-dimensional numerical simulations of a bubble rising in an unbounded weakly viscous fluid

    NASA Astrophysics Data System (ADS)

    Cano-Lozano, Jose Carlos; Martínez-Bazán, Carlos; Tchoufag, Joel; Magnaudet, Jacques

    2015-11-01

    Direct Numerical Simulations (DNS) of a freely rising bubble in an unbounded low-viscosity fluid are performed to analyze the bubble trajectory for values of Galileo and Bond numbers close to the transition between vertical and non-vertical paths. The simulations are performed with the Gerris Flow Solver, based on the Volume of Fluid technique to track the interface, allowing deformations of the bubble during its rising motion. We find the existence of novel regimes of the bubble rise which we describe by tracking the bubble shape, path geometry and wake vortical structures, as well as the temporal evolution of the instantaneous Reynolds number. Besides the traditional rectilinear, zigzag and spiral paths, we observe chaotic, reflectional-symmetry-breaking or reflectional-symmetry-preserving regimes previously reported for axisymmetric solid bodies. The DNS results also allow us to check the accuracy of the neutral curve defining the region of the parameter space within which the vertical path of a buoyancy-driven bubble with fore-and-aft asymmetric shape is linearly stable. Supported by the Spanish MINECO, Junta de Andalucía and EU Funds under projects DPI 2014-59292-C3-3-P and P11-TEP7495.

  18. Scattering from bubbles rising in a vertical line-Comparison between theory and experiments

    NASA Astrophysics Data System (ADS)

    Nikolovska, Aneta; Ooi, Andrew; Manasseh, Richard

    2004-05-01

    In this paper, the experimental data from the sound field around similar sized air bubbles rising in a vertical chain are analyzed. The data reveal a strong anisotropy in the acoustic field. The transition from individual to continuum behavior in a bubble chain is not correctly described with classical theory especially when the bubbles are uniformly sized, discretely populated, and the frequency of interest is close to the natural frequency of the individual bubbles. Single compact scatterers initiated at frequencies near their resonant frequency in isolation act preliminarily as monopole sources, amplifying the local pressure field by a factor of order 1/(k*a), a being the scattering radius and k the wave number at the resonant frequency in the surrounding material [Tolstoy, 1986]. A laboratory investigation used air bubbles in fresh water and varied the bubble sizes and separation by carefully controlling bubble production rates. A linear coupled equation method was developed to explain the result. The model reproduced the acoustic pressure anisotropy along the chain and the change in pulse waveform along the chain. The results suggest that the enhancement of sound intensity along the chain can be explained by bubbles acting as resonant scatterers retransmitting the acoustic energy.

  19. Analytical solution of the problem of the rise of a Taylor bubble

    NASA Astrophysics Data System (ADS)

    Zudin, Yuri B.

    2013-05-01

    In the classical works of Prandtl and Taylor devoted to the analysis of the problem of the rise of a Taylor bubble in a round tube, a solution of the Laplace equation is used, which contains divergent infinite series. The present paper outlines a method for the correct analysis of the mentioned problem. Using the method of superposition of "elementary flows," a solution was obtained for flow of an ideal fluid over a body of revolution in a pipe. Satisfying the free surface condition in the vicinity of the stagnation point and using the limiting transition with respect to the main parameter lead to the relation for the rise velocity of a Taylor bubble expressed in terms of the Froude number. In order to validate the method of superposition, it was applied to the problem of the rise of a plane Taylor bubble in a flat gap, which also has an exact analytical solution obtained with the help of the complex variable theory.

  20. Acoustic observations of gas bubble streams in the NW Black Sea as a method for estimation of gas flux from vent sites

    NASA Astrophysics Data System (ADS)

    Artemov, Yu. G.

    2003-04-01

    Relatively recent discovery of the natural CH_4 gas seepage from the sea bed had action upon the philosophy of CH_4 contribution to global budgets. So far as numerous gas vent sites are known, an acceptable method for released gas quantification is required. In particular, the questions should be answered as follows: 1) how much amount of gas comes into the water column due to a certain bubble stream, 2) how much amount of gas comes into the water column due to a certain seepage area of the see floor, 3) how much amount of gas diffuses into the water and how much gas phase enters the atmosphere. Echo-sounder is the habitual equipment for detecting gas plumes (flares) in the water column. To provide observations of gas seeps with bubbles tracking, single target and volume backscattering strength measurements, we use installed on board the R/V "Professor Vodyanitskiy" dual frequency (38 and 120 kHz) split-beam scientific echo-sounder SIMRAD EK-500. Dedicated software is developed to extract from the raw echo data and to handle the definite information for analyses of gas bubble streams features. This improved hydroacoustic techniques allows to determine gas bubbles size spectrum at different depths through the water column as well as rise velocity of bubbles of different sizes. For instance, bubble of 4.5 mm diameter has rising speed of 25.8 cm/sec at 105 m depth, while bubble of 1.7 mm diameter has rising speed of 16.3 cm/sec at 32 m depth. Using volume backscattering measurements in addition, it is possible to evaluate flux of the gas phase produced by methane bubble streams and to learn of its fate in the water column. Ranking of various gas plumes by flux rate value is available also. In this presentation results of acoustic observations at the shallow NW Black Sea seepage area are given.

  1. Simulation Studies on Cooling of Cryogenic Propellant by Gas Bubbling

    NASA Astrophysics Data System (ADS)

    Sandilya, Pavitra; Saha, Pritam; Sengupta, Sonali

    Injection cooling was proposed to store cryogenic liquids (Larsen et al. [1], Schmidt [2]). When a non-condensable gas is injected through a liquid, the liquid component would evaporate into the bubble if its partial pressure in the bubble is lower than its vapour pressure. This would tend to cool the liquid. Earlier works on injection cooling was analysed by Larsen et al. [1], Schmidt [2], Cho et al. [3] and Jung et al. [4], considering instantaneous mass transfer and finite heat transfer between gas bubble and liquid. It is felt that bubble dynamics (break up, coalescence, deformation, trajectory etc.) should also play a significant role in liquid cooling. The reported work are based on simple assumptions like single bubble, zero bubble deformation, and no inter-bubble interactions. Hence in this work, we propose a lumped parameter model considering both heat and mass interactions between bubble and the liquid to gain a preliminary insight into the cooling phenomenon during gas injection through a liquid.

  2. Bubble coalescence dynamics and supersaturation in electrolytic gas evolution

    SciTech Connect

    Stover, R.L. |

    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.

  3. The preparation and characterization of gas bubble containing liposomes.

    PubMed

    Liu, Rui; Wei, Xiaohui; Yao, Yanbin; Chai, Qiliang; Chen, Yue; Xu, Yuhong

    2005-01-01

    Liposomes and lipid nano-particles containing gas bubbles have great potentials to be used as ultrasound contrast agents or as drug and gene delivery vehicles. We developed a method to enable in situ CO2gas bubbles formation inside liposomes. The resulted bubbles containing liposomes were shown to be able to effectively echo ultrasound. Their acoustic properties were assessed by ultrasound imaging and intensity analysis. Compared to most other echogenic liposome formulations reported, our method is easier, faster, and more economical. It would be useful for many applications with improvements and optimization.

  4. Venous gas embolism - Time course of residual pulmonary intravascular bubbles

    NASA Technical Reports Server (NTRS)

    Butler, B. D.; Luehr, S.; Katz, J.

    1989-01-01

    A study was carried out to determine the time course of residual pulmonary intravascular bubbles after embolization with known amounts of venous air, using an N2O challenge technique. Attention was also given to the length of time that the venous gas emboli remained as discrete bubbles in the lungs with 100 percent oxygen ventilation. The data indicate that venous gas emboli can remain in the pulmonary vasculature as discrete bubbles for periods lasting up to 43 + or - 10.8 min in dogs ventilated with oxygen and nitrogen. With 100 percent oxygen ventilation, these values are reduced significantly to 19 + or - 2.5 min.

  5. Lattice Boltzmann simulation of rising bubble dynamics using an effective buoyancy method

    NASA Astrophysics Data System (ADS)

    Ngachin, Merlin; Galdamez, Rinaldo G.; Gokaltun, Seckin; Sukop, Michael C.

    2015-08-01

    This study describes the behavior of bubbles rising under gravity using the Shan and Chen-type multicomponent multiphase lattice Boltzmann method (LBM) [X. Shan and H. Chen, Phys. Rev. E47, 1815 (1993)]. Two-dimensional (2D) single bubble motions were simulated, considering the buoyancy effect for which the topology of the bubble was characterized by the nondimensional Eötvös (Eo), and Morton (M) numbers. In this study, a new approach based on the "effective buoyancy" was adopted and proven to be consistent with the expected bubble shape deformation. This approach expands the range of effective density differences between the bubble and the liquid that can be simulated. Based on the balance of forces acting on the bubble, it can deform from spherical to ellipsoidal shape with skirts appearing at high Eo number. A benchmark computational case for qualitative and quantitative validation was performed using COMSOL Multiphysics based on the level set method. Simulations were conducted for 1 ≤ Eo ≤ 100 and 3 × 10-6 ≤ M ≤ 2.73 × 10-3. Interfacial tension was checked through simulations without gravity, where Laplace's law was satisfied. Finally, quantitative analyses based on the terminal rise velocity and the degree of circularity was performed for various Eo and M values. Our results were compared with both the theoretical shape regimes given in literature and available simulation results.

  6. Surfactant effect on interaction of rising bubble and particle in a liquid subjected to vibrations

    NASA Astrophysics Data System (ADS)

    Lyubimov, D. V.; Klimenko, L. S.; Lyubimova, T. P.; Filippov, L. O.

    2017-07-01

    The paper investigates the surfactant effect on the interaction of solid particle and gas bubble in a liquid subjected to vibrations. Surfactant transport between the bubble surface and the surrounding liquid is limited by the adsorption-desorption process. The particle is subjected to the Stokes, Basset and buoyancy forces, and average force related to the inhomogeneity of the pulsational field. The problem is solved numerically. It is found that in the presence of surfactant, the impact of vibrations on the particle-bubble collision is weaker than in the absence of surfactant. Thus, higher vibrations intensity is needed for increasing the collision efficiency, together with a higher consumption in energy.

  7. Linear stability of the wake and path of a rising bubble with a realistic shape

    NASA Astrophysics Data System (ADS)

    Cano-Lozano, José Carlos; Tchoufag, Joel; Magnaudet, Jacques; Fabre, David; Martínez-Bazán, Carlos

    2014-11-01

    A global linear stability analysis of the flow past a bubble rising in still liquid is carried out using the real bubble shape and the terminal velocity obtained for various sets of Galileo (Ga) and Bond (Bo) numbers in axisymmetric simulations performed with the multiphase software Gerris Flow Solver. Once the bubble shape is known, the axisymmetric, steady base flow is computed by means of an iterative Newton method with the finite element software FreeFem++, and the eigenvalue problem is solved with the shift-invert Arnoldi technique implemented in the SLEPc library. The critical curve separating stable and unstable regimes is obtained in the (Ga, Bo) and (Reynolds number, aspect ratio) spaces. This allows us to discuss the effect of the bubble shape and aspect ratio on the wake and path instabilities. We observe that the fore-and-aft asymmetry of the bubble has some influence on the stability since, for a given aspect ratio, bubbles with a realistic shape (i.e. a flatter front and a more rounded rear) are more stable that perfectly spheroidal bubbles. Supported by the Spanish MINECO, Junta de Andalucía and EU Funds under Projects DPI2011-28356-C03-03 and P11-TEP7495.

  8. Why a falling drop does not in general behave like a rising bubble

    PubMed Central

    Tripathi, Manoj Kumar; Sahu, Kirti Chandra; Govindarajan, Rama

    2014-01-01

    Is a settling drop equivalent to a rising bubble? The answer is known to be in general a no, but we show that when the density of the drop is less than 1.2 times that of the surrounding fluid, an equivalent bubble can be designed for small inertia and large surface tension. Hadamard's exact solution is shown to be better for this than making the Boussinesq approximation. Scaling relationships and numerical simulations show a bubble-drop equivalence for moderate inertia and surface tension, so long as the density ratio of the drop to its surroundings is close to unity. When this ratio is far from unity, the drop and the bubble are very different. We show that this is due to the tendency for vorticity to be concentrated in the lighter fluid, i.e. within the bubble but outside the drop. As the Galilei and Bond numbers are increased, a bubble displays underdamped shape oscillations, whereas beyond critical values of these numbers, over-damped behavior resulting in break-up takes place. The different circulation patterns result in thin and cup-like drops but bubbles thick at their base. These shapes are then prone to break-up at the sides and centre, respectively. PMID:24759766

  9. Why a falling drop does not in general behave like a rising bubble.

    PubMed

    Tripathi, Manoj Kumar; Sahu, Kirti Chandra; Govindarajan, Rama

    2014-04-24

    Is a settling drop equivalent to a rising bubble? The answer is known to be in general a no, but we show that when the density of the drop is less than 1.2 times that of the surrounding fluid, an equivalent bubble can be designed for small inertia and large surface tension. Hadamard's exact solution is shown to be better for this than making the Boussinesq approximation. Scaling relationships and numerical simulations show a bubble-drop equivalence for moderate inertia and surface tension, so long as the density ratio of the drop to its surroundings is close to unity. When this ratio is far from unity, the drop and the bubble are very different. We show that this is due to the tendency for vorticity to be concentrated in the lighter fluid, i.e. within the bubble but outside the drop. As the Galilei and Bond numbers are increased, a bubble displays underdamped shape oscillations, whereas beyond critical values of these numbers, over-damped behavior resulting in break-up takes place. The different circulation patterns result in thin and cup-like drops but bubbles thick at their base. These shapes are then prone to break-up at the sides and centre, respectively.

  10. Parallel lattice Boltzmann simulation of bubble rising and coalescence in viscous flows

    NASA Astrophysics Data System (ADS)

    Shi, Dongyan; Wang, Zhikai

    2015-07-01

    A parallel three-dimensional lattice Boltzmann scheme for multicomponent immiscible fluids is proposed to simulate bubble rising and coalescence process in viscous flows. The lattice Boltzmann scheme is based on the free-energy model and is parallelized in the share-memory model by using the OpenMP. Bubble interface is described by a diffusion interface method solving the Cahn-Hilliard equation and both the surface tension force and the buoyancy are introduced in a form of discrete body force. To avoid the numerical instability caused by the interface deformation, the 18 point finite difference scheme is utilized to calculate the first- and second-order space derivative. The correction of the parallel scheme handling three-dimensional interfaces is verified by the Laplace law and the dynamic characteristics of an isolated bubble in stationary flows. Subsequently, effects of the initially relative position, accompanied by the size ratio on bubble-bubble interaction are studied. The results show that the present scheme can effectively describe the bubble interface dynamics, even if rupture and restructure occurs. In addition to the repulsion and coalescence phenomenon due to the relative position, the size ratio also plays an insignificant role in bubble deformation and trajectory.

  11. Gas-vapor bubble dynamics in therapeutic ultrasound

    NASA Astrophysics Data System (ADS)

    Kreider, Wayne

    In applications of therapeutic ultrasound such as shock wave lithotripsy (SWL) and high-intensity focused ultrasound (HIFU), cavitation and the associated bubble dynamics play an important role. Moreover, bubble dynamics have not been fully studied in the context of the large acoustic excitations, elevated temperatures, and gas-saturated conditions that characterize therapeutic ultrasound treatments. Because acoustic cavitation has been typically explored in the context of bubbles containing only non-condensable gases, relatively little is understood about the role of vapor under relevant conditions. Accordingly, the primary goal of this effort is to elucidate the role of vapor in the dynamics of gas-vapor bubbles. Given the large acoustic excitations of SWL and HIFU, the dynamics of violent inertial collapses are of particular interest. To investigate the impact of vapor, both numerical modeling and experiments were utilized. The model was developed for a single, spherical bubble and was designed to capture behavior associated with the collapse and rebound of a gas-vapor bubble. Numerical difficulties in modeling violent collapses were addressed by using scaling principles to approximate the spatial gradients used for estimating heat and mass transport in both liquid and gaseous phases, Model predictions demonstrate thermal effects from vapor transport through the coupling of the saturated vapor pressure to temperature changes in the surrounding liquid. Also, the model suggests that vapor transport affects the dynamics mechanically when vapor is diffusively trapped in the bubble interior. Moreover, predictions imply that the collapses of millimeter-sized lithotripsy bubbles are principally governed by the aforementioned mechanical effects. To test the model, collapses and rebounds of lithotripsy bubbles were experimentally observed using high-speed photography. Although bubble asymmetries added scatter to the data, experimental observations agree very well with

  12. Production of Gas Bubbles in Reduced Gravity Environments

    NASA Technical Reports Server (NTRS)

    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.

  13. Interaction of a shock with elliptical gas bubbles

    NASA Astrophysics Data System (ADS)

    Georgievskiy, P. Yu.; Levin, V. A.; Sutyrin, O. G.

    2015-07-01

    The interaction of a shock with spherical and elliptical bubbles of light or heavy gas is numerically studied using the axisymmetric Euler equations. A model with a single heat capacity ratio is implemented, where bubbles are modeled by areas of the same gas with lower or higher density. Details of the general shock refraction patterns—diverging and converging—are described. The formation and development of secondary, focusing shocks are discussed. A computational parameter study for different Atwood numbers , shock strengths , where is the Mach number, and bubble geometries is performed. A basic classification for the shock focusing (cumulation) regimes is suggested, with the division of the internal, external and transitional focusing regimes determined by the position of the shock focusing point relative to the bubble. It is shown that the focusing pattern is governed not only by the Atwood number but also heavily by the Mach number and bubble shape. The qualitative dependence of cumulative intensity on bubble geometry is determined. The theoretical possibility of realizing an extremely intense shock collapse with a relatively small variation in bubble shape is demonstrated for the heavy-bubble scenario.

  14. The role of gas in ultrasonically driven vapor bubble growth

    NASA Astrophysics Data System (ADS)

    Shpak, Oleksandr; Stricker, Laura; Versluis, Michel; Lohse, Detlef

    2013-04-01

    In this paper we study both experimentally and theoretically the dynamics of an ultrasound-driven vapor bubble of perfluoropentane (PFP) inside a droplet of the same liquid, immersed in a water medium superheated with respect to the PFP boiling point. We determine the temporal evolution of the bubble radius with ultra-high speed imaging at 20 million frames per second. In addition, we model the vapor-gas bubble dynamics, based on a Rayleigh-Plesset-type equation, including thermal and gas diffusion inside the liquid. We compare the numerical results with the experimental data and find good agreement. We underline the fundamental role of gas diffusion in order to prevent total recondensation of the bubble at collapse.

  15. The terminal rise velocity of 10-100 microm diameter bubbles in water.

    PubMed

    Parkinson, Luke; Sedev, Rossen; Fornasiero, Daniel; Ralston, John

    2008-06-01

    Single bubbles of very pure N2, He, air and CO2 were formed in a quiescent environment in ultra-clean water, with diameters ranging from 10 to 100 mum. Their terminal rise velocities were measured by high-speed video microscopy. For N2, He and air, excellent agreement with the Hadamard-Rybczynski (H-R) equation was observed, indicating that slip was occurring at the liquid-vapor interface. For CO2 bubbles with diameters less than 60 microm, the terminal rise velocities exceeded those predicted by the H-R equation. This effect was ascribed to the enhanced solubility of CO2 compared with the other gases examined. The presence of a diffusion boundary layer may be responsible for the increased terminal velocity of very small CO2 bubbles.

  16. Quantification of Methane Gas Flux and Bubble Fate on the Eastern Siberian Arctic Shelf Utilizing Calibrated Split-beam Echosounder Data.

    NASA Astrophysics Data System (ADS)

    Weidner, E. F.; Mayer, L. A.; Weber, T. C.; Jerram, K.; Jakobsson, M.; Chernykh, D.; Ananiev, R.; Mohammad, R.; Semiletov, I. P.

    2016-12-01

    On the Eastern Siberian Arctic Shelf (ESAS) subsea permafrost, shallow gas hydrates, and trapped free gas hold an estimated 1400 Gt of methane. Recent observations of methane bubble plumes and high concentrations of dissolved methane in the water column indicate methane release via ebullition. Methane gas released from the shallow ESAS (<50 m average depth) has high potential to be transported to the atmosphere. To directly and quantitatively address the magnitude of methane flux and the fate of rising bubbles in the ESAS, methane seeps were mapped with a broadband split-beam echosounder as part of the Swedish-Russian-US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions program (SWERUS-C3). Acoustic measurements were made over a broad range of frequencies (16 to 29 kHz). The broad bandwidth provided excellent discrimination of individual targets in the water column, allowing for the identification of single bubbles. Absolute bubble target strength values were determined by compensating apparent target strength measurements for beam pattern effects via standard calibration techniques. The bubble size distribution of seeps with individual bubble signatures was determined by exploiting bubble target strength models over the broad range of frequencies. For denser seeps, with potential higher methane flux, bubble size distribution was determined via extrapolation from seeps in similar geomorphological settings. By coupling bubble size distributions with rise velocity measurements, which are made possible by split-beam target tracking, methane gas flux can be estimated. Of the 56 identified seeps in the SWERUS data set, individual bubbles scatterers were identified in more than half (31) of the seeps. Preliminary bubble size distribution results indicate bubble radii range from 0.75 to 3.0 mm, with relatively constant bubble size distribution throughout the water column. Initial rise velocity observations indicate bubble rise velocity increases with

  17. Quantification of gas bubble emissions from submarine hydrocarbon seeps at the Makran continental margin (offshore Pakistan)

    NASA Astrophysics Data System (ADS)

    RöMer, Miriam; Sahling, Heiko; Pape, Thomas; Bohrmann, Gerhard; Spieß, Volkhard

    2012-10-01

    Evidence for twelve sites with gas bubble emissions causing hydroacoustic anomalies in 18 kHz echosounder records (`flares') was obtained at the convergent Makran continental margin. The hydroacoustic anomalies originating from hydrocarbon seeps at water depths between 575 and 2870 m disappeared after rising up to 2000 m in the water column. Dives with the remotely operated vehicle `Quest 4000 m' revealed that several individual bubble vents contributed to one hydroacoustic anomaly. Analyzed gas samples suggest that bubbles were mainly composed of methane of microbial origin. Bubble size distributions and rise velocities were determined and the volume flux was estimated by counting the emitted bubbles and using their average volume. We found that a low volume flux (Flare 1 at 575 mbsl: 90 ml/min) caused a weak hydroacoustic signal in echograms whereas high volume fluxes (Flare 2 at 1027 mbsl: 1590 ml/min; Flare 5 C at 2870 mbsl: 760 ml/min) caused strong anomalies. The total methane bubble flux in the study area was estimated by multiplying the average methane flux causing a strong hydroacoustic anomaly in the echosounder record with the total number of equivalent anomalies. An order-of-magnitude estimate further considers the temporal variability of some of the flares, assuming a constant flux over time, and allows a large range of uncertainty inherent to the method. Our results on the fate of bubbles and the order-of-magnitude estimate suggest that all of the ˜40 ± 32 × 106 mol methane emitted per year within the gas hydrate stability zone remain in the deep ocean.

  18. Shape oscillations on bubbles rising in clean and in tap water

    NASA Astrophysics Data System (ADS)

    Veldhuis, Christian; Biesheuvel, Arie; van Wijngaarden, Leen

    2008-04-01

    This paper deals with air bubbles rising in purified water in the range of equivalent diameters where surface oscillations appear on the interface. The shape of the bubbles including these capillary distortions is recorded by taking a large number of high speed pictures for each spiraling or zigzagging bubble trajectory. In analogy with surface harmonics, the oscillations are indicated as (2,0) axisymmetric and with wavelength equal to the distance from pole to pole and (2,2) nonaxisymmetric and with wavelength equal to one-half of the length of the equator. In the second series of experiments, the phenomena in the wakes of rising bubbles are made visible by using Schlieren optics, which are applicable because a temperature gradient is applied to the water. The frequencies of vortex shedding correspond to the (2,0) mode of surface oscillation, whereas in other works reported in the literature, they correspond to twice the frequency of the spiraling or zigzagging bubble paths. By measurements and by analysis, it is shown here that the latter is due to contamination of surfactants.

  19. Plasma formation inside deformed gas bubbles submerged in water

    NASA Astrophysics Data System (ADS)

    Sommers, Bradley; Foster, John

    2012-10-01

    Plasma formation in liquids produces highly reactive products that may be desirable for a variety of applications, including water purification and waste processing. The direct ignition of plasma in these environments, however, is limited by the large breakdown strength of liquids, which imposes severe voltage and energy requirements on the design of practical devices. One way to address this issue is by first igniting plasma in gas bubbles injected into the water. These bubbles provide an environment with higher reduced electric field (E/N) that is more suitable for plasma formation. If the same bubbles can be excited into strong distortions of their shape and volume, then it is possible to further alter E/N, both by field enhancement at the bubble's highly distorted dielectric interface (via E) and by fluctuations in its internal gas pressure (via N). This principle is investigated by trapping a single bubble at the node of a 26.4 kHz underwater acoustic field and driving it into violent oscillations using an A.C electric field. A third high voltage needle is placed nearby and used to ignite plasma in the bubble at various points during its oscillation. The bubble response is captured using a high speed camera capable of up to 30,000 frames per second.

  20. Investigating the role of gas bubble formation and entrapment in contaminated aquifers: Reactive transport modelling

    USGS Publications Warehouse

    Amos, Richard T.; Mayer, K. Ulrich

    2006-01-01

    In many natural and contaminated aquifers, geochemical processes result in the production or consumption of dissolved gases. In cases where methanogenesis or denitrification occurs, the production of gases may result in the formation and growth of gas bubbles below the water table. Near the water table, entrapment of atmospheric gases during water table rise may provide a significant source of O2 to waters otherwise depleted in O2. Furthermore, the presence of bubbles will affect the hydraulic conductivity of an aquifer, resulting in changes to the groundwater flow regime. The interactions between physical transport, biogeochemical processes, and gas bubble formation, entrapment and release is complex and requires suitable analysis tools. The objective of the present work is the development of a numerical model capable of quantitatively assessing these processes. The multicomponent reactive transport code MIN3P has been enhanced to simulate bubble growth and contraction due to in-situ gas production or consumption, bubble entrapment due to water table rise and subsequent re-equilibration of the bubble with ambient groundwater, and permeability changes due to trapped gas phase saturation. The resulting formulation allows for the investigation of complex geochemical systems where microbially mediated redox reactions both produce and consume gases as well as affect solution chemistry, alkalinity, and pH. The enhanced model has been used to simulate processes in a petroleum hydrocarbon contaminated aquifer where methanogenesis is an important redox process. The simulations are constrained by data from a crude oil spill site near Bemidji, MN. Our results suggest that permeability reduction in the methanogenic zone due to in-situ formation of gas bubbles, and dissolution of entrapped atmospheric bubbles near the water table, both work to attenuate the dissolved gas plume emanating from the source zone. Furthermore, the simulations demonstrate that under the given

  1. Investigating the role of gas bubble formation and entrapment in contaminated aquifers: Reactive transport modelling

    NASA Astrophysics Data System (ADS)

    Amos, Richard T.; Ulrich Mayer, K.

    2006-09-01

    In many natural and contaminated aquifers, geochemical processes result in the production or consumption of dissolved gases. In cases where methanogenesis or denitrification occurs, the production of gases may result in the formation and growth of gas bubbles below the water table. Near the water table, entrapment of atmospheric gases during water table rise may provide a significant source of O 2 to waters otherwise depleted in O 2. Furthermore, the presence of bubbles will affect the hydraulic conductivity of an aquifer, resulting in changes to the groundwater flow regime. The interactions between physical transport, biogeochemical processes, and gas bubble formation, entrapment and release is complex and requires suitable analysis tools. The objective of the present work is the development of a numerical model capable of quantitatively assessing these processes. The multicomponent reactive transport code MIN3P has been enhanced to simulate bubble growth and contraction due to in-situ gas production or consumption, bubble entrapment due to water table rise and subsequent re-equilibration of the bubble with ambient groundwater, and permeability changes due to trapped gas phase saturation. The resulting formulation allows for the investigation of complex geochemical systems where microbially mediated redox reactions both produce and consume gases as well as affect solution chemistry, alkalinity, and pH. The enhanced model has been used to simulate processes in a petroleum hydrocarbon contaminated aquifer where methanogenesis is an important redox process. The simulations are constrained by data from a crude oil spill site near Bemidji, MN. Our results suggest that permeability reduction in the methanogenic zone due to in-situ formation of gas bubbles, and dissolution of entrapped atmospheric bubbles near the water table, both work to attenuate the dissolved gas plume emanating from the source zone. Furthermore, the simulations demonstrate that under the given

  2. Three-dimensional simulations of a rising bubble in a self-rewetting fluid

    NASA Astrophysics Data System (ADS)

    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.

  3. Paths and wakes of deformable nearly spheroidal rising bubbles close to the transition to path instability

    NASA Astrophysics Data System (ADS)

    Cano-Lozano, José Carlos; Martínez-Bazán, Carlos; Magnaudet, Jacques; Tchoufag, Joël

    2016-09-01

    We report on a series of results provided by three-dimensional numerical simulations of nearly spheroidal bubbles freely rising and deforming in a still liquid in the regime close to the transition to path instability. These results improve upon those of recent computational studies [Cano-Lozano et al., Int. J. Multiphase Flow 51, 11 (2013), 10.1016/j.ijmultiphaseflow.2012.11.005; Phys. Fluids 28, 014102 (2016), 10.1063/1.4939703] in which the neutral curve associated with this transition was obtained by considering realistic but frozen bubble shapes. Depending on the dimensionless parameters that characterize the system, various paths geometries are observed by letting an initially spherical bubble starting from rest rise under the effect of buoyancy and adjust its shape to the surrounding flow. These include the well-documented rectilinear axisymmetric, planar zigzagging, and spiraling (or helical) regimes. A flattened spiraling regime that most often eventually turns into either a planar zigzagging or a helical regime is also frequently observed. Finally, a chaotic regime in which the bubble experiences small horizontal displacements (typically one order of magnitude smaller than in the other regimes) is found to take place in a region of the parameter space where no standing eddy exists at the back of the bubble. The discovery of this regime provides evidence that path instability does not always result from a wake instability as previously believed. In each regime, we examine the characteristics of the path, bubble shape, and vortical structure in the wake, as well as their couplings. In particular, we observe that, depending on the fluctuations of the rise velocity, two different vortex shedding modes exist in the zigzagging regime, confirming earlier findings with falling spheres. The simulations also reveal that significant bubble deformations may take place along zigzagging or spiraling paths and that, under certain circumstances, they dramatically alter

  4. Terminal velocity of a buoyant gas bubble in the stable gas body approximation

    NASA Astrophysics Data System (ADS)

    Peluso, Fabio

    2017-05-01

    The terminal velocity for a bubble of gas is determined as a function of its volume and gas temperature, and pressure as an effect of buoyancy. Only volume variation is considered and not shape deformation. The limits of applicability of the expression arrived at for the terminal velocity as function of the bubble sphericity are given and some typical examples are discussed in detail.

  5. Transient Flow Dynamics in Optical Micro Well Involving Gas Bubbles

    NASA Technical Reports Server (NTRS)

    Johnson, B.; Chen, C. P.; Jenkins, A.; Spearing, S.; Monaco, L. A.; Steele, A.; Flores, G.

    2006-01-01

    The Lab-On-a-Chip Application Development (LOCAD) team at NASA s Marshall Space Flight Center is utilizing Lab-On-a-Chip to support technology development specifically for Space Exploration. In this paper, we investigate the transient two-phase flow patterns in an optic well configuration with an entrapped bubble through numerical simulation. Specifically, the filling processes of a liquid inside an expanded chamber that has bubbles entrapped. Due to the back flow created by channel expansion, the entrapped bubbles tend to stay stationary at the immediate downstream of the expansion. Due to the huge difference between the gas and liquid densities, mass conservation issues associated with numerical diffusion need to be specially addressed. The results are presented in terms of the movement of the bubble through the optic well. Bubble removal strategies are developed that involve only pressure gradients across the optic well. Results show that for the bubble to be moved through the well, pressure pulsations must be utilized in order to create pressure gradients across the bubble itself.

  6. Effervescence in champagne and sparkling wines: From grape harvest to bubble rise

    NASA Astrophysics Data System (ADS)

    Liger-Belair, Gérard

    2017-01-01

    Bubbles in a glass of champagne may seem like the acme of frivolity to most of people, but in fact they may rather be considered as a fantastic playground for any fluid physicist. Under standard tasting conditions, about a million bubbles will nucleate and rise if you resist drinking from your flute. The so-called effervescence process, which enlivens champagne and sparkling wines tasting, is the result of the complex interplay between carbon dioxide (CO2) dissolved in the liquid phase, tiny air pockets trapped within microscopic particles during the pouring process, and some both glass and liquid properties. In this tutorial review, the journey of yeast-fermented CO2 is reviewed (from its progressive dissolution in the liquid phase during the fermentation process, to its progressive release in the headspace above glasses). The most recent advances about the physicochemical processes behind the nucleation, and rise of gaseous CO2 bubbles, under standard tasting conditions, have been gathered hereafter. Let's hope that your enjoyment of champagne will be enhanced after reading this tutorial review dedicated to the unsuspected physics hidden right under your nose each time you enjoy a glass of bubbly.

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

    NASA Astrophysics Data System (ADS)

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

    2003-01-01

    In this study, we propose a focused ultrasound surgery protocol that induces and then uses gas bubbles at the focus to enhance the ultrasound absorption and ultimately create larger lesions in vivo. MRI and ultrasound visualization and monitoring methods for this heating method are also investigated. Larger lesions created with a carefully monitored single ultrasound exposure could greatly improve the speed of tumour coagulation with focused ultrasound. All experiments were performed under MRI (clinical, 1.5 T) guidance with one of two eight-sector, spherically curved piezoelectric transducers. The transducer, either a 1.1 or 1.7 MHz array, was driven by a multi-channel RF driving system. The transducer was mounted in an MRI-compatible manual positioning system and the rabbit was situated on top of the system. An ultrasound detector ring was fixed with the therapy transducer to monitor gas bubble activity during treatment. Focused ultrasound surgery exposures were delivered to the thighs of seven New Zealand white rabbits. The experimental, gas-bubble-enhanced heating exposures consisted of a high amplitude 300 acoustic watt, half second pulse followed by a 7 W, 14 W or 21 W continuous wave exposure for 19.5 s. The respective control sonications were 20 s exposures of 14 W, 21 W and 28 W. During the exposures, MR thermometry was obtained from the temperature dependency of the proton resonance frequency shift. MR T2-enhanced imaging was used to evaluate the resulting lesions. Specific metrics were used to evaluate the differences between the gas-bubble-enhanced exposures and their respective control sonications: temperatures with respect to time and space, lesion size and shape, and their agreement with thermal dose predictions. The bubble-enhanced exposures showed a faster temperature rise within the first 4 s and higher overall temperatures than the sonications without bubble formation. The spatial temperature maps and the thermal dose maps derived from the MRI

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

    PubMed Central

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

    2015-01-01

    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. PMID:26690168

  9. Measurements of Gas Bubble Size Distributions in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Riemer, Bernie; Abdou, Ashraf A

    2012-01-01

    ABSTRACT Pressure waves created in liquid mercury pulsed spallation targets have been shown to induce cavitation damage on 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, measuring such a population in mercury is difficult since it is opaque and the mercury is involved in a turbulent flow. Ultrasonic measurements have been attempted on these types of flows, but the flow noise can interfere with the measurement, and the results are unverifiable and often unrealistic. Recently, a flow loop was built and operated at Oak Ridge National Labarotory to assess the capability of various bubbler designs to deliver an adequate population of bubbles to mitigate cavitation damage. The invented diagnostic technique involves flowing the mercury with entrained gas bubbles in a steady state through a horizontal piping section with a glass-window observation port located on the top. The mercury flow is then suddenly stopped and the bubbles are allowed to settle on the glass due to buoyancy. Using a bright-field illumination and a high-speed camera, the arriving bubbles are detected and counted, and then the images can be processed to determine the bubble populations. After using this technique to collect data on each bubbler, bubble size distributions were built for the purpose of quantifying bubbler performance, allowing the selection of the best bubbler options. This paper presents the novel procedure, photographic technique, sample visual results and some example bubble size distributions. The best bubbler options were subsequently used in proton beam irradiation tests performed at the Los Alamos National Laboratory. The cavitation damage results from the irradiated test plates in contact with the mercury are available for correlation with the bubble populations. The most effective mitigating population can now be designed into prototypical geometries for implementation into

  10. Preliminary study of the effects of a reversible chemical reaction on gas bubble dissolution. [for space glass refining

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.

    1982-01-01

    A preliminary investigation is carried out of the effects of a reversible chemical reaction on the dissolution of an isolated, stationary gas bubble in a glass melt. The exact governing equations for the model system are formulated and analyzed. The approximate quasi-steady-state version of these equations is solved analytically, and a calculation is made of bubble dissolution rates. The results are then compared with numerical solutions obtained from the finite difference form of the exact governing equations. It is pointed out that in the microgravity condition of space, the buoyant rise of a gas bubble in a glass melt will be negligible on the time scale of most experiments. For this reason, a determination of the behavior of a stationary gas bubble in a melt is relevant for an understanding of glass refining in space.

  11. Preliminary study of the effects of a reversible chemical reaction on gas bubble dissolution. [for space glass refining

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.

    1982-01-01

    A preliminary investigation is carried out of the effects of a reversible chemical reaction on the dissolution of an isolated, stationary gas bubble in a glass melt. The exact governing equations for the model system are formulated and analyzed. The approximate quasi-steady-state version of these equations is solved analytically, and a calculation is made of bubble dissolution rates. The results are then compared with numerical solutions obtained from the finite difference form of the exact governing equations. It is pointed out that in the microgravity condition of space, the buoyant rise of a gas bubble in a glass melt will be negligible on the time scale of most experiments. For this reason, a determination of the behavior of a stationary gas bubble in a melt is relevant for an understanding of glass refining in space.

  12. Bubble and bubble cloud dynamics

    NASA Astrophysics Data System (ADS)

    Matsumoto, Yoichiro

    2000-07-01

    Cavitation bubbles are formed from small air bubbles, so-called nuclei, with the surrounding pressure reduction caused by the flow, and then, the bubbles shrink and collapse with the surrounding pressure rise. Such volumetric changes of bubbles are calculated in detail and it is found that they are significantly influenced by the internal phenomena, such as thermal diffusion, mist formation due to a homogeneous condensation, mass diffusion between vapor and noncondensable gas, heat and mass transfer through the bubble wall. The structure in cavitating flow interacts with the cavitation bubbles, and those bubbles form a cloud cavitation. It is well known that cloud cavitation is one of the most destructive forms. The behavior of bubble clouds is simulated numerically. An inward propagating shock wave is formed during the collapse of the bubble cloud, and the shock wave and its precursor are focused at the cloud center area. These phenomena associate high frequency pressure oscillations and violent bubble collapses. Those bubble collapses emit high pressure peaks, which are several hundreds times larger than that of a single bubble collapse.

  13. Rising Bubbles.

    DTIC Science & Technology

    1982-12-01

    2. National Science Foundation; 3. Army Research Office; 4. Air Force Office of Scientific Research ; 5. Stanford University. The personnel...Mathematics Department, Stanford University. This group began functioning officially on September 1, 1979, and is supported by: 1. Office of Naval Research ...Stanford University; 13. Stephanos Venakides, Assistant Professor, Stanford University; 14. Margaret Cheney, Research Associate, Stanford University; 15

  14. Effect of peripheral temperature on the formation of venous gas bubbles.

    PubMed

    Mekjavić, I B; Kakitsuba, N

    1989-09-01

    -h cold exposure, and a subsequent hot shower suggests that a rapid rise in peripheral temperature may cause a significant rise in tissue gas tension. This increase in tension does not seem to be sufficiently reduced by increased perfusion to the tissues to prevent bubble formation.

  15. Behavior of bubbles in glassmelts. II - Dissolution of a stationary bubble containing a diffusing and a nondiffusing gas

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.; Onorato, P. I. K.; Uhlmann, D. R.

    1980-01-01

    The effect of a foreign nondiffusing gas on the rate of shrinkage of an oxygen bubble in a soda-lime-silica melt was studied. The rate of change of bubble radius with time was computed using the quasi-stationary approximation. The effects of melt undersaturation and initial fraction of foreign gas in the bubble are considered and compared with those calculated using previously derived expressions.

  16. Behavior of bubbles in glassmelts. II - Dissolution of a stationary bubble containing a diffusing and a nondiffusing gas

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.; Onorato, P. I. K.; Uhlmann, D. R.

    1980-01-01

    The effect of a foreign nondiffusing gas on the rate of shrinkage of an oxygen bubble in a soda-lime-silica melt was studied. The rate of change of bubble radius with time was computed using the quasi-stationary approximation. The effects of melt undersaturation and initial fraction of foreign gas in the bubble are considered and compared with those calculated using previously derived expressions.

  17. CFD-informed unified closure relation for the rise velocity of Taylor bubbles in pipes

    NASA Astrophysics Data System (ADS)

    Lizarraga-Garcia, Enrique; Buongiorno, Jacopo; Al-Safran, Eissa; Lakehal, Djamel

    2015-11-01

    Two-phase slug flow commonly occurs in gas and oil systems. Current predictive methods are based on the mechanistic models, which require the use of closure relations to complement the conservation equations to predict integral flow parameters such as liquid holdup (or void fraction) and pressure gradient. Taylor bubble velocity in slug flow is one of these closure relations which has been determined to significantly affect the calculation of these parameters. In this work, Computational Fluid Dynamics (CFD) with Level-Set as the Interface Tracking Method (ITM) are employed to simulate the motion of Taylor bubbles in slug flow, for which the commercial code TransAT is used. A large numerical database with stagnant and flowing liquid for various Reynolds numbers is being generated from which a unified Taylor bubble velocity correlation in stagnant liquids for an ample range of fluid properties and pipe geometries is proposed (Mo ∈ [ 1 .10-6 , 5 .103 ] , Eo ∈ [ 10 , 700 ]). Furthermore, it is found that the velocity of Taylor bubbles in inclined pipes is greatly affected by the presence of a lubricating thin film between the bubble and the pipe wall. An analytical and experimentally validated criterion, which predicts the film existence, draiage and breakup, is presented.

  18. Bubble size and gas-liquid interfacial area measurements using molten paraffin waxes in bubble columns

    SciTech Connect

    Bukur, D.B.; Patel, S.A.; Daly, J.G.; Raphael, M.L.

    1987-01-01

    Experiments were conducted in 0.05 m ID and 0.23 m ID by 3 m tall bubble columns with different types of molten waxes as the liquid medium and nitrogen as the gas, under processing conditions typical or Fischer-Tropsch synthesis over iron catalysts (i.e. gas velocities up to 0.15 m s, and temperatures between 200 and 270/sup 0/C) to estimate gas liquid interfacial area from measured values of average gas hold-up and Sauter mean bubble diameter. The gas hold-up was estimated from visual observations of the expanded and static liquid heights, and the Sauter was estimated from bubble size measurements obtained by photography and dynamic gas disengagement. The paraffin wax (FT-300) used in the authors' studies is non-coalescing and has a tendency to foam. The amount of foam is greater for runs conducted in the order of increasing gas velocities, than in runs with decreasing velocities. Thus, two values of hold-up are possible and the start-up procedure determines which one will be attained. At higher gas velocities (> 0.05 m/s) the foam disappears and a transition to the slug flow, churn-turbulent regime takes place. Reactor waxes are coalescing in nature and do not produce foam. Despite similar hold-ups for the different waxes at higher gas velocities, the Sauters are significantly different and this is reflected in the specific gas-liquid interfacial areas, with larger values obtained with the paraffin wax compared to values with reactor waxes.

  19. Analytical Solutions for Predicting Underwater Explosion Gas Bubble Behaviour

    DTIC Science & Technology

    2010-11-01

    report include the Rayleigh - Plesset equation which was original developed by Lamb [3], Herring EOM [4], Kirkwood and Bethe (KB) EOM [5], Keller and...implementation of nine analytical gas bubble models, in the form of nonlinear differential equations , and a fourth-order Runge-Kutta solution method...3 2.1 Similitude Equations

  20. A mass-conserving axisymmetric multiphase lattice Boltzmann method and its application in simulation of bubble rising

    NASA Astrophysics Data System (ADS)

    Huang, Haibo; Huang, Jun-Jie; Lu, Xi-Yun

    2014-07-01

    In many lattice Boltzmann studies about bubble rising, mass conservation is not satisfactory and the terminal bubble rising shape or velocity is not so consistent with experimental data as those obtained through other CFD techniques. In this paper, based on the multiphase model (He et al., 1999 [1]), a mass-conserving axisymmetric multiphase lattice Boltzmann model is developed. In the model, a mass correction step and an effective surface tension formula are introduced into the model. We demonstrate how the macroscopic axisymmetric Cahn-Hilliard equation and Navier-Stokes equation are recovered from the lattice Boltzmann equations through Chapman-Enskog expansion. The developed model is applied to simulate the bubble rising in viscous fluid. The mass correction step in our scheme significantly improves the bubble mass conservation. The surface tension calculation successfully predicts the terminal bubble shapes and reproduces the effect of initial bubble shape. The terminal bubble rising velocities are very consistent with experimental and numerical data in the literature. Qualitatively, the wakes behind the bubbles also agree well with experimental data. This model is useful for predicting the axisymmetric two-phase flows.

  1. Blind Deconvolution on Underwater Images for Gas Bubble Measurement

    NASA Astrophysics Data System (ADS)

    Zelenka, C.; Koch, R.

    2015-04-01

    Marine gas seeps, such as in the Panarea area near Sicily (McGinnis et al., 2011), emit large amounts of methane and carbon-dioxide, greenhouse gases. Better understanding their impact on the climate and the marine environment requires precise measurements of the gas flux. Camera based bubble measurement systems suffer from defocus blur caused by a combination of small depth of field, insufficient lighting and from motion blur due to rapid bubble movement. These adverse conditions are typical for open sea underwater bubble images. As a consequence so called 'bubble boxes' have been built, which use elaborate setups, specialized cameras and high power illumination. A typical value of light power used is 1000W (Leifer et al., 2003). In this paper we propose the compensation of defocus and motion blur in underwater images by using blind deconvolution techniques. The quality of the images can be greatly improved, which will relax requirements on bubble boxes, reduce their energy consumption and widen their usability.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Spread F plasma bubble vertical rise velocities determined from spaced ionosonde observations

    SciTech Connect

    Abdu, M.A.; de Medeiros, R.T.; Sobral, J.H.A.; Bittencourt, J.A.

    1983-11-01

    Systematic time differences in the onsets of spread F events in the ionograms are observed between the magnetic equatorial station Fortaleza (4/sup 0/S, 38/sup 0/W, dip latitude 1.8/sup 0/S) and the low-latitude station Cachoeira Paulista (23/sup 0/S, 45/sup 0/W, dip latitude 14/sup 0/S), two stations in Brazil, located at close-by magnetic meridional planes (actually some 12/sup 0/ of magnetic longitude apart). On the assumption, justified from different experimental observations, that the spread F irregularities occur in strongly field-aligned plasma bubbles that extend several degrees on either side of the magnetic equator, and rise up in vertically elongated columns over the magnteic equator, we have related the observed time differences in the onsets of spread F events at the two stations to the plasma bubble vertical rise velocities of the plasma bubbles so determined are found to be well within the values measured by VHF radar and satellite techniques, and further show, at times, good correlations with the amplitude of the prereversal peak in the vertical drift velocities and the heights of the evening equatorial F layer. Possible implications of these results are discussed.

  4. Step-Wise Velocity of an Air Bubble Rising in a Vertical Tube Filled with a Liquid Dispersion of Nanoparticles.

    PubMed

    Cho, Heon Ki; Nikolov, Alex D; Wasan, Darsh T

    2017-03-21

    The motion of air bubbles in tubes filled with aqueous suspensions of nanoparticles (nanofluids) is of practical interest for bubble jets, lab-on-a-chip, and transporting media. Therefore, the focus of this study is the dynamics of air bubbles rising in a tube in a nanofluid. Many authors experimentally and analytically proposed that the velocity of rising air bubbles is constant for long air bubbles suspended in a vertical tube in common liquids (e.g. an aqueous glycerol solution) when the capillary number is larger than 10(-4). For the first time, we report here a systematic study of an air bubble rising in a vertical tube in a nanofluid (e.g. an aqueous silica dioxide nanoparticle suspension, nominal particle size, 19 nm). We varied the bubble length scaled by the diameter of the tubes (L/D), the concentration of the nanofluid (10 and 12.5 v %), and the tube diameter (0.45, 0.47, and 0.50 cm). The presence of the nanoparticles creates a significant change in the bubble velocity compared with the bubble rising in the common liquid with the same bulk viscosity. We observed a novel phenomenon of a step-wise increase in the air bubble rising velocity versus bubble length for small capillary numbers less than 10(-7). This step-wise velocity increase versus the bubble length was not observed in a common fluid. The step-wise velocity increase is attributed to the nanoparticle self-layering phenomenon in the film adjacent to the tube wall. To elucidate the role of the nanoparticle film self-layering on the bubble rising velocity, the effect of the capillary number, the tube diameter (e.g. the capillary pressure), and nanofilm viscosity are investigated. We propose a model that takes into consideration the nanoparticle layering in the film confinement to explain the step-wise velocity phenomenon versus the length of the bubble. The oscillatory film interaction energy isotherm is calculated and the Frenkel approach is used to estimate the film viscosity.

  5. Porosity formation and gas bubble retention in laser metal deposition

    NASA Astrophysics Data System (ADS)

    Ng, G. K. L.; Jarfors, A. E. W.; Bi, G.; Zheng, H. Y.

    2009-11-01

    One of the inherent problems associated with laser metal deposition using gas-assisted powder transfer is the formation of porosity, which can be detrimental to the mechanical properties of the bulk material. In this work, a comprehensive investigation of porosity is carried out using gas atomised Inconel 718 powder. In the analysis, a clear distinction is made between two types of porosity; namely lack of fusion and gas porosity. The results show that the two types of porosity are attributed by different factors. The gas porosity, which is more difficult to eliminate than the lack of fusion, can be as high as 0.7%. The study shows that the gas porosity is dependent on the process parameters and the melt pool dynamics. The flotation of entrapped gas bubbles was analysed, showing that in a stationary melt pool the gas would be retained by Marangoni-driven flow. The overall Marangoni-driven flow of the melt pool is in the order of five times higher than the flotation effect, and this is the reason why the melt pool geometry would tend to dominate the flow direction of the gas bubbles. Through optimisation, the gas porosity can be reduced to 0.037%.

  6. Breakdown Voltage Scaling in Gas Bubbles Immersed in Liquid Water

    NASA Astrophysics Data System (ADS)

    Gucker, Sarah; Sommers, Bradley; Foster, John

    2013-09-01

    Radicals produced by the interaction of plasma with liquid water have the capacity to rapidly oxidize organic contaminants. This interaction is currently being investigated as a means to purify water. Direct plasma creation in water typically requires very high voltages to achieve breakdown. Igniting plasma in individual gas bubbles in liquid water on the other hand requires much less voltage. Furthermore, the use of an electrode-less plasma initiation in such bubbles is attractive in that it eliminates electrode erosion thereby circumventing the contamination issue. The breakdown physics of isolated bubbles in liquid water is still poorly understood. In this work, we investigate the relationship between applied voltage for breakdown and the associated pd. This is achieved by locating the breakdown voltage over a range of bubble sizes. This approach allows for the generation of a Paschen-type breakdown curve for isolated bubbles. Such a relationship yields insight into breakdown mechanics and even streamer propagation through water. This material is based upon work supported by the National Science Foundation (CBET 1033141) and the National Science Foundation Graduate Student Research Fellowship under Grant No. DGE 0718128.

  7. Periodic and aperiodic bubbling in submerged gas-liquid jets through a micro-channel

    NASA Astrophysics Data System (ADS)

    Shen, Yingnan; Hu, Liang; Chen, Wenyu; Fu, Xin

    2017-04-01

    The common phenomena of periodic and aperiodic bubbling, which were studied merely in single-phase gas jets, are discovered to exist in submerged gas-liquid jets through a micro-channel. Due to the participation of the liquid input flow which interacts with the gas phase, the periodic and aperiodic bubbling behaviors, as well as the regime transition mechanisms, are quite different from single-phase gas jets. Periodic bubbling is formed by injecting a regular Taylor flow into bulk liquid, in which a special motion of bubbles named "bubble bifurcation" is revealed. Bubbles move into the opposite orientation to the bubbles they touch because unequal contact angles make the bubbles tilt when they detach. The bifurcation process is described by the evolutions of the contact line, bubble centers, and the bifurcation point. The second bifurcation events cause the bubble branches to rotate simultaneously. The difference of periodicity between gas-liquid jets and single-phase gas jets is explained in a dimensionless form as a function of 1/St versus Fr. Aperiodic bubbling including double coalescence, triple, quadruple, and quintuple bubble formation is found to occur at lower gas velocities than single-phase gas jets because of the different mechanism of bubble detachment in which liquid rings make bubbles pitch off before necking. The effect of liquid rings on bubbling period, as well as the disturbance waves spreading over the bubble surface, is explained. Finally, the mechanisms of bubbling losing periodicity are figured out through analyzing the correspondence relationship between the evolutions of bubbling behaviors and the flow regime transitions in the micro-channel with regime boundaries well predicted by corresponding models.

  8. Investigation of Gas Holdup in a Vibrating Bubble Column

    NASA Astrophysics Data System (ADS)

    Mohagheghian, Shahrouz; Elbing, Brian

    2015-11-01

    Synthetic fuels are part of the solution to the world's energy crisis and climate change. Liquefaction of coal during the Fischer-Tropsch process in a bubble column reactor (BCR) is a key step in production of synthetic fuel. It is known from the 1960's that vibration improves mass transfer in bubble column. The current study experimentally investigates the effect that vibration frequency and amplitude has on gas holdup and bubble size distribution within a bubble column. Air (disperse phase) was injected into water (continuous phase) through a needle shape injector near the bottom of the column, which was open to atmospheric pressure. The air volumetric flow rate was measured with a variable area flow meter. Vibrations were generated with a custom-made shaker table, which oscillated the entire column with independently specified amplitude and frequency (0-30 Hz). Geometric dependencies can be investigated with four cast acrylic columns with aspect ratios ranging from 4.36 to 24, and injector needle internal diameters between 0.32 and 1.59 mm. The gas holdup within the column was measured with a flow visualization system, and a PIV system was used to measure phase velocities. Preliminary results for the non-vibrating and vibrating cases will be presented.

  9. Numerical and experimental investigations of an air bubble rising in a Carreau-Yasuda shear-thinning liquid

    NASA Astrophysics Data System (ADS)

    Premlata, A. R.; Tripathi, Manoj Kumar; Karri, Badarinath; Sahu, Kirti Chandra

    2017-03-01

    The dynamics of an air bubble rising in a quiescent shear-thinning fluid modelled using a simplified Carreau-Yasuda rheological model is investigated numerically and experimentally. For the parameter values considered in the present study, a rising bubble in a shear-thinning fluid exhibits a three-dimensional behaviour. Both path instabilities (zigzagging/spiralling motion) and topological changes are observed for an air bubble rising in a shear-thinning fluid. However, for a Newtonian surrounding fluid, a bubble maintains azimuthal symmetry and rises in a straight path for the same set of parameters. The mechanism of this three-dimensional behaviour is investigated by inspecting the variation of the vertical vorticity component and viscosity. Experiments have also been conducted using a high speed camera to visualise the bubble rise behaviour in both Newtonian and shear-thinning fluids as surrounding media. The shapes and trajectories of the bubble obtained from experiments show a qualitative agreement with those obtained from numerical simulations.

  10. HUBBLE PICTURES SHOW HOT GAS BUBBLE EJECTED BY YOUNG STAR

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These images taken with the Hubble Space Telescope's Wide Field and Planetary Camera 2 reveal the evolution of bubbles of glowing gas being blown out from the young binary star system XZ Tauri. Gas from an unseen disk around one or both of the stars is channeled through magnetic fields surrounding the binary system and then is forced out into space at nearly 300,000 miles per hour (540,000 kilometers per hour). This outflow, which is only about 30 years old, extends nearly 60 billion miles (96 billion kilometers). Hubble first discovered this unique bubble in 1995, and additional observations were made between 1998 and 2000. These images show that there was a dramatic change in its appearance between 1995 and 1998. In 1995, the bubble's edge was the same brightness as its interior. However, when Hubble took another look at XZ Tauri in 1998, the edge was suddenly brighter. This brightening is probably caused by the hot gas cooling off, which allows electrons in the gas to recombine with atoms, a process that gives off light. This is the first time that astronomers have seen such a cooling zone 'turn on.' These images provide an unprecedented opportunity to study the development of a very recent outflow from young (about 1 million years old) stars. Credits: NASA, John Krist (Space Telescope Science Institute), Karl Stapelfeldt (Jet Propulsion Laboratory), Jeff Hester (Arizona State University), Chris Burrows (European Space Agency/Space Telescope Science Institute)

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

    NASA Astrophysics Data System (ADS)

    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

  12. Gamma densitometry tomography of gas holdup spatial distribution in industrial scale bubble columns

    SciTech Connect

    Shollenberger, K.A.; Torczynski, J.R.; Adkins, D.R.; O`Hern, T.J.; Jackson, N.B.

    1995-12-31

    Gamma-densitometry tomography (GDT) experiments have been performed to measure gas holdup spatial variations in two bubble columns: a 0.19 m inside diameter Lucite column and a 0.48 m inside diameter stainless steel vessel. Air and water were used for the measurements. Horizontal scans at one vertical position in each column were made for several air flow rates. An axi-symmetric tomographic reconstruction algorithm based on the Abel transform has been used to calculate the time averaged gas holdup radial variation. Integration of these profiles over the column cross section has yielded area-averaged gas holdup results, which have been compared with volume-averaged gas holdups determined from differential pressure measurements and from the rise in the air/water interface during gas flow. The results agree reasonably well.

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

    NASA Astrophysics Data System (ADS)

    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 <110> directions in the body-centered cubic U matrix causes the gas bubble alignment along <110> 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.

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

    SciTech Connect

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

    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.

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

    USGS Publications Warehouse

    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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  18. Stability of a compressed gas bubble in a viscous fluid

    SciTech Connect

    Iooss, G.; Laure, P.; Rossi, M.

    1989-06-01

    The stability of the spherical shape of the free surface of a gas bubble compressed by an incompressible fluid as it appears in the inertial confinement fusion problem is considered. (i) The equations derived by Prosperetti (Accad. Naz. Lincei 62, 196 (1977)) generalizing the Plesset equation are recovered in cases when the outer fluid is nonviscous, the flow being not potential, and it is shown that vorticity may change drastically the results of the potential case. (ii) In the case of viscous external fluid, the equations derived by Prosperetti (Q. Appl. Math. 1, 399 (1977)) and other external conditions on a sphere of finite radius are derived. (iii) Assuming that the time scale of the dynamics of the spherical bubble is large with respect to the time scale of the perturbation (frozen assumption), the linear stability of the collapsing bubble is studied numerically. The parameters are here (a) an inertia force (related with acceleration R-italic-dieresis of the radius of the bubble), (b) the Reynolds number built with the decaying rate of the bubble, (c) surface tension, and (d) the aspect ratio (ratio between the gap width of the viscous fluid and the radius of the bubble). It is shown that the spherical shape is always linearly unstable in the absence of surface tension. In the presence of surface tension, there is a critical inertia parameter value and the most dangerous mode is always stationary. For the case of a large surface tension, the spherical wavenumber l of the most dangerous mode, is low. Finally, it is shown that the Rayleigh--Taylor instability might only be observed for both small aspect ratio and Reynolds number, depending on the surface tension.

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

    PubMed

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

    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 superlattice formation are not well known. In this work, the molecular dynamics (MD) method 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 MD simulations, the embedded-atom method (EAM) potential of U10Mo-Xe [1] is employed. Initial gas bubbles with a low Xe concentration (underpressured) are generated in a body-centered cubic (bcc) U10Mo single crystal. Then Xe atoms are sequentially added into the bubbles one by one, 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 an overpressured gas bubble emits partial dislocations with a Burgers vector along the <111> direction and a slip plane of (11-2). Meanwhile, dislocation loop punch out was not observed. The overpressured bubble also induces an anisotropic stress field. A tensile stress was found along <110> directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in bcc U10Mo fuels.

  2. PHASE-FIELD SIMULATION OF IRRADIATED METALS: PART II: GAS BUBBLE KINETICS

    SciTech Connect

    Paul C Millett; Anter El-Azab

    2011-01-01

    We present a phase-field model for inert gas bubble formation and evolution in irradiated metals. The model evolves vacancy, self-interstitial, and fission gas atoms through a coupled set of Cahn-Hilliard and Allen-Cahn equations, capturing the processes of defect generation, recombination, annihilation at GB sinks, as well as intragranular and intergranular bubble nucleation and growth in polycrystalline microstructures. Illustrative results are presented that characterize bubble growth and shrinkage, as well as the bubble density, size and nucleation rate as a function of varying irradiation conditions. Finally, intergranular bubble characteristics such as shape, pinning energy on GB motion, and bubble density are investigated.

  3. Pulsed electrical discharge in gas bubbles in water

    NASA Astrophysics Data System (ADS)

    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

  4. Modelling of Spherical Gas Bubble Oscillations and Sonoluminescence

    NASA Technical Reports Server (NTRS)

    Prosperetti, A.; Hao, Y.

    1999-01-01

    The discovery of single-bubble sonoluminescence has led to a renewed interest in the forced radial oscillations of gas bubbles. Many of the more recent studies devoted to this topic have used several simplifications in the modelling, and in particular in accounting for liquid compressibility and thermal processes in the bubble. In this paper the significance of these simplifications is explored by contrasting the results of Lohse and co-workers with those of a more detailed model. It is found that, even though there may be little apparent difference between the radius-versus time behaviour of the bubble as predicted by the two models, quantities such as the spherical stability boundary and the threshold for rectified diffusion are affected in a quantitatively significant way. These effects are a manifestation of the subtle dependence upon dissipative processes of the phase of radial motion with respect to the driving sound field. The parameter space region, where according to the theory of Lohse and co-workers, sonoluminescence should be observable, is recalculated with the new model and is found to be enlarged with respect to the earlier estimate. The dependence of this parameter region on sound frequency is also illustrated.

  5. Bangladesh to prepare for rise in gas demand

    SciTech Connect

    Not Available

    1992-06-01

    Bangladesh is moving to expand its natural gas infrastructure in response to rising domestic demand. This paper reports that Bangladesh natural gas demand is expected to rise to 700-850 MMcfd in the next few years from the current level of about 500 MMcfd, the Prime Minister Khaleda Zia.

  6. Gas structure and dynamics towards bipolar infrared bubble

    NASA Astrophysics Data System (ADS)

    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.

  7. A computational model of gas bubble evolution in liquid filled straight tubes

    NASA Astrophysics Data System (ADS)

    Himm, Jeff; Halpern, David

    1996-11-01

    Deep sea divers suffer from decompression sickness (DCS) when their rate of ascent to the surface is too quick. When the ambient pressure drops, inert gas bubbles are usually formed in blood vessels and tissues of divers. It is believed that the existence of gas bubbles is the cause of DCS that manifests itself as itching, joint pain, and neurological abnormalities. While models of gas bubbles in tissues are relatively well developed, the mechanism of bubble growth in the circulation is far less well understood. The existence of gas bubbles may affect gas exchange in small blood vessels by blocking the flow of blood. Gas bubble evolution in the circulation is investigated using an analytical method for small bubbles and the boundary element method for bubbles whose effective radius is close to the tube radius. The concentration field for the dissolved gas surrounding the bubble is solved numerically using finite differences. The bubble volume is adjusted over time according to the mass flux at the surface. It is shown that the effect of increasing the flow rate is to enhance bubble evolution, up to a factor of two compared with the evolution in tissue where there is no flow. This work was supported by the Naval Medical Research and Development Command work unit 62233N.MM33P30.0041509.

  8. Generation and characterization of gas bubbles in liquid metals

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Computation of the Knife-Edge Cusp of a Rising Bubble in a Viscoelastic Fluid

    NASA Astrophysics Data System (ADS)

    You, Ruobo; Haj-Hariri, Hossein

    2006-11-01

    We consider the buoyant rise of an originally-spherical bubble through a viscoelastic fluid. Experiments have demonstrated that the sharp trailing edge could develop a three dimensional cusp of ``knife-like'' shape under certain conditions (high capillary number, large drop size). In order to understand the complex physics of this phenomenon, we have conducted a linear, three-dimensional temporal stability analysis of a computationally-obtained axisymmetric cusped bubble. The in-house time-accurate code is control-volume based and uses a body-fitted grid. Flux-difference splitting is employed to handle large Deborah numbers. Artificial compressibility is used for time marching. The resulting eigenanalysis shows the only linearly-unstable mode to be the one with azimuthal wavenumber of 2. The eigenvalue is real and the nature of instability is an exchange of stability. Thus an axisymmetric cusp can indeed develop into a knife-like shape. An investigation of the energy production and dissipation for the disturbances shows that the normal pressure gradient of the base-state along the free surface plays an important role in the evolution of the instability.

  11. Bubble formation during horizontal gas injection into downward-flowing liquid

    NASA Astrophysics Data System (ADS)

    Bai, Hua; Thomas, Brian G.

    2001-12-01

    Bubble formation during gas injection into turbulent downward-flowing water is studied using high-speed videos and mathematical models. The bubble size is determined during the initial stages of injection and is very important to turbulent multiphase flow in molten-metal processes. The effects of liquid velocity, gas-injection flow rate, injection hole diameter, and gas composition on the initial bubble-formation behavior have been investigated. Specifically, the bubble-shape evolution, contact angles, size, size range, and formation mode are measured. The bubble size is found to increase with increasing gas-injection flow rate and decreasing liquid velocity and is relatively independent of the gas injection hole size and gas composition. Bubble formation occurs in one of four different modes, depending on the liquid velocity and gas flow rate. Uniform-sized spherical bubbles form and detach from the gas injection hole in mode I for a low liquid speed and small gas flow rate. Modes III and IV occur for high-velocity liquid flows, where the injected gas elongates down along the wall and breaks up into uneven-sized bubbles. An analytical two-stage model is developed to predict the average bubble size, based on realistic force balances, and shows good agreement with measurements. Preliminary results of numerical simulations of bubble formation using a volume-of-fluid (VOF) model qualitatively match experimental observations, but more work is needed to reach a quantitative match. The analytical model is then used to estimate the size of the argon bubbles expected in liquid steel in tundish nozzles for conditions typical of continuous casting with a slide gate. The average argon bubble sizes generated in liquid steel are predicted to be larger than air bubbles in water for the same flow conditions. However, the differences lessen with increasing liquid velocity.

  12. Increasing of Gas Bubbling at Wariishi Flowing Spring, Central Japan, before and after the 2014 Ontake Volcano Eruption

    NASA Astrophysics Data System (ADS)

    Kimata, F.; Tasaka, S.; Asai, Y.

    2016-12-01

    Wariishi Spa is locating at Atotsugawa active fault, and it is an flowing spring from the 850m depth by the bore hole. The spring is coming from the rain fall through the geological boundary. Discharge was measured 100L/minute by manual every week in 1977. In 1990, measurement system was updated to 1Hz by electromagnetic flowmeter system. Co-seismic discharge rises are measured for about 100 examples of the earthquake occurrence in around area. The discharge rise is decreasing asymptotic convergence with time. In 2011 Tohoku Earthquake, the discharge of spring is a rise of 30 L/minutes, and it took 1 and half year to return to 20 L/minute. Ontake Volcano is one of the active volcanoes in same mountain range, but it is located about 50 km south from the Wariishi spa. There are three active volcanoes between Wariishi Spa and Ontake Volcano. The volcano was erupted in a phreatic explosion on September 27, 2014. There is no observation of the discharge change at the eruption in the hot spring. There are other hot spring systems in Wariishi spa. The spa has a periodic spring with one to two-hour frequencies. The periodic frequencies are depended on the discharge volume. Therefore, at the co-seismic discharge rise, the shortenings of periodic frequencies are observed. Hence, the mechanism of main discharge and periodic spring is located at the depth of 850 m. Based on discussion on time series of discharge spa, there are observed many pulsed noises between the periodic springs. The noises are caused by gas bubbling from the precise examinations. It is suggested that gas bubbling is different mechanism with periodic spring, because no effects on the periodic spring frequency. Bubbling is sourced from more deep than 850 m. Gas bubbling was observed about 50 times between the periodic spa around the Ontake volcano eruption. There is no report on such gas bubbling rise since 2012. Discussed above, it is suggested some changes of strain field at central Japan, especially in

  13. Metabolic modeling of synthesis gas fermentation in bubble column reactors.

    PubMed

    Chen, Jin; Gomez, Jose A; Höffner, Kai; Barton, Paul I; Henson, Michael A

    2015-01-01

    A promising route to renewable liquid fuels and chemicals is the fermentation of synthesis gas (syngas) streams to synthesize desired products such as ethanol and 2,3-butanediol. While commercial development of syngas fermentation technology is underway, an unmet need is the development of integrated metabolic and transport models for industrially relevant syngas bubble column reactors. We developed and evaluated a spatiotemporal metabolic model for bubble column reactors with the syngas fermenting bacterium Clostridium ljungdahlii as the microbial catalyst. Our modeling approach involved combining a genome-scale reconstruction of C. ljungdahlii metabolism with multiphase transport equations that govern convective and dispersive processes within the spatially varying column. The reactor model was spatially discretized to yield a large set of ordinary differential equations (ODEs) in time with embedded linear programs (LPs) and solved using the MATLAB based code DFBAlab. Simulations were performed to analyze the effects of important process and cellular parameters on key measures of reactor performance including ethanol titer, ethanol-to-acetate ratio, and CO and H2 conversions. Our computational study demonstrated that mathematical modeling provides a complementary tool to experimentation for understanding, predicting, and optimizing syngas fermentation reactors. These model predictions could guide future cellular and process engineering efforts aimed at alleviating bottlenecks to biochemical production in syngas bubble column reactors.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  16. Sparger Effects on Gas Volume Fraction Distributions in Vertical Bubble-Column Flows as Measured by Gamma-Densitometry Tomography

    SciTech Connect

    GEORGE,DARIN L.; SHOLLENBERGER,KIM ANN; TORCZYNSKI,JOHN R.

    2000-01-18

    Gamma-densitometry tomography is applied to study the effect of sparger hole geometry, gas flow rate, column pressure, and phase properties on gas volume fraction profiles in bubble columns. Tests are conducted in a column 0.48 m in diameter, using air and mineral oil, superficial gas velocities ranging from 5 to 30 cm s{sup -1}, and absolute column pressures from 103 to 517 kPa. Reconstructed gas volume fraction profiles from two sparger geometries are presented. The development length of the gas volume fraction profile is found to increase with gas flow rate and column pressure. Increases in gas flow rate increase the local gas volume fraction preferentially on the column axis, whereas increases in column pressure produce a uniform rise in gas volume fraction across the column. A comparison of results from the two spargers indicates a significant change in development length with the number and size of sparger holes.

  17. The effect of flow pattern around a bubble rising near a vertical wall, on the wall to liquid heat transfer

    NASA Astrophysics Data System (ADS)

    Bhuvankar, Pramod; Dabiri, Sadegh

    2016-11-01

    Two-phase flow is an effective means for heat removal due to the enhanced convective effect caused by bubbly flow and the usually high latent heat of vaporization of the liquid phase. We present a numerical study of the effect of flow patterns around a single bubble rising in shear flow near a vertical wall, on the wall-to-liquid heat transfer. The Navier-Stokes equations are solved in a frame of reference moving with the bubble, by using the front tracking method for interface tracking. Our simulations reveal an enhancement of heat transfer downstream of the bubble, and a less pronounced diminishment of heat transfer upstream of the bubble. We observe that in the range of 5 <= Re <= 40 for Reynolds number based on shear and bubble diameter, heat transfer first increases, attains a maximum and decreases as Re increases. The optimum Re depends on the Archimedes number. The heat transfer enhancement is attributed to flow reversal happening in a confined region of the shear flow, in the presence of a bubble. The analytical solution of 2 - D inviscid shear flow over a cylinder near a wall is used to identify two parameters of flow reversal namely 'reversal height' and 'reversal width'. These parameters are then used to qualitatively explain what we observe in 3 - D simulations.

  18. Bubbles

    NASA Astrophysics Data System (ADS)

    Prosperetti, Andrea

    2004-06-01

    Vanitas vanitatum et omnia vanitas: bubbles are emptiness, non-liquid, a tiny cloud shielding a mathematical singularity. Born from chance, a violent and brief life ending in the union with the (nearly) infinite. But a wealth of phenomena spring forth from this nothingness: underwater noise, sonoluminescence, boiling, and many others. Some recent results on a "blinking bubble" micropump and vapor bubbles in sound fields are outlined. The last section describes Leonardo da Vinci's observation of the non-rectlinear ascent of buoyant bubbles and justifies the name Leonardo's paradox recently attributed to this phenomenon.

  19. Flow in the negative wake of a Taylor bubble rising in viscoelastic carboxymethylcellulose solutions: particle image velocimetry measurements

    NASA Astrophysics Data System (ADS)

    Sousa, Renato G.; Nogueira, S.; Pinto, A. M. F. R.; Riethmuller, M. L.; Campos, J. B. L. M.

    2004-07-01

    A simultaneous technique employing particle image velocimetry (PIV) and shadowgraphy was used to study vertical slug flow in non-Newtonian fluids. Two aqueous solutions of 0.8 and 1.0 wt% carboxymethylcellulose (CMC) were studied and the flow field around individual Taylor bubbles fully characterized. The rheological fluid properties and pipe dimension yielded Reynolds numbers of 8 and 4 and Deborah numbers of 0.2 and 0.4. A negative wake was found downstream of the Taylor bubbles in both fluids. Below the bubble trailing edge, along the axis region, the fluid flows in the opposite direction to the bubble (negative wake), originating rotational liquid movements in adjacent regions. Even far downward from the bubble, rotational liquid movements are clearly seen and measured. In the 1.0 wt% CMC solution, the bubble trailing edge has the shape of a two-dimensional cusp. This two-dimensional cusp, of small dimensions, is seen in different orientations during the bubble rise-indicating a fast rotational movement. The asymmetrical shape of the trailing edge is responsible for small asymmetries in the flow in the wake region (three-dimensional flow). The asymmetrical shape associated with the rotational movement is responsible for an unsteady flow of small amplitude. In the 0.8 wt% CMC solution, the shape of the trailing edge changes during the bubble rise. An axisymmetric axial oscillation a continuous expansion and contraction of the trailing edge, is the origin of this behaviour. This oscillatory movement is responsible for an unsteady flow of small amplitude in the wake region.

  20. Effect of Slotted Anode on Gas Bubble Behaviors in Aluminum Reduction Cell

    NASA Astrophysics Data System (ADS)

    Sun, Meijia; Li, Baokuan; Li, Linmin; Wang, Qiang; Peng, Jianping; Wang, Yaowu; Cheung, Sherman C. P.

    2017-08-01

    In the aluminum reduction cells, gas bubbles are generated at the bottom of the anode which eventually reduces the effective current contact area and the system efficiency. To encourage the removal of gas bubbles, slotted anode has been proposed and increasingly adopted by some industrial aluminum reduction cells. Nonetheless, the exact gas bubble removal mechanisms are yet to be fully understood. A three-dimensional (3D) transient, multiphase flow mathematical model coupled with magnetohydrodynamics has been developed to investigate the effect of slotted anode on the gas bubble movement. The Eulerian volume of fluid approach is applied to track the electrolyte (bath)-molten aluminum (metal) interface. Meanwhile, the Lagrangian discrete particle model is employed to handle the dynamics of gas bubbles with considerations of the buoyancy force, drag force, virtual mass force, and pressure gradient force. The gas bubble coalescence process is also taken into account based on the O'Rourke's algorithm. The two-way coupling between discrete bubbles and fluids is achieved by the inter-phase momentum exchange. Numerical predictions are validated against the anode current variation in an industrial test. Comparing the results using slotted anode with the traditional one, the time-averaged gas bubble removal rate increases from 36 to 63 pct; confirming that the slotted anode provides more escaping ways and shortens the trajectories for gas bubbles. Furthermore, the slotted anode also reduces gas bubble's residence time and the probability of coalescence. Moreover, the bubble layer thickness in aluminum cell with slotted anode is reduced about 3.5 mm (17.4 pct), so the resistance can be cut down for the sake of energy saving and the metal surface fluctuation amplitude is significantly reduced for the stable operation due to the slighter perturbation with smaller bubbles.

  1. Modulated single-bubble sonoluminescence: Dependence of phase of flashes, their intensity and rise/decay times on viscosity, the modulation strength, and frequency

    NASA Astrophysics Data System (ADS)

    Mastikhin, Igor; Djurkovic, Borko

    2004-05-01

    The single-bubble sonoluminescence (SBSL) signal was studied for the case of driving frequency modulated by lower frequency with an offset. In our work, the driving frequency of 28 kHz and the modulation frequencies of 25-1000 Hz were used. The modulation strength of 0.2, 0.5, and 0.8 was defined as the difference of highest and lowest pressures over modulation period. The measurements were performed for water-glycerol mixtures of various viscosities. The measured SBSL signal appeared as a train of flashes for modulation frequencies below 250 Hz, and as a continuous modulated signal for higher frequencies. At the same frequency, the flashes covered similar phase intervals for different modulation strengths and, accordingly, pressure ranges. At higher glycerol concentrations (up to 24%) both the intensity and the stability of flashes increased, due to damped shape instabilities and reduced dancing; however, the phase interval of flashes remained about the same. Such phase-locked behavior can be explained by translational movements of the bubble due to modulated Bjerknes force and changes in the symmetry of the bubble collapse. The changes in intensities and rise/decay times can serve as a measure of the gas exchange between the bubble and its surroundings during silent and luminescent intervals.

  2. Observations on gas-bubble disease of fish

    USGS Publications Warehouse

    1953-01-01

    SOME DIFFICULTY has been experienced in raising fry and young fingerlings at the Puyallup hatchery of the Washington State Department of Game, a hatchery now in its fourth year of operation. There has been evidence of gas in the yolk-sac fry, and the mortality was always excessive among the fingerlings while reared in the hatchery troughs. The mortality rate decreased and evidence of gas-bubble disease disappeared when the fish mere moved to outside ponds. Also, fish seemed less susceptible to parasitic diseases when held in the ponds rather than 1m hatchery troughs. Strains of fish raised at the station were cutthroat trout (Salmo clarkii clarkii and Salmo clarkii lewisi) rainbow trout (Salmo gairdnerii gairdnerii), and steelhead trout (Salmo gairdnerii iriatus)

  3. A model for fission-gas-bubble behavior in amorphous uranium silicide compounds

    NASA Astrophysics Data System (ADS)

    Rest, J.

    2004-02-01

    A model for the behavior of fission gas in irradiated amorphous materials is developed. The model proposes that gas bubble nucleation occurs within shear bands initiated around free volume regions. Small gas-atom clusters that form within these regions are susceptible to dissolution by forces generated by the plastic flow of material around the cluster. The bubble coarsening process depends on the materials viscosity and on irradiation-induced re-solution. The bubble distribution eventually reaches a point where larger bubbles from the tail of the evolving lognormal size distribution begin to contact the more numerous nanometer-sized bubbles from the peak region. This condition defines the knee in the swelling curve. The fission density at which the knee occurs is a function of fission rate. Calculations for the behavior of the knee, swelling, and the fraction of gas in bubbles in irradiated U 3Si 2 intermetallic compounds are compared to measured quantities.

  4. Bubble Combustion

    NASA Technical Reports Server (NTRS)

    Corrigan, Jackie

    2004-01-01

    A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM

  5. Bubble Combustion

    NASA Technical Reports Server (NTRS)

    Corrigan, Jackie

    2004-01-01

    A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM

  6. Gas bubble disease in farmed fish in Saudi Arabia.

    PubMed

    Saeed, M O; al-Thobaiti, S A

    1997-06-28

    Four outbreaks of gas bubble disease were encountered among farmed fish in Saudi Arabia. Two of them occurred among subadult (52.5 g) saltwater tilapia (Oreochromis spilurus), the first affecting about 50 per cent of the stock and resulting in about 30 per cent mortality, and the second affecting about 25 per cent of the population with about 5 per cent mortality. Another outbreak occurred among adult (270 g) brackish water (0.5 per cent salinity) tilapia (Oreochromis niloticus), affecting about 40 per cent of the population with about 25 per cent mortality. The fourth outbreak occurred among three-month-old (15 g) grouper (Epinephelus fuscogutiatus) and resulted in 10 per cent mortality. In all cases the total water gas pressure ranged between 111.2 and 113.4 per cent saturation and nitrogen was supersaturated while oxygen was undersaturated. The outbreaks were alleviated by reducing the gas pressure by splashing the source water or by switching to a source of water with lower gas pressure. However, in O niloticus the conditions of gas supersaturation resulted in a heavy infection by monogenetic trematodes which was treated with formalin at 40 mg/litre for seven hours on five successive days.

  7. Development of Liposomal Bubbles with Perfluoropropane Gas as Gene Delivery Carriers

    NASA Astrophysics Data System (ADS)

    Maruyama, Kazuo; Suzuki, Ryo; Sawamura, Kaori; Takizawa, Tomoko; Utoguchi, Naoki; Negishi, Yoichi

    2007-05-01

    Liposomes have some advantages as drug, antigen and gene delivery carriers. Their size can be easily controlled and they can be modified to add a targeting function. Based on liposome technology, we developed novel liposomal bubbles (Bubble liposomes) containing the ultrasound imaging gas, perfluoropropane. We assessed the feasibility of Bubble liposomes as carriers for gene delivery after cavitation induced by ultrasound. At first, we investigated their ability to deliver genes with Bubble liposomes and ultrasound to various types of cells such as mouse sarcoma cells, mouse melanoma cells, human T cell line and human umbilical vein endothelial cells. The results showed that the Bubble liposomes could deliver plasmid DNA to many cell types without cytotoxicity. In addition, we found that Bubble liposomes could effectively deliver plasmid DNA into mouse femoral artery in vivo. The gene transduction with Bubble liposomes was more effectively than conventional lipofection. We conclude that Bubble liposomes are unique and efficient gene delivery carriers in vitro and in vivo.

  8. Frequency dependence in seismoacoustic imaging of shallow free gas due to gas bubble resonance

    NASA Astrophysics Data System (ADS)

    Tóth, Zsuzsanna; Spiess, Volkhard; Keil, Hanno

    2015-12-01

    Shallow free gas is investigated in seismoacoustic data in 10 frequency bands covering a frequency range between 0.2 and 43 kHz. At the edge of a gassy patch in the Bornholm Basin (Baltic Sea), compressional wave attenuation caused by free gas is estimated from reflection amplitudes beneath the gassy sediment layer. Imaging of shallow free gas is considerably influenced by gas bubble resonance, because in the resonance frequency range attenuation is significantly increased. At the resonance frequency of the largest bubbles between 3 and 5 kHz, high scattering causes complete acoustic blanking beneath the top of the gassy sediment layer. In the wider resonance frequency range between 3 and 15 kHz, the effect of smaller bubbles becomes dominant and the attenuation slightly decreases. This allows acoustic waves to be transmitted and reflections can be observed beneath the gassy sediment layer for higher frequencies. Above resonance beginning at ˜19 kHz, attenuation is low and the presence of free gas can be inferred from the decreased reflection amplitudes beneath the gassy layer. Below the resonance frequency range (<1 kHz), attenuation is generally very low and not dependent on frequency. Using the geoacoustic model of Anderson and Hampton, the observed frequency boundaries suggest gas bubble sizes between 1 and 4-6 mm, and gas volume fractions up to 0.02% in a ˜2 m thick sediment layer, whose upper boundary is the gas front. With the multifrequency acoustic approach and the Anderson and Hampton model, quantification of free gas in shallow marine environments is possible if the measurement frequency range allows the identification of the resonance frequency peak. The method presented is limited to places with only moderate attenuation, where the amplitudes of a reflection can be analyzed beneath the gassy sediment layer.

  9. Spatio-temporal dynamics of an encapsulated gas bubble in an ultrasound field

    PubMed Central

    Doinikov, Alexander A.; Dayton, Paul A.

    2011-01-01

    Coupled equations describing the radial and translational dynamics of an encapsulated gas bubble in an ultrasound field are derived by using the Lagrangian formalism. The equations generalize Church’s theory by allowing for the translation motion of the bubble and radiation losses due to the compressibility of the surrounding liquid. The expression given by Church for the inner bubble radius corresponding to the unstrained state of the bubble shell is also refined, assuming that the shell can be of arbitrary thickness and impermeable to gas. Comparative linear analysis of the radial equation is carried out relative to Church’s theory. It is shown that there are substantial departures from predictions of Church’s theory. The proposed model is applied to evaluate radiation forces exerted on encapsulated bubbles and their translational displacements. It is shown that in the range of relatively high frequencies encapsulated bubbles are able to translate more efficiently than free bubbles of the equivalent size. PMID:21442034

  10. Detecting the gas bubbles in a liquid metal coolant by means of magnetic flowmeters

    NASA Astrophysics Data System (ADS)

    Mogilner, A. I.; Morozov, S. A.; Zakharov, S. O.; Uralets, A. Yu.

    Solution of some problems of control and diagnosis of circuits with a liquid-metal coolant (LMC) often requires the detection of gas bubbles penetrating the circulation loop. The sources of gas intake can be presented by failed fuel elements in reactor core, failed heat-exchange surfaces in sodium-water steam generators in the secondary circuits, gas capture by circulating coolant from gas circuits. Sometimes the gas is especially injected into circulating coolant to study the dynamics of accumulation and extraction of gas bubbles and to solve research problems related to simulations of emergency situations. The most commonly used methods for gas bubble detection include methods based on measuring coolant electric conductivity. A method for detecting gas bubbles in LMC, based on revealing the change of its electric conductivity is considered. Magnetic flowmeter is used as a detecting element of these changes. Approximate theory for describing spectral and energy noises in signals of a magnetic flowmeter, controlling the flow rate of LMC with gas bubbles is suggested. A new method for signal reading is suggested. Experimental results illustrating the possibility of using the method for measuring the rate of bubble movement and studying the dependence of gas bubble volume on the flow rate of injected gas are presented.

  11. Mathematical Models of Diffusion-Limited Gas Bubble Evolution in Perfused Tissue

    DTIC Science & Technology

    Mathematical models of gas and bubble dynamics in tissue are used in various algorithms to mitigate the incidence and severity of decompression ... sickness (DCS) in man. These are simple models that describe the diffusion and perfusion processes that underlie gas bubble growth and resolution in terms

  12. Natural frequency of a gas bubble in a tube: experimental and simulation results.

    PubMed

    Jang, Neo W; Gracewski, Sheryl M; Abrahamsen, Ben; Buttaccio, Travis; Halm, Robert; Dalecki, Diane

    2009-07-01

    Use of ultrasonically excited microbubbles within blood vessels has been proposed for a variety of clinical applications. In this paper, an axisymmetric coupled boundary element and finite element code and experiments have been used to investigate the effects of a surrounding tube on a bubble's response to acoustic excitation. A balloon model allowed measurement of spherical gas bubble response. Resonance frequencies match one-dimensional cylindrical model predictions for a bubble well within a rigid tube but deviate for a bubble near the tube end. Simulations also predict bubble translation along the tube axis and aspherical oscillations at higher amplitudes.

  13. CFD study on rise and deformation characteristics of buoyancy-driven spheroid bubbles in stagnant Carreau model non-Newtonian fluids

    NASA Astrophysics Data System (ADS)

    Gollakota, Anjani R. K.; Kishore, Nanda

    2017-06-01

    The bubbles are almost ubiquitous in many chemical and processing industries; and many of the polymeric solutions obey non-Newtonian rheological characteristics. Therefore, in this work the rise and deformation characteristics of spheroid bubbles in Carreau model non-Newtonian fluids are numerically investigated using a level set method. To demonstrate the validity of the moving bubble interface, the present simulations are compared with existing numerical and experimental results available in the literature; and for these comparisons, the computational geometries are considered same as reported in corresponding literatures. The present bubble deformation characteristics are satisfactorily agreeing with their literature counterparts. After establishing the validity of the numerical solution procedure, the same method is applied to obtain the deformation characteristics of an air bubble in Carreau model non-Newtonian fluids. Further, the results in terms of the volume fraction images, streamlines, and viscosity profiles around the deforming bubbles are presented as function of the bubble rise time.

  14. A new pressure formulation for gas-compressibility dampening in bubble dynamics models.

    PubMed

    Gadi Man, Yezaz Ahmed; Trujillo, Francisco J

    2016-09-01

    We formulated a pressure equation for bubbles performing nonlinear radial oscillations under ultrasonic high pressure amplitudes. The proposed equation corrects the gas pressure at the gas-liquid interface on inertial bubbles. This pressure formulation, expressed in terms of gas-Mach number, accounts for dampening due to gas compressibility during the violent collapse of cavitation bubbles and during subsequent rebounds. We refer to this as inhomogeneous pressure, where the gas pressure at the gas-liquid interface can differ to the pressure at the centre of the bubble, in contrast to homogenous pressure formulations that consider that pressure inside the bubble is spatially uniform from the wall to the centre. The pressure correction was applied to two bubble dynamic models: the incompressible Rayleigh-Plesset equation and the compressible Keller and Miksis equation. This improved the predictions of the nonlinear radial motion of the bubble vs time obtained with both models. Those simulations were also compared with other bubble dynamics models that account for liquid and gas compressibility effects. It was found that our corrected models are in closer agreement with experimental data than alternative models. It was concluded that the Rayleigh-Plesset family of equations improve accuracy by using our proposed pressure correction.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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% CO2, suggesting a higher predisposition of these species to suffer from decompression-related gas embolism. PMID:22675306

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

    PubMed

    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.

  18. Vertical rise velocity of equatorial plasma bubbles estimated from Equatorial Atmosphere Radar (EAR) observations and HIRB model simulations

    NASA Astrophysics Data System (ADS)

    Tulasi Ram, S.; Ajith, K. K.; Yokoyama, T.; Yamamoto, M.; Niranjan, K.

    2017-06-01

    The vertical rise velocity (Vr) and maximum altitude (Hm) of equatorial plasma bubbles (EPBs) were estimated using the two-dimensional fan sector maps of 47 MHz Equatorial Atmosphere Radar (EAR), Kototabang, during May 2010 to April 2013. A total of 86 EPBs were observed out of which 68 were postsunset EPBs and remaining 18 EPBs were observed around midnight hours. The vertical rise velocities of the EPBs observed around the midnight hours are significantly smaller ( 26-128 m/s) compared to those observed in postsunset hours ( 45-265 m/s). Further, the vertical growth of the EPBs around midnight hours ceases at relatively lower altitudes, whereas the majority of EPBs at postsunset hours found to have grown beyond the maximum detectable altitude of the EAR. The three-dimensional numerical high-resolution bubble (HIRB) model with varying background conditions are employed to investigate the possible factors that control the vertical rise velocity and maximum attainable altitudes of EPBs. The estimated rise velocities from EAR observations at both postsunset and midnight hours are, in general, consistent with the nonlinear evolution of EPBs from the HIRB model. The smaller vertical rise velocities (Vr) and lower maximum altitudes (Hm) of EPBs during midnight hours are discussed in terms of weak polarization electric fields within the bubble due to weaker background electric fields and reduced background ion density levels.Plain Language SummaryEquatorial plasma <span class="hlt">bubbles</span> are plasma density irregularities in the ionosphere. The radio waves passing through these irregular density structures undergo severe degradation/scintillation that could cause severe disruption of satellite-based communication and augmentation systems such as GPS navigation. These <span class="hlt">bubbles</span> develop at geomagnetic equator, grow vertically, and elongate along the field lines to latitudes away from the equator. The knowledge on <span class="hlt">bubble</span> <span class="hlt">rise</span> velocities and their</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCoPh.347..261W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCoPh.347..261W"><span>Advanced subgrid-scale modeling for convection-dominated species transport at fluid interfaces with application to mass transfer from <span class="hlt">rising</span> <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weiner, Andre; Bothe, Dieter</p> <p>2017-10-01</p> <p>This paper presents a novel subgrid scale (SGS) model for simulating convection-dominated species transport at deformable fluid interfaces. One possible application is the Direct Numerical Simulation (DNS) of mass transfer from <span class="hlt">rising</span> <span class="hlt">bubbles</span>. The transport of a dissolving <span class="hlt">gas</span> along the <span class="hlt">bubble</span>-liquid interface is determined by two transport phenomena: convection in streamwise direction and diffusion in interface normal direction. The convective transport for technical <span class="hlt">bubble</span> sizes is several orders of magnitude higher, leading to a thin concentration boundary layer around the <span class="hlt">bubble</span>. A true DNS, fully resolving hydrodynamic and mass transfer length scales results in infeasible computational costs. Our approach is therefore a DNS of the flow field combined with a SGS model to compute the mass transfer between <span class="hlt">bubble</span> and liquid. An appropriate model-function is used to compute the numerical fluxes on all cell faces of an interface cell. This allows to predict the mass transfer correctly even if the concentration boundary layer is fully contained in a single cell layer around the interface. We show that the SGS-model reduces the resolution requirements at the interface by a factor of ten and more. The integral flux correction is also applicable to other thin boundary layer problems. Two flow regimes are investigated to validate the model. A semi-analytical solution for creeping flow is used to assess local and global mass transfer quantities. For higher Reynolds numbers ranging from Re = 100 to Re = 460 and Péclet numbers between Pe =104 and Pe = 4 ṡ106 we compare the global Sherwood number against correlations from literature. In terms of accuracy, the predicted mass transfer never deviates more than 4% from the reference values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..GECLW1123H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..GECLW1123H"><span>Generation of pulsed discharge plasma in water with fine <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu; Goto laboratory Team</p> <p>2015-09-01</p> <p>Recently, some researchers have proposed electric discharge methods with <span class="hlt">bubbles</span> in water because the discharge plasma inside <span class="hlt">bubble</span> was easy to be generated compared to that in water. Almost all of these methods introduced <span class="hlt">bubbles</span> in the order of millimeter size from a nozzle placed in water. In these methods, <span class="hlt">bubbles</span> rose one after another owing to high <span class="hlt">rising</span> speed of millibubble, leading to inefficient <span class="hlt">gas</span> consumption. We proposed fine <span class="hlt">bubbles</span> introduction at the discharge area in water. A fine <span class="hlt">bubble</span> is determined a <span class="hlt">bubble</span> with less than 100 μm in a diameter. Fine <span class="hlt">bubbles</span> exhibit extremely slow <span class="hlt">rising</span> speed. Fine <span class="hlt">bubbles</span> decrease in size during <span class="hlt">bubble</span> <span class="hlt">rising</span> and subsequently collapse in water with OH radical generation. Therefore, combining the discharge plasma with fine <span class="hlt">bubbles</span> is expected to generate more active species with small amount of <span class="hlt">gas</span> consumption. In this work, fine <span class="hlt">bubbles</span> were introduced in water and pulsed discharge plasma was generated between two cylindrical electrodes which placed in water. We examined effects of fine <span class="hlt">bubbles</span> on electric discharge in water when argon or oxygen <span class="hlt">gas</span> was utilized as feed <span class="hlt">gas</span>. Fine <span class="hlt">bubbles</span> enhanced optical emission of hydrogen and oxygen atoms from H2O molecules, but that of feed <span class="hlt">gas</span> was not observed. The formation mechanism of H2O2 by electric discharge was supposed to be different from that with no <span class="hlt">bubbling</span>. Dissolved oxygen in water played a role in H2O2 formation by the discharge with fine <span class="hlt">bubbles</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/335410','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/335410"><span>Contribution to irradiation creep arising from <span class="hlt">gas</span>-driven <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Woo, C.H.; Garner, F.A.</p> <p>1998-03-01</p> <p>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, <span class="hlt">gas</span>-filled cavities that have not yet exceeded the critical radius for <span class="hlt">bubble</span>-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 <span class="hlt">gas</span>-generating environments. The creep rate is directly related to the <span class="hlt">gas</span> generation rate and thereby to the neutron flux and spectrum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDH21009A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDH21009A"><span>Growth and collapse of laser-induced <span class="hlt">bubbles</span> in <span class="hlt">gas</span>-supersaturated gelatin gels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ando, Keita; Nakamura, Nobuyuki</p> <p>2016-11-01</p> <p>We study, with experiments and theory, the growth and collapse of laser-induced <span class="hlt">bubbles</span> in a gelatin gel. The gel sample is prepared so as to obtain <span class="hlt">gas</span> supersaturation, according to a difference between heat and <span class="hlt">gas</span> diffusion rates. Spherical <span class="hlt">gas</span> <span class="hlt">bubbles</span> are created by focusing a nano-second laser pulse at 532 nm into the <span class="hlt">gas</span>-supersaturated gel. The <span class="hlt">bubble</span> dynamics are recorded by a high-speed camera. To explore effects of the gel elasticity on the <span class="hlt">bubble</span> collapse, the experimental observations are compared to an extended Rayleigh-Plesset model that accounts for linear/nonlinear elasticity of the gel surrounding <span class="hlt">bubbles</span>. This work is supported by JSPS KAKENHI Grant No. 25709008.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28260665','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28260665"><span>Optimizing the <span class="hlt">gas</span> distributor based on CO2 <span class="hlt">bubble</span> dynamic behaviors to improve microalgal biomass production in an air-lift photo-bioreactor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Yun; Zhao, Sha; Ding, Yu-Dong; Liao, Qiang; Huang, Yong; Zhu, Xun</p> <p>2017-06-01</p> <p>Dynamic behavior of <span class="hlt">bubbles</span> would significantly affect CO2 mass transfer and may cause microalgae cells uneven distribution due to the <span class="hlt">bubble</span> carrying effect. To improve microalgae growth, the <span class="hlt">gas</span> distributor and aeration conditions was optimized according to the <span class="hlt">bubble</span> <span class="hlt">rising</span> behavior. The CO2 <span class="hlt">bubble</span> <span class="hlt">rising</span> trajectory is similar to a Zigzag. The amplitude and wavelength of the Zigzag, which reflected the influenced zone of microalgae suspension in horizontal direction and disturbance intensity on culture, respectively, was controlled by the structure of <span class="hlt">gas</span> distributor and aeration conditions. An optimized round <span class="hlt">gas</span> distributor that full of holes with an inner diameter of 0.5mm and spacing of 1.5mm was designed. When cultivated with the optimized <span class="hlt">gas</span> distributor aerating 5% CO2 <span class="hlt">gas</span> at 0.250vvm, the maximum biomass concentration of Chlorella pyrenoidosa achieved 2.88gL(-1), increased by 83.44% compared to that of 1.57gL(-1)cultivated with the commercial micro-<span class="hlt">bubbles</span> aerator. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20094667','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20094667"><span>Nano <span class="hlt">bubbles</span> in liquid of a noble-<span class="hlt">gas</span> mixture.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yamamoto, Takenori; Ohnishi, Shuhei</p> <p>2010-02-07</p> <p>Large-scale molecular dynamics (MD) simulations with over one million atoms are used to investigate nano <span class="hlt">bubbles</span> in Ar-Ne liquid. The simulations demonstrate cavitations in the stretched liquid, and <span class="hlt">bubble</span> creation and collapse. We find that a small cavity created in the stretched liquid spontaneously transforms into a nano <span class="hlt">bubble</span> with the homogeneous vapor region. The equilibrium spherical <span class="hlt">bubble</span> of 11.4 nm in radius is obtained after the long-time MD run. The surface tension of the nano <span class="hlt">bubble</span> is found to be larger than that of the flat surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930060142&hterms=air+bubble&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dair%2Bbubble','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930060142&hterms=air+bubble&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dair%2Bbubble"><span>Shock-wave propagation in a sonoluminescing <span class="hlt">gas</span> <span class="hlt">bubble</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wu, C. C.; Roberts, Paul H.</p> <p>1993-01-01</p> <p>The motion of the <span class="hlt">bubble</span> radius and of the air trapped inside the <span class="hlt">bubble</span> during sonoluminescence are determined self-consistently by coupling the solution of the Rayleigh-Plesset equation governing the <span class="hlt">bubble</span> radius to the solution of Euler's equations for the motion of air in the <span class="hlt">bubble</span>. Results are presented for three slightly different conditions of excitation, in two of which shocks are formed during the collapse of the <span class="hlt">bubble</span>, and in which such high temperatures are attained that the air is ionized. Estimates are made of the duration and intensity of the light then radiated by the plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JChPh.132p4509G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JChPh.132p4509G"><span>Free energy wells for small <span class="hlt">gas</span> <span class="hlt">bubbles</span> in soft deformable materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goldman, Saul</p> <p>2010-04-01</p> <p>Thermodynamic expressions are derived for the system relative Gibbs free energy, and the relative Gibbs free energy per <span class="hlt">bubble</span>, for all possible equilibrium <span class="hlt">bubble</span> states that can form in a soft slightly rigid material, initially supersaturated with a dissolved inert <span class="hlt">gas</span> (N2). While the thermodynamic manipulations are exact, the final expressions are approximate, due to an approximation made in deriving the expression for the elastic free energy of a soft material containing more than a single <span class="hlt">bubble</span>. The expressions predict that provided the shear modulus of the soft material is not negligibly small, free energy wells which stabilize small <span class="hlt">gas</span> <span class="hlt">bubbles</span> for finite periods of time exist in such materials. This is consistent with a previous calculation, based solely on the <span class="hlt">bubble</span> pressure equation, which resulted in the conjecture that <span class="hlt">bubbles</span> found in soft materials with some rigidity (or shear resistance) are likely to be small. The possible relevance of this to the field of decompression sickness is outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19624209','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19624209"><span>Dynamics of <span class="hlt">gas</span> <span class="hlt">bubble</span> growth in a supersaturated solution with Sievert's solubility law.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gor, G Yu; Kuchma, A E</p> <p>2009-07-21</p> <p>This paper presents a theoretical description of diffusion growth of a <span class="hlt">gas</span> <span class="hlt">bubble</span> after its nucleation in supersaturated liquid solution. We study systems where <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> growth dynamics. Assuming that diffusion flux is steady we obtain a differential equation on <span class="hlt">bubble</span> radius. <span class="hlt">Bubble</span> dynamics equation is solved analytically for the case of homogeneous nucleation of a <span class="hlt">bubble</span>, 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 <span class="hlt">bubbles</span> in magmatic melts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JFM...461..127P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JFM...461..127P"><span>Experiments on the motion of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in turbulence generated by an active grid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poorte, R. E. G.; Biesheuvel, A.</p> <p>2002-06-01</p> <p>The random motion of nearly spherical <span class="hlt">bubbles</span> in the turbulent flow behind a grid is studied experimentally. In quiescent water these <span class="hlt">bubbles</span> <span class="hlt">rise</span> at high Reynolds number. The turbulence is generated by an active grid of the design of Makita (1991), and can have turbulence Reynolds number R[lambda] of up to 200. Minor changes in the geometry of the grid and in its mode of operation improves the isotropy of the turbulence, compared with that reported by Makita (1991) and Mydlarski & Warhaft (1996). The trajectory of each <span class="hlt">bubble</span> is measured with high spatial and temporal resolution with a specially developed technique that makes use of a position-sensitive detector. <span class="hlt">Bubble</span> statistics such as the mean <span class="hlt">rise</span> velocity and the root-mean-square velocity fluctuations are obtained by ensemble averaging over many identical <span class="hlt">bubbles</span>. The resulting <span class="hlt">bubble</span> mean <span class="hlt">rise</span> velocity is significantly reduced (up to 35%) compared with the quiescent conditions. The vertical <span class="hlt">bubble</span> velocity fluctuations are found to be non-Gaussian, whereas the horizontal displacements are Gaussian for all times. The diffusivity of <span class="hlt">bubbles</span> is considerably less than that of fluid particles. These findings are qualitatively consistent with results obtained through theoretical analysis and numerical simulations by Spelt & Biesheuvel (1997).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22482454','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22482454"><span>Linear oscillation of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in a viscoelastic material under ultrasound irradiation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hamaguchi, Fumiya; Ando, Keita</p> <p>2015-11-15</p> <p>Acoustically forced oscillation of spherical <span class="hlt">gas</span> <span class="hlt">bubbles</span> in a viscoelastic material is studied through comparisons between experiments and linear theory. An experimental setup has been designed to visualize <span class="hlt">bubble</span> dynamics in gelatin gels using a high-speed camera. A spherical <span class="hlt">gas</span> <span class="hlt">bubble</span> is created by focusing an infrared laser pulse into (<span class="hlt">gas</span>-supersaturated) gelatin gels. The <span class="hlt">bubble</span> radius (up to 150 μm) under mechanical equilibrium is controlled by gradual mass transfer of gases across the <span class="hlt">bubble</span> interface. The linearized <span class="hlt">bubble</span> dynamics are studied from the observation of spherical <span class="hlt">bubble</span> oscillation driven by low-intensity, planar ultrasound driven at 28 kHz. It follows from the experiment for an isolated <span class="hlt">bubble</span> 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 <span class="hlt">bubble-bubble</span> and <span class="hlt">bubble</span>-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 <span class="hlt">bubble</span> dynamics with more complex configuration such as a cloud of <span class="hlt">bubbles</span> in viscoelastic materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhFl...27k3103H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhFl...27k3103H"><span>Linear oscillation of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in a viscoelastic material under ultrasound irradiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hamaguchi, Fumiya; Ando, Keita</p> <p>2015-11-01</p> <p>Acoustically forced oscillation of spherical <span class="hlt">gas</span> <span class="hlt">bubbles</span> in a viscoelastic material is studied through comparisons between experiments and linear theory. An experimental setup has been designed to visualize <span class="hlt">bubble</span> dynamics in gelatin gels using a high-speed camera. A spherical <span class="hlt">gas</span> <span class="hlt">bubble</span> is created by focusing an infrared laser pulse into (<span class="hlt">gas</span>-supersaturated) gelatin gels. The <span class="hlt">bubble</span> radius (up to 150 μm) under mechanical equilibrium is controlled by gradual mass transfer of gases across the <span class="hlt">bubble</span> interface. The linearized <span class="hlt">bubble</span> dynamics are studied from the observation of spherical <span class="hlt">bubble</span> oscillation driven by low-intensity, planar ultrasound driven at 28 kHz. It follows from the experiment for an isolated <span class="hlt">bubble</span> 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 <span class="hlt">bubble-bubble</span> and <span class="hlt">bubble</span>-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 <span class="hlt">bubble</span> dynamics with more complex configuration such as a cloud of <span class="hlt">bubbles</span> in viscoelastic materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.656a2042Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.656a2042Y"><span>Three stages of <span class="hlt">bubble</span> formation on submerged orifice under constant <span class="hlt">gas</span> flow rate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Xianxian; Wang, Yiwei; Huang, Chenguang; Du, Tezhuan</p> <p>2015-12-01</p> <p><span class="hlt">Bubble</span> formation is involved in many engineering applications. It is important to understand the dynamics of <span class="hlt">bubble</span> formation. This work reports experimental and numerical results of <span class="hlt">bubble</span> formation on submerged orifice under constant <span class="hlt">gas</span> flow rate. Compressible large eddy simulation combined volume of fluid (VOF) was adopted in simulation and results was validated by experiment. <span class="hlt">Bubble</span> formation is divided into three stages in this paper, expansion stage, elongation stage and pinch-off stage. In expansion stage, The <span class="hlt">bubble</span> grows radially due to the incoming <span class="hlt">gas</span> flux, but the <span class="hlt">bubble</span> base remains attached to the orifice. But as <span class="hlt">gas</span> injected, the spherical <span class="hlt">bubble</span> will go into the elongation stage when the downward resultant force is lager than upward resultant force. And when <span class="hlt">bubble</span> neck's length is bigger than √2Ro the <span class="hlt">bubble</span> will go into pinch-off stage. Cylindrical Rayleigh-Plesset equation can be used to describe the pinch-off stage. Uncertain parameter r in it is given reference value in this paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22107858','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22107858"><span><span class="hlt">Gas</span> and liquid measurements in air-water <span class="hlt">bubbly</span> flows</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhou, X.; Doup, B.; Sun, X.</p> <p>2012-07-01</p> <p>Local measurements of <span class="hlt">gas</span>- and liquid-phase flow parameters are conducted in an air-water two-phase flow loop. The test section is a vertical pipe with an inner diameter of 50 mm and a height of 3.2 m. The measurements are performed at z/D = 10. The <span class="hlt">gas</span>-phase measurements are performed using a four-sensor conductivity probe. The data taken from this probe are processed using a signal processing program to yield radial profiles of the void fraction, <span class="hlt">bubble</span> velocity, and interfacial area concentration. The velocity measurements of the liquid-phase are performed using a state-of-the-art Particle Image Velocimetry (PIV) system. The raw PIV images are acquired using fluorescent particles and an optical filtration device. Image processing is used to remove noise in the raw PIV images. The statistical cross correlation is introduced to determine the axial velocity field and turbulence intensity of the liquid-phase. Measurements are currently being performed at z/D = 32 to provide a more complete data set. These data can be used for computational fluid dynamic model development and validation. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880041351&hterms=dissolution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddissolution','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880041351&hterms=dissolution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddissolution"><span>The dissolution or growth of a <span class="hlt">gas</span> <span class="hlt">bubble</span> inside a drop in zero gravity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kondos, Pericles A.; Subramanian, R. Shankar; Weinberg, Michael C.</p> <p>1987-01-01</p> <p>The radius-time history of a <span class="hlt">gas</span> <span class="hlt">bubble</span> located concentrically within a spherical liquid drop in a space laboratory is analyzed within the framework of the quasi-stationary approximation. Illustrative results are calculated from the theory which demonstrate interesting qualitative features. For instance, when a pure <span class="hlt">gas</span> <span class="hlt">bubble</span> dissolves within a liquid drop in an environment containing the same <span class="hlt">gas</span> and some inert species, the dissolution can be more or less rapid than that in an unbounded liquid depending on the initial relative size of the drop. Further, given a similar growth situation, indefinite growth is not possible, and the <span class="hlt">bubble</span> will initially grow, but always dissolve in the end.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880041351&hterms=dissolutions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddissolutions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880041351&hterms=dissolutions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddissolutions"><span>The dissolution or growth of a <span class="hlt">gas</span> <span class="hlt">bubble</span> inside a drop in zero gravity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kondos, Pericles A.; Subramanian, R. Shankar; Weinberg, Michael C.</p> <p>1987-01-01</p> <p>The radius-time history of a <span class="hlt">gas</span> <span class="hlt">bubble</span> located concentrically within a spherical liquid drop in a space laboratory is analyzed within the framework of the quasi-stationary approximation. Illustrative results are calculated from the theory which demonstrate interesting qualitative features. For instance, when a pure <span class="hlt">gas</span> <span class="hlt">bubble</span> dissolves within a liquid drop in an environment containing the same <span class="hlt">gas</span> and some inert species, the dissolution can be more or less rapid than that in an unbounded liquid depending on the initial relative size of the drop. Further, given a similar growth situation, indefinite growth is not possible, and the <span class="hlt">bubble</span> will initially grow, but always dissolve in the end.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040000030','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040000030"><span>Studies of the Hot <span class="hlt">Gas</span> in the Galactic halo and Local <span class="hlt">Bubble</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shelton, Robin L.</p> <p>2003-01-01</p> <p>This paper presents a report on the progress made on Studies of the Hot <span class="hlt">Gas</span> in the Galactic halo and Local <span class="hlt">Bubble</span> at Johns Hopkins University. The broad goals of this project are to determine the physical conditions and history of the hot phase of the Galaxy's interstellar medium. Such <span class="hlt">gas</span> resides in the Galactic halo, the Local <span class="hlt">Bubble</span> surrounding the solar neighborhood, other <span class="hlt">bubbles</span>, and supernova remnants. A better understanding of the hot <span class="hlt">gas</span> and the processes occurring within it requires several types of work, including ultraviolet and X-ray data analyses and computer modeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15790688','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15790688"><span><span class="hlt">Bubble</span> splitting in bifurcating tubes: a model study of cardiovascular <span class="hlt">gas</span> emboli transport.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Calderón, Andrés J; Fowlkes, J Brian; Bull, Joseph L</p> <p>2005-08-01</p> <p>The transport of long <span class="hlt">gas</span> <span class="hlt">bubbles</span>, suspended in liquid, through symmetric bifurcations, is investigated experimentally and theoretically as a model of cardiovascular <span class="hlt">gas</span> <span class="hlt">bubble</span> transport in air embolism and <span class="hlt">gas</span> embolotherapy. The relevant dimensionless parameters in the models match the corresponding values for arteries and arterioles. The effects of roll angle (the angle the plane of the bifurcation makes with the horizontal), capillary number (a dimensionless indicator of flow), and <span class="hlt">bubble</span> volume (or length) on the splitting of <span class="hlt">bubbles</span> as they pass through the bifurcation are examined. Splitting is observed to be more homogenous at higher capillary numbers and lower roll angles. It is shown that, at nonzero roll angles, there is a critical value of the capillary number below which the <span class="hlt">bubbles</span> do not split and are transported entirely into the upper branch. The value of the critical capillary number increases with roll angle and parent tube diameter. A unique <span class="hlt">bubble</span> motion is observed at the critical capillary number and for slightly slower flows: the <span class="hlt">bubble</span> begins to split, the meniscus in the lower branch then moves backward, and finally the entire <span class="hlt">bubble</span> enters the upper branch. These findings suggest that, in large vessels, emboli tend to be transported upward unless flow is unusually strong but that a more homogeneous distribution of emboli occurs in smaller vessels. This corresponds to previous observations that air emboli tend to lodge in the upper regions of the lungs and suggests that relatively uniform infarction of tumors by <span class="hlt">gas</span> embolotherapy may be possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS41A1942B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS41A1942B"><span><span class="hlt">Bubble</span> composition of natural <span class="hlt">gas</span> seeps discovered along the Cascadia Continental Margin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baumberger, T.; Merle, S. G.; Embley, R. W.; Seabrook, S.; Raineault, N.; Lilley, M. D.; Evans, L. J.; Walker, S. L.; Lupton, J. E.</p> <p>2016-12-01</p> <p><span class="hlt">Gas</span> hydrates and <span class="hlt">gas</span>-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 <span class="hlt">gas</span> seepage from sediments. During this expedition, over 400 <span class="hlt">bubble</span> plumes at water depths ranging from 125 and 1640 m were newly discovered, and five of them were sampled for <span class="hlt">gas</span> <span class="hlt">bubble</span> composition using specially designed <span class="hlt">gas</span> tight fluid samplers mounted on the Hercules remotely operated vehicle (ROV). These <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">bubbles</span> were seeping out from the seafloor. Other than the escaping <span class="hlt">gas</span> <span class="hlt">bubbles</span>, 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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> released at the different sites and depths. Noble <span class="hlt">gas</span> 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 <span class="hlt">gas</span> hydrates. The characterization of these <span class="hlt">gas</span> samples will also include total <span class="hlt">gas</span> (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 <span class="hlt">bubbles</span> as well as give information about the possible sources of the carbon contained in the seeping <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2806431','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2806431"><span>Natural frequency of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in a tube: Experimental and simulation results</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jang, Neo W.; Gracewski, Sheryl M.; Abrahamsen, Ben; Buttaccio, Travis; Halm, Robert; Dalecki, Diane</p> <p>2009-01-01</p> <p>Use of ultrasonically excited microbubbles within blood vessels has been proposed for a variety of clinical applications. In this paper, an axisymmetric coupled boundary element and finite element code and experiments have been used to investigate the effects of a surrounding tube on a bubble’s response to acoustic excitation. A balloon model allowed measurement of spherical <span class="hlt">gas</span> <span class="hlt">bubble</span> response. Resonance frequencies match one-dimensional cylindrical model predictions for a <span class="hlt">bubble</span> well within a rigid tube but deviate for a <span class="hlt">bubble</span> near the tube end. Simulations also predict <span class="hlt">bubble</span> translation along the tube axis and aspherical oscillations at higher amplitudes. PMID:19603851</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..GECFT1070S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..GECFT1070S"><span>Nonlinear Oscillations of <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> and Their Impact on Plasma Breakdown in Water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sommers, Bradley; Foster, John</p> <p>2011-10-01</p> <p>We investigate the effects of a time varying electric field on air <span class="hlt">bubbles</span> submerged in water. For a sufficiently strong field, a large electrical stress acting on the liquid-<span class="hlt">gas</span> boundary can deform the volume and shape of the <span class="hlt">bubble</span>. This deformation may drastically alter the internal pressure and polarization of the <span class="hlt">bubble</span>, thus easing the conditions for streamer formation within the <span class="hlt">gas</span> volume. This type of enhancement could have a broad impact on the viability of liquid plasma technologies, which tend to suffer from high voltage requirements. <span class="hlt">Bubbles</span> with 0.5-3 mm diameter are trapped in the node of a 26.5 kHz underwater acoustic field while either alternating or pulsed voltage signals of 5-20 kV are applied across their diameter. <span class="hlt">Bubble</span> response is captured using a high speed camera (10,000 fps), along with a high sensitivity hydrophone. The response is documented over a wide range of factors, including <span class="hlt">bubble</span> size, field frequency, and field strength. The observed deformations of the <span class="hlt">bubble</span> shape are then used to predict changes to the reduced field (E/N) within the <span class="hlt">bubble</span> volume. We investigate the effects of a time varying electric field on air <span class="hlt">bubbles</span> submerged in water. For a sufficiently strong field, a large electrical stress acting on the liquid-<span class="hlt">gas</span> boundary can deform the volume and shape of the <span class="hlt">bubble</span>. This deformation may drastically alter the internal pressure and polarization of the <span class="hlt">bubble</span>, thus easing the conditions for streamer formation within the <span class="hlt">gas</span> volume. This type of enhancement could have a broad impact on the viability of liquid plasma technologies, which tend to suffer from high voltage requirements. <span class="hlt">Bubbles</span> with 0.5-3 mm diameter are trapped in the node of a 26.5 kHz underwater acoustic field while either alternating or pulsed voltage signals of 5-20 kV are applied across their diameter. <span class="hlt">Bubble</span> response is captured using a high speed camera (10,000 fps), along with a high sensitivity hydrophone. The response is documented over a wide</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4751573','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4751573"><span>Magnetic field induced motion behavior of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in liquid</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang</p> <p>2016-01-01</p> <p>The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen <span class="hlt">bubbles</span> released by the reaction. Here we show that oxygen <span class="hlt">bubbles</span> during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen <span class="hlt">bubbles</span> when the magnet in parallel with the electrode, and exclusion movement of oxygen <span class="hlt">bubbles</span> when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen <span class="hlt">bubbles</span> movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen <span class="hlt">bubbles</span> is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen <span class="hlt">bubbles</span> in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen <span class="hlt">bubbles</span> coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen <span class="hlt">bubbles</span> movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields. PMID:26867515</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...621068W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...621068W"><span>Magnetic field induced motion behavior of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in liquid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang</p> <p>2016-02-01</p> <p>The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen <span class="hlt">bubbles</span> released by the reaction. Here we show that oxygen <span class="hlt">bubbles</span> during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen <span class="hlt">bubbles</span> when the magnet in parallel with the electrode, and exclusion movement of oxygen <span class="hlt">bubbles</span> when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen <span class="hlt">bubbles</span> movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen <span class="hlt">bubbles</span> is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen <span class="hlt">bubbles</span> in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen <span class="hlt">bubbles</span> coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen <span class="hlt">bubbles</span> movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJWC.14009002P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJWC.14009002P"><span>Influence of obstacles on <span class="hlt">bubbles</span> <span class="hlt">rising</span> in water-saturated sand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poryles, Raphaël; Varas, Germán; Vidal, Valérie</p> <p>2017-06-01</p> <p>This work investigates the dynamics of air <span class="hlt">rising</span> through a water-saturated sand confined in a Hele- Shaw cell in which a circular obstacle is trapped. The air is injected at constant flow rate through a single nozzle at the bottom center of the cell. Without obstacle, in a similar configuration, previous studies pointed out the existence of a fluidized zone generated by the central upward <span class="hlt">gas</span> motion which entrains two granular convection rolls on its sides. Here, a circular obstacle which diameter is of the order of the central air channel width is trapped at the vertical of the injection nozzle. We analyze the influence of the obstacle location on the size of the fluidized zone and its impact on the morphology of the central air channel. Finally, we quantify the variations of the granular free surface. Two configurations with multiple obstacles are also considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS31B..02R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS31B..02R"><span>Tidal influence on <span class="hlt">gas</span> <span class="hlt">bubble</span> emissions from permanent seafloor observations at Ocean Networks Canada's cabled array NEPTUNE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roemer, M.; Scherwath, M.; Heesemann, M.; Spence, G.; Riedel, M.</p> <p>2015-12-01</p> <p>Sonar data from the northern Cascadia margin correlate well with tidal pressure changes and not so well with currents, seafloor shaking from storms or earthquakes, or temperature changes. These data are available from Ocean Networks Canada which operates the NEPTUNE observatory with power and communications to <span class="hlt">gas</span> hydrate sites on the continental slope, allowing 24/7 monitoring of the dynamic <span class="hlt">gas</span> hydrate activity. Clayoquot Slope at Cascadia's Bullseye Vent and <span class="hlt">Bubbly</span> Gulch, is equipped with a variety of sensors including a 270 kHz Imagenex 100 m range multibeam sonar, as well as Conductivity-Temperature-Depth (CTD) sensors, high precision Bottom Pressure Recorders (BPR), current meter and Ocean Bottom Seismograph (OBS). This enables statistically meaningful correlation of these data. Hourly sonar data were collected showing venting activity in the form of <span class="hlt">gas</span> plumes of various strengths. For four years the sonar was located at what appears to be a transient <span class="hlt">gas</span> site, with longer periods of absolutely no venting observed activity. Here, the strongest correlation of <span class="hlt">gas</span> <span class="hlt">bubbling</span> is with rapid decreasing tidal pressure, where subsequent increasing tidal pressure is shutting down the degassing. In May 2014, the sonar was moved by 500 m to a more actively venting site termed Gastown Alley, over a zone of seismic blanking interpreted as having high subsurface <span class="hlt">gas</span> content. This site is continuously emitting <span class="hlt">gas</span> <span class="hlt">bubbles</span> albeit with varying numbers of plumes and intensities. The strongest correlation of <span class="hlt">gas</span> discharge is with absolute pressures, with maximum flows at higher tidal pressures, hinting at a steady subsurface <span class="hlt">rise</span> of <span class="hlt">gas</span> that is squeezed out stronger at high tides, partially emptying the shallow reservoirs, and with subsiding tidal pressure the venting activity also decreases again. Thus, the two sonar sites, though only 500 m apart, show a different behavior in degassing, however, both reacting most strongly to tidal pressure changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21254879','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21254879"><span>Laser generation of <span class="hlt">gas</span> <span class="hlt">bubbles</span>: Photoacoustic and photothermal effects recorded in transient grating experiments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Frez, Clifford; Diebold, Gerald J.</p> <p>2008-11-14</p> <p>Absorption of high power laser radiation by colloidal suspensions or solutions containing photoreactive chemicals can result in <span class="hlt">bubble</span> production. Here, transient grating experiments are reported where picosecond and nanosecond lasers are used to initiate photoinduced processes that lead to <span class="hlt">bubble</span> formation. Irradiation of colloidal Pt suspensions is found to produce water vapor <span class="hlt">bubbles</span> that condense back to liquid on a nanosecond time scale. Laser irradiation of Pt suspensions supersaturated with CO{sub 2} liberates dissolved <span class="hlt">gas</span> to produce <span class="hlt">bubbles</span> at the sites of the colloidal particles. Laser induced chemical reactions that produce <span class="hlt">bubbles</span> are found in suspensions of particulate C in water, and in the sensitized decarboxylation of oxalic acid. Theory based on linear acoustics as well as the Rayleigh-Plesset equation is given for description of the <span class="hlt">bubble</span> motion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22492643','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22492643"><span>Nonlinear activity of acoustically driven <span class="hlt">gas</span> <span class="hlt">bubble</span> near a rigid boundary</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Maksimov, Alexey</p> <p>2015-10-28</p> <p>The presence of a boundary can produce considerable changes in the oscillation amplitude of the <span class="hlt">bubble</span> and its scattered echo. The present study fills a gap in the literature, in that it is concerned theoretically with the <span class="hlt">bubble</span> activity at relatively small distances from the rigid boundary. It was shown that the bi-spherical coordinates provide separation of variables and are more suitable for analysis of the dynamics of these constrained <span class="hlt">bubbles</span>. Explicit formulas have been derived which describe the dependence of the <span class="hlt">bubble</span> emission near a rigid wall on its size and the separation distance between the <span class="hlt">bubble</span> and the boundary. As applications, time reversal technique for <span class="hlt">gas</span> leakage detection and radiation forces that are induced by an acoustic wave on a constrained <span class="hlt">bubble</span> were analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDKP1023S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDKP1023S"><span>Diffusion-driven growth of a spherical <span class="hlt">gas</span> <span class="hlt">bubble</span> in gelatin gels supersaturated with air</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shirota, Eriko; Ando, Keita</p> <p>2016-11-01</p> <p>We experimentally and theoretically study diffusion-driven growth of laser-induced <span class="hlt">gas</span> <span class="hlt">bubbles</span> in gelatin gels supersaturated with air. The supersaturation in the gels is realized by using a large separation between heat and mass diffusion rates. An optical system is developed to induce <span class="hlt">bubble</span> nucleation by laser focusing and visualize the subsequent <span class="hlt">bubble</span> growth. To evaluate the effect of the gel elasticity on the <span class="hlt">bubble</span> growth rate, we propose the extended Epstein-Plesset theory that considers <span class="hlt">bubble</span> pressure modifications due to linear/nonlinear elasticity (in addition to Laplace pressure). From comparisons between the experiments and the proposed theory, the <span class="hlt">bubble</span> growth rate is found to be hindered by the elasticity. This study is supported by JSPS KAKENHI Grant Number 25709008.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvF...1f4202C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvF...1f4202C"><span>History effects on the <span class="hlt">gas</span> exchange between a <span class="hlt">bubble</span> and a liquid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chu, Shigan; Prosperetti, Andrea</p> <p>2016-10-01</p> <p>Diffusive processes exhibit a strong dependence on history effects. For a <span class="hlt">gas</span> <span class="hlt">bubble</span> at rest in a liquid, such effects arise when the concentration of dissolved <span class="hlt">gas</span> at the <span class="hlt">bubble</span> surface, dictated by Henry's law, depends on time. In this paper we consider several such situations. An oscillating ambient pressure field causes the occurrence of rectified diffusion of <span class="hlt">gas</span> into or out of the <span class="hlt">bubble</span>. Unlike previous investigators, who considered the opposite limit, we study this process for conditions when the diffusion length is larger than the <span class="hlt">bubble</span> radius. It is found that history effects are important in determining the threshold conditions. Under a static ambient pressure, the time dependence of the <span class="hlt">gas</span> concentration can arise due to the action of surface tension, which increases the <span class="hlt">gas</span> pressure as the <span class="hlt">bubble</span> dissolves or, when the <span class="hlt">bubble</span> contains a mixture of two or more gases, due to the different rates at which they dissolve. In these latter cases history effects prove mostly negligible for <span class="hlt">bubbles</span> larger than a few hundred nanometers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20995409','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20995409"><span>A Model for Surface Induced Growth of Inert <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Irradiated Copper-Boron Alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tiwari, G.P.; Ramadasan, E.</p> <p>2006-07-01</p> <p>A matrix containing inert <span class="hlt">gas</span> <span class="hlt">bubbles</span> dilates in direct proportion to the growth experienced by the <span class="hlt">gas</span> <span class="hlt">bubbles</span>. This phenomenon is termed as swelling. A model for the swelling induced by the growth of the helium <span class="hlt">gas</span> <span class="hlt">bubbles</span> in irradiated copper-boron alloys is presented. The <span class="hlt">bubbles</span> grow by acquiring vacancies from the external surface, which acts as a source of vacancies. The vacancies reach the surface of the <span class="hlt">bubbles</span> mainly via lattice diffusion and to a limited extent via diffusion through short-circuiting paths such as grain boundaries and dislocation pipes. The model predicts that overall swelling of the matrix varies as 1.5 power of time. Another consequence of the present model is that the growth rate of a <span class="hlt">gas</span> <span class="hlt">bubble</span> varies inversely as the cube of its distance from the external surface. The model has been applied to the data on irradiated copper-boron alloys and found to be in accord with the experimental results. The model is general and can be applied to the growth of all kinds of stationary inert <span class="hlt">gas</span> <span class="hlt">bubbles</span> trapped within a crystalline matrix. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999PhDT........62O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999PhDT........62O"><span>Three-dimensional experimental investigation of the shape and dynamics of a <span class="hlt">rising</span> <span class="hlt">bubble</span> in stagnant water with particle tracking velocimetry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortiz-Villafuerte, Javier</p> <p></p> <p>The Particle Tracking Velocimetry technique has been used for a three-dimensional, transient, experimental study of a single <span class="hlt">bubble</span> dynamics in a restricted medium. The three-dimensional velocity field was reconstructed via stereoscopic matching of two-dimensional images. A hybrid tracking technique has been used to determine the flow around a <span class="hlt">bubble</span>. The development of the Shadow Particle Image Velocimetry allowed studying the <span class="hlt">bubble</span> shape and rotation. An accurate estimate of the <span class="hlt">bubble</span> dimensions, orientation, trajectory, and velocity and acceleration of a <span class="hlt">bubble</span> <span class="hlt">rising</span> in water, was obtained. The flow around and within the wake of the <span class="hlt">bubble</span> was determined from ensemble averaging instantaneous velocity fields. The ensemble average operation was performed by considering a conditional sampling technique. The conditional ensemble averaging was performed for specified <span class="hlt">bubble</span> trajectories. It was found that <span class="hlt">bubbles</span> <span class="hlt">rising</span> close to the wall generate more turbulence, and the disturbances induced in the liquid reach further downstream, when compared to <span class="hlt">bubbles</span> <span class="hlt">rising</span> along the pipe core. The <span class="hlt">bubble</span> Reynolds number was in the range from 350 to 700. Regarding the <span class="hlt">bubble</span> motion, it was found that the inclusion of the disturbed flow field in the <span class="hlt">bubble</span> motion equation generates a scattering of the data for the drag and lift coefficients. The wall influence on these coefficients was introduced through the velocities and accelerations of the liquid and the <span class="hlt">bubble</span>. The results indicate that the presence of the seed particles in the liquid have an influence on the <span class="hlt">bubble</span> velocity and <span class="hlt">bubble</span> shape. The instantaneous drag coefficient did not delineate a trend with respect to the rotation parameter; however, it shows a behavior similar to the standard drag curve as function of the Reynolds number. The average drag coefficient values are 0.90 and 0.98 for the <span class="hlt">bubble</span> trajectories along the pipe core and close to the pipe wall, respectively. No trend for the instantaneous lift</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010024993&hterms=liquids+densities&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dliquids%2Bdensities','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010024993&hterms=liquids+densities&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dliquids%2Bdensities"><span>A Study of <span class="hlt">Bubble</span> and Slug <span class="hlt">Gas</span>-Liquid Flow in a Microgravity Environment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McQuillen, J.</p> <p>2000-01-01</p> <p>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 <span class="hlt">bubbly</span> flow,the absence of drift velocity leads to spherical-shaped <span class="hlt">bubbles</span> with a rectilinear trajectory.Slug flow is a succession of long <span class="hlt">bubbles</span> and liquid slug carrying a few <span class="hlt">bubbles</span>. There is no flow reversal in the thin liquid film as the long <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated <span class="hlt">bubbles</span> in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated <span class="hlt">bubbles</span> and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the <span class="hlt">bubbles</span> in accelerated or decelerated flows,and the dynamics of isolated cylindrical <span class="hlt">bubbles</span>, their deformation in accelerated/decelerated flows (in converging or diverging channels), and <span class="hlt">bubble/bubble</span> interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical <span class="hlt">bubble</span> and single and two cylindrical <span class="hlt">bubble</span> behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of <span class="hlt">bubbly</span> and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from <span class="hlt">bubbly</span> to slug flow (effect of fluid properties and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010024993&hterms=gas+liquid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgas%2Bliquid','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010024993&hterms=gas+liquid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgas%2Bliquid"><span>A Study of <span class="hlt">Bubble</span> and Slug <span class="hlt">Gas</span>-Liquid Flow in a Microgravity Environment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McQuillen, J.</p> <p>2000-01-01</p> <p>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 <span class="hlt">bubbly</span> flow,the absence of drift velocity leads to spherical-shaped <span class="hlt">bubbles</span> with a rectilinear trajectory.Slug flow is a succession of long <span class="hlt">bubbles</span> and liquid slug carrying a few <span class="hlt">bubbles</span>. There is no flow reversal in the thin liquid film as the long <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated <span class="hlt">bubbles</span> in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated <span class="hlt">bubbles</span> and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the <span class="hlt">bubbles</span> in accelerated or decelerated flows,and the dynamics of isolated cylindrical <span class="hlt">bubbles</span>, their deformation in accelerated/decelerated flows (in converging or diverging channels), and <span class="hlt">bubble/bubble</span> interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical <span class="hlt">bubble</span> and single and two cylindrical <span class="hlt">bubble</span> behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of <span class="hlt">bubbly</span> and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from <span class="hlt">bubbly</span> to slug flow (effect of fluid properties and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...836..130R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...836..130R"><span>Alma Observations of Massive Molecular <span class="hlt">Gas</span> Filaments Encasing Radio <span class="hlt">Bubbles</span> in the Phoenix Cluster</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>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.</p> <p>2017-02-01</p> <p>We report new ALMA observations of the CO(3-2) line emission from the 2.1+/- 0.3× {10}10 {M}ȯ molecular <span class="hlt">gas</span> reservoir in the central galaxy of the Phoenix cluster. The cold molecular <span class="hlt">gas</span> 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 <span class="hlt">bubbles</span> filled with relativistic plasma into the hot, X-ray atmospheres surrounding the host galaxy. The ALMA observations show that extended filaments of molecular <span class="hlt">gas</span>, each 10{--}20 {kpc} long with a mass of several billion solar masses, are located along the peripheries of the radio <span class="hlt">bubbles</span>. The smooth velocity gradients and narrow line widths along each filament reveal massive, ordered molecular <span class="hlt">gas</span> flows around each <span class="hlt">bubble</span>, which are inconsistent with gravitational free-fall. The molecular clouds have been lifted directly by the radio <span class="hlt">bubbles</span>, or formed via thermal instabilities induced in low-entropy <span class="hlt">gas</span> lifted in the updraft of the <span class="hlt">bubbles</span>. These new data provide compelling evidence for close coupling between the radio <span class="hlt">bubbles</span> and the cold <span class="hlt">gas</span>, 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 <span class="hlt">gas</span> required to sustain feedback in massive galaxies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170007280','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170007280"><span>A Study of Heat Transfer and Flow Characteristics of <span class="hlt">Rising</span> Taylor <span class="hlt">Bubbles</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scammell, Alexander David</p> <p>2016-01-01</p> <p>Practical application of flow boiling to ground- and space-based thermal management systems hinges on the ability to predict the systems heat removal capabilities under expected operating conditions. Research in this field has shown that the heat transfer coefficient within two-phase heat exchangers can be largely dependent on the experienced flow regime. This finding has inspired an effort to develop mechanistic heat transfer models for each flow pattern which are likely to outperform traditional empirical correlations. As a contribution to the effort, this work aimed to identify the heat transfer mechanisms for the slug flow regime through analysis of individual Taylor <span class="hlt">bubbles</span>.An experimental apparatus was developed to inject single vapor Taylor <span class="hlt">bubbles</span> into co-currently flowing liquid HFE 7100. The heat transfer was measured as the <span class="hlt">bubble</span> rose through a 6 mm inner diameter heated tube using an infrared thermography technique. High-speed flow visualization was obtained and the <span class="hlt">bubble</span> film thickness measured in an adiabatic section. Experiments were conducted at various liquid mass fluxes (43-200 kgm2s) and gravity levels (0.01g-1.8g) to characterize the effect of <span class="hlt">bubble</span> drift velocityon the heat transfer mechanisms. Variable gravity testing was conducted during a NASA parabolic flight campaign.Results from the experiments showed that the drift velocity strongly affects the hydrodynamics and heat transfer of single elongated <span class="hlt">bubbles</span>. At low gravity levels, <span class="hlt">bubbles</span> exhibited shapes characteristic of capillary flows and the heat transfer enhancement due to the <span class="hlt">bubble</span> was dominated by conduction through the thin film. At moderate to high gravity, traditional Taylor <span class="hlt">bubbles</span> provided small values of enhancement within the film, but large peaks in the wake heat transfer occurred due to turbulent vortices induced by the film plunging into the trailing liquid slug. Characteristics of the wake heat transfer profiles were analyzed and related to the predicted velocity field</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HMT...tmp..154A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HMT...tmp..154A"><span>Wall effects on the thermocapillary migration of single <span class="hlt">gas</span> <span class="hlt">bubbles</span> in stagnant liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alhendal, Yousuf; Turan, Ali; Kalendar, Abdulrahim</p> <p>2016-09-01</p> <p>In this paper, the governing continuum conservation equations for two-phase flow are solved using the commercial software package (Ansys-Fluent 1) to investigate the thermocapillary movement of a single <span class="hlt">bubble</span> in stagnant liquid under zero-gravity condition. The current results show that different temperature gradients lead to different <span class="hlt">bubble</span> migration velocities, and <span class="hlt">bubble</span> migration velocity varies linearly with the temperature gradient for the given conditions. Furthermore the inside column diameter was found to have a significant influence on the thermocapillary migration of the <span class="hlt">bubble</span>. Calculation were made in columns with inside diameters Dr 15, 20, 30, 40, 60, 80, 100 and 120 mm. Reduction on <span class="hlt">bubble</span> migration velocity only occurred when the ratio of the <span class="hlt">bubble</span> diameter to the column diameter, db/Dr, is greater than 0.267 due to column wall effect. On the other hand, the influence of the column diameter on the <span class="hlt">rise</span> velocity is negligible when db/Dr is equal to or smaller than 0.267. No <span class="hlt">bubble</span> shape deformation were observed and the <span class="hlt">bubble</span> were spherical in shape for all column width. Present investigation of the shape and trajectory of <span class="hlt">bubble</span> motion driven by surface tension-gradient in different column width is a new area of study and aims to support research into space applications which can help to determine the new migration time and speed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27243604','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27243604"><span>Improving microalgal growth with small <span class="hlt">bubbles</span> in a raceway pond with swing <span class="hlt">gas</span> aerators.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Zongbo; Cheng, Jun; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa</p> <p>2016-09-01</p> <p>A novel swing <span class="hlt">gas</span> aerator was developed to generate small <span class="hlt">bubbles</span> for improving the mass transfer coefficient and microalgal growth rate in a raceway pond. A high-speed photography system (HSP) was used to measure the <span class="hlt">bubble</span> diameter and generation time, and online precise dissolved oxygen probes and pH probes were used to measure the mass transfer coefficient and mixing time. <span class="hlt">Bubble</span> generation time and diameter decreased by 21% and 9%, respectively, when rubber <span class="hlt">gas</span> aerators were swung in the microalgae solution. When water pump power and <span class="hlt">gas</span> aeration rate increased in a raceway pond with swing <span class="hlt">gas</span> aerators and oscillating baffles (SGAOB), <span class="hlt">bubble</span> generation time and diameter decreased but solution velocity and mass transfer coefficient increased. The mass transfer coefficient increased by 25% and the solution velocity increased by 11% when SGAOB was used, and the microalgal biomass yield increased by 18%. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1236627','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1236627"><span>Dispersed <span class="hlt">bubble</span> reactor for enhanced <span class="hlt">gas</span>-liquid-solids contact and mass transfer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang; Bonsu, Alexander</p> <p>2016-01-26</p> <p>An apparatus to promote <span class="hlt">gas</span>-liquid contact and facilitate enhanced mass transfer. The dispersed <span class="hlt">bubble</span> reactor (DBR) operates in the dispersed <span class="hlt">bubble</span> flow regime to selectively absorb <span class="hlt">gas</span> phase constituents into the liquid phase. The dispersion is achieved by shearing the large inlet <span class="hlt">gas</span> <span class="hlt">bubbles</span> into fine <span class="hlt">bubbles</span> with circulating liquid and additional pumped liquid solvent when necessary. The DBR is capable of handling precipitates that may form during absorption or fine catalysts that may be necessary to promote liquid phase reactions. The DBR can be configured with multistage counter current flow sections by inserting concentric cylindrical sections into the riser to facilitate annular flow. While the DBR can absorb CO.sub.2 in liquid solvents that may lead to precipitates at high loadings, it is equally capable of handling many different types of chemical processes involving solids (precipitates/catalysts) along with <span class="hlt">gas</span> and liquid phases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDH21002C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDH21002C"><span>History effects on the <span class="hlt">gas</span> exchange between a <span class="hlt">bubble</span> and a liquid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chu, Shigan; Prosperetti, Andrea</p> <p>2016-11-01</p> <p>History effects are a distinctive feature of diffusive processes. For a diffusing <span class="hlt">gas</span> <span class="hlt">bubble</span> at rest in a liquid, such effects arise when the concentration of dissolved <span class="hlt">gas</span> at the <span class="hlt">bubble</span> surface, connected to the <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span>, 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 <span class="hlt">bubble</span> 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").</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006APS..SES.CC004S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006APS..SES.CC004S"><span>Radial oscillation of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in a fluid as a problem in canonical perturbation theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stephens, James</p> <p>2006-11-01</p> <p>The oscillation of a <span class="hlt">gas</span> <span class="hlt">bubble</span> is in a fluid is of interest in many areas of physics and technology. Lord Rayleigh treated the pressure developed in the collapse of cavitation <span class="hlt">bubbles</span> and developed an expression for the collapse period. Minnaert developed a harmonic oscillator approximation to <span class="hlt">bubble</span> oscillation in his study of the sound produced by running water. Besides recent interest in <span class="hlt">bubble</span> oscillation in connection to sonoluminescence, an understanding of oscillating <span class="hlt">bubbles</span> is of important to oceanographers studying the sound spectrum produced by water waves, geophysicists employing air guns as acoustic probes, mechanical engineers concerned with erosion of turbine blades, and military engineers concerned with the acoustic signatures developed by the propeller screws of ships and submarines. For the oceanographer, Minnaert's approximation is useful, for the latter two examples, Lord Rayleigh's analysis is appropriate. For the case of the airgun, a period of twice Rayleigh's period for the ``total collapse'' of the cavitation <span class="hlt">bubble</span> is often cited as a good approximation for the period of an air <span class="hlt">bubble</span> ejected from an air gun port, typically at ˜2000 psi), however for the geophysical example, numerical integration is employed from the outset to determine the dynamics of the <span class="hlt">bubble</span> and the emitted acoustic energy. On the one hand, a <span class="hlt">bubble</span> can be treated as a harmonic oscillator in the small amplitude regime, whereas even in the relatively moderate pressure regime characteristic of air guns the oscillation is strongly nonlinear and amplitude dependent. Is it possible to develop an analytic approximation that affords insight into the behavior of a <span class="hlt">bubble</span> beyond the harmonic approximation of Minnaert? In this spirit, the free radial oscillation of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in a fluid is treated as a problem in canonical perturbation theory. Several orders of the expansion are determined in order to explore the dependence of the oscillation frequency with <span class="hlt">bubble</span> amplitude</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.9302S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.9302S"><span>900-m high <span class="hlt">gas</span> plumes <span class="hlt">rising</span> from marine sediments containing structure II hydrates at Vestnesa Ridge, offshore W-Svalbard</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Andrew J.; Mienert, Jürgen; Bünz, Stefan; Greinert, Jens; Rasmussen, Tine L.</p> <p>2013-04-01</p> <p>We study an arctic sediment drift in ~1200 m water depth at Vestnesa Ridge, offshore western Svalbard. The ridge is spotted with pockmarks that range in size from a few meters to hundreds of meters in diameter and centimeters to tens of meters in height (e.g. Vogt et al., 1994). There is a strong negative-polarity seismic reflection below the ridge that is interpreted to record a negative impedance contrast marking the boundary between <span class="hlt">gas</span> hydrate and water above and free <span class="hlt">gas</span> and water below: it is the bottom-simulating reflector (BSR). Seismically transparent zones, interpreted as <span class="hlt">gas</span> chimneys, extend from pockmarks at the seafloor to depths below the BSR (180-220 meters below the seafloor) (Bünz et al., 2012). <span class="hlt">Gas</span> flares, <span class="hlt">gas</span> hydrate, and methane-seep-specific biological communities (pogonphora and begiatoa bacterial mats) have been observed adjacent to pockmarks at the ridge (Bünz et al., 2012). We present new single-beam echosounding data that were acquired during 2010 and 2012 cruises on the R/V Helmer Hanssen at Vestnesa Ridge using a Simrad EK60 system that operates at frequencies of 18 and 38 kHz. During both cruises which lasted 3-5 days, we detected continuous <span class="hlt">bubble</span> release from 4 separate pockmarks in 2010 and 6 separate pockmarks in 2012. There were no noticeable, short-term (hourly or daily) variations in the <span class="hlt">bubble</span> release from the pockmarks, indicating that the venting from the pockmarks does not undergo rapid changes. Plumes from the pockmarks <span class="hlt">rise</span> between 875 to 925m above the seafloor to a final water depth of 325 to 275m, respectively. This depth is in excellent agreement with the top of the hydrate stability zone (275 meters below sea level) for the <span class="hlt">gas</span> composition of hydrate sampled at the ridge (96.31% C1; 3.36% C2; 0.21% C3; 0.11% IC4; 0.01% NC4). This suggests that hydrate skins are forming around the <span class="hlt">gas</span> <span class="hlt">bubbles</span>, inhibiting the dissolution of <span class="hlt">gas</span>, and allowing the <span class="hlt">bubbles</span> to <span class="hlt">rise</span> to such great heights in the water column. Our results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1091987','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1091987"><span>Phase-field simulations of intragranular fission <span class="hlt">gas</span> <span class="hlt">bubble</span> evolution in UO2 under post-irradiation thermal annealing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Li, Yulan; Hu, Shenyang Y.; Montgomery, Robert O.; Gao, Fei; Sun, Xin</p> <p>2013-05-15</p> <p>Fission <span class="hlt">gas</span> <span class="hlt">bubble</span> is one of evolving microstructures, which affect thermal mechanical properties such as thermo-conductivity, <span class="hlt">gas</span> release, volume swelling, and cracking, in operating nuclear fuels. Therefore, fundamental understanding of <span class="hlt">gas</span> <span class="hlt">bubble</span> evolution kinetics is essential to predict the thermodynamic property and performance changes of fuels. In this work, a generic phasefield model was developed to describe the evolution kinetics of intra-granular fission <span class="hlt">gas</span> <span class="hlt">bubbles</span> in UO2 fuels under post-irradiation thermal annealing conditions. Free energy functional and model parameters are evaluated from atomistic simulations and experiments. Critical nuclei size of the <span class="hlt">gas</span> <span class="hlt">bubble</span> and <span class="hlt">gas</span> <span class="hlt">bubble</span> evolution were simulated. A linear relationship between logarithmic <span class="hlt">bubble</span> number density and logarithmic mean <span class="hlt">bubble</span> diameter is predicted which is in a good agreement with experimental data.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1364390-characterization-fission-gas-bubbles-irradiated-fuel','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1364390-characterization-fission-gas-bubbles-irradiated-fuel"><span>Characterization of fission <span class="hlt">gas</span> <span class="hlt">bubbles</span> in irradiated U-10Mo fuel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Casella, Andrew M.; Burkes, Douglas E.; MacFarlan, Paul J.; ...</p> <p>2017-06-06</p> <p>A simple, repeatable method for characterization of fission <span class="hlt">gas</span> <span class="hlt">bubbles</span> in irradiated U-Mo fuels has been developed. This method involves mechanical potting and polishing of samples along with examination with a scanning electron microscope located outside of a hot cell. The commercially available software packages CellProfiler, MATLAB, and Mathematica are used to segment and analyze the captured images. The results are compared and contrasted. Finally, baseline methods for fission <span class="hlt">gas</span> <span class="hlt">bubble</span> characterization are suggested for consideration and further development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28106748','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28106748"><span>Two-Dimensional Numerical Simulations of Ultrasound in Liquids with <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Agglomerates: Examples of <span class="hlt">Bubbly</span>-Liquid-Type Acoustic Metamaterials (BLAMMs).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vanhille, Christian</p> <p>2017-01-17</p> <p>This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding <span class="hlt">gas</span> <span class="hlt">bubbles</span> of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and several monodisperse <span class="hlt">bubble</span> 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 <span class="hlt">bubbly</span>-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 <span class="hlt">bubbly</span> fluids, which can be extremely high near <span class="hlt">bubble</span> resonance. They allow us to observe how <span class="hlt">gas</span> <span class="hlt">bubbles</span> can change acoustic signals. Variations of the <span class="hlt">bubbly</span> medium parameters induce alterations of the effects undergone by ultrasound. Results suggest that acoustic signals can be manipulated by <span class="hlt">bubbles</span>. This capacity to achieve the modification and control of sound with oscillating <span class="hlt">gas</span> <span class="hlt">bubbles</span> introduces the concept of <span class="hlt">bubbly</span>-liquid-based acoustic metamaterials (BLAMMs).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5298746','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5298746"><span>Two-Dimensional Numerical Simulations of Ultrasound in Liquids with <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Agglomerates: Examples of <span class="hlt">Bubbly</span>-Liquid-Type Acoustic Metamaterials (BLAMMs)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vanhille, Christian</p> <p>2017-01-01</p> <p>This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding <span class="hlt">gas</span> <span class="hlt">bubbles</span> of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and several monodisperse <span class="hlt">bubble</span> 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 <span class="hlt">bubbly</span>-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 <span class="hlt">bubbly</span> fluids, which can be extremely high near <span class="hlt">bubble</span> resonance. They allow us to observe how <span class="hlt">gas</span> <span class="hlt">bubbles</span> can change acoustic signals. Variations of the <span class="hlt">bubbly</span> medium parameters induce alterations of the effects undergone by ultrasound. Results suggest that acoustic signals can be manipulated by <span class="hlt">bubbles</span>. This capacity to achieve the modification and control of sound with oscillating <span class="hlt">gas</span> <span class="hlt">bubbles</span> introduces the concept of <span class="hlt">bubbly</span>-liquid-based acoustic metamaterials (BLAMMs). PMID:28106748</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28389057','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28389057"><span>Acoustic wave propagation in <span class="hlt">bubbly</span> flow with <span class="hlt">gas</span>, vapor or their mixtures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yuning; Guo, Zhongyu; Gao, Yuhang; Du, Xiaoze</p> <p>2017-03-29</p> <p>Presence of <span class="hlt">bubbles</span> in liquids could significantly alter the acoustic waves in terms of wave speed and attenuation. In the present paper, acoustic wave propagation in <span class="hlt">bubbly</span> flows with <span class="hlt">gas</span>, vapor and <span class="hlt">gas</span>/vapor mixtures is theoretically investigated in a wide range of parameters (including frequency, <span class="hlt">bubble</span> radius, void fraction, and vapor mass fraction). Our finding reveals two types of wave propagation behavior depending on the vapor mass fraction. Furthermore, the minimum wave speed (required for the closure of cavitation modelling in the sonochemical reactor design) is analyzed and the influences of paramount parameters on it are quantitatively discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...829....9M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...829....9M"><span>The Interaction of the Fermi <span class="hlt">Bubbles</span> with the Milky Way’s Hot <span class="hlt">Gas</span> Halo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, Matthew J.; Bregman, Joel N.</p> <p>2016-09-01</p> <p>The Fermi <span class="hlt">bubbles</span> are two lobes filled with non-thermal particles that emit gamma rays, extend ≈ 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 <span class="hlt">bubbles</span> expand into the surrounding hot <span class="hlt">gas</span> halo ({T}{halo}≈ 2× {10}6 K), but with significant uncertainties in the energetics, age, and thermal <span class="hlt">gas</span> structure. The <span class="hlt">bubbles</span> should contain thermal <span class="hlt">gas</span> with temperatures between 106 and 108 K, with potential X-ray signatures. In this work, we constrain the bubbles’ thermal <span class="hlt">gas</span> structure by modeling O vii and O viii emission line strengths from archival XMM-Newton and Suzaku data. Our emission model includes a hot thermal volume-filled <span class="hlt">bubble</span> component cospatial with the gamma-ray region, and a shell of compressed material. We find that a <span class="hlt">bubble</span>/shell model with n≈ 1× {10}-3 cm-3 and with log(T) ≈ 6.60-6.70 is consistent with the observed line intensities. In the framework of a continuous Galactic outflow, we infer a <span class="hlt">bubble</span> expansion rate, age, and energy injection rate of {490}-77+230 km s-1, {4.3}-1.4+0.8 Myr, and {2.3}-0.9+5.1× {10}42 erg s-1. These estimates are consistent with the <span class="hlt">bubbles</span> forming from a Sgr A* accretion event rather than from nuclear star formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1049666','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1049666"><span>Enhanced Generic Phase-field Model of Irradiation Materials: Fission <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Growth Kinetics in Polycrystalline UO2</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Li, Yulan; Hu, Shenyang Y.; Montgomery, Robert O.; Gao, Fei; Sun, Xin</p> <p>2012-05-30</p> <p>Experiments show that inter-granular and intra-granular <span class="hlt">gas</span> <span class="hlt">bubbles</span> have different growth kinetics which results in heterogeneous <span class="hlt">gas</span> <span class="hlt">bubble</span> microstructures in irradiated nuclear fuels. A science-based model predicting the heterogeneous microstructure evolution kinetics is desired, which enables one to study the effect of thermodynamic and kinetic properties of the system on <span class="hlt">gas</span> <span class="hlt">bubble</span> microstructure evolution kinetics and morphology, improve the understanding of the formation mechanisms of heterogeneous <span class="hlt">gas</span> <span class="hlt">bubble</span> microstructure, and provide the microstructure to macroscale approaches to study their impact on thermo-mechanical properties such as thermo-conductivity, <span class="hlt">gas</span> release, volume swelling, and cracking. In our previous report 'Mesoscale Benchmark Demonstration, Problem 1: Mesoscale Simulations of Intra-granular Fission <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in UO2 under Post-irradiation Thermal Annealing', we developed a phase-field model to simulate the intra-granular <span class="hlt">gas</span> <span class="hlt">bubble</span> evolution in a single crystal during post-irradiation thermal annealing. In this work, we enhanced the model by incorporating thermodynamic and kinetic properties at grain boundaries, which can be obtained from atomistic simulations, to simulate fission <span class="hlt">gas</span> <span class="hlt">bubble</span> growth kinetics in polycrystalline UO2 fuels. The model takes into account of <span class="hlt">gas</span> atom and vacancy diffusion, vacancy trapping and emission at defects, <span class="hlt">gas</span> atom absorption and resolution at <span class="hlt">gas</span> <span class="hlt">bubbles</span>, internal pressure in <span class="hlt">gas</span> <span class="hlt">bubbles</span>, elastic interaction between defects and <span class="hlt">gas</span> <span class="hlt">bubbles</span>, and the difference of thermodynamic and kinetic properties in matrix and grain boundaries. We applied the model to simulate <span class="hlt">gas</span> atom segregation at grain boundaries and the effect of interfacial energy and <span class="hlt">gas</span> mobility on <span class="hlt">gas</span> <span class="hlt">bubble</span> morphology and growth kinetics in a bi-crystal UO2 during post-irradiation thermal annealing. The preliminary results demonstrate that the model can produce the equilibrium thermodynamic properties and the morphology of <span class="hlt">gas</span> <span class="hlt">bubbles</span> at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25238127','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25238127"><span>Facile nanofibrillation of chitin derivatives by <span class="hlt">gas</span> <span class="hlt">bubbling</span> and ultrasonic treatments in water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tanaka, Kohei; Yamamoto, Kazuya; Kadokawa, Jun-ichi</p> <p>2014-10-29</p> <p>In this paper, we report that nanofiber network structures were constructed from chitin derivatives by <span class="hlt">gas</span> <span class="hlt">bubbling</span> and ultrasonic treatments in water. When chitin was first subjected to N2 <span class="hlt">gas</span> <span class="hlt">bubbling</span> with ultrasonication in water, the SEM images of the product showed nanofiber network morphology. However, nanofiber network was not re-constructed by the same N2 <span class="hlt">gas</span> <span class="hlt">bubbling</span> and ultrasonic treatments after agglomeration. We then have paid attention to an amidine group to provide the agglomeration-nanofibrillation behavior of chitin derivatives. An amidinated chitin was synthesized by the reaction of the amino groups in a partially deacetylated chitin with N,N-dimethylacetamide dimethyl acetal, which was subjected to CO2 <span class="hlt">gas</span> <span class="hlt">bubbling</span> and ultrasonic treatments in water to convert into an amidinium chitin by protonation. The SEM images of the product clearly showed nanofiber network morphology. We further examined re-nanofibrillation of the agglomerated material, which was obtained by mixing the nanofibrillated amidinium chitin with water, followed by drying under reduced pressure. Consequently, the material was re-nanofibrillated by N2 <span class="hlt">gas</span> <span class="hlt">bubbling</span> with ultrasonication in water owing to electrostatic repulsion between the amidinium groups. Furthermore, deprotonation of the amidinium chitin and re-protonation of the resulting amidinated chitin were conducted by alkaline treatment and CO2 <span class="hlt">gas</span> <span class="hlt">bubbling</span>-ultrasonic treatments, respectively. The material showed the agglomeration-nanofibrillation behavior during the processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26857370','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26857370"><span>The influence of polymeric membrane <span class="hlt">gas</span> spargers on hydrodynamics and mass transfer in <span class="hlt">bubble</span> column bioreactors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tirunehe, Gossaye; Norddahl, B</p> <p>2016-04-01</p> <p><span class="hlt">Gas</span> sparging performances of a flat sheet and tubular polymeric membranes were investigated in 3.1 m <span class="hlt">bubble</span> 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 <span class="hlt">gas</span>-liquid mediums. CMC solutions were employed in the study to simulate rheological properties of bioreactor broth. <span class="hlt">Gas</span> holdup, <span class="hlt">bubble</span> size distribution, interfacial area and <span class="hlt">gas</span>-liquid mass transfer were studied in the homogeneous <span class="hlt">bubbly</span> flow hydrodynamic regime with superficial <span class="hlt">gas</span> velocity (U(G)) range of 0.0004-0.0025 m/s. The study indicated that the tubular membrane sparger produced the highest <span class="hlt">gas</span> holdup and densely populated fine <span class="hlt">bubbles</span> with narrow size distribution. An increase in liquid viscosity promoted a shift in <span class="hlt">bubble</span> size distribution to large stable <span class="hlt">bubbles</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25688855','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25688855"><span>Bioinspired <span class="hlt">gas</span> <span class="hlt">bubble</span> spontaneous and directional transportation effects in an aqueous medium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ma, Rui; Wang, Jingming; Yang, Zhongjia; Liu, Meng; Zhang, Jingjing; Jiang, Lei</p> <p>2015-04-08</p> <p>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 <span class="hlt">gas</span> film can be trapped around its interface in an aqueous medium acting as an effective channel for <span class="hlt">gas</span> transportation. Driving by the difference of the Laplace pressure, <span class="hlt">gas</span> <span class="hlt">bubbles</span> can be transported spontaneously and directionally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19426320','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19426320"><span>Coalescence of drops and <span class="hlt">bubbles</span> <span class="hlt">rising</span> through a non-Newtonian fluid in a tube.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Al-Matroushi, Eisa; Borhan, Ali</p> <p>2009-04-01</p> <p>We conducted an experimental study of the interaction and coalescence of two drops (of the same fluid) or <span class="hlt">bubbles</span> translating under the action of buoyancy in a cylindrical tube. The close approach of two Newtonian fluid particles of different size in a non-Newtonian continuous phase was examined using image analysis, and measurements of the coalescence time are reported for various particle size ratios, Bond numbers, and particle-to-suspending-fluid viscosity ratios. The flow disturbance behind the leading <span class="hlt">bubble</span> and the viscoelastic nature of the continuous phase seemed to retard <span class="hlt">bubble</span> coalescence. The time scale for coalescence of liquid drops in highly elastic continuous phase was influenced by the relative motion of the drops and their coalescence behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28702573','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28702573"><span>Liter-scale production of uniform <span class="hlt">gas</span> <span class="hlt">bubbles</span> via parallelization of flow-focusing generators.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jeong, Heon-Ho; Yadavali, Sagar; Issadore, David; Lee, Daeyeon</p> <p>2017-07-25</p> <p>Microscale <span class="hlt">gas</span> <span class="hlt">bubbles</span> have demonstrated enormous utility as versatile templates for the synthesis of functional materials in medicine, ultra-lightweight materials and acoustic metamaterials. In many of these applications, high uniformity of the size of the <span class="hlt">gas</span> <span class="hlt">bubbles</span> is critical to achieve the desired properties and functionality. While microfluidics have been used with success to create <span class="hlt">gas</span> <span class="hlt">bubbles</span> that have a uniformity not achievable using conventional methods, the inherently low volumetric flow rate of microfluidics has limited its use in most applications. Parallelization of liquid droplet generators, in which many droplet generators are incorporated onto a single chip, has shown great promise for the large scale production of monodisperse liquid emulsion droplets. However, the scale-up of monodisperse <span class="hlt">gas</span> <span class="hlt">bubbles</span> using such an approach has remained a challenge because of possible coupling between parallel <span class="hlt">bubbles</span> generators and feedback effects from the downstream channels. In this report, we systematically investigate the effect of factors such as viscosity of the continuous phase, capillary number, and <span class="hlt">gas</span> pressure as well as the channel uniformity on the size distribution of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in a parallelized microfluidic device. We show that, by optimizing the flow conditions, a device with 400 parallel flow focusing generators on a footprint of 5 × 5 cm(2) can be used to generate <span class="hlt">gas</span> <span class="hlt">bubbles</span> with a coefficient of variation of less than 5% at a production rate of approximately 1 L h(-1). Our results suggest that the optimization of flow conditions using a device with a small number (e.g., 8) of parallel FFGs can facilitate large-scale <span class="hlt">bubble</span> production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1615169S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615169S"><span>The North Sea Blowout: A <span class="hlt">gas</span> <span class="hlt">bubble</span> megaplume with spiral vortex motion and why it might, or might not, contribute much to the atmospheric methane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schneider von Deimling, Jens; Leifer, Ira; Schmidt, Mark; Rehder, Gregor; Linke, Peter</p> <p>2014-05-01</p> <p>In the Central North Sea, during drilling operations, a <span class="hlt">gas</span> blowout accident happened in 1990. Thereafter, natural <span class="hlt">gas</span> has leaked prodigiously from a 60 m diameter and 20 m deep crater located at 95 m depth into the water column and to the sea surface. A series of field studies was carried out at this site since 2005 evidencing ongoing intense seepage activity. Three <span class="hlt">gas</span> <span class="hlt">bubble</span> megaplumes and dozens of minor to major <span class="hlt">bubble</span> seeps were observed in the crater during a manned submersible dive, ROV mapped hundreds. Analysis of <span class="hlt">gas</span> <span class="hlt">bubbles</span> captured at 118 m water depth revealed concentrations between 88-90%Vol CH4 with δ 13C-CH4 values around -74‰ VPDB, consistent with a biogenic origin. Blowout site flux estimates derived from ROV video show the site's emissions are the strongest and most intense marine methane seepage quantified to date with seabed emissions of ~32.6 kt/y. Based on previous research suggesting greater flux correlates with greater transport efficiency, the direct <span class="hlt">bubble</span>-mediated atmospheric flux to the atmosphere was estimated at a surprisingly low 0.7kt/y. This is orders of magnitude smaller compared to the seabed flux, thus the bulk methane dissolves before reaching the atmosphere, suggesting enhanced <span class="hlt">bubble</span> dissolution rates for megaplumes. Analysis of more than 120 water samples from near the blowout plume showed dissolved methane concentration distributions consistent with enhanced <span class="hlt">bubble</span> dissolution at depth. CH4 concentrations ranged from 0.2 µmol/L at 20 m depth to a peak in the crater of an extraordinary 400 µmol/L. To evaluate further the controlling factors on the <span class="hlt">rising</span> <span class="hlt">bubble</span> plume, multibeam water column data were analyzed. The <span class="hlt">bubble</span> plume spatial distribution revealed a horizontal intrusion of <span class="hlt">gas</span> <span class="hlt">bubbles</span> just below the thermocline. This pronounced pattern was traced 200 m horizontally with a downflow plume orientation suggesting trapping of methane-enriched fluids at depth. A numerical <span class="hlt">bubble</span> propagation model was used to simulate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005APS..SES.CC006S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005APS..SES.CC006S"><span>Radial oscillation of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in a fluid as a problem in canonical perturbation theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stephens, James</p> <p>2005-11-01</p> <p>The oscillation of a <span class="hlt">gas</span> <span class="hlt">bubble</span> is in a fluid is of interest in many areas of physics and technology. Lord Rayleigh treated the pressure developed in the collapse of cavitation <span class="hlt">bubbles</span> and developed an expression for the collapse period. Minnaert developed a harmonic oscillator approximation to <span class="hlt">bubble</span> oscillation in his study of the sound produced by running water. Oscillating <span class="hlt">bubbles</span> are important to oceanographers studying the sound spectrum produced by water waves, geophysicists employing air guns as acoustic probes, mechanical engineers concerned with erosion of turbine blades, and military engineers concerned with the acoustic signatures developed by the propeller screws of ships and submarines. For the oceanographer, Minnaert's approximation is useful, for the latter two examples, Lord Rayleigh's analysis is appropriate. On the one hand, a <span class="hlt">bubble</span> can be treated as a harmonic oscillator in the small amplitude regime, whereas even in the relatively moderate pressure regime characteristic of air guns the oscillation is strongly nonlinear and amplitude dependent. Is it possible to develop an analytic approximation that affords insight into the behavior of a <span class="hlt">bubble</span> beyond the harmonic approximation of Minnaert? In this spirit, the free radial oscillation of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in a fluid is treated as a problem in canonical perturbation theory. Several orders of the expansion are determined in order to explore the dependence of the oscillation frequency with <span class="hlt">bubble</span> amplitude. The expansion to second order is inverted to express the time dependence of the oscillation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MeScT..25l5302H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MeScT..25l5302H"><span>A novel ultrasound based technique for classifying <span class="hlt">gas</span> <span class="hlt">bubble</span> sizes in liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hussein, Walid; Salman Khan, Muhammad; Zamorano, Juan; Espic, Felipe; Becerra Yoma, Nestor</p> <p>2014-12-01</p> <p>Characterizing <span class="hlt">gas</span> <span class="hlt">bubbles</span> in liquids is crucial to many biomedical, environmental and industrial applications. In this paper a novel method is proposed for the classification of <span class="hlt">bubble</span> sizes using ultrasound analysis, which is widely acknowledged for being non-invasive, non-contact and inexpensive. This classification is based on 2D templates, i.e. the average spectrum of events representing the trace of <span class="hlt">bubbles</span> when they cross an ultrasound field. The 2D patterns are obtained by capturing ultrasound signals reflected by <span class="hlt">bubbles</span>. Frequency-domain based features are analyzed that provide discrimination between <span class="hlt">bubble</span> sizes. These features are then fed to an artificial neural network, which is designed and trained to classify <span class="hlt">bubble</span> sizes. The benefits of the proposed method are that it facilitates the processing of multiple <span class="hlt">bubbles</span> simultaneously, the issues concerning masking interference among <span class="hlt">bubbles</span> are potentially reduced and using a single sinusoidal component makes the transmitter-receiver electronics relatively simpler. Results from three <span class="hlt">bubble</span> sizes indicate that the proposed scheme can achieve an accuracy in their classification that is as high as 99%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12833188','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12833188"><span>Effects of air <span class="hlt">bubbles</span> and tube transportation on blood oxygen tension in arterial blood <span class="hlt">gas</span> analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lu, Jin Ying; Kao, Jau Tsuen; Chien, Tzu I; Lee, Tai Fen; Tsai, Keh Sung</p> <p>2003-04-01</p> <p>Pneumatic tube transport has been reported to aggravate the error in partial pressure of oxygen (PO(2)) measurements caused by air <span class="hlt">bubbles</span>. The aim of this study was to clarify the effect of manual and pneumatic tube methods of sample transportation and different amounts of air <span class="hlt">bubbles</span> on arterial blood <span class="hlt">gas</span> analysis. Blood <span class="hlt">gas</span> 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 <span class="hlt">bubbles</span> and manual versus pneumatic tube transportation on PO(2) levels. PO(2) increased significantly in samples containing 10% air <span class="hlt">bubbles</span> and was exaggerated by pneumatic tube transport (from 115.63 +/- 9.31 mm Hg to 180.51 +/- 11.29 mm Hg, p < 0.001). In samples with low PO(2) ( approximately 30 mm Hg), the measurement was not aberrant regardless of the method of transportation or the amount of air <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> were introduced, respectively, to samples with medium PO(2) (p < 0.05). The interaction between the amount of air <span class="hlt">bubbles</span> and the method of transportation was significant (p < 0.001). Trapped air in the syringe should be expelled as thoroughly as possible, since the presence of only 1% air <span class="hlt">bubbles</span> can result in aberrance in PO(2) measurement. Samples for blood <span class="hlt">gas</span> analysis should be carried in ambient pressure to the laboratory because pneumatic tube delivery systems significantly aggravate the air <span class="hlt">bubble</span>-related aberrance in PO(2) measurement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ExFl...55.1652K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ExFl...55.1652K"><span>A study of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in liquid mercury in a vertical Hele-Shaw cell</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klaasen, B.; Verhaeghe, F.; Blanpain, B.; Fransaer, J.</p> <p>2014-01-01</p> <p>High-quality observations of mesoscopic <span class="hlt">gas</span> <span class="hlt">bubbles</span> in liquid metal are vital for a further development of pyrometallurgical <span class="hlt">gas</span> 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 <span class="hlt">gas</span> in a thin layer of liquid metal entrapped between two flat and closely spaced plates, <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> can be observed directly. The feasibility of this approach is demonstrated by observations on buoyancy-driven nitrogen <span class="hlt">bubbles</span> in liquid mercury in a vertical Hele-Shaw cell. By using a moving high-speed camera to make continuous close up recordings of individual <span class="hlt">bubbles</span>, the position and geometry of these <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> expansion along the path. While the observed <span class="hlt">bubble</span> growth is mainly caused by the hydrostatic pressure gradient, a careful assessment of the volume variations for smaller <span class="hlt">bubbles</span> shows that an accurate <span class="hlt">bubble</span> description should account for significant dynamic pressure variations that seem to be largely regime dependent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710167U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710167U"><span>Lander based hydroacoustic monitoring of marine single <span class="hlt">bubble</span> releases in Eckernförde Bay utilizing the multibeam based <span class="hlt">Gas</span>Quant II system.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Urban, Peter; Schneider von Deimling, Jens; Greinert, Jens</p> <p>2015-04-01</p> <p>The GEOMAR Helmholtz Centre for Ocean Research Kiel is currently developing a Imagenex Delta T based lander system for monitoring and quantifying marine <span class="hlt">gas</span> release (<span class="hlt">bubbles</span>). The <span class="hlt">Gas</span>Quant II is built as the successor of the <span class="hlt">Gas</span>Quant I system (Greinert, 2008), that has been successfully used for monitoring tempo-spatial variability of <span class="hlt">gas</span> release in the past (Schneider von Deimling et al., 2010). The new system is lightweight (40 kg), energy efficient, flexible to use and built for ROV deployment with autonomous operation of up to three days. A prototype has been successfully deployed in Eckernförde Bay during the R/V ALKOR cruise AL447 in October/November 2014 to monitor the tempo-spatial variability of <span class="hlt">gas</span> <span class="hlt">bubble</span> seepage and to detect a possible correlation with tidal variations. Two deployments, one in forward- and one in upward looking mode, reveal extensive but scattered single <span class="hlt">bubble</span> releases rather than distinct and more continuous sources. While these releases are difficult to detect in forward looking mode, they can unambiguously be detected in the upward looking mode even for minor <span class="hlt">gas</span> releases, <span class="hlt">bubble</span> <span class="hlt">rising</span> speeds can be determined. Greinert, J., 2008. Monitoring temporal variability of <span class="hlt">bubble</span> release at seeps: The hydroacoustic swath system <span class="hlt">Gas</span>Quant. J. Geophys. Res. Oceans Vol. 113 Issue C7 CiteID C07048 113, 7048. doi:10.1029/2007JC004704 Schneider von Deimling, J., Greinert, J., Chapman, N.R., Rabbel, W., Linke, P., 2010. Acoustic imaging of natural <span class="hlt">gas</span> seepage in the North Sea: Sensing <span class="hlt">bubbles</span> controlled by variable currents. Limnol. Oceanogr. Methods 8, 155. doi:10.4319/lom.2010.8.155</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDR37005D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDR37005D"><span>A parametric study on the <span class="hlt">rise</span> of a pair of <span class="hlt">bubbles</span> using algebraic volume of fluid method: effect of diameter and viscosity ratio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dalal, Amaresh; Kulkarni, Amol C.; Manik, Jai; Natarajan, Ganesh</p> <p>2016-11-01</p> <p>The effect of droplet diameter and viscosity ratio on the coalescence of two <span class="hlt">bubbles</span> <span class="hlt">rising</span> in a quiescent liquid has been studied numerically using algebraic volume of fluid (VOF) method. If the upper <span class="hlt">bubble</span> diameter is 75% of the lower <span class="hlt">bubble</span>, the time taken for their coalescence increases in comparison with the case of equal <span class="hlt">bubble</span> diameter. For the case, when the diameter of the upper <span class="hlt">bubble</span> is reduced, this delay may be attributed to comparatively weaker jet formed behind the leading <span class="hlt">bubble</span>, ultimately resulting in lesser acceleration of the trailing <span class="hlt">bubble</span>. While for the other case, when the diameter of the lower <span class="hlt">bubble</span> is reduced, it is because of a totally different scenario of liquid entrapment observed during coalescence. The effect of viscosity of the surrounding fluid is also noticed separately for the situation when the diameters of the <span class="hlt">bubbles</span> are equal. It has been observed that, the increase in viscosity of the surrounding fluid will increase the form drag over the <span class="hlt">bubbles</span>, eventually leading to the delay in their coalescence. This study is funded by a Grant from BRNS, DAE, Government of India.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MMTB...47.1649Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTB...47.1649Y"><span>Effect of Orifice Diameter on <span class="hlt">Bubble</span> Generation Process in Melt <span class="hlt">Gas</span> Injection to Prepare Aluminum Foams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yuan, Jianyu; Li, Yanxiang; Wang, Ningzhen; Cheng, Ying; Chen, Xiang</p> <p>2016-06-01</p> <p>The <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> flow rate and chamber pressure relationship for each orifice is first determined when blowing <span class="hlt">gas</span> in atmospheric environment. The effects of chamber pressure ( P c) and orifice diameter ( D o) on <span class="hlt">bubble</span> size are then analyzed separately when blowing <span class="hlt">gas</span> in melt. A three-dimensional fitting curve is obtained illustrating both the influences of orifice diameter and chamber pressure on <span class="hlt">bubble</span> size based on the experimental data. It is found that the <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> generation mechanism is proposed based on the Rayleigh-Plesset equation. It is found that the <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> growth stage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021002','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021002"><span>Rate of disappearance of <span class="hlt">gas</span> <span class="hlt">bubble</span> trauma signs in juvenile salmonids</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hans, K.M.; Mesa, M.G.; Maule, A.G.</p> <p>1999-01-01</p> <p>To assess the rate of disappearance of <span class="hlt">gas</span> <span class="hlt">bubble</span> trauma (GBT) signs in juvenile salmonids, we exposed spring chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss to water containing high levels of dissolved <span class="hlt">gas</span> supersaturation (DGS) for a time period sufficient to induce signs of GBT, reduced the DGS to minimal levels, and then sampled fish through time to document changes in severity of GBT. Because of the tendency of GBT signs to dissipate at different rates, we conducted trials focusing on emboli (<span class="hlt">bubbles</span>) in the gill filaments and lateral line and separate trials that focused on <span class="hlt">bubbles</span> in the external surfaces (fins, eyes, and opercula). <span class="hlt">Bubbles</span> in gill filaments dissipated almost completely within 2 h after transfer of fish to water of nearly normal DGS (104%), whereas <span class="hlt">bubbles</span> in the lateral line dissipated to negligible levels within 5 h. <span class="hlt">Bubbles</span> on external surfaces were more persistent through time than they were in gill filaments and the lateral line. Although typically dissipating to low levels within 48 h, external <span class="hlt">bubbles</span> sometimes remained for 4 d. Assuming a direct relation exists between easily observable signs and direct mortality, our results suggest that fish can recover quickly from the potentially lethal effects of DGS once they move from water with high DGS to water of almost normal <span class="hlt">gas</span> saturation. These results should be of fundamental importance to fishery managers interpreting the results of monitoring for the severity and prevalence of GBT in juvenile salmonids in the Columbia River system and perhaps elsewhere.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IAUS..316..175Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IAUS..316..175Z"><span>N131: A dust <span class="hlt">bubble</span> was born from the disruption of a <span class="hlt">gas</span> filament?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Chuan-Peng</p> <p>2017-03-01</p> <p>N131 is an infrared dust <span class="hlt">bubble</span> residing in a molecular filament. We aim to study the formation and fragmentation of this <span class="hlt">bubble</span> with multi-wavelength dust and <span class="hlt">gas</span> observations. Towards the <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> observations reveal a ringlike shell with compact fragments, two filamentary structures, and a secondary <span class="hlt">bubble</span> N131-A. The <span class="hlt">bubble</span> N131 is a rare object with a large hole at 24 μm and 21 cm in the direction of its center. The dust and <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> N131 might be triggered by the strong stellar winds from a group of massive stars inside the <span class="hlt">bubble</span>. We propose a scenario in which the <span class="hlt">bubble</span> N131 forms from the disruption of a <span class="hlt">gas</span> filament by expansion of H II region, strong stellar winds, and fragments under self-gravity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28178417','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28178417"><span>Surface Forces and Interaction Mechanisms of Emulsion Drops and <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Complex Fluids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xie, Lei; Shi, Chen; Cui, Xin; Zeng, Hongbo</p> <p>2017-02-22</p> <p>The interactions of emulsion drops and <span class="hlt">gas</span> <span class="hlt">bubbles</span> in complex fluids play important roles in a wide range of biological and technological applications, such as programmable drug and gene delivery, emulsion and foam formation, and froth flotation of mineral particles. In this feature article, we have reviewed our recent progress on the quantification of surface forces and interaction mechanisms of <span class="hlt">gas</span> <span class="hlt">bubbles</span> and emulsion drops in different material systems by using several complementary techniques, including the drop/<span class="hlt">bubble</span> probe atomic force microscope (AFM), surface forces apparatus (SFA), and four-roll mill fluidic device. These material systems include the <span class="hlt">bubble</span>-self-assembled monolayer (SAM), <span class="hlt">bubble</span>-polymer, <span class="hlt">bubble</span>-superhydrophobic surface, <span class="hlt">bubble</span>-mineral, water-in-oil and oil-in-water emulsions with interface-active components in oil production, and oil/water wetting on polyelectrolyte surfaces. The <span class="hlt">bubble</span> probe AFM combined with reflection interference contrast microscopy (RICM) was applied for the first time to simultaneously quantify the interaction forces and spatiotemporal evolution of a confined thin liquid film between <span class="hlt">gas</span> <span class="hlt">bubbles</span> and solid surfaces with varying hydrophobicity. The nanomechanical results have provided useful insights into the fundamental interaction mechanisms (e.g., hydrophobic interaction in aqueous media) at <span class="hlt">gas</span>/water/solid interfaces, the stabilization/destabilization mechanisms of emulsion drops, and oil/water wetting mechanisms on solid surfaces. A long-range hydrophilic attraction was found between water and polyelectrolyte surfaces in oil, with the strongest attraction for polyzwitterions, contributing to their superior water wettability in oil and self-cleaning capability of oil contamination. Some remaining challenges and future research directions are discussed and provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.4360E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.4360E"><span>The role of <span class="hlt">bubbles</span> during air-sea <span class="hlt">gas</span> exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Emerson, Steven; Bushinsky, Seth</p> <p>2016-06-01</p> <p>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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> processes. We find that models must have an explicit <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> plumes and categorizes <span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9246276','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9246276"><span>The effect of anaesthesia on the intraocular volume of the C3F8 <span class="hlt">gas</span> <span class="hlt">bubble</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Briggs, M; Wong, D; Groenewald, C; McGalliard, J; Kelly, J; Harper, J</p> <p>1997-01-01</p> <p>Long-acting intraocular <span class="hlt">gas</span> <span class="hlt">bubbles</span> are frequently used during vitrectomy to tamponade retinal breaks. The aim of this study was to determine the effect of nitrous oxide anaesthesia on the size and effectiveness of the post-vitrectomy <span class="hlt">gas</span> <span class="hlt">bubble</span>. Twenty vitrectomy procedures with injection of 12% perfluoropropane (C3F8) <span class="hlt">gas</span> were performed. For 10 of the cases routine anaesthesia with nitrous oxide was used and for 10 cases non-nitrous anaesthesia with propofol was used. The volume of the intraocular <span class="hlt">gas</span> <span class="hlt">bubble</span> was estimated 24 hours post-operatively using A-scan biometry. At 24 hours the <span class="hlt">gas</span> <span class="hlt">bubble</span> occupied a mean of 65.1% of the eye in anaesthesia with nitrous oxide and a mean of 66.1% in anaesthesia with intravenous propofol. The wide range of values of <span class="hlt">gas</span>-fill recorded at 24 hours makes comparison of the two groups inappropriate. Several factors may account for this spread of values, but in our opinion it is the uncontrolled leakage from the sclerostomies which is the most likely. This study suggests that anaesthesia using nitrous oxide does not adversely affect the size of the C3F8 <span class="hlt">gas</span> <span class="hlt">bubble</span> at 24 hours post-vitrectomy when compared with anaesthesia without nitrous oxide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..228a2009K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..228a2009K"><span>Validation of X-ray radiography for characterization of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in liquid metals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keplinger, O.; Shevchenko, N.; Eckert, S.</p> <p>2017-07-01</p> <p>X-ray radiography has proved to be an efficient and powerful tool for the visualization of two-phase flows in non-transparent fluids, in particular in liquid metals. This paper presents a validation of the X-ray radiography by comparing measurements in water with corresponding results obtained by optical methods. For that purpose Ar <span class="hlt">bubbles</span> were injected through a single orifice. The measurements results are compared in terms of <span class="hlt">bubble</span> size, <span class="hlt">bubble</span> shape and velocity. Furthermore, visualization experiments were performed in the eutectic alloy GaInSn where the image contrast between the liquid phase and the <span class="hlt">gas</span> <span class="hlt">bubble</span> is much stronger. Some obvious differences of the <span class="hlt">bubble</span> dynamics in water and GaInSn are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30Q.542M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30Q.542M"><span>A Philippinite with an Unusually Large <span class="hlt">Bubble</span>: <span class="hlt">Gas</span> Pressure and Noble <span class="hlt">Gas</span> Composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsuda, J.; Maruoka, T.; Pinti, D. L.; Koeberl, C.</p> <p>1995-09-01</p> <p><span class="hlt">Bubbles</span> are common in tektites, but usually their sizes range up to only a few mm. They are most abundant in Muong Nong-type tektites. The gases contained in these <span class="hlt">bubbles</span> are of terrestrial atmospheric composition, with pressures below 1 atm (e.g., [1]). The abundances of light noble gases (He, Ne) are controlled by diffusion from the atmosphere [2], and noble gases dissolved in tektite glass indicate that the glass solidified at atmospheric pressures equivalent to about 40 km altitude [3]. Large <span class="hlt">bubbles</span> in splash-form tektites are rather rare. Thus, the finding that a philippinite (size: 6.0 x 4.5 cm; weight: 199.6 g) contains an unusually large <span class="hlt">bubble</span> justified a detailed study. The volume of the <span class="hlt">bubble</span>, which was confirmed by X-ray photography, was estimated at 5.4 cm^3, by comparing the density of this tektite (2.288 g/cm^3) to that of normal philippinites (2.438 g/cm^3). A device was specifically constructed for crushing the present sample under vacuum. The 10x10 cm cylindrical device has a piston that allows to gently crush the sample by turning a handle. Various disk spacers can be used to adjust the inner height to that of the sample. The device is made of stainless steel, yielding a low noble <span class="hlt">gas</span> blank. The crushing device is connected to a purification line and a noble <span class="hlt">gas</span> sector-type mass spectrometer (VG 5400) [4]. Before crushing, the complete tektite was wrapped in aluminum foil. A first crushing attempt, using stainless steel disk spacers, failed and resulted in damage to the steel spacers, indicating a high strength of the tektite. Using iron disk spacers resulted in an ambient pressure increase (probably due to hydrogen from the Fe) in the sample chamber. However, the noble <span class="hlt">gas</span> blanks were negligible. The background pressure, at 2 x 10-4 Torr, increased to 3 x 10-4 Torr when the sample was crushed. From the volume of the crushing device and that of the <span class="hlt">bubble</span> in the tektite, the total <span class="hlt">gas</span> pressure in the <span class="hlt">bubble</span> was estimated at about 1 x 10-4 atm</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..DFD.NG006R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..DFD.NG006R"><span>Experimental studies of a strongly shocked <span class="hlt">gas</span> <span class="hlt">bubble</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ranjan, Devesh; Oakley, Jason; Anderson, Mark; Bonazza, Riccardo</p> <p>2004-11-01</p> <p>The interaction of a planar shock wave (M=1.34, 2.84 and 3.34) propagating in nitrogen with a free-falling spherical soap <span class="hlt">bubble</span> (5 cm diameter) filled with argon leads initially to the compression of the <span class="hlt">bubble</span> into a disk-like object and, at later times, to the formation of a vortex ring at the periphery of the disk which entrains outside fluid into the argon. The evolution of some of the relevant geometrical properties of the <span class="hlt">bubble</span> and the vortex ring are studied in the laboratory with a vertical shock tube with a square internal cross section; a retractable injector releases an argon <span class="hlt">bubble</span> in the shock tube and a downward-propagating, planar shock wave reaches the <span class="hlt">bubble</span> within 70 ms of its release from the injector. The flow is imaged with a laser sheet illuminated across the shock-accelerated <span class="hlt">bubble</span> and collecting the Mie scattering signal from the soap film, which acts as a flow tracer. The planar image represents a 2D slice of the flow, however, the shocked <span class="hlt">bubble</span> geometry evolution is in fact 3D due to an azimuthal instability (Widnall). The presence of a droplet of film results in additional Rayleigh-Taylor and Kelvin-Helmholtz instabilites due to an observed jet; this may help to explain the jetting observed following core-collapse in a supernova. Experimental results are compared with numerical simulations using the Raptor code (LLNL) which solves the full Navier-Stokes equations using the Piecewise Linear Method (PLM) with Adaptive Mesh Refinement (AMR).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDG21009Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDG21009Z"><span>Effects of non-condensable <span class="hlt">gas</span> on the dynamic oscillations of cavitation <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yuning</p> <p>2016-11-01</p> <p>Cavitation is an essential topic of multiphase flow with a broad range of applications. Generally, there exists non-condensable <span class="hlt">gas</span> in the liquid and a complex vapor/<span class="hlt">gas</span> mixture <span class="hlt">bubble</span> will be formed. A rigorous prediction of the dynamic behavior of the aforementioned mixture <span class="hlt">bubble</span> is essential for the development of a complete cavitation model. In the present paper, effects of non-condensable <span class="hlt">gas</span> on the dynamic oscillations of the vapor/<span class="hlt">gas</span> mixture <span class="hlt">bubble</span> are numerically investigated in great detail. For the completeness, a large parameter zone (e.g. <span class="hlt">bubble</span> radius, frequency and ratio between <span class="hlt">gas</span> and vapor) is investigated with many demonstrating examples. The mechanisms of mass diffusion are categorized into different groups with their characteristics and dominated regions given. Influences of non-condensable <span class="hlt">gas</span> on the wave propagation (e.g. wave speed and attenuation) in the <span class="hlt">bubbly</span> liquids are also briefly discussed. Specifically, the minimum wave speed is quantitatively predicted in order to close the pressure-density coupling relationship usually employed for the cavitation modelling. Finally, the application of the present finding on the development of cavitation model is demonstrated with a brief discussion of its influence on the cavitation dynamics. This work was financially supported by the National Natural Science Foundation of China (Project No.: 51506051).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/929261','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/929261"><span>Characterization of intergranular fission <span class="hlt">gas</span> <span class="hlt">bubbles</span> in U-Mo fuel.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, Y. S.; Hofman, G.; Rest, J.; Shevlyakov, G. V.; Nuclear Engineering Division; SSCR RIAR</p> <p>2008-04-14</p> <p>This report can be divided into two parts: the first part, which is composed of sections 1, 2, and 3, is devoted to report the analyses of fission <span class="hlt">gas</span> <span class="hlt">bubbles</span>; the second part, which is in section 4, is allocated to describe the mechanistic model development. Swelling data of irradiated U-Mo alloy typically show that the kinetics of fission <span class="hlt">gas</span> <span class="hlt">bubbles</span> is composed of two different rates: lower initially and higher later. The transition corresponds to a burnup of {approx}0 at% U-235 (LEU) or a fission density of {approx}3 x 10{sup 21} fissions/cm{sup 3}. Scanning electron microscopy (SEM) shows that <span class="hlt">gas</span> <span class="hlt">bubbles</span> appear only on the grain boundaries in the pretransition regime. At intermediate burnup where the transition begins, <span class="hlt">gas</span> <span class="hlt">bubbles</span> are observed to spread into the intragranular regions. At high burnup, they are uniformly distributed throughout fuel. In highly irradiated U-Mo alloy fuel large-scale <span class="hlt">gas</span> <span class="hlt">bubbles</span> form on some fuel particle peripheries. In some cases, these <span class="hlt">bubbles</span> appear to be interconnected and occupy the interface region between fuel and the aluminum matrix for dispersion fuel, and fuel and cladding for monolithic fuel, respectively. This is a potential performance limit for U-Mo alloy fuel. Microscopic characterization of the evolution of fission <span class="hlt">gas</span> <span class="hlt">bubbles</span> is necessary to understand the underlying phenomena of the macroscopic behavior of fission <span class="hlt">gas</span> swelling that can lead to a counter measure to potential performance limit. The microscopic characterization data, particularly in the pre-transition regime, can also be used in developing a mechanistic model that predicts fission <span class="hlt">gas</span> <span class="hlt">bubble</span> behavior as a function of burnup and helps identify critical physical properties for the future tests. Analyses of grain and grain boundary morphology were performed. Optical micrographs and scanning electron micrographs of irradiated fuel from RERTR-1, 2, 3 and 5 tests were used. Micrographic comparisons between as-fabricated and as-irradiated fuel revealed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA199582','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA199582"><span>Observation of Brewster Angle Light Scattering from Air <span class="hlt">Bubbles</span> <span class="hlt">Rising</span> in Water</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1988-08-25</p> <p>At the bottom of this pipe a hollow needle is placed which is connected to an air supply. By regulating the air through the needle <span class="hlt">bubbles</span> were...back scattering direction a beamsplitter was inserted in the light path. Then a retroreflector was placed behind the beamsplitter. The beam coming...out of the retroreflector is reflected at 45’ off the beamsplitter and then focused to a point. This point now defines the backwards direction. 03 0 t W</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/712124','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/712124"><span><span class="hlt">Gas-bubble</span> growth mechanisms in the analysis of metal fuel swelling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gruber, E E; Kramer, J M</p> <p>1985-10-01</p> <p>The FRAS3 code has been applied to analysis of a series of experiments on irradiated uranium fuel. Comparison of the predicted <span class="hlt">bubble</span>-size distributions to those measured indicate that grain-boundary <span class="hlt">bubbles</span> are an important component of the fission-<span class="hlt">gas</span> inventory. In these experiments, <span class="hlt">bubble</span> growth rates were not a factor because of the long heating times. On transient time scales, however, various <span class="hlt">bubble</span>-growth mechanisms become important in determining swelling rates. These mechanisms include growth by diffusion, for <span class="hlt">bubbles</span> within grains and on grain boundaries; dislocation nucleation at the <span class="hlt">bubble</span> surface, or "punchout"; and <span class="hlt">bubble</span> growth by creep. Analyses of these mechanisms are presented and applied to provide information on the conditions and the relative time scales for which the various processes should dominate fuel swelling. The results are compared to a series of experiments in which the swelling of irradiated metal fuel was determined after annealing at various temperatures and pressures. The diffusive growth of <span class="hlt">bubbles</span> on grain boundaries is concluded to be dominant in these experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090019007','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090019007"><span>Vapor-<span class="hlt">Gas</span> <span class="hlt">Bubble</span> Evolution and Growth in Extremely Viscous Fluids Under Vacuum</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kizito, John; Balasubramaniam, R.; Nahra, Henry; Agui, Juan; Truong, Duc</p> <p>2008-01-01</p> <p>Formation of vapor and <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> expansion process may ensue. <span class="hlt">Bubble</span> 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 <span class="hlt">bubbling</span> 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 <span class="hlt">bubbles</span>. Another aspect of the present study was to determine the likelihood of <span class="hlt">bubbling</span> resulting from dissolved gases nucleating from solution. These experimental studies of the <span class="hlt">bubble</span> expansion are compared with predictions using a modified Rayleigh- Plesset equation, which models the <span class="hlt">bubble</span> expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS24C..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS24C..07M"><span>How sea level <span class="hlt">rise</span> and storm climate impact the looming morpho-economic <span class="hlt">bubble</span> in coastal property value.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McNamara, D.; Keeler, A.; Smith, M.; Gopalakrishnan, S.; Murray, A.</p> <p>2012-12-01</p> <p>In the United States, the coastal region is now the most densely populated zone in the country and as a result has become a significant source of tax revenue and has some of the highest property values in the country. The loss of land at the coastline from erosion and damage to property from storms has always been a source of vulnerability to coastal economies. To manage this vulnerability, humans have long engaged in the act of nourishing the coastline - placing sand, typically from offshore sources, onto the beach to widen the beach and increase the height of dunes. As humans alter natural coastal dynamics by nourishing, the altered natural dynamics then influence future beach management decisions. In this way human-occupied coastlines are a strongly coupled dynamical system and because of this coupling, the act of nourishment has become an intrinsic part of the economic value of a coastline. Predictions of increased rates of sea level <span class="hlt">rise</span> and changing storminess suggest that coastal vulnerability is likely to increase. The evolving vulnerability of the coast has already caused changes to occur in the way humans manage the coastline. For example, the federal government has recently reduced subsidies to help coastal communities nourish their beaches. With a future of changing environmental forcing from sea level and storms, the prospect of changes in nourishment cost could have profound consequences on coastal value and sustainability. We utilize two modeling approaches to investigate how disappearing nourishment subsidies reduce coastal property value and to explore the potential for a <span class="hlt">bubble</span> and subsequent crash in coastal property value as subsidies dwindle and vulnerability <span class="hlt">rises</span>. The first model is an optimal control model that couples a cost benefit analysis to coastline dynamics. In the second model, we couple a numerical coastline model with an agent-based model for real estate markets. Results from both models suggest the total present value of coastal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5819697','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5819697"><span><span class="hlt">Gas-bubble</span> growth mechanisms in the analysis of metal fuel swelling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gruber, E.E.; Kramer, J.M.</p> <p>1986-06-01</p> <p>During steady-state irradiation, swelling rates associated with growth of fission-<span class="hlt">gas</span> <span class="hlt">bubbles</span> in metallic fast reactor fuels may be expected to remain small. As a consequence, <span class="hlt">bubble</span>-growth mechanisms are not a major consideration in modeling the steady-state fuel behavior, and it is usually adequate to consider the <span class="hlt">gas</span> pressure to be in equilibrium with the external pressure and surface tension restraint. On transient time scales, however, various <span class="hlt">bubble</span>-growth mechanisms become important components of the swelling rate. These mechanisms include growth by diffusion, for <span class="hlt">bubbles</span> within grains and on grain boundaries; dislocation nucleation at the <span class="hlt">bubble</span> surface, or ''punchout''; and <span class="hlt">bubble</span> growth by creep. Analyses of these mechanisms are presented and applied to provide information on the conditions and the relative time scales for which the various processes should dominate fuel swelling. The results are compared to a series of experiments in which the swelling of irradiated metal fuel was determined after annealing at various temperatures and pressures. The diffusive growth of <span class="hlt">bubbles</span> on grain boundaries is concluded to be dominant in these experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6850454','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6850454"><span><span class="hlt">Gas</span> <span class="hlt">bubble</span> disease in smallmouth bass and northern squawfish from the Snake and Columbia Rivers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Montgomery, J.C.; Becker, C.D.</p> <p>1980-11-01</p> <p>In 1975 and 1976, 179 smallmouth bass (Micropterus dolomieui) and 85 northern squawfish (Ptychocheilus oregonensis) were collected by angling from the lower Snake and mid-Columbia rivers, southeastern Washington. All fish were examined externally for <span class="hlt">gas</span> <span class="hlt">bubble</span> syndrome. Emboli were found beneath membranes of the opercula, body, and fins of 72% of the smallmouth bass and 84% of the northern squawfish. Hemorrhage was also noted on the caudal, anal, and pectoral fins of several smallmouth bass. Presence of <span class="hlt">gas</span> <span class="hlt">bubble</span> syndrome corresponded to the spring runoff when total dissolved <span class="hlt">gas</span> supersaturations in river water exceeded 115%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850049053&hterms=HABER&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHABER','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850049053&hterms=HABER&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHABER"><span>Analysis of an oscillatory oil squeeze film containing a central <span class="hlt">gas</span> <span class="hlt">bubble</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haber, S.; Etsion, I.</p> <p>1985-01-01</p> <p>A squeeze-film damper, consisting of two circular plates, having only normal oscillatory relative motion is considered. The liquid lubricant between the plates is assumed to contain a single central <span class="hlt">gas</span> <span class="hlt">bubble</span>. The effect of the <span class="hlt">bubble</span> on the damper performance is analyzed. Comparison is made with the performance of a pure liquid damper. Substantial deviations in peak dynamic pressures are predicted which explain discrepancies between experimental and theoretical results reported in the literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/650232','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/650232"><span><span class="hlt">Gas</span> <span class="hlt">Bubble</span> Disease Monitoring and Research of Juvenile Salmonids : Annual Report 1996.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Maule, Alec G.; Beeman, John W.; Hans, Karen M.; Mesa, M.G.; Haner, P.; Warren, J.J.</p> <p>1997-10-01</p> <p>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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> supersaturation (Chapter 1). As in 1995, few fish had any signs of <span class="hlt">gas</span> <span class="hlt">bubble</span> disease, but it appeared that prevalence and severity increased as fish migrated downstream and in response to changing <span class="hlt">gas</span> supersaturation (Chapter 2). It appeared to <span class="hlt">gas</span> <span class="hlt">bubble</span> disease was not a threat to migrating juvenile salmonids when total dissolved <span class="hlt">gas</span> supersaturation was < 120% (Chapter 2). Laboratory studies suggest that external examinations are appropriate for determining the severity of <span class="hlt">gas</span> <span class="hlt">bubble</span> disease in juvenile salmonids (Chapter 3). The authors developed a new method for examining gill arches for intravascular <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> disease is a progressive trauma that can be monitored (Chapter 3).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ExFl...56..177A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ExFl...56..177A"><span>Shadow imaging in <span class="hlt">bubbly</span> <span class="hlt">gas</span>-liquid two-phase flow in porous structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Altheimer, Marco; Häfeli, Richard; Wälchli, Carmen; Rudolf von Rohr, Philipp</p> <p>2015-09-01</p> <p>Shadow imaging is used for the investigation of <span class="hlt">bubbly</span> <span class="hlt">gas</span>-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 <span class="hlt">bubble</span> shadows are processed to measure the <span class="hlt">bubble</span> dimensions. Therefore, a new processing sequence is developed to determine <span class="hlt">bubble</span> dimensions from overlapping <span class="hlt">bubble</span> shadows by ellipse fitting. The accuracy of the <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> hold-up and total interfacial area can be measured with only one camera. Operation parameters for <span class="hlt">gas</span>-liquid two-phase flows are determined to improve mass and heat transfer between the phases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APhy...62..179G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APhy...62..179G"><span>Sound waves in a liquid with polydisperse vapor-<span class="hlt">gas</span> <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gubaidullin, D. A.; Fedorov, Yu. V.</p> <p>2016-03-01</p> <p>A mathematical model is presented for the propagation of plane, spherical, and cylindrical sound waves in a liquid containing polydisperse vapor-<span class="hlt">gas</span> <span class="hlt">bubbles</span> with allowance for phase transitions. A system of integro-differential equations is constructed to describe perturbed motion of a two-phase mixture, and a dispersion relation is derived. An expression for equilibrium sound velocity is obtained for a <span class="hlt">gas</span>-liquid or vapor-liquid mixture. The theoretical results agree well with the known experimental data. The dispersion curves obtained for the phase velocity and the attenuation coefficient in a mixture of water with vapor-<span class="hlt">gas</span> <span class="hlt">bubbles</span> are compared for various values of vapor concentration in the <span class="hlt">bubbles</span> and various <span class="hlt">bubble</span> distributions in size. The evolution of pressure pulses of plane and cylindrical waves is demonstrated for different values of the initial vapor concentration in <span class="hlt">bubbles</span>. The calculated frequency dependence of the phase sound velocity in a mixture of water with vapor <span class="hlt">bubbles</span> is compared with experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15000170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15000170"><span>Nonlinear dynamics of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in an incompressible elastic medium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Emelianov, Stanislav Y; Hamilton, Mark F; Ilinskii, Yurii A; Zabolotskaya, Evgenia A</p> <p>2004-02-01</p> <p>A nonlinear model in the form of the Rayleigh-Plesset equation is developed for a <span class="hlt">gas</span> <span class="hlt">bubble</span> in an essentially incompressible elastic medium such as a tissue or rubberlike medium. Two constitutive laws for the elastic medium are considered: the Mooney potential, and Landau's expansion of the strain energy density. These two constitutive laws are compared at quadratic order to obtain a relation between their respective elastic constants. Attention is devoted to the relative importance of shear stress on the <span class="hlt">bubble</span> dynamics, allowing for the equilibrium <span class="hlt">gas</span> pressure in the <span class="hlt">bubble</span> to differ substantially from the pressure at infinity. The model for the <span class="hlt">bubble</span> motion is approximated to quadratic order to assess the importance of shear stress in the surrounding medium relative to that of the <span class="hlt">gas</span> pressure in the <span class="hlt">bubble</span>. Relations are derived for the value of the shear wave speed at which the two contributions are comparable, which provide an assessment of when shear stress in the surrounding medium must be taken into account when modeling <span class="hlt">bubble</span> dynamics.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Ocgy...50..995M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Ocgy...50..995M"><span>The hydroacoustic method for the quantification of the <span class="hlt">gas</span> flux from a submersed <span class="hlt">bubble</span> plume</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muyakshin, S. I.; Sauter, E.</p> <p>2010-12-01</p> <p>This article presents an inverse hydroacoustic method for the remote quantification of the total <span class="hlt">gas</span> flux transported from an underwater <span class="hlt">bubble</span> plume. The method includes the surveying of the <span class="hlt">bubble</span> plume by a vertically looking echo sounder and the calculation of the flux using the spatial distribution of the ultrasound backscattering at a fixed depth. A simplified parameterization containing only a few parameters is introduced to describe the empirical <span class="hlt">bubble</span> size distribution. The linear correlation between the backscattering cross section of the <span class="hlt">bubble</span> stream and the vertical <span class="hlt">gas</span> flux is found. The calculation procedure takes into account the occurrence of a <span class="hlt">gas</span> hydrate film at the <span class="hlt">bubble</span>'s surface. The influence of different parameters on the accuracy of the method is investigated. The resolution volume of the echo sounder corresponding to the fixed distance is considered as a two-dimensional spatial window. The method was applied to quantify the total convective methane flux at the Haakon-Mosby mud volcano (HMMV) depth 1280 m. The calculated values of the total flux near the bottom (100-400 t/year) are in good agreement with the independently estimated flux for the single <span class="hlt">bubble</span> jet observed from the ROV (70 t/year). These calculations also show significant temporal variability of the flux at the HMMV. The total flux was found to vary by about a factor of 2-3 within time scales of days.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16309977','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16309977"><span>A physiological model of the release of <span class="hlt">gas</span> <span class="hlt">bubbles</span> from crevices under decompression.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chappell, M A; Payne, S J</p> <p>2006-09-28</p> <p>Moving <span class="hlt">bubbles</span> have been observed in the blood during or after decompression using ultrasonic techniques. It has been proposed that these may grow from nuclei housed on the blood vessel wall. One candidate for <span class="hlt">bubble</span> nucleation is hydrophobic crevices. This work explores the growth of <span class="hlt">gas</span> pockets that might exist in conical crevices and the release of <span class="hlt">bubbles</span> from these crevices under decompression. An existing dynamic mathematical model for the stability of <span class="hlt">gas</span> pockets in crevices [Chappell, M.A., Payne, S.J., in press. A physiological model of <span class="hlt">gas</span> pockets in crevices and their behavior under compression. Respir. Physiol. Neurobiol.] is extended to include the behavior as the <span class="hlt">gas</span> pocket reaches the crevice mouth and <span class="hlt">bubbles</span> seed into the bloodstream. The behavior of the crevice <span class="hlt">bubble</span> is explored for a single inert <span class="hlt">gas</span>, both alone and with metabolic gases included. It was found that the presence of metabolic gases has a significant effect on the behavior under decompression and that this appears to be due to the high diffusivity of these gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017WRR....53.2755T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017WRR....53.2755T"><span><span class="hlt">Gas</span> <span class="hlt">bubble</span> size estimation in peat soils from EM wave scattering observed with ground penetrating radar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Terry, Neil; Slater, Lee</p> <p>2017-04-01</p> <p>The size of biogenic <span class="hlt">gas</span> <span class="hlt">bubbles</span> in peatlands is believed to regulate ebullition of carbon gases to the atmosphere. The measurement of electromagnetic (EM) wave travel times using ground penetrating radar (GPR) is a proven field-scale method for indirect estimation of volumetric <span class="hlt">gas</span> content. However, there is also the possibility that information on the size of the <span class="hlt">gas</span> <span class="hlt">bubbles</span> can be determined from the analysis of the spectral content of GPR signals as scattering attenuation possesses a frequency dependence for <span class="hlt">bubbles</span> smaller than the EM wavelength (Rayleigh-type scattering). Theoretical modeling shows that GPR data acquired with typical antenna frequencies are likely to be affected by <span class="hlt">bubble</span> size in peat soils. Analysis of GPR data from two recent studies on peat monoliths where biogenic <span class="hlt">gas</span> production was documented produced results consistent with the model predictions. Using the approach, zero offset cross-borehole GPR data in a northern peatland suggest that large <span class="hlt">bubble</span> clusters (i.e., 0.05 m radius) occur in peat. These findings broaden the utility of GPR for providing information on biogenic <span class="hlt">gas</span> dynamics in peatlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSHI54B1859P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSHI54B1859P"><span>In Situ Raman Spectroscopic Observations of <span class="hlt">Gas</span>-Saturated <span class="hlt">Rising</span> Oil droplets: Simulation with Decane as an Oil-Equivalent Substitute</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peltzer, E. T.; Walz, P. M.; Brewer, P. G.</p> <p>2016-02-01</p> <p>Oil droplets <span class="hlt">rising</span> from the sea floor, whether from seeps or well leakage, contain very large quantities of dissolved <span class="hlt">gas</span> that profoundly affects their density and critical oil-water interfacial characteristics. The primary dissolved <span class="hlt">gas</span> is methane which may be up to 30% of the molar volume. This can create a hydrate skin as the methane <span class="hlt">gas</span> is shed from the oil as it <span class="hlt">rises</span> through the water column, thus decreasing in pressure and increasing in temperature, and steadily changing the <span class="hlt">rising</span> droplet buoyancy. We have explored this phenomenon by executing controlled ROV based experiments with a "<span class="hlt">bubble</span> cup" technique in which a small volume of <span class="hlt">gas</span> saturated decane (saturated with pure methane, a mix of methane and nitrogen , or a mix of methane and CO2) is interrogated by laser Raman spectroscopy. The use of decane as an oil "substitute" is required since natural oil samples are highly fluorescent due to the presence of polycyclic aromatic hydrocarbons. We have devised Matlab techniques for extracting the spectroscopic dissolved methane signal from the thicket of decane peaks that surround it. We have directly observed the rate at which gases are lost from the "oil" per unit area at depths in the water column that are both within and outside the hydrate forming phase boundary. We have compared the behavior of both a non-hydrate forming dissolved <span class="hlt">gas</span> (nitrogen) with CO2 where the hydrate phase boundary is at significantly shallower depth. The results indicate complex interfacial behavior and physical chemistry. We did not observe direct <span class="hlt">gas</span> <span class="hlt">bubble</span> formation on the decane outer surface but did observe <span class="hlt">gas</span> <span class="hlt">bubble</span> formation within the oil droplets as they rose through the water column. Because there are significant energy barriers for homogeneous <span class="hlt">bubble</span> formation within the decane phase, we took this as evidence of significant <span class="hlt">gas</span> super-saturation within the oil droplet. The <span class="hlt">gas</span> loss rates increased significantly in all cases when the hydrate phase boundary was crossed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AnRFM..49..221P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AnRFM..49..221P"><span>Vapor <span class="hlt">Bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prosperetti, Andrea</p> <p>2017-01-01</p> <p>This article reviews the fundamental physics of vapor <span class="hlt">bubbles</span> in liquids. Work on <span class="hlt">bubble</span> growth and condensation for stationary and translating <span class="hlt">bubbles</span> is summarized and the differences with <span class="hlt">bubbles</span> containing a permanent <span class="hlt">gas</span> stressed. In particular, it is shown that the natural frequency of a vapor <span class="hlt">bubble</span> is proportional not to the inverse radius, as for a <span class="hlt">gas</span> <span class="hlt">bubble</span>, but to the inverse radius raised to the power 2/3. Permanent <span class="hlt">gas</span> dissolved in the liquid diffuses into the <span class="hlt">bubble</span> with strong effects on its dynamics. The effects of the diffusion of heat and mass on the propagation of pressure waves in a vaporous <span class="hlt">bubbly</span> liquid are discussed. Other topics briefly touched on include thermocapillary flow, plasmonic nanobubbles, and vapor <span class="hlt">bubbles</span> in an immiscible liquid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26293176','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26293176"><span><span class="hlt">Gas</span> holdup in cyclone-static micro-<span class="hlt">bubble</span> flotation column.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Xiaobing; Zhu, Wei; Liu, Jiongtian; Zhang, Jian; Xu, Hongxiang; Deng, Xiaowei</p> <p>2016-01-01</p> <p>The present work has been carried out to investigate the effect of process variables on <span class="hlt">gas</span> holdup and develop an empirical equation and a neural network model for online process control of the <span class="hlt">gas</span> holdup based on the operating variables. In this study, the effect of process variables (nozzle diameter, circulation pressure, aeration rate, and frother dosage) on <span class="hlt">gas</span> holdup in a cyclone-static micro-<span class="hlt">bubble</span> flotation column of an air/oily wastewater system was investigated. <span class="hlt">Gas</span> holdup was estimated using a pressure difference method and an empirical equation was proposed to predict <span class="hlt">gas</span> holdup. A general regression neural network (GRNN) model was also introduced to predict <span class="hlt">gas</span> holdup for the cyclone-static micro-<span class="hlt">bubble</span> flotation column. The predictions from the empirical equation and the GRNN are in good agreement with the experiment data for <span class="hlt">gas</span> holdup, while the GRNN provides higher accuracy and stability compared with that of the empirical equation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22949261','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22949261"><span><span class="hlt">Gas</span> pockets in a wastewater <span class="hlt">rising</span> main: a case study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pozos-Estrada, Oscar; Fuentes-Mariles, Oscar A; Pozos-Estrada, Adrian</p> <p>2012-01-01</p> <p>This paper presents a case study of an existing wastewater <span class="hlt">rising</span> main (WWRM) in which an extreme transient event produced by simultaneous power failure of the pumps caused the rupture of a 1.2 m (48 in) prestressed concrete cylinder pipe (PCCP), causing an important leakage of sewage. The event and the methodology followed in order to validate the diagnostics of the failure are described. The detail study included in situ observation of the system, experimental investigation in a setup, hydraulic analysis, as well as details of the structural strength of the WWRM. After the extensive investigation and several simulations of fluid transients for different scenarios and flow conditions, it was found that stationary small <span class="hlt">gas</span> pockets accumulated at high points of the WWRM were identified as the principal contributory factor of the failure. This case study serves as clear warning of the consequences of operating a WWRM with <span class="hlt">gas</span> pockets at its high points.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GBioC..19.1003S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GBioC..19.1003S"><span>Dynamics of biogenic <span class="hlt">gas</span> <span class="hlt">bubbles</span> in peat and their effects on peatland biogeochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strack, M.; Kellner, E.; Waddington, J. M.</p> <p>2005-03-01</p> <p>Production and emission of peat <span class="hlt">gas</span> has attracted great interest because substantial amounts of methane (CH4) are emitted to the atmosphere from peat soils. Many studies indicate supersaturation of CH4 in peat water, implying a high potential for <span class="hlt">gas</span> <span class="hlt">bubble</span> formation. However, observations of <span class="hlt">bubbles</span> in peat are often only qualitatively described, and in most cases the presence of entrapped <span class="hlt">gas</span> has been largely ignored in peatland studies. On the basis of a review of literature, a conceptual model of entrapped <span class="hlt">gas</span> dynamics was developed and investigated using field and laboratory measurements at a poor fen in central Québec. We investigated variations in production and volume of <span class="hlt">gas</span> and the effect of this <span class="hlt">gas</span> on trace <span class="hlt">gas</span> emissions, peat buoyancy, and pore water chemistry during 2002 and 2003. Measurements made with moisture probes and subsurface <span class="hlt">gas</span> collectors revealed that <span class="hlt">gas</span> volume varied throughout the growing season in relation to hydrostatic and barometric pressure. Shifts in entrapped <span class="hlt">gas</span> volume were also coincident with changes in dissolved pore water CH4. The presence of these <span class="hlt">bubbles</span> has important biogeochemical effects, including the development of localized CH4 diffusion gradients, alteration of local flow paths affecting substrate delivery, peat buoyancy, and the potential episodic release of CH4 via ebullition events. These interactions must be included in peatland models to describe accurately the hydrology and greenhouse <span class="hlt">gas</span> emissions from these ecosystems and to make predictions about their response to environmental change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1353468-alma-observations-massive-molecular-gas-filaments-encasing-radio-bubbles-phoenix-cluster','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1353468-alma-observations-massive-molecular-gas-filaments-encasing-radio-bubbles-phoenix-cluster"><span>Alma observations of massive molecular <span class="hlt">gas</span> filaments encasing radio <span class="hlt">bubbles</span> in the Phoenix cluster</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Russell, H. R.; McDonald, M.; McNamara, B. R.; ...</p> <p>2017-02-14</p> <p>We report new ALMA observations of the CO(3-2) line emission from themore » $$2.1\\pm0.3\\times10^{10}\\rm\\thinspace M_{\\odot}$$ molecular <span class="hlt">gas</span> reservoir in the central galaxy of the Phoenix cluster. The cold molecular <span class="hlt">gas</span> 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 <span class="hlt">bubbles</span> filled with relativistic plasma into the hot, X-ray atmospheres surrounding the host galaxy. The ALMA observations show that extended filaments of molecular <span class="hlt">gas</span>, each $$10-20\\rm\\; kpc$$ long with a mass of several billion solar masses, are located along the peripheries of the radio <span class="hlt">bubbles</span>. The smooth velocity gradients and narrow line widths along each filament reveal massive, ordered molecular <span class="hlt">gas</span> flows around each <span class="hlt">bubble</span>, which are inconsistent with gravitational free-fall. The molecular clouds have been lifted directly by the radio <span class="hlt">bubbles</span>, or formed via thermal instabilities induced in low entropy <span class="hlt">gas</span> lifted in the updraft of the <span class="hlt">bubbles</span>. These new data provide compelling evidence for close coupling between the radio <span class="hlt">bubbles</span> and the cold <span class="hlt">gas</span>, which is essential to explain the self-regulation of feedback. As a result, the very feedback mechanism that heats hot atmospheres and suppresses star formation may also paradoxically stimulate production of the cold <span class="hlt">gas</span> required to sustain feedback in massive galaxies.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28696476','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28696476"><span>On the origin of the driving force in the Marangoni propelled <span class="hlt">gas</span> <span class="hlt">bubble</span> trapping mechanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miniewicz, A; Quintard, C; Orlikowska, H; Bartkiewicz, S</p> <p>2017-07-19</p> <p><span class="hlt">Gas</span> <span class="hlt">bubbles</span> can be trapped and then manipulated with laser light. In this report, we propose the detailed optical trapping mechanism of <span class="hlt">gas</span> <span class="hlt">bubbles</span> confined inside a thin light-absorbing liquid layer between two glass plates. The necessary condition of <span class="hlt">bubble</span> trapping in this case is the direct absorption of light by the solution containing a dye. Due to heat release, fluid whirls propelled by the surface Marangoni effect at the liquid/<span class="hlt">gas</span> interface emerge and extend to large distances. We report the experimental microscopic observation of the origin of whirls at an initially flat liquid/air interface as well as at the curved interface of a liquid/<span class="hlt">gas</span> <span class="hlt">bubble</span> and support this finding with advanced numerical simulations using the finite element method within the COMSOL Multiphysics platform. The simulation results were in good agreement with the observations, which allowed us to propose a simple physical model for this particular trapping mechanism, to establish the origin of forces attracting <span class="hlt">bubbles</span> toward a laser beam and to predict other phenomena related to this effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005WRR....4108417K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005WRR....4108417K"><span>Dynamics of biogenic <span class="hlt">gas</span> <span class="hlt">bubbles</span> in peat: Potential effects on water storage and peat deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kellner, E.; Waddington, J. M.; Price, J. S.</p> <p>2005-08-01</p> <p>Dynamics of biogenic <span class="hlt">bubbles</span> in peat soils were studied at a field site in southern Québec, Canada. The maximum <span class="hlt">gas</span> content measured in this study varied spatially with a maximum seasonal increase in volumetric <span class="hlt">gas</span> content of 0.15. The size of changes in total <span class="hlt">gas</span> content of a 1 m deep profile was comparable to the seasonal water storage change. Changes in <span class="hlt">bubble</span> volume in the saturated zone alter the water table level and, consequently, the water content in the unsaturated zone and the apparent water budget. In highly compressible soils (and floating root mats), buoyancy forces from <span class="hlt">bubbles</span> also cause relations between the surface and the water table to change. These effects cannot be omitted in modeling the hydrology of peatlands. Our results indicate a great spatial variability of trapped <span class="hlt">bubbles</span>. Using pressure transducers sealed to the surface, we found pressure deviations indicating small areas closed off by <span class="hlt">bubbles</span> clogging the pores. The hydrological influence of these areas may be considerable as they may restrict or deflect water flows. Open pipe piezometers did not show these pressure deviations, possibly because the closed zones were too small to influence the head in pipes or because of less amount of <span class="hlt">gas</span> close to the pipe screen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016A%26A...585A.117Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016A%26A...585A.117Z"><span>N131: A dust <span class="hlt">bubble</span> born from the disruption of a <span class="hlt">gas</span> filament</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Chuan-Peng; Li, Guang-Xing; Wyrowski, Friedrich; Wang, Jun-Jie; Yuan, Jing-Hua; Xu, Jin-Long; Gong, Yan; Yeh, Cosmos C.; Menten, Karl M.</p> <p>2016-01-01</p> <p>Context. OB-type stars have strong ionizing radiation and drive energetic winds. The ultraviolet radiation from ionizing stars may heat dust and ionize <span class="hlt">gas</span> to sweep up an expanding <span class="hlt">bubble</span> shell. This shell may be the result of feedback leading to a new generation of stars. Aims: N131 is an infrared dust <span class="hlt">bubble</span> residing in a molecular filament. We study the formation and fragmentation of this <span class="hlt">bubble</span> with multiwavelength dust and <span class="hlt">gas</span> observations. Methods: Towards the <span class="hlt">bubble</span> N131, we analysed archival multiwavelength 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. Results: Multiwavelength dust and <span class="hlt">gas</span> observations reveal a ring-like shell with compact fragments, two filamentary structures, and the secondary <span class="hlt">bubble</span> N131-A. <span class="hlt">Bubble</span> N131 is a rare object with a large hole at 24 μm and 21 cm in the direction of its centre. The dust and <span class="hlt">gas</span> clumps are compact and might have been compressed at the inner edge of the ring-like 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 ring-like shell. We also detected the front and back sides of the secondary <span class="hlt">bubble</span> N131-A in the direction of its centre. 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 <span class="hlt">bubble</span> N131 might be triggered by the strong stellar winds from a group of massive stars inside the <span class="hlt">bubble</span>. Conclusions: We propose a scenario in which the <span class="hlt">bubble</span> N131 forms from the disruption of a <span class="hlt">gas</span> filament by the expansion of the H II region, strong stellar winds, and fragments under self-gravity. The reduced datacubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1061013','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1061013"><span>Random-Walk Monte Carlo Simulation of Intergranular <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Nucleation in UO2 Fuel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yongfeng Zhang; Michael R. Tonks; S. B. Biner; D.A. Andersson</p> <p>2012-11-01</p> <p>Using a random-walk particle algorithm, we investigate the clustering of fission <span class="hlt">gas</span> atoms on grain bound- aries in oxide fuels. The computational algorithm implemented in this work considers a planar surface representing a grain boundary on which particles appear at a rate dictated by the Booth flux, migrate two dimensionally according to their grain boundary diffusivity, and coalesce by random encounters. Specifically, the intergranular <span class="hlt">bubble</span> nucleation density is the key variable we investigate using a parametric study in which the temperature, grain boundary <span class="hlt">gas</span> diffusivity, and grain boundary segregation energy are varied. The results reveal that the grain boundary <span class="hlt">bubble</span> nucleation density can vary widely due to these three parameters, which may be an important factor in the observed variability in intergranular <span class="hlt">bubble</span> percolation among grain boundaries in oxide fuel during fission <span class="hlt">gas</span> release.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1136318','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1136318"><span>Modeling the influence of <span class="hlt">bubble</span> pressure on grain boundary separation and fission <span class="hlt">gas</span> release</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pritam Chakraborty; Michael R. Tonks; Giovanni Pastore</p> <p>2014-09-01</p> <p>Grain boundary (GB) separation as a mechanism for fission <span class="hlt">gas</span> release (FGR), complementary to <span class="hlt">gas</span> <span class="hlt">bubble</span> interlinkage, has been experimentally observed in irradiated light water reactor fuel. However there has been limited effort to develop physics-based models incorporating this mechanism for the analysis of FGR. In this work, a computational study is carried out to investigate GB separation in UO2 fuel under the effect of <span class="hlt">gas</span> <span class="hlt">bubble</span> pressure and hydrostatic stress. A non-dimensional stress intensity factor formula is obtained through 2D axisymmetric analyses considering lenticular <span class="hlt">bubbles</span> and Mode-I crack growth. The obtained functional form can be used in higher length-scale models to estimate the contribution of GB separation to FGR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28088847','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28088847"><span>Vapor and <span class="hlt">Gas-Bubble</span> Growth Dynamics around Laser-Irradiated, Water-Immersed Plasmonic Nanoparticles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yuliang; Zaytsev, Mikhail E; The, Hai Le; Eijkel, Jan C T; Zandvliet, Harold J W; Zhang, Xuehua; Lohse, Detlef</p> <p>2017-02-28</p> <p>Microbubbles produced by exposing water-immersed metallic nanoparticles to resonant light play an important role in emerging and efficient plasmonic-enhanced processes for catalytic conversion, solar energy harvesting, biomedical imaging, and cancer therapy. How do these <span class="hlt">bubbles</span> form, and what is their <span class="hlt">gas</span> composition? In this paper, the growth dynamics of nucleating <span class="hlt">bubbles</span> around laser-irradiated, water-immersed Au plasmonic nanoparticles are studied to determine the exact origin of the occurrence and growth of these <span class="hlt">bubbles</span>. The microbubbles' contact angle, footprint diameter, and radius of curvature were measured in air-equilibrated water (AEW) and degassed water (DGW) with fast imaging. Our experimental data reveals that the growth dynamics can be divided into two regimes: an initial <span class="hlt">bubble</span> nucleation phase (regime I, < 10 ms) and, subsequently a <span class="hlt">bubble</span> growth phase (regime II). The explosive growth in regime I is identical for AEW and DGW due to the vaporization of water. However, the slower growth in regime II is distinctly different for AEW and DGW, which is attributed to the uptake of dissolved <span class="hlt">gas</span> expelled from the water around the hot nanoparticle. Our scaling analysis reveals that the <span class="hlt">bubble</span> radius scales with time as R(t) ∝ t(1/6) for both AEW and DGW in the initial regime I, whereas in the later regime II it scales as R(t) ∝ t(1/3) for AEW and is constant for perfectly degassed water. These scaling relations are consistent with the experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/95187','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/95187"><span><span class="hlt">Bubble</span> retention in synthetic sludge: Testing of alternative <span class="hlt">gas</span> retention apparatus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rassat, S.D.; Gauglitz, P.A.</p> <p>1995-07-01</p> <p>Several of the underground storage tanks currently used to store waste at Hanford have been placed on the Flammable <span class="hlt">Gas</span> Watch List, because the waste is either known or suspected to generate, store, and episodically release flammable gases. The objective of this experimental study is to develop a method to measure <span class="hlt">gas</span> <span class="hlt">bubble</span> retention in simulated tank waste and in diluted simulant. The method and apparatus should (1) allow for reasonably rapid experiments, (2) minimize sample disturbance, and (3) provide realistic <span class="hlt">bubble</span> nucleation and growth. The scope of this experimental study is to build an apparatus for measuring <span class="hlt">gas</span> retention in simulated waste and to design the apparatus to be compatible with future testing on actual waste. The approach employed for creating <span class="hlt">bubbles</span> in sludge involves dissolving a soluble <span class="hlt">gas</span> into the supernatant liquid at an elevated pressure, recirculating the liquid containing the dissolved <span class="hlt">gas</span> through the sludge, then reducing the pressure to allow <span class="hlt">bubbles</span> to nucleate and grow. Results have been obtained for ammonia as the soluble <span class="hlt">gas</span> and SY1-SIM-91A, a chemically representative simulated tank waste. In addition, proof-of-principle experiments were conducted with both ammonia and CO{sub 2} as soluble gases and sludge composed of 90-micron glass beads. Results are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011HMT....47.1621M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011HMT....47.1621M"><span>Growth of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in a supersaturated and slightly compressible liquid at low Mach number</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohammadein, S. A.; Mohamed, K. G.</p> <p>2011-12-01</p> <p>In this paper, the growth of a <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA250135','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA250135"><span>A Detector for Stationary <span class="hlt">Gas</span> <span class="hlt">Bubbles</span>: Feasibility Studies</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1992-04-01</p> <p>transmitted signal off of a slab of Wall-Gone rubber sound absorber with the divide-by-2 circuit in use and no <span class="hlt">bubbles</span> apparent. Using Wall-Gone as the...transmitting transducer, and a mixer), and by nonlinear vibration of the Wall-Gone rubber . On the other hand, noise levels are considerably lower with Wall...attained during a steady state oscillation. In Prosperetti, Crum , and Commander,𔃿 simplified governing equations are derived from the conservation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/95668','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/95668"><span>Leak testing of <span class="hlt">bubble</span>-tight dampers using tracer <span class="hlt">gas</span> techniques</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lagus, P.L.; DuBois, L.J.; Fleming, K.M.</p> <p>1995-02-01</p> <p>Recently tracer <span class="hlt">gas</span> techniques have been applied to the problem of measuring the leakage across an installed <span class="hlt">bubble</span>-tight damper. A significant advantage of using a tracer <span class="hlt">gas</span> 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 <span class="hlt">gas</span> technique can be used to provide an accurate field evaluation of the performance of installed <span class="hlt">bubble</span>-tight dampers on a periodic basis. Actual leakage flowrates were obtained at Zion Generating Station on four installed <span class="hlt">bubble</span>-tight dampers using a tracer <span class="hlt">gas</span> 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 <span class="hlt">bubble</span>-tight dampers--are not acceptable. These imprecise estimates can skew radioactive dose assessments as well as chemical contaminant exposure calculations. Using a tracer <span class="hlt">gas</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16968053','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16968053"><span>Champagne experiences various rhythmical <span class="hlt">bubbling</span> regimes in a flute.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liger-Belair, Gérard; Tufaile, Alberto; Jeandet, Philippe; Sartorelli, José-Carlos</p> <p>2006-09-20</p> <p><span class="hlt">Bubble</span> trains are seen <span class="hlt">rising</span> gracefully from a few points on the glass wall (called nucleation sites) whenever champagne is poured into a glass. As time passes during the <span class="hlt">gas</span>-discharging process, the careful observation of some given <span class="hlt">bubble</span> columns reveals that the interbubble distance may change suddenly, thus revealing different rhythmical <span class="hlt">bubbling</span> regimes. Here, it is reported that the transitions between the different <span class="hlt">bubbling</span> regimes of some nucleation sites during <span class="hlt">gas</span> discharging is a process which may be ruled by a strong interaction between tiny <span class="hlt">gas</span> pockets trapped inside the nucleation site and/or also by an interaction between the tiny <span class="hlt">bubbles</span> just blown from the nucleation site.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........47B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........47B"><span>Effects of <span class="hlt">gas</span> <span class="hlt">bubble</span> production on heat transfer from a volumetrically heated liquid pool</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bull, Geoffrey R.</p> <p></p> <p>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, <span class="hlt">bubbles</span> will form in the solution. <span class="hlt">Bubbles</span> 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 <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> characteristics and patterns on heat transfer from the pool. The manifold type did not appear to have significant impact on the <span class="hlt">bubble</span> size distributions in water. However, air injected into solutions of magnesium sulfate resulted in smaller <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> velocity in the pool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C11C0785F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C11C0785F"><span>Estimating Trapped <span class="hlt">Gas</span> Concentrations as <span class="hlt">Bubbles</span> Within Lake Ice Using Ground Penetrating Radar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fantello, N.; Parsekian, A.; Walter Anthony, K. M.</p> <p>2015-12-01</p> <p>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 (<span class="hlt">bubbling</span>) 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 <span class="hlt">gas</span> 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, <span class="hlt">gas</span> <span class="hlt">bubbles</span> are trapped in the ice and spatial variability in <span class="hlt">bubble</span> concentration within the ice is evident. To assess the variability in bulk physical properties of the ice due to <span class="hlt">bubbles</span>, 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 <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> 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 <span class="hlt">gas</span> content; and employing groundwave velocity we found 0.0712 and 2.9%, respectively. If locations of <span class="hlt">gas</span> seeps in lakes could be detected and quantified using GPR along with field measurements, this could help to constrain future lake-source carbon <span class="hlt">gas</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28511939','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28511939"><span>Droplet and <span class="hlt">bubble</span> formation of combined oil and <span class="hlt">gas</span> releases in subsea blowouts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Lin; Boufadel, Michel C; King, Thomas; Robinson, Brian; Gao, Feng; Socolofsky, Scott A; Lee, Kenneth</p> <p>2017-07-15</p> <p>Underwater blowouts from <span class="hlt">gas</span> and oil operations often involve the simultaneous release of oil and <span class="hlt">gas</span>. Presence of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in jets/plumes could greatly influence oil droplet formation. With the aim of understanding and quantifying the droplet formation from Deepwater Horizon blowout (DWH) we developed a new formulation for <span class="hlt">gas</span>-oil interaction with jets/plumes. We used the jet-droplet formation model VDROP-J with the new module and the updated model was validated against laboratory and field experimental data. Application to DWH revealed that, in the absence of dispersant, <span class="hlt">gas</span> input resulted in a reduction of d50 by up to 1.5mm, and maximum impact occurred at intermediate <span class="hlt">gas</span> fractions (30-50%). In the presence of dispersant, reduction in d50 due to <span class="hlt">bubbles</span> was small because of the promoted small sizes of both <span class="hlt">bubbles</span> and droplets by surfactants. The new development could largely enhance the prediction and response to oil and <span class="hlt">gas</span> blowouts. Copyright © 2017. Published by Elsevier Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApPhL.103v3106H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApPhL.103v3106H"><span>Field nano-localization of <span class="hlt">gas</span> <span class="hlt">bubble</span> production from water electrolysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hammadi, Z.; Morin, R.; Olives, J.</p> <p>2013-11-01</p> <p>Using a tip shaped electrode and ac voltages, we show that the production of micro <span class="hlt">bubbles</span> of <span class="hlt">gas</span> from water electrolysis is localized at the tip apex inside a domain in the voltage frequency phase space. A model taking into account the electrode shape and dimensions explains these results which suggest a field effect control of the electrolysis reaction rate at a nanometer scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JPS...139...79Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JPS...139...79Y"><span>In situ visualization study of CO 2 <span class="hlt">gas</span> <span class="hlt">bubble</span> behavior in DMFC anode flow fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, H.; Zhao, T. S.; Ye, Q.</p> <p></p> <p>This paper reports on a visual study of the CO 2 <span class="hlt">bubble</span> 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 <span class="hlt">bubbles</span> appeared in the anode flow field. At moderate current densities, a number of <span class="hlt">gas</span> slugs formed, in addition to small discrete <span class="hlt">bubbles</span>. And at high current densities, the flow field was predominated by rather long <span class="hlt">gas</span> 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 <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> slugs was never encountered under all the test conditions in this work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JPhCS.147a2032J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JPhCS.147a2032J"><span><span class="hlt">Gas</span>-Liquid flow characterization in <span class="hlt">bubble</span> columns with various <span class="hlt">gas</span>-liquid using electrical resistance tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, Haibo; Yuhuan, Han; Suohe, Yang</p> <p>2009-02-01</p> <p>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 <span class="hlt">gas</span>-liquid <span class="hlt">bubble</span> column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key <span class="hlt">bubble</span> flow characteristics in multi-phase medium. Radial variation of the <span class="hlt">gas</span> holdup and mean holdups are investigated in a 0.160 m i. d. <span class="hlt">bubble</span> column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the <span class="hlt">gas</span> 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 <span class="hlt">gas</span> velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial <span class="hlt">gas</span> holdup distribution is discussed. The results showed that the <span class="hlt">gas</span> 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 <span class="hlt">gas</span> holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AcAau..67..344Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AcAau..67..344Z"><span>Network simulation method applied to models of diffusion-limited <span class="hlt">gas</span> <span class="hlt">bubble</span> dynamics in tissue</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zueco, Joaquín; Hernández-González, A.</p> <p>2010-08-01</p> <p>In this work the Network Simulation Method is used to study decompression sickness (DCS) in human subjects after diving and/or flying exposures. <span class="hlt">Bubble</span> dynamics models suitable for these applications assume the <span class="hlt">bubble</span> to be either contained in an unstirred tissue (two-region model) or surrounded by a boundary layer within a well stirred tissue (three-region model). The main results are obtained using the three-region model of <span class="hlt">gas</span> <span class="hlt">bubble</span> dynamics, which consists of a <span class="hlt">bubble</span> and a well-stirred tissue region with an intervening unperfused diffusion region previously assumed to have a constant thickness and uniform <span class="hlt">gas</span> diffusivity. Spatial discretization is used to numerically solve the diffusion equation considering the transitory term, where programming does not involve manipulation of the sophisticated mathematical software that is inherent in other numerical methods. The technique in question is always stable and convergent. Different effects (among them, tissue volume, initial <span class="hlt">bubble</span> radius, surface tension of intercellular fluid and boundary layer thickness) are studied and plotted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.774a2202T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.774a2202T"><span>The effect of <span class="hlt">gas</span> <span class="hlt">bubbles</span> on electrical breakdown in transformer oil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tyuftyaev, A. S.; Gadzhiev, M. Kh; Sargsyan, M. A.; Akimov, P. L.; Demirov, N. A.</p> <p>2016-11-01</p> <p>To study the breakdown of transformer oil with <span class="hlt">gas</span> <span class="hlt">bubbles</span> an experimental setup was created that allows to determine electrical and optical properties of the discharge. Oil was sparged with air and sulfur hexafluoride <span class="hlt">gas</span>. It was found that sparging oil with <span class="hlt">gas</span> lowers the breakdown voltage of the oil. When a <span class="hlt">gas</span> <span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088498&hterms=squat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsquat','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088498&hterms=squat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsquat"><span>The effect of exercise and rest duration on the generation of venous <span class="hlt">gas</span> <span class="hlt">bubbles</span> at altitude</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dervay, Joseph P.; Powell, Michael R.; Butler, Bruce; Fife, Caroline E.</p> <p>2002-01-01</p> <p>BACKGROUND: Decompression, as occurs with aviators and astronauts undergoing high altitude operations or with deep-sea divers returning to surface, can cause <span class="hlt">gas</span> <span class="hlt">bubbles</span> to form within the organism. Pressure changes to evoke <span class="hlt">bubble</span> formation in vivo during depressurization are several orders of magnitude less than those required for <span class="hlt">gas</span> phase formation in vitro in quiescent liquids. Preformed micronuclei acting as "seeds" have been proposed, dating back to the 1940's. These tissue <span class="hlt">gas</span> micronuclei have been attributed to a minute <span class="hlt">gas</span> 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 <span class="hlt">gas</span> 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 <span class="hlt">bubbles</span> with exercise performed just prior to depressurization, compared with decreasing <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> formation at 6.2 psia when lower extremity exercise is performed just prior to depressurization as compared with longer rest intervals</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088498&hterms=musculoskeletal+pathology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmusculoskeletal%2Bpathology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088498&hterms=musculoskeletal+pathology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmusculoskeletal%2Bpathology"><span>The effect of exercise and rest duration on the generation of venous <span class="hlt">gas</span> <span class="hlt">bubbles</span> at altitude</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dervay, Joseph P.; Powell, Michael R.; Butler, Bruce; Fife, Caroline E.</p> <p>2002-01-01</p> <p>BACKGROUND: Decompression, as occurs with aviators and astronauts undergoing high altitude operations or with deep-sea divers returning to surface, can cause <span class="hlt">gas</span> <span class="hlt">bubbles</span> to form within the organism. Pressure changes to evoke <span class="hlt">bubble</span> formation in vivo during depressurization are several orders of magnitude less than those required for <span class="hlt">gas</span> phase formation in vitro in quiescent liquids. Preformed micronuclei acting as "seeds" have been proposed, dating back to the 1940's. These tissue <span class="hlt">gas</span> micronuclei have been attributed to a minute <span class="hlt">gas</span> 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 <span class="hlt">gas</span> 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 <span class="hlt">bubbles</span> with exercise performed just prior to depressurization, compared with decreasing <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> formation at 6.2 psia when lower extremity exercise is performed just prior to depressurization as compared with longer rest intervals</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11817616','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11817616"><span>The effect of exercise and rest duration on the generation of venous <span class="hlt">gas</span> <span class="hlt">bubbles</span> at altitude.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dervay, Joseph P; Powell, Michael R; Butler, Bruce; Fife, Caroline E</p> <p>2002-01-01</p> <p>Decompression, as occurs with aviators and astronauts undergoing high altitude operations or with deep-sea divers returning to surface, can cause <span class="hlt">gas</span> <span class="hlt">bubbles</span> to form within the organism. Pressure changes to evoke <span class="hlt">bubble</span> formation in vivo during depressurization are several orders of magnitude less than those required for <span class="hlt">gas</span> phase formation in vitro in quiescent liquids. Preformed micronuclei acting as "seeds" have been proposed, dating back to the 1940's. These tissue <span class="hlt">gas</span> micronuclei have been attributed to a minute <span class="hlt">gas</span> 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. The greatest incidence of venous <span class="hlt">gas</span> 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. 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. Of the 20 subjects with VGE in the pulmonary artery, 10 demonstrated a greater incidence of <span class="hlt">bubbles</span> with exercise performed just prior to depressurization, compared with decreasing <span class="hlt">bubble</span> grades and incidence as the interval of rest increased prior to depressurization. No decompression illness was reported. There is a significant increase in decompression-induced <span class="hlt">bubble</span> formation at 6.2 psia when lower extremity exercise is performed just prior to depressurization as compared with longer rest intervals. Analysis indicated that micronuclei half-life is on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20025340','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20025340"><span>Steady-state composition of a two-component <span class="hlt">gas</span> <span class="hlt">bubble</span> growing in a liquid solution: self-similar approach.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gor, G Yu; Kuchma, A E</p> <p>2009-12-21</p> <p>The paper presents an analytical description of the growth of a two-component <span class="hlt">bubble</span> in a binary liquid-<span class="hlt">gas</span> solution. We obtain asymptotic self-similar time dependence of the <span class="hlt">bubble</span> radius and analytical expressions for the nonsteady profiles of dissolved gases around the <span class="hlt">bubble</span>. We show that the necessary condition for the self-similar regime of <span class="hlt">bubble</span> growth is the constant, steady-state composition of the <span class="hlt">bubble</span>. The equation for the steady-state composition is obtained. We reveal the dependence of the steady-state composition on the solubility laws of the <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1041636','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1041636"><span>Bacillus cereus panophthalmitis associated with intraocular <span class="hlt">gas</span> <span class="hlt">bubble</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>al-Hemidan, A; Byrne-Rhodes, K A; Tabbara, K F</p> <p>1989-01-01</p> <p>It has become increasingly apparent that Bacillus cereus can cause a severe and devastating form of endophthalmitis following penetrating trauma by a metallic object. B. cereus is an uncommon aetiological agent in non-clostridial <span class="hlt">gas</span>-forming infections. The patient studied in this single case report showed evidence of intraocular <span class="hlt">gas</span> mimicking <span class="hlt">gas</span> gangrene infection. The physiology of non-clostridial bacteria producing <span class="hlt">gas</span> from anaerobic metabolic conditions is reviewed. Further intraocular and systemic complications which may be avoided by accurate and early diagnosis and the use of recommended treatment with antibiotics such as clindamycin. Images PMID:2493262</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3895922','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3895922"><span>Removal of dichloromethane from waste <span class="hlt">gas</span> streams using a hybrid <span class="hlt">bubble</span> column/biofilter bioreactor</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>The performance of a hybrid <span class="hlt">bubble</span> column/biofilter (HBCB) bioreactor for the removal of dichloromethane (DCM) from waste <span class="hlt">gas</span> streams was studied in continuous mode for several months. The HBCB bioreactor consisted of two compartments: <span class="hlt">bubble</span> column bioreactor removing DCM from liquid phase and biofilter removing DCM from <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> column and biofilter reactors and could remove DCM from waste <span class="hlt">gas</span> streams in a better manner. PMID:24406056</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24406056','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24406056"><span>Removal of dichloromethane from waste <span class="hlt">gas</span> streams using a hybrid <span class="hlt">bubble</span> column/biofilter bioreactor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abtahi, Mehrnoosh; Naddafi, Kazem; Mesdaghinia, Alireza; Yaghmaeian, Kamyar; Nabizadeh, Ramin; Jaafarzadeh, Nematollah; Rastkari, Noushin; Nazmara, Shahrokh; Saeedi, Reza</p> <p>2014-01-09</p> <p>The performance of a hybrid <span class="hlt">bubble</span> column/biofilter (HBCB) bioreactor for the removal of dichloromethane (DCM) from waste <span class="hlt">gas</span> streams was studied in continuous mode for several months. The HBCB bioreactor consisted of two compartments: <span class="hlt">bubble</span> column bioreactor removing DCM from liquid phase and biofilter removing DCM from <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> column and biofilter reactors and could remove DCM from waste <span class="hlt">gas</span> streams in a better manner.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27794353','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27794353"><span>Relative acoustic frequency response of induced methane, carbon dioxide and air <span class="hlt">gas</span> <span class="hlt">bubble</span> plumes, observed laterally.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kubilius, Rokas; Pedersen, Geir</p> <p>2016-10-01</p> <p>There is an increased need to detect, identify, and monitor natural and manmade seabed <span class="hlt">gas</span> leaks. Fisheries echosounders are well suited to monitor large volumes of water and acoustic frequency response [normalized acoustic backscatter, when a measure at one selected frequency is used as a denominator, r(f)] is commonly used to identify echoes from fish and zooplankton species. Information on <span class="hlt">gas</span> plume r(f) would be valuable for automatic detection of subsea leaks and for separating <span class="hlt">bubble</span> plumes from natural targets such as swimbladder-bearing fish. Controlled leaks were produced with a specially designed instrument frame suspended in mid-water in a sheltered fjord. The frame was equipped with echosounders, stereo-camera, and <span class="hlt">gas</span>-release nozzles. The r(f) of laterally observed methane, carbon dioxide, and air plumes (0.040-29 l/min) were measured at 70, 120, 200, and 333 kHz, with <span class="hlt">bubble</span> sizes determined optically. The observed <span class="hlt">bubble</span> size range (1-25 mm) was comparable to that reported in the literature for natural cold seeps of methane. A negative r(f) with increasing frequency was observed, namely, r(f) of about 0.7, 0.6, and 0.5 at 120, 200, and 333 kHz when normalized to 70 kHz. Measured plume r(f) is also compared to resolved, single <span class="hlt">bubble</span> target strength-based, and modeled r(f).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApPhL.104m3511B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApPhL.104m3511B"><span>Helium <span class="hlt">gas</span> <span class="hlt">bubble</span> trapped in liquid helium in high magnetic field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bai, H.; Hannahs, S. T.; Markiewicz, W. D.; Weijers, H. W.</p> <p>2014-03-01</p> <p>High magnetic field magnets are used widely in the area of the condensed matter physics, material science, chemistry, geochemistry, and biology at the National High Magnetic Field Laboratory. New high field magnets of state-of-the-art are being pursued and developed at the lab, such as the current developing 32 T, 32 mm bore fully superconducting magnet. Liquid Helium (LHe) is used as the coolant for superconducting magnets or samples tested in a high magnetic field. When the magnetic field reaches a relatively high value the boil-off helium <span class="hlt">gas</span> <span class="hlt">bubble</span> generated by heat losses in the cryostat can be trapped in the LHe bath in the region where BzdBz/dz is less than negative 2100 T2/m, instead of floating up to the top of LHe. Then the magnet or sample in the trapped <span class="hlt">bubble</span> region may lose efficient cooling. In the development of the 32 T magnet, a prototype Yttrium Barium Copper Oxide coil of 6 double pancakes with an inner diameter of 40 mm and an outer diameter of 140 mm was fabricated and tested in a resistive magnet providing a background field of 15 T. The trapped <span class="hlt">gas</span> <span class="hlt">bubble</span> was observed in the tests when the prototype coil was ramped up to 7.5 T at a current of 200 A. This letter reports the test results on the trapped <span class="hlt">gas</span> <span class="hlt">bubble</span> and the comparison with the analytical results which shows they are in a good agreement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JEPT...90..301G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JEPT...90..301G"><span>Acoustics of a Polydisperse Vapor-<span class="hlt">Gas</span> <span class="hlt">Bubbles</span>-Laden Liquid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gubaidullin, D. A.; Fedorov, Yu. V.</p> <p>2017-03-01</p> <p>A mathematical model is presented that determines the propagation of acoustic waves in a liquid containing polydisperse vapor-<span class="hlt">gas</span> <span class="hlt">bubbles</span> with account for mass transfer processes. A system of integrodifferential equations of a disturbed motion of a two-phase mixture is written, and a dispersion relation is obtained. A general expression for the equilibrium velocity of sound has been found for a vapor-<span class="hlt">gas</span> liquid mixture, and the influence of vapor concentration and of the volume content of <span class="hlt">bubbles</span> on the value of the equilibrium velocity of sound has been analyzed. In particular cases, expressions of the equilibrium velocity of sound are presented for <span class="hlt">gas</span>-liquid and vapor-liquid mixtures, and satisfactory agreement of the obtained values with the familiar experimental data has been obtained. The results of comparison of the dispersion curves of phase velocity and of the attenuation coefficient for a mixture of water with vapor-air <span class="hlt">bubbles</span> at different values of the initial concentration of vapor in <span class="hlt">bubbles</span> are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFD.G5007P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.G5007P"><span>Simulation of Interaction of Strong Shocks with <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> using the Direct Simulation Monte Carlo Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puranik, Bhalchandra; Watvisave, Deepak; Bhandarkar, Upendra</p> <p>2016-11-01</p> <p>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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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-<span class="hlt">bubble</span> interaction using the DSMC method for such situations. Specifically, an investigation of the shock-<span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDKP1020K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDKP1020K"><span>Numerical simulation of ultrasound-induced dynamics of a <span class="hlt">gas</span> <span class="hlt">bubble</span> neighboring a rigid wall</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kobayashi, Tatsuya; Ando, Keita</p> <p>2016-11-01</p> <p>Cavitation erosion has been a technical issue in ultrasonic cleaning under which cavitation <span class="hlt">bubbles</span> appear near target surfaces to be cleaned. In the present study, we numerically study the interaction of ultrasonic standing waves with a <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> collapse that may explain cavitation erosion in ultrasonic cleaning.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870066363&hterms=effects+migration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffects%2Bmigration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870066363&hterms=effects+migration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffects%2Bmigration"><span>Thermocapillary migration of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in an arbitrary direction with respect to a plane surface</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meyyappan, M.; Shankar Subramanian, R.</p> <p>1987-01-01</p> <p>The thermocapillary migration of a <span class="hlt">gas</span> <span class="hlt">bubble</span> in an unbounded fluid in the presence of a neighboring rigid plane surface is considered in the limit of negligible Reynolds and Marangoni numbers. Results are given for a scalar interaction parameter defined as the ratio of the speed of the <span class="hlt">bubble</span> in the presence of the plane surface to the speed in its absence. It is suggested that the weaker interaction effects noted for the case of thermocapillary migration relative to the case of motion due to a body force such as that caused by a gravitational field is attributable to the more rapid decay, away from the <span class="hlt">bubble</span>, of the disturbance velocity and temperature gradient fields. The surface is found to exert the greatest influence in the case of motion normal to it, and the weakest influence in the case of parallel motion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19373828','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19373828"><span>Catalytic microtubular jet engines self-propelled by accumulated <span class="hlt">gas</span> <span class="hlt">bubbles</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Solovev, Alexander A; Mei, Yongfeng; Bermúdez Ureña, Esteban; Huang, Gaoshan; Schmidt, Oliver G</p> <p>2009-07-01</p> <p>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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> ejecting from one opening of the tube, and the velocity can be well approximated by the product of the <span class="hlt">bubble</span> radius and the <span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26442146','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26442146"><span>The speed of sound in a <span class="hlt">gas</span>-vapour <span class="hlt">bubbly</span> liquid.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prosperetti, Andrea</p> <p>2015-10-06</p> <p>In addition to the vapour of the liquid, <span class="hlt">bubbles</span> in cavitating flows usually contain also a certain amount of permanent <span class="hlt">gas</span> 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 <span class="hlt">bubbly</span> liquid with these characteristics. Phase change effects are included in detail, while the <span class="hlt">gas</span> is assumed to follow a polytropic law. It is shown that even a small amount of permanent <span class="hlt">gas</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3868626','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3868626"><span>Compositional Discrimination of Decompression and Decomposition <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Bycaught Seals and Dolphins</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bernaldo de Quirós, Yara; Seewald, Jeffrey S.; Sylva, Sean P.; Greer, Bill; Niemeyer, Misty; Bogomolni, Andrea L.; Moore, Michael J.</p> <p>2013-01-01</p> <p><span class="hlt">Gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> was produced peri- or post-mortem by a fast decompression, probably by quickly hauling animals entangled in the net at depth to the surface. <span class="hlt">Gas</span> composition analysis and <span class="hlt">gas</span> scoring are two new diagnostic tools available to distinguish <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> scores than stranded animals. <span class="hlt">Gas</span> composition analyses indicate that <span class="hlt">gas</span> was formed by decompression, confirming the decompression hypothesis. PMID:24367623</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24367623','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24367623"><span>Compositional discrimination of decompression and decomposition <span class="hlt">gas</span> <span class="hlt">bubbles</span> in bycaught seals and dolphins.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bernaldo de Quirós, Yara; Seewald, Jeffrey S; Sylva, Sean P; Greer, Bill; Niemeyer, Misty; Bogomolni, Andrea L; Moore, Michael J</p> <p>2013-01-01</p> <p><span class="hlt">Gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> was produced peri- or post-mortem by a fast decompression, probably by quickly hauling animals entangled in the net at depth to the surface. <span class="hlt">Gas</span> composition analysis and <span class="hlt">gas</span> scoring are two new diagnostic tools available to distinguish <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> scores than stranded animals. <span class="hlt">Gas</span> composition analyses indicate that <span class="hlt">gas</span> was formed by decompression, confirming the decompression hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000095935&hterms=gas+laws&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dgas%2Blaws','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000095935&hterms=gas+laws&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dgas%2Blaws"><span>A Mathematical Model of Diffusion-Limited <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Dynamics in Tissue with Varying Diffusion Region Thickness</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Srinivasan, R. Srini; Gerth, Wayne A.; Powell, Michael R.; Paloski, William H. (Technical Monitor)</p> <p>2000-01-01</p> <p>A three-region mathematical model of <span class="hlt">gas</span> <span class="hlt">bubble</span> dynamics has been shown suitable for describing diffusion-limited dynamics of more than one <span class="hlt">bubble</span> in a given volume of extravascular tissue. The model is based on the dynamics of <span class="hlt">gas</span> exchange between a <span class="hlt">bubble</span> and a well-stirred tissue region through an intervening unperfused diffusion region previously assumed to have constant thickness and uniform <span class="hlt">gas</span> diffusivity. As a result, the <span class="hlt">gas</span> content of the diffusion region remains constant as the volume of the region increases with <span class="hlt">bubble</span> growth, causing dissolved <span class="hlt">gas</span> in the region to violate Henry's law. Earlier work also neglected the relationship between the varying diffusion region volume and the fixed total tissue volume, because only cases in which the diffusion region volume is a small fraction of the overall tissue volume were considered. We herein extend the three-region model to correct these theoretical inconsistencies by allowing both the thickness and <span class="hlt">gas</span> content of the diffusion region to vary during <span class="hlt">bubble</span> evolution. A postulated difference in <span class="hlt">gas</span> diffusivity between an infinitesimally thin layer at the <span class="hlt">bubble</span> surface and the remainder of the diffusion region leads to variation in diffusion region <span class="hlt">gas</span> content and thickness during <span class="hlt">bubble</span> growth and resolution. This variable thickness, differential diffusivity (VTDD) model can yield <span class="hlt">bubble</span> lifetimes considerably longer than those yielded by earlier three-region models for given model and decompression parameters, and meets a need for theoretically consistent but relatively simple <span class="hlt">bubble</span> dynamics models for use in studies of decompression sickness (DCS) in human subjects, Keywords: decompression sickness, <span class="hlt">gas</span> diffusion in tissue, diffusivity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23624230','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23624230"><span>Evolution of <span class="hlt">bubbles</span> from <span class="hlt">gas</span> micronuclei formed on the luminal aspect of ovine large blood vessels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Arieli, R; Marmur, A</p> <p>2013-08-01</p> <p>It has been shown that tiny <span class="hlt">gas</span> nanobubbles form spontaneously on a smooth hydrophobic surface submerged in water. These nanobubbles were shown to be the source of <span class="hlt">gas</span> micronuclei from which <span class="hlt">bubbles</span> evolved during decompression of silicon wafers. We suggest that the hydrophobic inner surface of blood vessels may be a site of nanobubble production. Sections from the right and left atria, pulmonary artery and vein, aorta, and superior vena cava of sheep (n=6) were gently stretched on microscope slides and exposed to 1013 kPa for 18 h. Hydrophobicity was checked in the six blood vessels by advancing contact angle with a drop of saline of 71±19°, with a maximum of about 110±7° (mean±SD). Tiny <span class="hlt">bubbles</span> ~30 μm in diameter rose vertically from the blood vessels and grew on the surface of the saline, where they were photographed. All of the blood vessels produced <span class="hlt">bubbles</span> over a period of 80 min. The number of <span class="hlt">bubbles</span> produced from a square cm was: in the aorta, 20.5; left atrium, 27.3; pulmonary artery, 17.9; pulmonary vein, 24.3; right atrium, 29.5; superior vena cava, 36.4. More than half of the <span class="hlt">bubbles</span> were present for less than 2 min, but some remained on the saline-air interface for as long as 18 min. Nucleation was evident in both the venous (superior vena cava, pulmonary artery, right atrium) and arterial (aorta, pulmonary vein, left atrium) blood vessels. This newly suggested mechanism of nucleation may be the main mechanism underlying <span class="hlt">bubble</span> formation on decompression. Copyright © 2013 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014314','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014314"><span><span class="hlt">Gas</span> <span class="hlt">bubbles</span> in fossil amber as possible indicators of the major <span class="hlt">gas</span> composition of ancient air</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Berner, R.A.; Landis, G.P.</p> <p>1988-01-01</p> <p>Gases trapped in Miocene to Upper Cretaceous amber were released by gently crushing the amber under vacuum and were analyzed by quadrupole mass spectrometry. After discounting the possibility that the major gases N2, O2, and CO2 underwent appreciable diffusion and diagenetic exchange with their surroundings or reaction with the amber, it has been concluded that in primary <span class="hlt">bubbles</span> (<span class="hlt">gas</span> released during initial breakage) these gases represent mainly original ancient air modified by the aerobic respiration of microorganisms. Values of N2/(CO2+O2) for each time period give consistent results despite varying O2/CO2 ratios that presumably were due to varying degrees of respiration. This allows calculation of original oxygen concentrations, which, on the basis of these preliminary results, appear to have changed from greater than 30 percent O2 during one part ofthe Late Cretaceous (between 75 and 95 million years ago) to 21 percent during the Eocene-Oligocene and for present-day samples, with possibly lower values during the Oligocene-Early Miocene. Variable O2 levels over time in general confirm theoretical isotope-mass balance calculations and suggest that the atmosphere has evolved over Phanerozoic time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016805','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016805"><span>Prospecting for zones of contaminated ground-water discharge to streams using bottom-sediment <span class="hlt">gas</span> <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Vroblesky, Don A.; Lorah, Michelle M.</p> <p>1991-01-01</p> <p>Decomposition of organic-rich bottom sediment in a tidal creek in Maryland results in production of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in the bottom sediment during summer and fall. In areas where volatile organic contaminants discharge from ground water, through the bottom sediment, and into the creek, part of the volatile contamination diffuses into the <span class="hlt">gas</span> <span class="hlt">bubbles</span> and is released to the atmosphere by ebullition. Collection and analysis of <span class="hlt">gas</span> <span class="hlt">bubbles</span> for their volatile organic contaminant content indicate that relative concentrations of the volatile organic contaminants in the <span class="hlt">gas</span> <span class="hlt">bubbles</span> are substantially higher in areas where the same contaminants occur in the ground water that discharges to the streams. Analyses of the <span class="hlt">bubbles</span> located an area of previously unknown ground-water contamination. The method developed for this study consisted of disturbing the bottom sediment to release <span class="hlt">gas</span> <span class="hlt">bubbles</span>, and then capturing the <span class="hlt">bubbles</span> in a polyethylene bag at the water-column surface. The captured <span class="hlt">gas</span> was transferred either into sealable polyethylene bags for immediate analysis with a photoionization detector or by syringe to glass tubes containing wires coated with an activated-carbon adsorbent. Relative concentrations were determined by mass spectral analysis for chloroform and trichloroethylene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/102363','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/102363"><span>The influence of <span class="hlt">bubble</span> plumes on air-seawater <span class="hlt">gas</span> transfer velocities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Asher, W.E.; Karle, L.M.; Higgins, B.J.</p> <p>1995-07-01</p> <p>Air-sea <span class="hlt">gas</span> exchange is an important process in the geochemical cycling of carbon dioxide (CO{sub 2}). The air-sea flux of CO{sub 2} is determined in part by the physical forcing functions, which are parameterized in terms of the air-sea transfer velocity, k{sub L}. Past studies have attempted to correlate k{sub L} with wind speed, U. Because strong winds occur in ocean regions thought to be important sources or sinks of CO{sub 2}, accurate knowledge of k{sub L} at high U is important in estimating the global air-sea flux of CO{sub 2}. Better understanding of the physical processes affecting <span class="hlt">gas</span> transfer at large U will increase the accuracy in estimating k{sub L} in ocean regions with high CO{sub 2}, fluxes. Increased accuracy in estimating k{sub L} will increase the accuracy in calculating the net global air-sea CO{sub 2} flux and provide more accurate boundary and initial conditions for global ocean carbon cycle models. High wind speeds are associated with the presence of whitecaps, which can increase the <span class="hlt">gas</span> flux by generating turbulence, disrupting surface films, and creating <span class="hlt">bubble</span> plumes. <span class="hlt">Bubble</span> plumes will create additional turbulence, prolong the surface disruption, and transfer <span class="hlt">gas</span> to or from individual <span class="hlt">bubbles</span> while they are beneath the surface. These turbulence and <span class="hlt">bubble</span> processes very effectively promote <span class="hlt">gas</span> transfer. Because of this, it is postulated that breaking waves, if present, will dominate non-whitecap related <span class="hlt">gas</span> exchange. Under this assumption, k{sub L} Will increase linearly with increasing fractional area whitecap coverage, W{sub c}. In support of this, researchers found k{sub L} measured in a whitecap simulation tank (WSI) was linearly correlated with <span class="hlt">bubble</span> plume coverage, B{sub c} (the laboratory analog of W{sub c}). However, it is not definitively known how the presence of breaking waves and <span class="hlt">bubble</span> plumes affect the dependence of k{sub L} on Schmidt number, Sc, and aqueous-phase solubility, {alpha}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5509333','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5509333"><span>Effect of surfactants on <span class="hlt">gas</span> holdup of two-phase <span class="hlt">bubble</span> columns</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Estevez, L.A. ); Saez, E.; Pachino, J.; Cavicchioli, I. )</p> <p>1988-01-01</p> <p>Two-phase experiments have been carried out using organic liquids with a surfactant and air in a <span class="hlt">bubble</span> column 30 (cm) inside diameter and 3 (m) tall. Under the presence of the surfactant, two distinct regions are observed: a <span class="hlt">bubbling</span> region is the lower part, and a froth zone in the upper part of the column. Intrinsic <span class="hlt">gas</span> holdups were measured in each region. Results showed that intrinsic <span class="hlt">gas</span> holdup did not change significantly with surfactant concentration. However, the position of the limiting surface separating the two regions varied considerably with surfactant concentration, thus affecting strongly the overall <span class="hlt">gas</span> holdup. Based on the described experimental observations, correlations for intrinsic and overall <span class="hlt">gas</span> holdups have been proposed. Intrinsic <span class="hlt">gas</span> holdups have been correlated and a function of <span class="hlt">gas</span> and liquid superficial velocities, and not as functions of surfactant concentration. Overall <span class="hlt">gas</span> holdups have been expressed in terms of intrinsic <span class="hlt">gas</span> holdup and of the fraction PHI of the column that is occupied by the froth region. The variable PHI is the one that has been correlated in terms of the surfactant concentration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1177642','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1177642"><span>Transmission electron microscopy characterization of the fission <span class="hlt">gas</span> <span class="hlt">bubble</span> superlattice in irradiated U-7wt% Mo dispersion fuels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>B.D. Miller; J. Gan; D.D. Keiser Jr.; A.B. Robinson; J.-F. Jue; J.W. Madden; P.G. Medvedev</p> <p>2015-03-01</p> <p>Transmission electron microscopy characterization of irradiated U-7wt% Mo dispersion fuel was performed on various samples to understand the effect of irradiation parameters (fission density, fission rate, and temperature) on the self-organized fission-<span class="hlt">gas-bubble</span> superlattice that forms in the irradiated U-Mo fuel. The <span class="hlt">bubble</span> superlattice was seen to form a face-centered cubic structure coherent with the host U-7wt% Mo body centered cubic structure. At a fission density between 3.0 and 4.5 x 10<sup>21</sup> fiss/cm<sup>3</sup>, the superlattice <span class="hlt">bubbles</span> appear to have reached a saturation size with additional fission <span class="hlt">gas</span> associated with increasing burnup predominately accumulating along grain boundaries. At a fission density of ~4.5x10<sup>21 </sup>fiss/cm<sup>3</sup>, the U-7wt% Mo microstructure undergoes grain subdivision and can no longer support the ordered <span class="hlt">bubble</span> superlattice. The fuel grains are primarily less than 500 nm in diameter with micron-size fission-<span class="hlt">gas</span> <span class="hlt">bubbles</span> present on the grain boundaries. Solid fission products decorate the inside surface of the micron-sized fission-<span class="hlt">gas</span> <span class="hlt">bubbles</span>. Residual superlattice <span class="hlt">bubbles</span> are seen in areas where fuel grains remain micron sized. Potential mechanisms of the formation and collapse of the <span class="hlt">bubble</span> superlattice are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JNuM..458..115M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JNuM..458..115M"><span>Transmission electron microscopy characterization of the fission <span class="hlt">gas</span> <span class="hlt">bubble</span> superlattice in irradiated U-7 wt%Mo dispersion fuels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, B. D.; Gan, J.; Keiser, D. D.; Robinson, A. B.; Jue, J. F.; Madden, J. W.; Medvedev, P. G.</p> <p>2015-03-01</p> <p>Transmission electron microscopy characterization of irradiated U-7 wt%Mo dispersion fuel were performed on various U-Mo fuel samples to understand the effect of irradiation parameters (fission density, fission rate, and temperature) on the self-organized fission-<span class="hlt">gas-bubble</span> superlattice that forms in the irradiated U-Mo fuel. The <span class="hlt">bubble</span> superlattice was seen to form a face centered cubic structure coherent with the host U-7 wt%Mo body-centered cubic structure. At a fission density between 3.0 and 4.5 × 1021 fiss/cm3, the superlattice <span class="hlt">bubbles</span> appear to have reached a saturation size with additional fission <span class="hlt">gas</span> associated with increasing burnup predominately accumulating along grain boundaries. At a fission density of ∼4.5 × 1021 fiss/cm3, the U-7 wt%Mo microstructure starts to undergo grain subdivision and can no longer support the ordered <span class="hlt">bubble</span> superlattice. The sub-divided fuel grains are less than 500 nm in diameter with what appears to be micron-size fission-<span class="hlt">gas</span> <span class="hlt">bubbles</span> present on the grain boundaries. Solid fission products typically decorate the inside surface of the micron-sized fission-<span class="hlt">gas</span> <span class="hlt">bubbles</span>. Residual superlattice <span class="hlt">bubbles</span> are seen in areas where fuel grains remain micron sized. Potential mechanisms of the formation and collapse of the <span class="hlt">bubble</span> superlattice are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS33A2004H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS33A2004H"><span>Entrapment of Hydrate-coated <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> into Oil and Separation of <span class="hlt">Gas</span> and Hydrate-film; Seafloor Experiments with ROV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hiruta, A.; Matsumoto, R.</p> <p>2015-12-01</p> <p>We trapped <span class="hlt">gas</span> <span class="hlt">bubbles</span> emitted from the seafloor into oil-containing collector and observed an unique phenomena. <span class="hlt">Gas</span> hydrate formation needs water for the crystal lattice; however, <span class="hlt">gas</span> hydrates in some areas are associated with hydrophobic crude oil or asphalt. In order to understand <span class="hlt">gas</span> hydrate growth in oil-bearing sediments, an experiment with cooking oil was made at <span class="hlt">gas</span> hydrate stability condition. We collected venting <span class="hlt">gas</span> <span class="hlt">bubbles</span> into a collector with canola oil during ROV survey at a <span class="hlt">gas</span> hydrate area in the eastern margin of the Sea of Japan. When the <span class="hlt">gas</span> <span class="hlt">bubbles</span> were trapped into collector with oil, <span class="hlt">gas</span> phase appeared above the oil and <span class="hlt">gas</span> hydrates, between oil and <span class="hlt">gas</span> phase. At this study area within <span class="hlt">gas</span> hydrate stability condition, control experiment with oil-free collector suggested that <span class="hlt">gas</span> <span class="hlt">bubbles</span> emitted from the seafloor were quickly covered with <span class="hlt">gas</span> hydrate film. Therefore it is improbable that <span class="hlt">gas</span> <span class="hlt">bubbles</span> entered into the oil phase before hydrate skin formation. After the <span class="hlt">gas</span> phase formation in oil-containing collector, the ROV floated outside of hydrate stability condition for <span class="hlt">gas</span> hydrate dissociation and re-dived to the venting site. During the re-dive within hydrate stability condition, <span class="hlt">gas</span> hydrate was not formed. The result suggests that moisture in the oil is not enough for hydrate formation. Therefore <span class="hlt">gas</span> hydrates that appeared at the oil/<span class="hlt">gas</span> phase boundary were already formed before <span class="hlt">bubbles</span> enter into the oil. Hydrate film is the only possible origin. This observation suggests that hydrate film coating <span class="hlt">gas</span> hydrate was broken at the sea water/oil boundary or inside oil. Further experiments may contribute for revealing kinetics of hydrate film and formation. This work was a part of METI (Ministry of Economy, Trade and Industry)'s project entitled "FY2014 Promoting research and development of methane hydrate". We also appreciate support of AIST (National Institute of Advanced Industrial Science and Technology).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/104988','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/104988"><span><span class="hlt">Gas</span> <span class="hlt">bubble</span> retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gauglitz, P.A.; Rassat, S.D.; Powell, M.R.</p> <p>1995-08-01</p> <p>Several of the underground nuclear storage tanks at Hanford have been placed on a flammable <span class="hlt">gas</span> 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 <span class="hlt">gas</span> release from these storage tanks. This study is being conducted for Westinghouse Hanford Company as part of the PNL Flammable <span class="hlt">Gas</span> project. Previous investigations have concluded that <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> and the dynamics of how these <span class="hlt">bubbles</span> are released from the waste. The presence of <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span>. The objectives of this study were to conduct experiments and develop theories to understand better how <span class="hlt">bubbles</span> are retained by slurries and sludges, to measure the effect of <span class="hlt">gas</span> <span class="hlt">bubbles</span> on the viscosity of simulated slurries, and to measure the effect of <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SCPMA..57.1169W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SCPMA..57.1169W"><span>Lagrangian coherent structures analysis of <span class="hlt">gas</span>-liquid flow in a <span class="hlt">bubble</span> column</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Qin; Wang, GuoYu; Huang, Biao; Bai, ZeYu</p> <p>2014-06-01</p> <p>The objective of this paper is to apply a new identifying method to investigating the <span class="hlt">gas</span>-liquid two-phase flow behaviors in a <span class="hlt">bubble</span> column with air injected into water. In the numerical simulations, the standard k- ɛ turbulence model is employed to describe the turbulence phenomenon occurring in the continuous fluid. The Finite-Time Lyapunov Exponent (FTLE) and Lagrangian Coherent Structures (LCS) are applied to analyze the vortex structures in multiphase flow. Reasonable agreements are obtained between the numerical and experimental data. The numerical results show that the evolution of <span class="hlt">gas</span>-liquid in the column includes initial and periodical developing stages. During the initial stage, the <span class="hlt">bubble</span> hose is forming and extending along the vertical direction with the vortex structures formed symmetrically. During the periodical developing stage, the <span class="hlt">bubble</span> hose starts to oscillate periodically, and the vortexes move along the <span class="hlt">bubble</span> hose to the bottom of column alternately. Compared to the Euler-system-based identification criterion of a vortex, the FTLE field presents the boundary of a vortex without any threshold defined and the LCS represents the divergence extent of infinite neighboring particles. During the initial stage, the interfaces between the forward and backward flows are highlighted by the LCS. As for the periodical developing stage, the LCS curls near the vortex centers, providing a method of analyzing a flow field from a dynamical system perspective.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/621867','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/621867"><span><span class="hlt">Gas</span> <span class="hlt">Bubble</span> Trauma Monitoring and Research of Juvenile Salmonids, 1994-1995 Progress Report.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hans, Karen M.</p> <p>1997-07-01</p> <p>This report describes laboratory and field monitoring studies of <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> (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) <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> had high prevalence, progressively worsened, and may be a persistent sign of GBT; and (5) gill <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> supersaturated water; and (4) it appeared that GBT was not a threat to migrating juvenile salmonids. 24 refs., 26 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JAMTP..48..346D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JAMTP..48..346D"><span>Shock waves in water with Freon-12 <span class="hlt">bubbles</span> and formation of <span class="hlt">gas</span> hydrates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dontsov, V. E.; Nakoryakov, V. E.; Chernov, A. A.</p> <p>2007-05-01</p> <p>The evolution of a shock wave and its reflection from a wall in a <span class="hlt">gas</span>-liquid medium with dissolution and hydration are experimentally investigated. Dissolution and hydration behind the front of a moderate-amplitude shock wave are demonstrated to be caused by fragmentation of <span class="hlt">gas</span> <span class="hlt">bubbles</span>, resulting in a drastic increase in the area of the interphase surface and in a decrease in size of <span class="hlt">gas</span> inclusions. The mechanisms of hydration behind the wave front are examined. Hydration behind the front of a shock wave with a stepwise profile is theoretically analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4954815','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4954815"><span><span class="hlt">Bubbles</span> Quantified In vivo by Ultrasound Relates to Amount of <span class="hlt">Gas</span> Detected Post-mortem in Rabbits Decompressed from High Pressure</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bernaldo de Quirós, Yara; Møllerløkken, Andreas; Havnes, Marianne B.; Brubakk, Alf O.; González-Díaz, Oscar; Fernández, Antonio</p> <p>2016-01-01</p> <p>The pathophysiological mechanism of decompression sickness is not fully understood but there is evidence that it can be caused by intravascular and autochthonous <span class="hlt">bubbles</span>. Doppler ultrasound at a given circulatory location is used to detect and quantify the presence of intravascular <span class="hlt">gas</span> <span class="hlt">bubbles</span> as an indicator of decompression stress. In this manuscript we studied the relationship between presence and quantity of <span class="hlt">gas</span> <span class="hlt">bubbles</span> by echosonography of the pulmonary artery of anesthetized, air-breathing New Zealand White rabbits that were compressed and decompressed. Mortality rate, presence, quantity, and distribution of <span class="hlt">gas</span> <span class="hlt">bubbles</span> elsewhere in the body was examined postmortem. We found a strong positive relationship between high ultrasound <span class="hlt">bubble</span> grades in the pulmonary artery, sudden death, and high amount of intra and extra vascular <span class="hlt">gas</span> <span class="hlt">bubbles</span> widespread throughout the entire organism. In contrast, animals with lower <span class="hlt">bubble</span> grades survived for 1 h after decompression until sacrificed, and showed no <span class="hlt">gas</span> <span class="hlt">bubbles</span> during dissection. PMID:27493634</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhRvE..78c6303M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhRvE..78c6303M"><span>Finite-sized <span class="hlt">gas</span> <span class="hlt">bubble</span> motion in a blood vessel: Non-Newtonian effects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S.; Eckmann, David M.</p> <p>2008-09-01</p> <p>We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air <span class="hlt">bubble</span> through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid model—a cell-free layer and a non-Newtonian core together with the <span class="hlt">gas</span> <span class="hlt">bubble</span>. This problem is of interest to the field of rheology and for <span class="hlt">gas</span> embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=ρlUmaxd/μapp , in the neighborhood of 0.2, 2, and 200 are investigated. Here, ρl is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and μapp is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of <span class="hlt">bubble</span> occlusion is characterized by the ratio of <span class="hlt">bubble</span> to vessel radius (aspect ratio), λ , in the range 0.9⩽λ⩽1.05 . For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) <span class="hlt">bubble</span> motion causes large temporal and spatial gradients of shear stress at the “endothelial cell” (EC) surface lining the blood vessel wall as the <span class="hlt">bubble</span> approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ → - → +) imparted to the cell surface during <span class="hlt">bubble</span> motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the rear of the <span class="hlt">bubble</span></p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18851139','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18851139"><span>Finite-sized <span class="hlt">gas</span> <span class="hlt">bubble</span> motion in a blood vessel: non-Newtonian effects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S; Eckmann, David M</p> <p>2008-09-01</p> <p>We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air <span class="hlt">bubble</span> through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid model--a cell-free layer and a non-Newtonian core together with the <span class="hlt">gas</span> <span class="hlt">bubble</span>. This problem is of interest to the field of rheology and for <span class="hlt">gas</span> embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=rholUmaxdmicroapp , in the neighborhood of 0.2, 2, and 200 are investigated. Here, rhol is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and microapp is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of <span class="hlt">bubble</span> occlusion is characterized by the ratio of <span class="hlt">bubble</span> to vessel radius (aspect ratio), lambda , in the range 0.9< or =lambda< or =1.05 . For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) <span class="hlt">bubble</span> motion causes large temporal and spatial gradients of shear stress at the "endothelial cell" (EC) surface lining the blood vessel wall as the <span class="hlt">bubble</span> approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ --> - --> +) imparted to the cell surface during <span class="hlt">bubble</span> motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1182222','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1182222"><span>Thermal stability of fission <span class="hlt">gas</span> <span class="hlt">bubble</span> superlattice in irradiated U–10Mo fuel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gan, J.; Keiser, D. D.; Miller, B. D.; Robinson, A. B.; Wachs, D. M.; Meyer, M. K.</p> <p>2015-09-01</p> <p>To investigate the thermal stability of the fission <span class="hlt">gas</span> <span class="hlt">bubble</span> superlattice, a key microstructural feature in both irradiated U-7Mo dispersion and U-10Mo monolithic fuel plates, a FIB-TEM sample of the irradiated U-10Mo fuel with a local fission density of 3.5×10<sup>21</sup> fissions/cm<sup>3</sup> was used for an in-situ heating TEM experiment. The temperature of the heating holder was raised at a ramp rate of approximately 10 ºC/min up to ~700 ºC, kept at that temperature for about 34 min, continued to 850 ºC with a reduced rate of 5 ºC/min. The result shows a high thermal stability of the fission <span class="hlt">gas</span> <span class="hlt">bubble</span> superlattice. The implication of this observation on the fuel microstructural evolution and performance under irradiation is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016A%26A...585A..30C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016A%26A...585A..30C"><span>Molecular <span class="hlt">gas</span> and star formation toward the IR dust <span class="hlt">bubble</span> S 24 and its environs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cappa, C. E.; Duronea, N.; Firpo, V.; Vasquez, J.; López-Caraballo, C. H.; Rubio, M.; Vazzano, M. M.</p> <p>2016-01-01</p> <p>Aims: We present a multiwavelength analysis of the infrared dust <span class="hlt">bubble</span> S 24 and the extended IR sources G341.220-0.213 and G341.217-0.237 located in its environs. We aim to investigate the characteristics of the molecular <span class="hlt">gas</span> and the interstellar dust linked to them and analyze the evolutionary state of the young stellar objects identified there and the relation of the <span class="hlt">bubble</span> to S 24 and the IR sources. Methods: Using the APEX telescope, we mapped the molecular emission in the CO(2-1), 13CO(2-1), C18O(2-1), and 13CO(3-2) lines in a region of about 5' × 5' in size around the <span class="hlt">bubble</span>. The cold dust distribution was analyzed using submillimeter continuum images from ATLASGAL and Herschel. Complementary IR and radio data at different wavelengths were used to complete the study of the interstellar medium in the region. Results: The molecular <span class="hlt">gas</span> distribution shows that <span class="hlt">gas</span> linked to the S 24 <span class="hlt">bubble</span> and to G341.220-0.213 and G341.217-0.237 has velocities of between -48.0 km s-1 and -40.0 km s-1, compatible with the kinematical distance of 3.7 kpc that is generally adopted for the region. The <span class="hlt">gas</span> distribution reveals a shell-like molecular structure of ~0.8 pc in radius bordering the S 24 <span class="hlt">bubble</span>. A cold dust counterpart of the shell is detected in the LABOCA and Herschel-SPIRE images. The weak extended emission at 24 μm from warm dust and radio continuum emission projected inside the <span class="hlt">bubble</span> indicates exciting sources and that the <span class="hlt">bubble</span> is a compact HII region. Part of the molecular <span class="hlt">gas</span> bordering the S 24 HII region coincides with the extended infrared dust cloud SDC341.194-0.221. A molecular and cold dust clump is present at the interface between the S 24 HII region and G341.217-0.237, shaping the eastern border of the IR <span class="hlt">bubble</span>. The arc-like molecular structure encircling the northern and eastern sections of the IR source G341.220-0.213 indicates that the source is interacting with the molecular <span class="hlt">gas</span>. The analysis of the available IR point source catalogs reveals some</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=MSFC-0300723&hterms=matter+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmatter%2Bformation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=MSFC-0300723&hterms=matter+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmatter%2Bformation"><span>Burst of Star Formation Drives Galactic <span class="hlt">Bubble</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2001-01-01</p> <p>NASA's Hubble Space Telescope (HST) captures a lumpy <span class="hlt">bubble</span> of hot <span class="hlt">gas</span> <span class="hlt">rising</span> from a cauldron of glowing matter in Galaxy NGC 3079, located 50 million light-years from Earth in the constellation Ursa Major. Astronomers suspect the <span class="hlt">bubble</span> is being blown by 'winds' or high speed streams of particles, released during a burst of star formation. The <span class="hlt">bubble</span>'s lumpy surface has four columns of gaseous filaments towering above the galaxy's disc that whirl around in a vortex and are expelled into space. Eventually, this <span class="hlt">gas</span> will rain down on the disc and may collide with <span class="hlt">gas</span> clouds, compress them, and form a new generation of stars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1294583','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1294583"><span>Fission <span class="hlt">gas</span> <span class="hlt">bubble</span> identification using MATLAB's image processing toolbox</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collette, R.; King, J.; Keiser, Jr., D.; Miller, B.; Madden, J.; Schulthess, J.</p> <p>2016-06-08</p> <p>Automated image processing routines have the potential to aid in the fuel performance evaluation process by eliminating bias in human judgment that may vary from person-to-person or sample-to-sample. In addition, this study presents several MATLAB based image analysis routines designed for fission <span class="hlt">gas</span> void identification in post-irradiation examination of uranium molybdenum (U–Mo) monolithic-type plate fuels. Frequency domain filtration, enlisted as a pre-processing technique, can eliminate artifacts from the image without compromising the critical features of interest. This process is coupled with a bilateral filter, an edge-preserving noise removal technique aimed at preparing the image for optimal segmentation. Adaptive thresholding proved to be the most consistent gray-level feature segmentation technique for U–Mo fuel microstructures. The Sauvola adaptive threshold technique segments the image based on histogram weighting factors in stable contrast regions and local statistics in variable contrast regions. Once all processing is complete, the algorithm outputs the total fission <span class="hlt">gas</span> void count, the mean void size, and the average porosity. The final results demonstrate an ability to extract fission <span class="hlt">gas</span> void morphological data faster, more consistently, and at least as accurately as manual segmentation methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1294583-fission-gas-bubble-identification-using-matlab-image-processing-toolbox','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1294583-fission-gas-bubble-identification-using-matlab-image-processing-toolbox"><span>Fission <span class="hlt">gas</span> <span class="hlt">bubble</span> identification using MATLAB's image processing toolbox</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Collette, R.; King, J.; Keiser, Jr., D.; ...</p> <p>2016-06-08</p> <p>Automated image processing routines have the potential to aid in the fuel performance evaluation process by eliminating bias in human judgment that may vary from person-to-person or sample-to-sample. In addition, this study presents several MATLAB based image analysis routines designed for fission <span class="hlt">gas</span> void identification in post-irradiation examination of uranium molybdenum (U–Mo) monolithic-type plate fuels. Frequency domain filtration, enlisted as a pre-processing technique, can eliminate artifacts from the image without compromising the critical features of interest. This process is coupled with a bilateral filter, an edge-preserving noise removal technique aimed at preparing the image for optimal segmentation. Adaptive thresholding provedmore » to be the most consistent gray-level feature segmentation technique for U–Mo fuel microstructures. The Sauvola adaptive threshold technique segments the image based on histogram weighting factors in stable contrast regions and local statistics in variable contrast regions. Once all processing is complete, the algorithm outputs the total fission <span class="hlt">gas</span> void count, the mean void size, and the average porosity. The final results demonstrate an ability to extract fission <span class="hlt">gas</span> void morphological data faster, more consistently, and at least as accurately as manual segmentation methods.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1294583','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1294583"><span>Fission <span class="hlt">gas</span> <span class="hlt">bubble</span> identification using MATLAB's image processing toolbox</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collette, R.; King, J.; Keiser, Jr., D.; Miller, B.; Madden, J.; Schulthess, J.</p> <p>2016-06-08</p> <p>Automated image processing routines have the potential to aid in the fuel performance evaluation process by eliminating bias in human judgment that may vary from person-to-person or sample-to-sample. In addition, this study presents several MATLAB based image analysis routines designed for fission <span class="hlt">gas</span> void identification in post-irradiation examination of uranium molybdenum (U–Mo) monolithic-type plate fuels. Frequency domain filtration, enlisted as a pre-processing technique, can eliminate artifacts from the image without compromising the critical features of interest. This process is coupled with a bilateral filter, an edge-preserving noise removal technique aimed at preparing the image for optimal segmentation. Adaptive thresholding proved to be the most consistent gray-level feature segmentation technique for U–Mo fuel microstructures. The Sauvola adaptive threshold technique segments the image based on histogram weighting factors in stable contrast regions and local statistics in variable contrast regions. Once all processing is complete, the algorithm outputs the total fission <span class="hlt">gas</span> void count, the mean void size, and the average porosity. The final results demonstrate an ability to extract fission <span class="hlt">gas</span> void morphological data faster, more consistently, and at least as accurately as manual segmentation methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/751544','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/751544"><span>Changes in <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Disease Signs for Migrating Juvenile Salmonids Experimentally Exposed to Supersaturated Gasses, 1996-1997 Progress Report.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Absolon, Randall F.</p> <p>1999-03-01</p> <p>This study was designed to answer the question of whether <span class="hlt">gas</span> <span class="hlt">bubble</span> disease (GBD) signs change as a result of the hydrostatic conditions juvenile salmonids encounter when they enter the turbine intake of hydroelectric projects during their downstream migration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA573791','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA573791"><span>Photosynthesis as a Possible Source of <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Shallow Sandy Coastal Sediments</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2012-09-30</p> <p>clearly demonstrates that <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA541774','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA541774"><span>Photosynthesis as a Possible Source of <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Shallow Sandy Coastal Sediments</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-09-30</p> <p><span class="hlt">gas</span> <span class="hlt">bubbles</span> can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen. OBJECTIVES The...acoustic reflectivity. We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present... microalgae in the samples. Following the untimely death of Dr. D.V. Holliday, the remaining team members are sharing the responsibility of analyzing data and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRG..121.1992L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRG..121.1992L"><span>The role of sediment structure in <span class="hlt">gas</span> <span class="hlt">bubble</span> storage and release</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, L.; Wilkinson, J.; Koca, K.; Buchmann, C.; Lorke, A.</p> <p>2016-07-01</p> <p>Ebullition is an important pathway for methane emission from inland waters. However, the mechanisms controlling methane <span class="hlt">bubble</span> formation and release in aquatic sediments remain unclear. A laboratory incubation experiment was conducted to investigate the dynamics of methane <span class="hlt">bubble</span> formation, storage, and release in response to hydrostatic head drops in three different types of natural sediment. Homogenized clayey, silty, and sandy sediments (initially quasi-uniform through the depth of the columns) were incubated in chambers for 3 weeks. We observed three distinct stages of methane <span class="hlt">bubble</span> formation and release: stage I—microbubble formation-displacing mobile water from sediment pores with negligible ebullition; stage II—formation of large <span class="hlt">bubbles</span>, displacing the surrounding sediment with concurrent increase in ebullition; and stage III—formation of conduits with relatively steady ebullition. The maximum depth-averaged volumetric <span class="hlt">gas</span> content at steady state varied from 18.8% in clayey to 12.0% in silty and 13.2% in sandy sediment. <span class="hlt">Gas</span> storage in the sediment columns showed strong vertical stratification: most of the free <span class="hlt">gas</span> was stored in an upper layer, whose thickness varied with sediment grain size. The magnitude of individual ebullition episodes was linearly correlated to hydrostatic head drop and decreased from clayey to sandy to silty sediment and was in excess of that estimated from <span class="hlt">gas</span> expansion alone, indicating the release of pore water methane. These findings combined with a hydrodynamic model capable of determining dominant sediment type and depositional zones could help resolve spatial heterogeneities in methane ebullition at medium to larger scales in inland waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150000146','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150000146"><span>Warm Pressurant <span class="hlt">Gas</span> Effects on the <span class="hlt">Bubble</span> Point Pressure for Cryogenic LADs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hartwig, Jason W.; McQuillen, John B.; Chato, David J.</p> <p>2014-01-01</p> <p>This paper presents experimental results for the liquid hydrogen and nitrogen <span class="hlt">bubble</span> point tests using warm pressurant gases conducted at the NASA Glenn Research Center. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant <span class="hlt">gas</span> on the performance of a liquid acquisition device (LAD). Three fine mesh screen samples (325x2300, 450x2750, 510x3600) were tested in liquid hydrogen and liquid nitrogen using cold and warm non-condensable (gaseous helium) and condensable (gaseous hydrogen or nitrogen) pressurization schemes. Gases were conditioned from 0K 90K above the liquid temperature. Results clearly indicate degradation in <span class="hlt">bubble</span> point pressure using warm <span class="hlt">gas</span>, with a greater reduction in performance using condensable over non-condensable pressurization. Degradation in the <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> tests is also presented for comparison to current results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27713512','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27713512"><span>Marangoni effect visualized in two-dimensions Optical tweezers for <span class="hlt">gas</span> <span class="hlt">bubbles</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miniewicz, A; Bartkiewicz, S; Orlikowska, H; Dradrach, K</p> <p>2016-10-07</p> <p>In the report we demonstrate how, using laser light, effectively trap <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140016764','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140016764"><span>Warm Pressurant <span class="hlt">Gas</span> Effects on the Static <span class="hlt">Bubble</span> Point Pressure for Cryogenic LADs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hartwig, Jason W.; McQuillen, John; Chato, Daniel J.</p> <p>2014-01-01</p> <p>This paper presents experimental results for the liquid hydrogen and nitrogen <span class="hlt">bubble</span> point tests using warm pressurant gases conducted at the NASA Glenn Research Center. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant <span class="hlt">gas</span> on the performance of a liquid acquisition device (LAD). Three fine mesh screen samples (325x2300, 450x2750, 510x3600) were tested in liquid hydrogen and liquid nitrogen using cold and warm non-condensable (gaseous helium) and condensable (gaseous hydrogen or nitrogen) pressurization schemes. Gases were conditioned from 0K - 90K above the liquid temperature. Results clearly indicate degradation in <span class="hlt">bubble</span> point pressure using warm <span class="hlt">gas</span>, with a greater reduction in performance using condensable over non-condensable pressurization. Degradation in the <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> tests is also presented for comparison to current results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1484192','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1484192"><span>Mass Transfer from <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> to Impinging Flow of Biological Fluids with Chemical Reaction</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yang, Wen-Jei; Echigo, R.; Wotton, D. R.; Ou, J. W.; Hwang, J. B.</p> <p>1972-01-01</p> <p>The rates of mass transfer from a <span class="hlt">gas</span> <span class="hlt">bubble</span> to an impinging flow of a biological fluid such as whole blood and plasma are investigated analytically and experimentally. Gases commonly found dissolved in body fluids are included. Consideration is given to the effects of the chemical reaction between the dissolved <span class="hlt">gas</span> and the liquid on the rate of mass transfer. Through the application of boundary layer theory the over-all transfer is found to be Sh/(Re)1/2 = 0.845 Sc1/3 in the absence of chemical reaction, and Sh/(Re) 1/2 = F′ (0) in the presence of chemical reaction, where Sh, Re, and Sc are the Sherwood, Reynolds, and Schmidt numbers, respectively, and F′ (0) is a function of Sc and the dimensionless reaction rate constant. Analytical results are also obtained for the <span class="hlt">bubble</span> lifetime and the <span class="hlt">bubble</span> radius-time history. These results, which are not incompatible with experimental results, can be applied to predict the dissolution of the entrapped <span class="hlt">gas</span> emboli in the circulatory system of the human body. PMID:4642218</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5054428','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5054428"><span>Marangoni effect visualized in two-dimensions Optical tweezers for <span class="hlt">gas</span> <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miniewicz, A.; Bartkiewicz, S.; Orlikowska, H.; Dradrach, K.</p> <p>2016-01-01</p> <p>In the report we demonstrate how, using laser light, effectively trap <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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. PMID:27713512</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...634787M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...634787M"><span>Marangoni effect visualized in two-dimensions Optical tweezers for <span class="hlt">gas</span> <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miniewicz, A.; Bartkiewicz, S.; Orlikowska, H.; Dradrach, K.</p> <p>2016-10-01</p> <p>In the report we demonstrate how, using laser light, effectively trap <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27630918','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27630918"><span><span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in the Bone: A Case Report.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abbasi, Bita; Seilanian-Toosi, Farrokh; Nekooei, Sirous; Kakhki, Behrang Rezvani; Akhavan, Reza</p> <p>2016-07-01</p> <p>Intraosseous pneumatocysts are benign <span class="hlt">gas</span>-filled cavities within bones which are most commonly found in ilium, sacrum and vertebrae. The lesions are asymptomatic and found incidentally while evaluating for other injuries. Here, we present an intraosseous pneumatocyst of ilium in a 23-year-old male patient. Although once thought to be rare, intraossseous pneumatocyst are now believed to be more common. Thus, familiarity with their appearance is essential to avoid unnecessary workup. Intraosseous pneumatocysts are differentiated from more clinically significant differential diagnoses like osteonecrosis and osteomyelitis by their characteristic appearance of intraosseous air collections with sclerotic rim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5020306','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5020306"><span><span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in the Bone: A Case Report</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Abbasi, Bita; Seilanian-Toosi, Farrokh; Nekooei, Sirous; Kakhki, Behrang Rezvani</p> <p>2016-01-01</p> <p>Intraosseous pneumatocysts are benign <span class="hlt">gas</span>-filled cavities within bones which are most commonly found in ilium, sacrum and vertebrae. The lesions are asymptomatic and found incidentally while evaluating for other injuries. Here, we present an intraosseous pneumatocyst of ilium in a 23-year-old male patient. Although once thought to be rare, intraossseous pneumatocyst are now believed to be more common. Thus, familiarity with their appearance is essential to avoid unnecessary workup. Intraosseous pneumatocysts are differentiated from more clinically significant differential diagnoses like osteonecrosis and osteomyelitis by their characteristic appearance of intraosseous air collections with sclerotic rim. PMID:27630918</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017TCry...11.1333L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017TCry...11.1333L"><span>Sonar <span class="hlt">gas</span> flux estimation by <span class="hlt">bubble</span> insonification: application to methane <span class="hlt">bubble</span> flux from seep areas in the outer Laptev Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leifer, Ira; Chernykh, Denis; Shakhova, Natalia; Semiletov, Igor</p> <p>2017-06-01</p> <p>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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> acoustic scattering - precluding the use of a theoretical approach to derive Q(σ) from the product of the <span class="hlt">bubble</span> σ(r) and the <span class="hlt">bubble</span> size distribution where r is <span class="hlt">bubble</span> radius. The <span class="hlt">bubble</span> 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-<span class="hlt">bubble</span> dispersion and was strongly depth dependent. Ψ(σ) for strong σ was largely depth independent, consistent with <span class="hlt">bubble</span> plume behavior where large <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvF...2h4001M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvF...2h4001M"><span>Undulations on the surface of elongated <span class="hlt">bubbles</span> in confined <span class="hlt">gas</span>-liquid flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Magnini, M.; Ferrari, A.; Thome, J. R.; Stone, H. A.</p> <p>2017-08-01</p> <p>A systematic analysis is presented of the undulations appearing on the surface of long <span class="hlt">bubbles</span> in confined <span class="hlt">gas</span>-liquid flows. CFD simulations of the flow are performed with a self-improved version of the open-source solver ESI OpenFOAM (release 2.3.1), for Ca =0.002 -0.1 and Re =0.1 -1000 , where Ca =μ U /σ and Re =2 ρ U R /μ , with μ and ρ being, respectively, the viscosity and density of the liquid, σ the surface tension, U the <span class="hlt">bubble</span> velocity, and R the tube radius. A model, based on an extension of the classical axisymmetric Bretherton theory, accounting for inertia and for the curvature of the tube's wall, is adopted to better understand the CFD results. The thickness of the liquid film, and the wavelength and decay rate of the undulations extracted from the CFD simulations, agree well with those obtained with the theoretical model. Inertial effects appear when the Weber number of the flow We =Ca Re =O (10-1) and are manifest by a larger number of undulation crests that become evident on the surface of the rear meniscus of the <span class="hlt">bubble</span>. This study demonstrates that the necessary <span class="hlt">bubble</span> length for a flat liquid film region to exist between the rear and front menisci rapidly increases above 10 R when Ca >0.01 and the value of the Reynolds number approaches 1000.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ASAJ..114R2318B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ASAJ..114R2318B"><span>Determining <span class="hlt">gas</span> <span class="hlt">bubble</span> morphology and size distribution in mud using CT imagery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Briggs, Kevin B.; Reed, Allen H.</p> <p>2003-10-01</p> <p>Sampling for the measurement and description of methane <span class="hlt">gas</span> <span class="hlt">bubbles</span> in situ was accomplished using the method of Abegg and Anderson [Mar. Geol. 137, 137-147 (1997)]. Sediment cores from East Bay, off the mouth of the Mississippi River, were collected by divers and placed into aluminum pressure transfer chambers while on the seafloor. With the cores at seafloor pressure within the chambers, they were transferred to an x-ray computed tomography (CT) scanner where high-resolution images were made of the sediment within the cores. Data, in the format of series of cross-sectional images of x-ray attenuation reconstructed in 3-D, were evaluated in terms of spatial distribution, sizes, and shapes of <span class="hlt">bubbles</span>. CT imagery was obtained from a GE LS medical CT scanner at a local hospital and the Naval Research Laboratory's new HD-500 industrial CT scanner specifically designed for core sample imaging. The medical scanner provided images of stationary cores at 625-μm intervals with a rotating x-ray source and was able to resolve <span class="hlt">bubbles</span> down to 625 μm in diameter. The industrial scanner provided images of rotating cores at 25-μm intervals with a stationary source and was able to resolve <span class="hlt">bubbles</span> down to 10 μm in diameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25801796','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25801796"><span>Acoustical scattering cross section of <span class="hlt">gas</span> <span class="hlt">bubbles</span> under dual-frequency acoustic excitation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yuning; Li, Shengcai</p> <p>2015-09-01</p> <p>The acoustical scattering cross section is a paramount parameter determining the scattering ability of cavitation <span class="hlt">bubbles</span> when they are excited by the incident acoustic waves. This parameter is strongly related with many important applications of acoustic cavitation including facilitating the reaction of chemical process, boosting <span class="hlt">bubble</span> sonoluminescence, and performing non-invasive therapy and drug delivery. In present paper, both the analytical and numerical solutions of acoustical scattering cross section of <span class="hlt">gas</span> <span class="hlt">bubbles</span> under dual-frequency excitation are obtained. The validity of the analytical solution is shown with demonstrating examples. The nonlinear characteristics (e.g., harmonics, subharmonics and ultraharmonics) of the scattering cross section curve under dual-frequency approach are investigated. Compared with single-frequency approach, the dual-frequency approach displays more resonances termed as "combination resonances" and could promote the acoustical scattering cross section significantly within a much broader range of <span class="hlt">bubble</span> sizes due to the generation of more resonances. The influence of several paramount parameters (e.g., acoustic pressure amplitude, power allocations between two acoustic components, and the ratio of the frequencies) in the dual-frequency system on the predictions of scattering cross section has been discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.7384R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.7384R"><span>Intense <span class="hlt">gas</span> <span class="hlt">bubble</span> emissions in the Kerch seep area - A newly discovered high-flux seep site in the Black Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Römer, M.; Sahling, H.; Pape, T.; Bahr, A.; Feseker, T.; Wintersteller, P.; Bohrmann, G.</p> <p>2012-04-01</p> <p>More than 500 <span class="hlt">bubble</span>-induced hydroacoustic anomalies (flares) were found in the water column above the seafloor in the study area comprising about 430 km2 at the Don-Kuban paleo-fan (Eastern Black Sea) by using ship mounted single beam and multibeam echosounders. Almost all flares originated from the seafloor above the <span class="hlt">gas</span> hydrate stability zone (GHSZ), which in that region is located below ~700 m water depth. This observation confirms the sealing mechanism of <span class="hlt">gas</span> hydrate, which impedes migration of free <span class="hlt">gas</span> through the GHSZ and subsequent <span class="hlt">bubble</span> emission from the seafloor. However, an intense seep site, called the "Kerch seep area" was discovered as an exception at 890 m water depth well within the GHSZ. In situ temperature measurements in shallow sediments indicate locally elevated temperatures probably caused by enhanced upward fluid flow. The base of the GHSZ in this region is generally situated at about 150 m below the seafloor. However, the local thermal anomalies result in a thinning of the <span class="hlt">gas</span> hydrate occurrence zone to only a few meters below the seafloor and allow free <span class="hlt">gas</span> to reach the seafloor. At sites where <span class="hlt">gas</span> migrated into near-surface deposits, shallow <span class="hlt">gas</span> hydrate deposits evolved and up-doming of overlying sediments led to the formation of mounds <span class="hlt">rising</span> several meters from the surrounding seafloor. Further <span class="hlt">gas</span> <span class="hlt">bubbles</span> ascending from greater depth are accumulated below the <span class="hlt">gas</span> hydrate layer at the base of the mound structures and migrate horizontally to their rims. At the mound edges <span class="hlt">gas</span> <span class="hlt">bubbles</span> either might form fresh <span class="hlt">gas</span> hydrates and increase the extent of the mound structures by pushing up overlying sediments or escape at several sites into the water column. Two mounds were mapped in ultra-high resolution during dives with the autonomous underwater vehicle 'AUV MARUM SEAL 5000'. Several individual flares were detected in the Kerch seep area using hydroacoustic systems. Repeated surveys in that area conducted during three cruises within four years</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998APS..DFD..AA05H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998APS..DFD..AA05H"><span>Buoyancy Driven Shear Flows of <span class="hlt">Bubble</span> Suspensions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hill, R. J.; Zenit, R.; Chellppannair, T.; Koch, D. L.; Spelt, P. D. M.; Sangani, A.</p> <p>1998-11-01</p> <p>In this work the <span class="hlt">gas</span> volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of <span class="hlt">bubble</span> suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1 and Re >> 1 , so that the <span class="hlt">bubbles</span> are relatively undeformed and the flow is inviscid and approximately irrotational. Nitrogen is introduced through an array of capillaries at the base of a .2x.02x2 m channel filled with an aqueous electrolyte solution (0.06 molL-1 MgSO_4). The <span class="hlt">rising</span> <span class="hlt">bubbles</span> generate a unidirectional shear flow, where the denser suspension at the lower surface of the channel falls, while the less dense suspension at the upper surface <span class="hlt">rises</span>. Hot-film anemometry is used to measure the resulting <span class="hlt">gas</span> volume fraction and fluid velocity profiles. The <span class="hlt">bubble</span> collision rate with the sensor is related to the <span class="hlt">gas</span> volume fraction and the mean and variance of the <span class="hlt">bubble</span> velocity using an experimentally measured collision surface area for the sensor. <span class="hlt">Bubble</span> collisions with the sensor are identified by the characteristic slope of the hot-film anemometer signal when <span class="hlt">bubbles</span> collide with the sensor. It is observed that the steady shear flow develops a <span class="hlt">bubble</span> phase pressure gradient across the channel gap as the <span class="hlt">bubbles</span> interchange momentum through direct collisions. The discrete phase presssure gradient balances the buoyancy force driving <span class="hlt">bubbles</span> toward the upper surface resulting in a steady void fraction profile across the gap width. The strength of the shear flow is controlled by the extent of <span class="hlt">bubble</span> segregation and by the effective viscosity of the <span class="hlt">bubble</span> phase. The measurements are compared with solutions of the averaged equations of motion (Kang et al. 1997; Spelt and Sangani, 1998), for a range of <span class="hlt">gas</span> volume fractions and channel inclination angles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22261598','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22261598"><span>Helium <span class="hlt">gas</span> <span class="hlt">bubble</span> trapped in liquid helium in high magnetic field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bai, H. Hannahs, S. T.; Markiewicz, W. D.; Weijers, H. W.</p> <p>2014-03-31</p> <p>High magnetic field magnets are used widely in the area of the condensed matter physics, material science, chemistry, geochemistry, and biology at the National High Magnetic Field Laboratory. New high field magnets of state-of-the-art are being pursued and developed at the lab, such as the current developing 32 T, 32 mm bore fully superconducting magnet. Liquid Helium (LHe) is used as the coolant for superconducting magnets or samples tested in a high magnetic field. When the magnetic field reaches a relatively high value the boil-off helium <span class="hlt">gas</span> <span class="hlt">bubble</span> generated by heat losses in the cryostat can be trapped in the LHe bath in the region where BzdBz/dz is less than negative 2100 T{sup 2}/m, instead of floating up to the top of LHe. Then the magnet or sample in the trapped <span class="hlt">bubble</span> region may lose efficient cooling. In the development of the 32 T magnet, a prototype Yttrium Barium Copper Oxide coil of 6 double pancakes with an inner diameter of 40 mm and an outer diameter of 140 mm was fabricated and tested in a resistive magnet providing a background field of 15 T. The trapped <span class="hlt">gas</span> <span class="hlt">bubble</span> was observed in the tests when the prototype coil was ramped up to 7.5 T at a current of 200 A. This letter reports the test results on the trapped <span class="hlt">gas</span> <span class="hlt">bubble</span> and the comparison with the analytical results which shows they are in a good agreement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24571292','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24571292"><span>Kinetics of CH4 and CO2 hydrate dissociation and <span class="hlt">gas</span> <span class="hlt">bubble</span> evolution via MD simulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Uddin, M; Coombe, D</p> <p>2014-03-20</p> <p>Molecular dynamics simulations of <span class="hlt">gas</span> hydrate dissociation comparing the behavior of CH4 and CO2 hydrates are presented. These simulations were based on a structurally correct theoretical <span class="hlt">gas</span> 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. <span class="hlt">Gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span>) 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.V31A3070O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.V31A3070O"><span>Contortionist <span class="hlt">bubbles</span> in andesitic enclaves: implications for <span class="hlt">gas</span> migration and phase segregation in crystal-rich magmas.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oppenheimer, J. C.; Cashman, K. V.; Rust, A.; Dobson, K. J.; Bacon, C. R.; Dingwell, D. B.</p> <p>2016-12-01</p> <p>In order to constrain <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> deformation and coalescence when particle fractions increased beyond a critical value (the random loose packing). At high particle fractions, <span class="hlt">bubble</span> growth re-organized (compacted) the particles adjacent to the <span class="hlt">bubble</span> 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 <span class="hlt">gas</span>-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 <span class="hlt">bubble</span> 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. <span class="hlt">Bubble</span> morphologies reveal two main types of <span class="hlt">bubbles</span>. (1) Lobate and finger-like <span class="hlt">bubbles</span>, similar to the deformed <span class="hlt">bubbles</span> in experiments, are found exclusively in the groundmass patches. They are also often associated with compacted crystal structures at the <span class="hlt">bubble</span> walls. (2) Diktytaxitic textures - angular <span class="hlt">bubbles</span> flattened against phenocrysts - are abundant in the crystal networks. These voids are entirely connected in 3D and formed the <span class="hlt">gas</span>-rich center of the enclave. They likely represent a <span class="hlt">gas</span> migration regime where the expanding <span class="hlt">gas</span> front cannot deform the crystal structure but instead invades the pore-space between</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=nitrogen+AND+andean+AND+paramo+AND+%7dbacterias&id=EJ876116','ERIC'); return false;" href="https://eric.ed.gov/?q=nitrogen+AND+andean+AND+paramo+AND+%7dbacterias&id=EJ876116"><span>The Answer to <span class="hlt">Rising</span> <span class="hlt">Gas</span> Prices...Nitrogen?</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lee, Frank; Batelaan, Herman</p> <p>2010-01-01</p> <p>It is claimed by the company NitroFill and the GetNitrogen Institute that filling car tires with nitrogen improves <span class="hlt">gas</span> mileage considerably. The reason given is that oxygen leaks out of tires so that the increased rolling friction causes a reduced <span class="hlt">gas</span> mileage. Because it is hard to do an actual road test, we report on a simple visual test of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=oxygen&pg=2&id=EJ876116','ERIC'); return false;" href="http://eric.ed.gov/?q=oxygen&pg=2&id=EJ876116"><span>The Answer to <span class="hlt">Rising</span> <span class="hlt">Gas</span> Prices...Nitrogen?</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lee, Frank; Batelaan, Herman</p> <p>2010-01-01</p> <p>It is claimed by the company NitroFill and the GetNitrogen Institute that filling car tires with nitrogen improves <span class="hlt">gas</span> mileage considerably. The reason given is that oxygen leaks out of tires so that the increased rolling friction causes a reduced <span class="hlt">gas</span> mileage. Because it is hard to do an actual road test, we report on a simple visual test of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....10342A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....10342A"><span>Free <span class="hlt">gas</span> <span class="hlt">bubbles</span> in the hydrate stability zone: evidence from CT investigation under in situ conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abegg, F.; Freitag, J.; Bohrmann, G.; Brueckmann, W.; Eisenhauer, A.; Amann, H.; Hohnberg, H.-J.</p> <p>2003-04-01</p> <p>Determination of the internal structures and the fabric of natural marine <span class="hlt">gas</span> hydrate as well as its distribution in shallow subseafloor depth was restricted because of dissociation during recovery. Investigation under in situ conditions becomes possible with a pressure coring device. The newly developed MultiAutoclaveCorer (MAC) can take up to four cores which are housed in a pressure vessel called LabTransferChamber (LTC), which is compatible with CT imaging technology. During a video-guided deployment on Hydrate Ridge, a well known near-surface <span class="hlt">gas</span> hydrate-rich environment, two LTCs were filled and recovered under pressure. CT imaging was performed four days after retrieval in a medical clinic in Palo Alto/Ca., a second round was run 2 months later in Kiel/Germany, still under pressure. The same type of scanner was used for both rounds of imaging. The function and the pressure preserving capability of the MAC was confirmed. Although only 0.8 m apart, both cores showed different <span class="hlt">gas</span> hydrate contents, varying between a maximum of 5 vol-% in LTC 3 and 48 vol-% in LTC 4, documenting the high variability of <span class="hlt">gas</span> hydrate occurrences in near-surface sediments. The uppermost layer of <span class="hlt">gas</span> hydrate was observed 0.1 m below the seafloor. The high <span class="hlt">gas</span> hydrate content in LTC 4 is concentrated in a horizon between 0.28 and 0.32 m subseafloor depth. Within this hoizon a significant quantity of <span class="hlt">bubbles</span> was detected with a free <span class="hlt">gas</span> content of up to 2.4 vol-%. <span class="hlt">Bubble</span> sizes reach a maximum of 1.8 x 10-2 m in either x, y or z direction. Integrating across the mentioned core interval, the <span class="hlt">gas</span> hydrate content is 19 vol-% and the free <span class="hlt">gas</span> content is 0.8 vol-%. Assuming several simplifications, the normalised calculated methane volume of the <span class="hlt">gas</span> hydrate is 9.15 x 10-3 m^3 and the amount of methane in the <span class="hlt">bubbles</span> is 1.49 x 10-4 m^3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhFl...25f2101H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhFl...25f2101H"><span>Energy transfer between the shape and volume modes of a nonspherical <span class="hlt">gas</span> <span class="hlt">bubble</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harkin, Anthony A.; Kaper, Tasso J.; Nadim, Ali</p> <p>2013-06-01</p> <p>A model of a nonspherical <span class="hlt">gas</span> <span class="hlt">bubble</span> is developed in which the Rayleigh-Plesset equation is augmented with second order terms that back-couple the volume mode to a single shape mode. These additional terms in the Rayleigh-Plesset equation permit oscillation energy to be transferred back and forth between the shape and volume modes. The parametric stability of the shape mode is analyzed for a driven <span class="hlt">bubble</span>, and it is seen that the bidirectional coupling yields an enhanced, albeit minor, stabilizing effect on the shape mode when compared with a model where the shape-volume coupling is unidirectional. It is also demonstrated how a pure shape distortion can excite significant volume pulsations when the volume mode is in 2:1 internal resonance with the shape mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ZNatA..72..535G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ZNatA..72..535G"><span><span class="hlt">Gas</span> <span class="hlt">Bubbles</span> and Slugs Crossover in Air-Water Two-phase Flow by Multifractals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gorski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej</p> <p>2017-05-01</p> <p>Slugs and <span class="hlt">bubbles</span> two-phase flow patterns dynamics in a minichannel are analysed. During the experiment, the volume flow rates of air and water were changed. We study transition of <span class="hlt">bubbles</span> to slugs two-phase flow patterns using Fourier and multifractal approaches to optical transitivity signal. The sequences of light transmission time series are recorded by a laser-phototransistor sensor. Multifractal analysis helps to identify the two-phase structure and estimate the signal complexity. Especially, we discuss occurrence and identification of a self-aggregation phenomenon. These results are compared to corresponding Fourier spectra. The results indicate that the fractality is a an important factor influencing the distribution of the <span class="hlt">gas</span> phase in water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020087661&hterms=Viscosity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DViscosity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020087661&hterms=Viscosity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DViscosity"><span>The Effect of Viscosity on the Spherical Stability of Oscillating <span class="hlt">Gas</span> <span class="hlt">Bubbles</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hao, Y.; Prosperetti, A.</p> <p>1999-01-01</p> <p><span class="hlt">Gas</span> <span class="hlt">bubbles</span> driven in radial oscillations are subject to an instability of the spherical shape that is opposed by surface tension and viscosity. An exact linear formulation for the study of the phenomenon has been available for many years, but its complexity has discouraged a detailed investigation. With the recent theory of sonoluminescence of Lohse and co-workers, there has been a renewed interest in the problem and new data have become available. This paper presents a numerical method for the solution of the pertinent equations and compares the theory with these new data. The coupling of the strong nonlinearity of the <span class="hlt">bubble</span> radial oscillations with the parametric mechanism of the surface instability results in a very complex structure for the stability boundary. Nevertheless, a good agreement between theory and data is found. A comparison with earlier approximate models is also made.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AAS...22914505H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AAS...22914505H"><span>The <span class="hlt">rise</span> of ionized <span class="hlt">gas</span> in the Magellanic Stream</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hernandez, Michael; Barger, Kathleen; Smart, Brianna; Haffner, L. Matthew</p> <p>2017-01-01</p> <p>The Small and Large Magellanic Clouds are a pair of interacting galaxies near the Milky Way. Tidal interactions have stripped <span class="hlt">gas</span> from these galaxies, leaving behind gaseous debris such as the Magellanic Stream. We explore the morphology and kinematics of the neutral and ionized hydrogen <span class="hlt">gas</span> in the trailing stream traveling toward the Milky Way. This comparison provides us with insight into the physical processes that are affecting the <span class="hlt">gas</span> flowing through the Galactic halo. This is done using mapped H-alpha emission-line spectroscopy, obtained with the Wisconsin H-alpha Mapper (WHAM), and archival 21-cm HI observations of the Stream near the Magellanic Clouds. We found that the neutral and ionized <span class="hlt">gas</span> spatially and kinematically trace each other. With a map of the ionized <span class="hlt">gas</span> in hand, we will continue to study the survival of this tidal relic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDA21002K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDA21002K"><span>Sinking <span class="hlt">Bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koch, Jeremy; Ewoldt, Randy</p> <p>2016-11-01</p> <p>Intuition tells us that <span class="hlt">bubbles</span> will <span class="hlt">rise</span> and steel objects will sink in liquids, though here we describe the opposite. With experimental demonstration and theoretical rationale, we describe how the motion of containers of liquid with immersed solid objects and air <span class="hlt">bubbles</span> can cause curious behaviors: sinking <span class="hlt">bubbles</span> and <span class="hlt">rising</span> high-density particles. <span class="hlt">Bubbles</span> and solid spheres of diameter on the order of a few millimeters are introduced into fluids with different rheological constitutive behaviors. Imposed motion of the rigid container allows for control of the trajectories of the immersed particles - without the container imparting direct shearing motion on the fluid. Results demonstrate the necessary conditions to prevent or produce net motion of the <span class="hlt">bubbles</span> and heavy particles, both with and against gravitational expectations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15001321','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15001321"><span>Estimated Maximum <span class="hlt">Gas</span> Retention from Uniformly Dispersed <span class="hlt">Bubbles</span> in K Basin Sludge Stored in Large-Diameter Containers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gauglitz, Phillip A.; Terrones, Guillermo</p> <p>2002-05-15</p> <p>This letter report addresses the KE Basin sludge that will be retrieved and stored in large-diameter containers (LDCs.) A fraction of the hydrogen <span class="hlt">gas</span> <span class="hlt">bubbles</span> generated from the corrosion of uranium metal and oxides may be retained within the sludge matrix. Those entrapped <span class="hlt">bubbles</span> will expand the sludge bed volume and, therefore, will affect how much sludge can be loaded into a container. The entrapped <span class="hlt">gas</span> <span class="hlt">bubbles</span> will also impact the overall thermal conductivity and heat capacity of the sludge bed. The evaluation summarized here was performed to estimate the maximum <span class="hlt">gas</span> holdup (volume fraction <span class="hlt">gas</span>) that could occur sludge stored in large-diameter containers, assuming uniform <span class="hlt">gas</span> generation (i.e., uniform distribution of metallic uranium particles). This report represents an evaluation of the retention of uniformly distributed <span class="hlt">bubbles</span> and an estimate of the maximum <span class="hlt">gas</span> fraction that might be retained in K Basin LDCs based on existing literature data on <span class="hlt">bubble</span> retention and Basin sludge characterization data. Existing data show that the maximum <span class="hlt">gas</span> fraction varies, depending on physical properties and the configuration of the material or waste.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......171G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......171G"><span>Plasma Discharges in <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Liquid Water: Breakdown Mechanisms and Resultant Chemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gucker, Sarah M. N.</p> <p></p> <p>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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> in liquids. Two primary experimental configurations are investigated: the first allows for single <span class="hlt">bubble</span> analysis through the use of an acoustic trap. Electrodes may be brought in around the <span class="hlt">bubble</span> to allow for plasma formation without physically touching the <span class="hlt">bubble</span>. 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..109a2002C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..109a2002C"><span>A complementary approach to estimate the internal pressure of fission <span class="hlt">gas</span> <span class="hlt">bubbles</span> by SEM-SIMS-EPMA in irradiated nuclear fuels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cagna, C.; Zacharie-Aubrun, I.; Bienvenu, P.; Barrallier, L.; Michel, B.; Noirot, J.</p> <p>2016-02-01</p> <p>The behaviour of gases produced by fission is of great importance for nuclear fuel in operation. Within this context, a decade ago, a general method for the characterisation of the fission <span class="hlt">gas</span> including <span class="hlt">gas</span> <span class="hlt">bubbles</span> in an irradiated UO2 nuclear fuel was developed and applied to determine the <span class="hlt">bubbles</span> internal pressure. The method consists in the determination of the pressure, over a large population of <span class="hlt">bubbles</span>, using three techniques: SEM, EPMA and SIMS. In this paper, a complementary approach using the information given by the same techniques is performed on an isolated <span class="hlt">bubble</span> under the surface and is aiming for a better accuracy compared to the more general measurement of <span class="hlt">gas</span> content. SEM and EPMA enable the detection of a <span class="hlt">bubble</span> filled with xenon under the surface. SIMS enables the detection of the <span class="hlt">gas</span> filling the <span class="hlt">bubble</span>. The quantification is achieved using the EPMA data as reference at positions where no or nearly no <span class="hlt">bubbles</span> are detected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1859b0076R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1859b0076R"><span><span class="hlt">Gas</span> holdup in a <span class="hlt">bubble</span> column in the presence of coaxially placed string of spheres promoter as internal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rohinikumar, P.; Reddy, M. G. Muni; Venkateswarlu, P.; Ramesh, K. V.</p> <p>2017-07-01</p> <p><span class="hlt">Gas</span> holdup was obtained in a <span class="hlt">gas</span>-liquid upflow <span class="hlt">bubble</span> column using quick-closing valve technique. Coaxially placed string of spheres is the promoter internal. An electrolyte solution of ferri-ferro redox couple was the liquid phase and nitrogen was the <span class="hlt">gas</span> phase. Using promoter the <span class="hlt">gas</span> holdup obtained was about 22 percent more. The influence of liquid velocity and rod diameter on <span class="hlt">gas</span> holdup was found to be negligible. The <span class="hlt">gas</span> holdup increased with <span class="hlt">gas</span> velocity, pitch and sphere diameter. A correlation equation is obtained for the prediction of <span class="hlt">gas</span> holdup as a function of Reynolds number and Froude number.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JOM....69b.281Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JOM....69b.281Z"><span>Effects of Anode Wettability and Slots on Anodic <span class="hlt">Bubble</span> Behavior Using Transparent Aluminium Electrolytic Cells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Zhibin; Gao, Bingliang; Feng, Yuqing; Huang, Yipeng; Wang, Zhaowen; Shi, Zhongning; Hu, Xianwei</p> <p>2017-02-01</p> <p>Transparent aluminum electrolytic cells were used to study the effects of anode wettability and slots on <span class="hlt">bubble</span> behavior in a similar environment to that used in industrial cells. Observations were conducted using two types of transparent cells, one with side-observation and the other with a bottom-observation cell design. Anodic <span class="hlt">bubbles</span> <span class="hlt">rising</span> process in the side channel is strongly affected by the wettability of the anode. After <span class="hlt">rising</span> a short distance, the <span class="hlt">bubbles</span> detach from the anode vertical surface at good-wetting anode cases, while the <span class="hlt">bubbles</span> still attach to the vertical surface at poor-wetting anode cases. Anode slots of width of 4 mm are able to prevent smaller <span class="hlt">bubbles</span> from coalescing into larger <span class="hlt">bubbles</span> and thus decrease the <span class="hlt">bubble</span> size and <span class="hlt">gas</span> coverage on the anode. Anode slots also make a contribution in slightly reducing <span class="hlt">bubble</span> thickness. With the presence of slots, the <span class="hlt">bubble</span>-induced cell voltage oscillation decreases as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.460...50F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.460...50F"><span>Trapped <span class="hlt">bubbles</span> keep pumice afloat and <span class="hlt">gas</span> diffusion makes pumice sink</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fauria, Kristen E.; Manga, Michael; Wei, Zihan</p> <p>2017-02-01</p> <p>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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> by water within the pumice. <span class="hlt">Gas</span> trapping refers to the isolation of <span class="hlt">gas</span> by water within pore throats such that the <span class="hlt">gas</span> becomes disconnected from the atmosphere and unable to escape. We use X-ray microtomography to image partially saturated pumice and demonstrate that non-condensable <span class="hlt">gas</span> trapping occurs in both ambient temperature and hot (500 °C) pumice. Furthermore, we show that the size distribution of trapped <span class="hlt">gas</span> clusters matches predictions of percolation theory. Finally, we propose that diffusion of trapped <span class="hlt">gas</span> 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 <span class="hlt">gas</span>-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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27722703','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27722703"><span>Electrochemistry of single nanobubbles. Estimating the critical size of <span class="hlt">bubble</span>-forming nuclei for <span class="hlt">gas</span>-evolving electrode reactions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>German, Sean R; Edwards, Martin A; Chen, Qianjin; Liu, Yuwen; Luo, Long; White, Henry S</p> <p>2016-12-12</p> <p>In this article, we address the fundamental question: "What is the critical size of a single cluster of <span class="hlt">gas</span> molecules that grows and becomes a stable (or continuously growing) <span class="hlt">gas</span> <span class="hlt">bubble</span> during <span class="hlt">gas</span> evolving reactions?" Electrochemical reactions that produce dissolved <span class="hlt">gas</span> molecules are ubiquitous in electrochemical technologies, e.g., water electrolysis, photoelectrochemistry, chlorine production, corrosion, and often lead to the formation of gaseous <span class="hlt">bubbles</span>. Herein, we demonstrate that electrochemical measurements of the dissolved <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> nucleus that grows into a stable <span class="hlt">bubble</span>. We further demonstrate that this critical nucleus size is independent of the radius of the Pt nanodisk employed (<100 nm radius), and weakly dependent on the nature of the <span class="hlt">gas</span>. For example, the measured critical surface concentration of H2 of ∼0.23 M at the instant of <span class="hlt">bubble</span> 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 <span class="hlt">gas</span>, at or near the Pt/solution interface, controlling the rate of <span class="hlt">bubble</span> 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) <span class="hlt">gas</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820015564','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820015564"><span><span class="hlt">Bubble</span> shapes in steady axisymmetric flows at intermediate Reynolds number</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ryskin, G.; Leal, L. G.</p> <p>1982-01-01</p> <p>The shape of a <span class="hlt">gas</span> <span class="hlt">bubble</span> which <span class="hlt">rises</span> through a quiescent incompressible, Newtonian fluid at intermediate Reynolds numbers is considered. Exact numerical solutions for the velocity and pressure fields, as well as the <span class="hlt">bubble</span> shape, are obtained using finite difference techniques and a numerically generated transformation to an orthogonal, boundary-fitted coordinate system. No restriction is placed on the allowable magnitude of deformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1003516','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1003516"><span>EXPERIMENTS AND SIMULATIONS WITH LARGE <span class="hlt">GAS</span> <span class="hlt">BUBBLES</span> IN MERCURY TOWARDS ESTABLISHING A <span class="hlt">GAS</span> LAYER TO MITIGATE CAVITATION DAMAGE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wendel, Mark W; Riemer, Bernie; Felde, David K; Ruggles, Arthur; Karnowski, Thomas Paul</p> <p>2006-01-01</p> <p>One of several options that shows promise for protecting solid surfaces from cavitation damage in liquid metal spallation targets, involves introducing an interstitial <span class="hlt">gas</span> layer between the liquid metal and the containment vessel wall. Several approaches toward establishing such a protective <span class="hlt">gas</span> layer are being investigated at the Oak Ridge National Laboratory including large <span class="hlt">bubble</span> injection, and methods that involve stabilization of the layer by surface modifications to enhance <span class="hlt">gas</span> hold-up on the wall or by inserting a porous media. It has previously been reported that using a <span class="hlt">gas</span> layer configuration in a test target showed an order-of-magnitude decrease in damage for an in-beam experiment. Video images that were taken of the successful <span class="hlt">gas</span>/mercury flow configuration have been analyzed and correlated. The results show that the success was obtained under conditions where only 60% of the solid wall was covered with <span class="hlt">gas</span>. Such a result implies that this mitigation scheme may have much more potential. Additional experiments with <span class="hlt">gas</span> injection into water are underway. Multi-component flow simulations are also being used to provide direction for these new experiments. These simulations have been used to size the <span class="hlt">gas</span> layer and position multiple inlet nozzles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPUO7005S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPUO7005S"><span>The Evolution of the Gold <span class="hlt">Bubble</span> in NIF Ignition <span class="hlt">Gas</span>-Filled Hohlraums</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>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</p> <p>2015-11-01</p> <p>At the National Ignition Facility (NIF), the energy from 192 laser beams is converted to an x-ray drive in a <span class="hlt">gas</span>-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 <span class="hlt">bubble</span>'') Time-resolved and time-integrated images in the hard x-ray range (>3 keV) reveal an 8-fold symmetry in the gold <span class="hlt">bubble</span>. The Au plasma in the <span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6733961','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6733961"><span>Heat transfer between immiscible liquids enhanced by <span class="hlt">gas</span> <span class="hlt">bubbling</span>. [PWR; BWR</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Greene, G.A.; Schwarz, C.E.; Klages, J.; Klein, J.</p> <p>1982-08-01</p> <p>The phenomena of core-concrete interactions impact upon containment integrity of light water reactors (LWR) following postulated complete meltdown of the core by containment pressurization, production of combustible gases, and basemat penetration. Experiments have been performed with non-reactor materials to investigate one aspect of this problem, heat transfer between overlying immiscible liquids whose interface is disturbed by a transverse non-condensable <span class="hlt">gas</span> flux emanating from below. Hydrodynamic studies have been performed to test a criterion for onset of entrainment due to <span class="hlt">bubbling</span> through the interface and subsequent heat transfer studies were performed to assess the effect of <span class="hlt">bubbling</span> on interfacial heat transfer rates, both with and without <span class="hlt">bubble</span> induced entrainment. Non-entraining interfacial heat transfer data with mercury-water/oil fluid pairs were observed to be bounded from below within a factor of two to three by the Szekeley surface renewal heat transfer model. However heat transfer data for fluid pairs which are found to entrain (water-oil), believed to be characteristic of molten reactor core-concrete conditions, were measured to be up to two orders of magnitude greater than surface renewal predictions and are calculated by a simple entrainment heat transfer model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhTea..48..160L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhTea..48..160L"><span>The Answer to <span class="hlt">Rising</span> <span class="hlt">Gas</span> Prices...Nitrogen?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Frank; Batelaan, Herman</p> <p>2010-03-01</p> <p>It is claimed by the company NitroFill and the GetNitrogen Institute that filling car tires with nitrogen improves <span class="hlt">gas</span> mileage considerably. The reason given is that oxygen leaks out of tires so that the increased rolling friction causes a reduced <span class="hlt">gas</span> mileage. Because it is hard to do an actual road test, we report on a simple visual test of leakage from oxygen- and nitrogen-filled balloons. This experiment can be repeated in classrooms to address a controversial and topical issue, while at the same time highlighting hypothesis formulation, verification, and falsification in scientific experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://wfrc.usgs.gov/publications/reportpdf/usgsfrgbdgrandcouleedam.pdf','USGSPUBS'); return false;" href="https://wfrc.usgs.gov/publications/reportpdf/usgsfrgbdgrandcouleedam.pdf"><span><span class="hlt">Gas</span> <span class="hlt">bubble</span> disease in resident fish below Grand Coulee Dam: final report of research</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Beeman, J.W.; Venditti, D.A.; Morris, R.G.; Gadomski, D.M.; Adams, B.J.; Vanderkooi, S.J.; Robinson, T.C.; Maule, A.G.</p> <p>2003-01-01</p> <p>Fish kills have occurred in the reservoir below Grand Coulee Dam possibly due to total dissolved <span class="hlt">gas</span> supersaturation (TDGS), which occurs when water cascades over a dam or waterfall. The highest TDGS below Grand Coulee Dam has occurred after spilling water via the outlet tubes, though TDGS from upstream sources has also been recorded. Exposure to TDGS can cause <span class="hlt">gas</span> <span class="hlt">bubble</span> disease in aquatic organisms. This disease, analogous to ‘the bends’ in human divers, can range from mild to fatal depending on the level of supersaturation, species, life cycle stage, condition of the fish, fish depth, and the water temperature. The USGS, Western Fisheries Research Center’s Columbia River Research Laboratory conducted field and laboratory experiments to determine the relative risks of TDGS to various species of fish in the reservoir below the dam (Rufus Woods Lake). Field work included examination of over 8000 resident fish for signs of <span class="hlt">gas</span> <span class="hlt">bubble</span> disease, examination of the annual growth increments of several species relative to ambient TDGS, and recording the in-situ depths and temperatures of several species using miniature recorders surgically implanted in both resident fish and triploid steelhead reared in commercial net pens. Laboratory experiments included bioassays of the progression of signs and mortality of several species at various TDGS levels. The overarching objective of these studies was to provide data to enable sound management decisions regarding the effects of TDGS in the reservoir below Grand Coulee Dam, though the data may also be applicable to other locations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1064409','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1064409"><span>A Study of Vertical <span class="hlt">Gas</span> Jets in a <span class="hlt">Bubbling</span> Fluidized Bed</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ceccio, Steven; Curtis, Jennifer</p> <p>2011-04-15</p> <p>A detailed experimental study of a vertical <span class="hlt">gas</span> 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 <span class="hlt">bubbling</span> beds, such as in coal and biomass gasification, and also in building more fundamental <span class="hlt">gas</span>-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 <span class="hlt">gas</span>-solid <span class="hlt">bubbling</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA132858','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA132858"><span>An Acoustic Levitation Technique for the Study of Nonlinear Oscillations of <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Liquids.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1983-08-15</p> <p>PHYSICS AND ASTRONOMY J"IC FILE CO 0 9 0741 • 9 Technical Report for Office of Naval Research Contract N00014-81-K-0691 AN ACOUSTIC LEVITATION TECHNIQUE FOR...nweeeewy and Identify by block nMber) A technique of acoustic levitation was developed for the study of individual <span class="hlt">gas</span> <span class="hlt">bubbles</span> in a liquid. Isopropyl... acoustic pressure antinode of an acoustic wave in the range of 20-2.2 kHz. Measurements - were made of the levitation number as a function of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/870286','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/870286"><span>Method for <span class="hlt">gas</span> <span class="hlt">bubble</span> and void control and removal from metals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Van Siclen, Clinton D.; Wright, Richard N.</p> <p>1996-01-01</p> <p>A method for enhancing the diffusion of <span class="hlt">gas</span> <span class="hlt">bubbles</span> or voids attached to impurity precipitates, and biasing their direction of migration out of the host metal (or metal alloy) by applying a temperature gradient across the host metal (or metal alloy). In the preferred embodiment of the present invention, the impurity metal is insoluble in the host metal and has a melting point lower than the melting point of the host material. Also, preferably the impurity metal is lead or indium and the host metal is aluminum or a metal alloy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/187056','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/187056"><span>Method for <span class="hlt">gas</span> <span class="hlt">bubble</span> and void control and removal from metals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Siclen, C.D. Van; Wright, R.N.</p> <p>1996-02-06</p> <p>A method is described for enhancing the diffusion of <span class="hlt">gas</span> <span class="hlt">bubbles</span> or voids attached to impurity precipitates, and biasing their direction of migration out of the host metal (or metal alloy) by applying a temperature gradient across the host metal (or metal alloy). In the preferred embodiment of the present invention, the impurity metal is insoluble in the host metal and has a melting point lower than the melting point of the host material. Also, preferably the impurity metal is lead or indium and the host metal is aluminum or a metal alloy. 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/383079','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/383079"><span>Review of Monitoring Plans for <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Disease Signs and <span class="hlt">Gas</span> Supersaturation Levels on the Columbia and Snake Rivers.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fidler, Larry; Elston, Ralph; Colt, John</p> <p>1994-07-01</p> <p>Montgomery Watson was retained by the Bonneville Power Administration to evaluate the monitoring program for <span class="hlt">gas</span> <span class="hlt">bubble</span> disease signs and dissolved <span class="hlt">gas</span> supersaturation levels on the Columbia and Snake rivers. The results of this evaluation will provide the basis for improving protocols and procedures for future monitoring efforts. Key study team members were Dr. John Colt, Dr. Larry Fidler, and Dr. Ralph Elston. On the week of June 6 through 10, 1994 the study team visited eight monitoring sites (smolt, adult, and resident fish) on the Columbia and Snake rivers. Additional protocol evaluations were conducted at the Willard Field Station (National Biological Survey) and Pacific Northwest Laboratories at Richland (Battelle). On June 13 and 14, 1994, the study team visited the North Pacific Division office of the U.S. Corps of Engineers and the Fish Passage Center to collect additional information and data on the monitoring programs. Considering the speed at which the <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Trauma Monitoring Program was implemented this year, the Fish Passage Center and cooperating Federal, State, and Tribal Agencies have been doing an incredible job. Thirty-one specific recommendations are presented in this report and are summarized in Section 14.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4411458','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4411458"><span>Incidence and Outcomes of Anterior Chamber <span class="hlt">Gas</span> <span class="hlt">Bubble</span> during Femtosecond Flap Creation for Laser-Assisted In Situ Keratomileusis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rush, Sloan W.; Cofoid, Philip; Rush, Ryan B.</p> <p>2015-01-01</p> <p>Purpose. To report the incidence and outcomes of anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during femtosecond laser flap creation for laser-assisted in situ keratomileusis (LASIK). Methods. The charts of 2,886 consecutive eyes that underwent femtosecond LASIK from May 2011 through August 2014 were retrospectively reviewed. The incidence, preoperative characteristics, intraoperative details, and postoperative outcomes were analyzed in subjects developing anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during the procedure. Results. A total of 4 cases (0.14%) developed anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during femtosecond laser flap creation. In all four cases, the excimer laser was unable to successfully track the pupil immediately following the anterior chamber <span class="hlt">bubble</span> formation, temporarily postponing the completion of the procedure. There was an ethnicity predilection of anterior chamber <span class="hlt">gas</span> formation toward Asians (p = 0.0055). An uncorrected visual acuity of 20/20 was ultimately achieved in all four cases without further complications. Conclusions. Anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during femtosecond laser flap creation for LASIK is an uncommon event that typically results in a delay in treatment completion; nevertheless, it does influence final positive visual outcome. PMID:25954511</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25954511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25954511"><span>Incidence and Outcomes of Anterior Chamber <span class="hlt">Gas</span> <span class="hlt">Bubble</span> during Femtosecond Flap Creation for Laser-Assisted In Situ Keratomileusis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rush, Sloan W; Cofoid, Philip; Rush, Ryan B</p> <p>2015-01-01</p> <p>Purpose. To report the incidence and outcomes of anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during femtosecond laser flap creation for laser-assisted in situ keratomileusis (LASIK). Methods. The charts of 2,886 consecutive eyes that underwent femtosecond LASIK from May 2011 through August 2014 were retrospectively reviewed. The incidence, preoperative characteristics, intraoperative details, and postoperative outcomes were analyzed in subjects developing anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during the procedure. Results. A total of 4 cases (0.14%) developed anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during femtosecond laser flap creation. In all four cases, the excimer laser was unable to successfully track the pupil immediately following the anterior chamber <span class="hlt">bubble</span> formation, temporarily postponing the completion of the procedure. There was an ethnicity predilection of anterior chamber <span class="hlt">gas</span> formation toward Asians (p = 0.0055). An uncorrected visual acuity of 20/20 was ultimately achieved in all four cases without further complications. Conclusions. Anterior chamber <span class="hlt">gas</span> <span class="hlt">bubble</span> formation during femtosecond laser flap creation for LASIK is an uncommon event that typically results in a delay in treatment completion; nevertheless, it does influence final positive visual outcome.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRG..116.1024K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRG..116.1024K"><span>Characterization of peat structure using X-ray computed tomography and its control on the ebullition of biogenic <span class="hlt">gas</span> <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kettridge, Nicholas; Binley, Andrew</p> <p>2011-03-01</p> <p>The structural arrangement of peat constituents controls the hydrological and thermal properties of peat. However, the importance of these structural characteristics on other physical processes within a peatland has not been fully assessed. Here, we evaluate the importance of peat structure on its ability to entrain biogenic <span class="hlt">gas</span> <span class="hlt">bubbles</span> and control ebullition, an important transport mechanism for methane. X-ray computed tomography (CT) was applied to characterize the structure of a range of peats at varying levels of decomposition. The structural properties of the peat were quantified from a vector representation of the CT images, and the potential of each sample to entrain biogenic <span class="hlt">gas</span> <span class="hlt">bubbles</span> was quantified using a rule-based Monte Carlo model that calculates the tortuosity of <span class="hlt">bubbles</span> pathways through the peat. Sixty-six percent of the variability in the trapping potential of the peat results from porosity variations and 34% from structural variations between samples. A metric that represents this structural control was not identified for all peat types because of difficulties adequately representing some peats as a vector network. However, for S. magellanicum peat we were able to establish that the influence of peat structure on the entrainment of <span class="hlt">gas</span> <span class="hlt">bubbles</span> is characterized by ?v, the average vector length of the stems and branches. Peat characterized by longer structural components (larger ?v) enhances the entrainment of <span class="hlt">gas</span> <span class="hlt">bubbles</span>. Our findings demonstrate the need to incorporate some representation of the peat structure in numerical models of biogenic <span class="hlt">gas</span> transport in peat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1073557','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1073557"><span>The effects of total dissolved <span class="hlt">gas</span> on chum salmon fry survival, growth, <span class="hlt">gas</span> <span class="hlt">bubble</span> disease, and seawater tolerance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Geist, David R.; Linley, Timothy J.; Cullinan, Valerie I.; Deng, Zhiqun</p> <p>2013-02-01</p> <p>Chum salmon Oncorhynchus keta alevin developing in gravel habitats downstream of Bonneville Dam on the Columbia River are exposed to elevated levels of total dissolved <span class="hlt">gas</span> (TDG) when water is spilled at the dam to move migrating salmon smolts downstream to the Pacific Ocean. Current water quality criteria for the management of dissolved <span class="hlt">gas</span> in dam tailwaters were developed primarily to protect salmonid smolts and are assumed to be protective of alevin if adequate depth compensation is provided. We studied whether chum salmon alevin exposed to six levels of dissolved <span class="hlt">gas</span> ranging from 100% to 130% TDG at three development periods between hatch and emergence (hereafter early, middle, and late stage) suffered differential mortality, growth, <span class="hlt">gas</span> <span class="hlt">bubble</span> disease, or seawater tolerance. Each life stage was exposed for 50 d (early stage), 29 d (middle stage), or 16 d (late stage) beginning at 13, 34, and 37 d post-hatch, respectively, through 50% emergence. The mortality for all stages from exposure to emergence was estimated to be 8% (95% confidence interval (CI) of 4% to 12%) when dissolved <span class="hlt">gas</span> levels were between 100% and 117% TDG. Mortality significantly increased as dissolved <span class="hlt">gas</span> levels rose above 117% TDG,; with the lethal concentration that produced 50% mortality (LC50 ) was estimated to be 128.7% TDG (95% CI of 127.2% to 130.2% TDG) in the early and middle stages. By contrast, there was no evidence that dissolved <span class="hlt">gas</span> level significantly affected growth in any life stage except that the mean wet weight at emergence of early stage fish exposed to 130% TDG was significantly less than the modeled growth of unexposed fish. The proportion of fish afflicted with <span class="hlt">gas</span> <span class="hlt">bubble</span> disease increased with increasing <span class="hlt">gas</span> concentrations and occurred most commonly in the nares and gastrointestinal tract. Early stage fish exhibited higher ratios of filament to lamellar gill chloride cells than late stage fish, and these ratios increased and decreased for early and late stage fish</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27547596','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27547596"><span>Laboratory investigation of the factors impact on <span class="hlt">bubble</span> size, pore blocking and enhanced oil recovery with aqueous Colloidal <span class="hlt">Gas</span> Aphron.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shi, Shenglong; Wang, Yefei; Li, Zhongpeng; Chen, Qingguo; Zhao, Zenghao</p> <p></p> <p>Colloidal <span class="hlt">Gas</span> Aphron as a mobility control in enhanced oil recovery is becoming attractive; it is also designed to block porous media with micro-<span class="hlt">bubbles</span>. In this paper, the effects of surfactant concentration, polymer concentration, temperature and salinity on the <span class="hlt">bubble</span> size of the Colloidal <span class="hlt">Gas</span> Aphron were studied. Effects of injection rates, Colloidal <span class="hlt">Gas</span> Aphron fluid composition, heterogeneity of reservoir on the resistance to the flow of Colloidal <span class="hlt">Gas</span> Aphron fluid through porous media were investigated. Effects of Colloidal <span class="hlt">Gas</span> Aphron fluid composition and temperature on residual oil recovery were also studied. The results showed that <span class="hlt">bubble</span> 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 <span class="hlt">Gas</span> Aphron fluid was injected, indicating that Colloidal <span class="hlt">Gas</span> 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 <span class="hlt">Gas</span> 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 <span class="hlt">Gas</span> Aphron fluid was about three times that of the XG solution. As the temperature increased, the Colloidal <span class="hlt">Gas</span> Aphron fluid became less stable; the maximum injection pressure and tertiary oil recovery of Colloidal <span class="hlt">Gas</span> Aphron fluid decreased.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JSV...331.4438G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JSV...331.4438G"><span>On sound generated by <span class="hlt">gas</span>-jet impingement on a <span class="hlt">bubbly</span> <span class="hlt">gas</span>-water interface, with application to supercavity self-noise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gilbert, J. B.; Howe, M. S.; Koch, R. M.</p> <p>2012-09-01</p> <p>An analysis is made of the sound produced when a high speed turbulent <span class="hlt">gas</span> jet impinges at normal incidence on a planar <span class="hlt">gas</span>-water interface in the presence of a uniform, thin homogeneous <span class="hlt">bubble</span> layer between the <span class="hlt">gas</span> and the water. It is shown that the <span class="hlt">bubble</span> layer exhibits a behaviour similar to a 'quarter-wave' resonator, storing energy supplied by <span class="hlt">gas</span> impingement which is subsequently released as high amplitude sound into the water. In the absence of <span class="hlt">bubbles</span> the radiation into the water has dipole characteristics, peaking strongly in the direction normal to the interface. The <span class="hlt">bubbles</span> diffuse this sharp dipole lobe, and are predicted to increase the sound power in the water by up to 10 dB or more over a range of intermediate frequencies when the layer properties are similar to those encountered in experiments using a model scale supercavitating vehicle. At higher frequencies, in the range important for vehicle guidance and control, the <span class="hlt">bubble</span> layer tends to reduce this source of self-noise. The same mechanism of resonant amplification should be effective more generally, when the <span class="hlt">bubbles</span> lie within a more confined surface envelope, such as the surface 'wake' of the jet impact zone, whose shape defines a different set of interior eigenmodes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22429728','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22429728"><span>Effect of air on energy and <span class="hlt">rise</span>-time spectra measured by proportional <span class="hlt">gas</span> counter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kawano, T.; Tanaka, M.; Isozumi, S.; Isozumi, Y.; Tosaki, M.; Sugiyama, T.</p> <p>2015-03-15</p> <p>Air exerts a negative effect on radiation detection using a <span class="hlt">gas</span> counter because oxygen contained in air has a high electron attachment coefficient and can trap electrons from electron-ion pairs created by ionization from incident radiation in counting <span class="hlt">gas</span>. This reduces radiation counts. The present study examined the influence of air on energy and <span class="hlt">rise</span>-time spectra measurements using a proportional <span class="hlt">gas</span> counter. In addition, a decompression procedure method was proposed to reduce the influence of air and its effectiveness was investigated. For the decompression procedure, the counting <span class="hlt">gas</span> inside the <span class="hlt">gas</span> counter was decompressed below atmospheric pressure before radiation detection. For the spectrum measurement, methane as well as various methane and air mixtures were used as the counting <span class="hlt">gas</span> to determine the effect of air on energy and <span class="hlt">rise</span>-time spectra. Results showed that the decompression procedure was effective for reducing or eliminating the influence of air on spectra measurement using a proportional <span class="hlt">gas</span> counter. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/953170','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/953170"><span>Experimental formation of massive hydrate deposits from accumulation of CH4 <span class="hlt">gas</span> <span class="hlt">bubbles</span> within synthetic and natural sediments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Madden, Megan Elwood; Szymcek, Phillip; Ulrich, Shannon M; McCallum, Scott D; Phelps, Tommy Joe</p> <p>2009-01-01</p> <p>In order for methane to be economically produced from the seafloor, prediction and detection of massive hydrate deposits will be necessary. In many cases, hydrate samples recovered from seafloor sediments appear as veins or nodules, suggesting that there are strong geologic controls on where hydrate is likely to accumulate. Experiments have been conducted examining massive hydrate accumulation from methane <span class="hlt">gas</span> <span class="hlt">bubbles</span> within natural and synthetic sediments in a large volume pressure vessels through temperature and pressure data, as well as visual observations. Observations of hydrate growth suggest that accumulation of <span class="hlt">gas</span> <span class="hlt">bubbles</span> within void spaces and at sediment interfaces likely results in the formation of massive hydrate deposits. Methane hydrate was first observed as a thin film forming at the <span class="hlt">gas</span>/water interface of methane <span class="hlt">bubbles</span> trapped within sediment void spaces. As <span class="hlt">bubbles</span> accumulated, massive hydrate growth occurred. These experiments suggest that in systems containing free methane <span class="hlt">gas</span>, <span class="hlt">bubble</span> pathways and accumulation points likely control the location and habit of massive hydrate deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994BVol...56..447W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994BVol...56..447W"><span><span class="hlt">Gas</span> transport and <span class="hlt">bubble</span> collapse in rhyolitic magma: an experimental approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Westrich, Henry R.; Eichelberger, John C.</p> <p>1994-12-01</p> <p>A series of experiments was conducted to test concepts of porous flow degassing of rhyolitic magma during ascent and of the subsequent collapse of vesicles in degassed magma to form obsidian. Dense, synthetically hydrated, natural glasses were pressurized under water-saturated conditions and then decompressed to achieve a range of porosities in the presence of a tracer vapor, D2O. Rapid isotopic exchange indicative of vapor transport rather than of simple diffusion occurred at a porosity >60 vol.%, in accord with earlier <span class="hlt">gas</span> permeability measurements on cold natural samples. In another series of experiments, natural and synthetic pumices, vesiculated by degassing to atmospheric pressure, rapidly collapsed to dense glass on repressurization to the modest pressures prevailing in lava flows. No relict <span class="hlt">bubble</span> textures remained. These results support the hypothesis that effusive eruptions result from the syneruptive escape of <span class="hlt">gas</span> from permeable magmatic foam, and that a process analogous to welding yields dense lavas when such foams are extruded.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUSMNS24A..01K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUSMNS24A..01K"><span>Measurement of Entrapped Biogenic <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> in Northern Peat Soils: Application of Resistivity and X-ray Computed Tomography.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kettridge, N.; Binley, A.; Baird, A.</p> <p>2008-05-01</p> <p>Peatlands are the largest natural source per annum of CH4 emissions to the atmosphere. CH4 is lost from peatlands via diffusion or active transport through vascular plants, and as <span class="hlt">bubbles</span> moving to the peatland surface - ebullition. The build up and ebullition of biogenic <span class="hlt">gas</span> <span class="hlt">bubbles</span> within northern peatlands is spatially variable and depends on the rate of CH4 production, the transport of dissolved CH4 to <span class="hlt">bubbles</span> through pore water, and the physical properties of the peat. Recent measurements suggest a threshold <span class="hlt">bubble</span> volume must be reached to trigger episodic or cyclic ebullition, which is assumed to be dependent on peat type. However, this threshold theory lacks a secure physical basis and therefore cannot be applied to simulate methane ebullition from northern peatlands with any confidence. We develop an approach to examine the structural attributes of the peat that cause and promote the trapping and release of <span class="hlt">bubbles</span> by combining resistivity and X-ray computed tomography (CT). The spatial and temporal variation in the biogenic <span class="hlt">gas</span> content of peat cores are identified from resistivity measurements. Areas of high and low entrapped <span class="hlt">gas</span> content are subsequently correlated with the pore structure of the peat samples, characterised using CT. The CT images of the peat structure are vectorised to allow them to be analysed for metrics which relate to the ability of the peat to trap <span class="hlt">bubbles</span>: e.g. stem length and width, number of branches, angle of branches. Difficulties applying these approaches within northern peatlands are examined. The low pore water conductivity of poorly decomposed near surface peat can hamper resistivity measurements at the laboratory scale, and electrolytic reactions induce the development of artificial <span class="hlt">gas</span> <span class="hlt">bubbles</span>. The similarity in linear attenuations between poorly decomposed Sphagnum and pore water also makes the peat structure indistinguishable from the pore water within standard CT scans. The peat samples must, therefore, first be doped</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4434445','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4434445"><span>Does nitrogen <span class="hlt">gas</span> <span class="hlt">bubbled</span> through a low density polymer gel dosimeter solution affect the polymerization process?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shahbazi-Gahrouei, Daryoush; Gholami, Mehrdad; Pourfallah, Tayyeb Allahverdi; Keshtkar, Mohammad</p> <p>2015-01-01</p> <p>Background: On account of the lower electron density in the lung tissue, the dose distribution in the lung cannot be verified with the existing polymer gel dosimeters. Thus, the aims of this study are to make a low density polymer gel dosimeter and investigate the effect of nitrogen <span class="hlt">gas</span> <span class="hlt">bubbles</span> on the R2 responses and its homogeneity. Materials and Methods: Two different types of low density polymer gel dosimeters were prepared according to a composition proposed by De Deene, with some modifications. In the first type, no nitrogen <span class="hlt">gas</span> was perfused through the gel solution and water. In the second type, to expel the dissolved oxygen, nitrogen <span class="hlt">gas</span> was perfused through the water and gel solution. The post-irradiation times in the gels were 24 and 5 hours, respectively, with and without perfusion of nitrogen <span class="hlt">gas</span> through the water and gel solution. Results: In the first type of gel, there was a linear correlation between the doses and R2 responses from 0 to 12 Gy. The fabricated gel had a higher dynamic range than the other low density polymer gel dosimeter; but its background R2 response was higher. In the second type, no difference in R2 response was seen in the dose ranges from 0 to 18 Gy. Both gels had a mass density between 0.35 and 0.45 g.cm-3 and CT values of about -650 to -750 Hounsfield units. 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 R2-background response. In the second type of gel, it seemed that the collapse of the nitrogen <span class="hlt">bubbles</span> was the main factor that affected the R2-responses. PMID:26015914</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006E%26PSL.243..354S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006E%26PSL.243..354S"><span>Methane discharge from a deep-sea submarine mud volcano into the upper water column by <span class="hlt">gas</span> hydrate-coated methane <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sauter, Eberhard J.; Muyakshin, Sergey I.; Charlou, Jean-Luc; Schlüter, Michael; Boetius, Antje; Jerosch, Kerstin; Damm, Ellen; Foucher, Jean-Paul; Klages, Michael</p> <p>2006-03-01</p> <p>The assessment of climate change factors includes a constraint of methane sources and sinks. Although marine geological sources are recognized as significant, unfortunately, most submarine sources remain poorly quantified. Beside cold vents and coastal anoxic sediments, the large number of submarine mud volcanoes (SMV) may contribute significantly to the oceanic methane pool. Recent research suggests that methane primarily released diffusively from deep-sea SMVs is immediately oxidized and, thus, has little climatic impact. New hydro-acoustic, visual, and geochemical observations performed at the deep-sea mud volcano Håkon Mosby reveal the discharge of <span class="hlt">gas</span> hydrate-coated methane <span class="hlt">bubbles</span> and <span class="hlt">gas</span> hydrate flakes forming huge methane plumes extending from the seabed in 1250 m depth up to 750 m high into the water column. This depth coincides with the upper limit of the temperature-pressure field of <span class="hlt">gas</span> hydrate stability. Hydrographic evidence suggests <span class="hlt">bubble</span>-induced upwelling within the plume and extending above the hydrate stability zone. Thus, we propose that a significant portion of the methane from discharged methane <span class="hlt">bubbles</span> can reach the upper water column, which may be explained due to the formation of hydrate skins. As the water mass of the plume <span class="hlt">rises</span> to shallow water depths, methane dissolved from hydrated <span class="hlt">bubbles</span> may be transported towards the surface and released to the atmosphere. Repeated acoustic surveys performed in 2002 and 2003 suggest continuous methane emission to the ocean. From seafloor visual observations we estimated a <span class="hlt">gas</span> flux of 0.2 (0.08-0.36) mol s -1 which translates to several hundred tons yr -1 under the assumption of a steady discharge. Besides, methane was observed to be released by diffusion from sediments as well as by focused outflow of methane-rich water. In contrast to the <span class="hlt">bubble</span> discharge, emission rates of these two pathways are estimated to be in the range of several tons yr -1 and, thus, to be of minor importance. Very low</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19787945','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19787945"><span>An experimental verification of the possible influence of <span class="hlt">gas</span> nano-<span class="hlt">bubbles</span> on the response of an electrochemical quartz crystal microbalance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tsionsky, Vladimir; Kaverin, Alexander; Daikhin, Leonid; Katz, Galina; Gileadi, Eliezer</p> <p>2005-04-21</p> <p>Electrochemical removal of oxygen and hydrogen from aqueous solution in the vicinity of gold electrodes, with simultaneous measurements of the response of the quartz crystal microbalance, show no evidence of <span class="hlt">gas</span> nano-<span class="hlt">bubbles</span> attached to the surface, irrespective of its roughness and hydrophobicity. The contact between gold and frozen electrolyte, which forms a liquid-like layer between them, also does not contain <span class="hlt">gas</span> <span class="hlt">bubbles</span>. These statements could be extended to nano-<span class="hlt">bubbles</span> with characteristic dimensions larger than a few nanometers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JMiMi..27j5016Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JMiMi..27j5016Z"><span>Advanced <span class="hlt">gas</span>-emission anode design for microfluidic fuel cell eliminating <span class="hlt">bubble</span> accumulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Hao; Xuan, Jin; Leung, Dennis Y. C.; Wang, Huizhi; Xu, Hong; Zhang, Li</p> <p>2017-10-01</p> <p>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 <span class="hlt">bubble</span> problem especially when operating at high current density conditions. In this work, a <span class="hlt">gas</span>-emission anode is presented to eliminate the <span class="hlt">gas</span> accumulation at the anode. This <span class="hlt">gas</span>-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 <span class="hlt">gas</span>-emission anode was measured. The results indicate that the specific design of the <span class="hlt">gas</span>-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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24478724','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24478724"><span>How man-made interference might cause <span class="hlt">gas</span> <span class="hlt">bubble</span> emboli in deep diving whales.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fahlman, Andreas; Tyack, Peter L; Miller, Patrick J O; Kvadsheim, Petter H</p> <p>2014-01-01</p> <p>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 <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> 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, forms <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3904108','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3904108"><span>How man-made interference might cause <span class="hlt">gas</span> <span class="hlt">bubble</span> emboli in deep diving whales</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fahlman, Andreas; Tyack, Peter L.; Miller, Patrick J. O.; Kvadsheim, Petter H.</p> <p>2014-01-01</p> <p>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 <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> 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, forms <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> 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. PMID:24478724</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12146872','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12146872"><span>Macro- and microscopic in-situ observation of <span class="hlt">gas</span> <span class="hlt">bubbles</span> and sludge particles in a biogas tower reactor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pietsch, Torsten; Mehrwald, Ralf; Grajetzki, Ralf; Sens, Jan; Pakendorf, Tim; Ulrich, Reinhard; Kumpart, Jörn; Matz, Gerhard; Märkl, Herbert</p> <p>2002-06-01</p> <p>Macroscopic and microscopic in-situ observation of particles and <span class="hlt">gas</span> <span class="hlt">bubbles</span> are used to get precise impressions of the hydrodynamical characteristics of a biologically active suspension. Moreover, values of in-situ velocities and particle densities can be gained by using these methods. The suspended anaerobic sludge revealed an extensive fibrous structure ('fur') on its surface. The observed microfibers have a profound influence on the settling/flotation behavior of the particles because they increase the effective particle volume, they may trap <span class="hlt">gas</span> <span class="hlt">bubbles</span> and they favor agglomeration. The biomass particles do not appear as single spherical objects but due to its fibrous structure on the outside as strongly interacting mass. The compressibility of the <span class="hlt">bubbles</span> which are entrapped in the sludge agglomerates results in a pressure-dependent density of the sludge particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16313012','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16313012"><span>A pilot-scale jet <span class="hlt">bubbling</span> reactor for wet flue <span class="hlt">gas</span> desulfurization with pyrolusite.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Su, Shi-jun; Zhu, Xiao-fan; Liu, Yong-jun; Jiang, Wen-ju; Jin, Yan</p> <p>2005-01-01</p> <p>MnO2 in pyrolusite can react with SO2 in flue <span class="hlt">gas</span> and obtain by-product MnSO4 x H2O. A pilot scale jet <span class="hlt">bubbling</span> 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 <span class="hlt">gas</span> flue, ration of liquid/solid mass flow rate (L/S), pyrolusite grade, and SO2 concentration in the inlet flue <span class="hlt">gas</span>. 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 <span class="hlt">gas</span> 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, Mg, Ca, Fe, Al and heavy metals, last product MnSO4 x H2O was obtained which quality could reach China GB1622-86, the industry grade standards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Cryo...77...65L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Cryo...77...65L"><span>Modeling effects of <span class="hlt">gas</span> <span class="hlt">bubbles</span> on the mechanical behaviors of Ag/Bi-2212 round wires using a double cantilever beam bridge model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, Yurong; Wang, Zhongtong; Yong, Huadong; Zhou, Youhe</p> <p>2016-07-01</p> <p>Due to the larger current-carrying property, Bi2Sr2CaCu2Ox (Bi2212) superconductors have a great potential application in high field magnet. Bi2212 superconducting material can be fabricated as an isotropic round wire. However, there is 30% void space in the wire, such as <span class="hlt">gas</span> <span class="hlt">bubbles</span>. The void space has a larger influence on the property of the wire. In this paper, we will study the effect of <span class="hlt">gas</span> <span class="hlt">bubble</span> on the fracture behavior. Based on the double cantilever beam model and critical state theory, the mechanical behavior of Bi2212 wire is studied for decreasing field. Two different damage mechanisms are discussed using the strain energy release rate and strain of bridge. The results show that the large <span class="hlt">gas</span> <span class="hlt">bubble</span> can increase the strain of bridge. The central filaments with <span class="hlt">gas</span> <span class="hlt">bubble</span> are easier to be damaged than the edge filaments with <span class="hlt">gas</span> <span class="hlt">bubble</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003A%26A...411..447L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003A%26A...411..447L"><span>3D mapping of the dense interstellar <span class="hlt">gas</span> around the Local <span class="hlt">Bubble</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lallement, R.; Welsh, B. Y.; Vergely, J. L.; Crifo, F.; Sfeir, D.</p> <p>2003-12-01</p> <p>We present intermediate results from a long-term program of mapping the neutral absorption characteristics of the local interstellar medium, motivated by the availability of accurate and consistent parallaxes from the Hipparcos satellite. Equivalent widths of the interstellar NaI D-line doublet at 5890 Å are presented for the lines-of-sight towards some 311 new target stars lying within ~ 350 pc of the Sun. Using these data, together with NaI absorption measurements towards a further ~ 240 nearby targets published in the literature (for many of them, in the directions of molecular clouds), and the ~ 450 lines-of-sight already presented by (Sfeir et al. \\cite{sfeir99}), we show 3D absorption maps of the local distribution of neutral <span class="hlt">gas</span> towards 1005 sight-lines with Hipparcos distances as viewed from a variety of different galactic projections. The data are synthesized by means of two complementary methods, (i) by mapping of iso-equivalent width contours, and (ii) by density distribution calculation from the inversion of column-densities, a method devised by Vergely et al. (\\cite{vergely01}). Our present data confirms the view that the local cavity is deficient in cold and neutral interstellar <span class="hlt">gas</span>. The closest dense and cold <span class="hlt">gas</span> ``wall'', in the first quadrant, is at ~ 55-60 pc. There are a few isolated clouds at closer distance, if the detected absorption is not produced by circumstellar material. The maps reveal narrow or wide ``interstellar tunnels'' which connect the Local <span class="hlt">Bubble</span> to surrounding cavities, as predicted by the model of Cox & Smith (1974). In particular, one of these tunnels, defined by stars at 300 to 600 pc from the Sun showing negligible sodium absorption, connects the well known CMa void (Gry et al. \\cite{gry85}), which is part of the Local <span class="hlt">Bubble</span>, with the supershell GSH 238+00+09 (Heiles \\cite{heiles98}). High latitude lines-of-sight with the smallest absorption are found in two ``chimneys'', whose directions are perpendicular to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3557455','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3557455"><span><span class="hlt">Gas</span> <span class="hlt">Bubble</span> Disease in the Brain of a Living California Sea Lion (Zalophus californianus)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Van Bonn, William; Dennison, Sophie; Cook, Peter; Fahlman, Andreas</p> <p>2013-01-01</p> <p>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 <span class="hlt">gas</span>, and cerebral lesions that were fluid filled. Over a maximum period of 4 months, the brain lesions reduced in size and the <span class="hlt">gas</span> resorbed and was replaced by CSF-like fluid. In humans, the cerebellum is known to be essential for automating practiced movement patterns (e.g., learning to touch-type), also known as procedural learning or the consolidation of “motor memory.” 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 <span class="hlt">gas</span> could not be determined. The live status of the patient with recovery suggests that the most likely etiologies for the <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> formation to occur. The similarity in distribution of the <span class="hlt">gas</span> <span class="hlt">bubble</span> related lesions in this case compared with another previously published case of pneumocerebellum suggests that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010004356','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010004356"><span>Buoyancy Driven Shear Flows of <span class="hlt">Bubble</span> Suspensions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koch, D. L.; Hill, R. J.; Chellppannair, T.; Zenit, R.; Zenit, R.; Spelt, P. D. M.</p> <p>1999-01-01</p> <p>In this work the <span class="hlt">gas</span> volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of <span class="hlt">bubble</span> suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1a nd Re >> 1, for which comparisons are made with kinetic theory and numerical simulations. Here Re = gamma(a(exp 2)/nu is the Reynolds number and We = rho(gamma(exp 2))a(exp 3)/sigma is the Weber number; gamma is the shear rate, a is the <span class="hlt">bubble</span> radius, nu is the kinematic viscosity of the liquid, rho is the density of the liquid, and sigma is the surface tension of the <span class="hlt">gas</span>/liquid interface. Kang et al. calculated the <span class="hlt">bubble</span> phase pressure and velocity variance of sheared <span class="hlt">bubble</span> suspensions under conditions where the <span class="hlt">bubbles</span> are spherical and the liquid phase velocity field can be approximated using potential flow theory, i.e. We= 0 and Re >> 1. Such conditions can be achieved in an experiment using <span class="hlt">gas</span> <span class="hlt">bubbles</span>, with a radius of O(0.5mm), in water. The theory requires that there be no average relative motion of the <span class="hlt">gas</span> and liquid phases, hence the motivation for an experimental program in microgravity. The necessity of performing preliminary, Earth based experiments, however, requires performing experiments where the <span class="hlt">gas</span> phase <span class="hlt">rises</span> in the liquid, which significantly complicates the comparison of experiments with theory. Rather than comparing experimental results with theory for a uniform, homogeneous shear flow, experiments can be compared directly with solutions of the averaged equations of motion for <span class="hlt">bubble</span> suspensions. This requires accounting for the significant lift force acting on the <span class="hlt">gas</span> phase when the <span class="hlt">bubbles</span> <span class="hlt">rise</span> parallel to the average velocity of the sheared suspension. Shear flows can be produced in which the <span class="hlt">bubble</span> phase pressure gradient, arising from shear induced collisions amongst the <span class="hlt">bubbles</span>, balances a body force (centrifugal or gravitational) on the <span class="hlt">gas</span> phase. A steady, non-uniform <span class="hlt">gas</span> volume fraction</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1154735','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1154735"><span>Fuel Performance Experiments and Modeling: Fission <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Nucleation and Growth in Alloy Nuclear Fuels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McDeavitt, Sean; Shao, Lin; Tsvetkov, Pavel; Wirth, Brian; Kennedy, Rory</p> <p>2014-04-07</p> <p>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, <span class="hlt">bubble</span> coalescience, and <span class="hlt">gas</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1339783-acoustic-characterization-fluorinert-fc-liquid-helium-gas-bubbles-numerical-experiments','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1339783-acoustic-characterization-fluorinert-fc-liquid-helium-gas-bubbles-numerical-experiments"><span>Acoustic Characterization of Fluorinert FC-43 Liquid with Helium <span class="hlt">Gas</span> <span class="hlt">Bubbles</span>: Numerical Experiments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Vanhille, Christian; Pantea, Cristian; Sinha, Dipen N.</p> <p>2017-01-01</p> <p>In this work, we define the acoustic characteristics of a biphasic fluid consisting of static helium <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 couldmore » 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.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/14323','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/14323"><span><span class="hlt">Gas</span> <span class="hlt">Bubble</span> Trauma Monitoring in the Clearwater River Drainage, Idaho 1998.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cochnauer, Tim</p> <p>1998-12-01</p> <p>Select portions of the Clearwater and North Fork of the Clearwater rivers were electroshocked to estimate the incidence of <span class="hlt">gas</span> <span class="hlt">bubble</span> trauma (GBT) occurring in resident fish populations for the spring and summer months of 1998. The study area was divided into four sections and sampled weekly during periods of spill and non-spill from Dworshak Dam. Five thousand five hundred and forty one fish, representing 22 different species, were captured and examined for GBT. Two fish were detected with signs of GBT; exhibiting the lowest incidence of GBT in the last four years (0.04%). Reduced discharge and lower levels of total dissolved gases may have resulted in lower incidence of GBT in the 1998 monitoring period.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B31D0448C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B31D0448C"><span>Passive acoustic derived <span class="hlt">bubble</span> flux and applications to natural <span class="hlt">gas</span> seepage in the Mackenzie Delta, NWT, Canada and Coal Oil Point, CA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Culling, D.; Leifer, I.; Dallimore, S.; Alcala, K.</p> <p>2012-12-01</p> <p>Methane is a prominent greenhouse <span class="hlt">gas</span> that escapes naturally from thermogenic reservoirs as seepage from marine and lacustrine biogenic sources as <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> can easily transit as <span class="hlt">bubbles</span> through the water column and directly influence global atmospheric budgets. Video and active acoustic (sonar) measurements of <span class="hlt">bubble</span> flux have spatial limitations requiring predictable <span class="hlt">bubble</span> emission location. Passive acoustics are less affected by these limitations, in addition, they can provide data in water too shallow for effective sonar <span class="hlt">bubble</span> observations. Lab tests were undertaken to quantify the acoustic signature of <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span> radius and acoustic frequency. <span class="hlt">Bubble</span> 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 <span class="hlt">bubble</span> formation and the resultant <span class="hlt">bubble</span> acoustic signal. These complex signals were investigated in a lab tank with a thick, cohesive fine-grained sediment bed, through which <span class="hlt">bubbles</span> produced by a syringe pump migrated to the sediment-water interface. Then, the resultant <span class="hlt">bubbles</span> were diverted into clear water and measured from high speed, high definition video, while the acoustic signature of <span class="hlt">bubble</span> formation was recorded concurrently by a hydrophone. <span class="hlt">Bubble</span> formation is influenced by currents, which shifts the acoustical signal towards a higher frequency with a more complex pattern than the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22087992','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22087992"><span>Review of scattering and extinction cross-sections, damping factors, and resonance frequencies of a spherical <span class="hlt">gas</span> <span class="hlt">bubble</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ainslie, Michael A; Leighton, Timothy G</p> <p>2011-11-01</p> <p>Perhaps the most familiar concepts when discussing acoustic scattering by <span class="hlt">bubbles</span> are the resonance frequency for <span class="hlt">bubble</span> pulsation, the <span class="hlt">bubbles</span>' damping, and their scattering and extinction cross-sections, all of which are used routinely in oceanography, sonochemistry, and biomedicine. The apparent simplicity of these concepts is illusory: there exist multiple, sometimes contradictory definitions for their components. This paper reviews expressions and definitions in the literature for acoustical cross-sections, resonance frequencies, and damping factors of a spherically pulsating <span class="hlt">gas</span> <span class="hlt">bubble</span> in an infinite liquid medium, deriving two expressions for "resonance frequency" that are compared and reconciled with two others from the reviewed literature. In order to prevent errors, care is needed by researchers when combining results from different publications that might have used internally correct but mutually inconsistent definitions. Expressions are presented for acoustical cross-sections associated with forced pulsations damped by liquid shear and (oft-neglected) bulk or dilatational viscosities, <span class="hlt">gas</span> thermal diffusivity, and acoustic re-radiation. The concept of a dimensionless "damping coefficient" is unsuitable for radiation damping because different cross-sections would require different functional forms for this parameter. Instead, terms based on the ratio of <span class="hlt">bubble</span> radius to acoustic wavelength are included explicitly in the cross-sections where needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040173148&hterms=Courses+English&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCourses%2BEnglish','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040173148&hterms=Courses+English&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCourses%2BEnglish"><span>Relationship of the time course of venous <span class="hlt">gas</span> <span class="hlt">bubbles</span> to altitude decompression illness</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Conkin, J.; Foster, P. P.; Powell, M. R.; Waligora, J. M.</p> <p>1996-01-01</p> <p>The correlation is low between the occurrence of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in the pulmonary artery, called venous <span class="hlt">gas</span> emboli (VGE), and subsequent decompression illness (DCI). The correlation improves when a "grade" of VGE is considered; a zero to four categorical classification based on the intensity and duration of the VGE signal from a Doppler <span class="hlt">bubble</span> detector. Additional insight about DCI might come from an analysis of the time course of the occurrence of VGE. Using the NASA Hypobaric Decompression Sickness Databank, we compared the time course of the VGE outcome between 322 subjects who exercised and 133 Doppler technicians who did not exercise to evaluate the role of physical activity on the VGE outcome and incidence of DCI. We also compared 61 subjects with VGE and DCI with 110 subjects with VGE but without DCI to identify unique characteristics about the time course of the VGE outcome to try to discriminate between DCI and no-DCI cases. The VGE outcome as a function of time showed a characteristic short lag, rapid response, and gradual recovery phase that was related to physical activity at altitude and the presence or absence of DCI. The average time for DCI symptoms in a limb occurred just before the time of the highest fraction of VGE in the pulmonary artery. It is likely, but not certain, that an individual will report a DCI symptom if VGE are detected early in the altitude exposure, the intensity or grade of VGE rapidly increases from a limb region, and the intensity or grade of VGE remains high.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040173148&hterms=dci&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Ddci','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040173148&hterms=dci&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Ddci"><span>Relationship of the time course of venous <span class="hlt">gas</span> <span class="hlt">bubbles</span> to altitude decompression illness</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Conkin, J.; Foster, P. P.; Powell, M. R.; Waligora, J. M.</p> <p>1996-01-01</p> <p>The correlation is low between the occurrence of <span class="hlt">gas</span> <span class="hlt">bubbles</span> in the pulmonary artery, called venous <span class="hlt">gas</span> emboli (VGE), and subsequent decompression illness (DCI). The correlation improves when a "grade" of VGE is considered; a zero to four categorical classification based on the intensity and duration of the VGE signal from a Doppler <span class="hlt">bubble</span> detector. Additional insight about DCI might come from an analysis of the time course of the occurrence of VGE. Using the NASA Hypobaric Decompression Sickness Databank, we compared the time course of the VGE outcome between 322 subjects who exercised and 133 Doppler technicians who did not exercise to evaluate the role of physical activity on the VGE outcome and incidence of DCI. We also compared 61 subjects with VGE and DCI with 110 subjects with VGE but without DCI to identify unique characteristics about the time course of the VGE outcome to try to discriminate between DCI and no-DCI cases. The VGE outcome as a function of time showed a characteristic short lag, rapid response, and gradual recovery phase that was related to physical activity at altitude and the presence or absence of DCI. The average time for DCI symptoms in a limb occurred just before the time of the highest fraction of VGE in the pulmonary artery. It is likely, but not certain, that an individual will report a DCI symptom if VGE are detected early in the altitude exposure, the intensity or grade of VGE rapidly increases from a limb region, and the intensity or grade of VGE remains high.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020014840&hterms=Till&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTill','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020014840&hterms=Till&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTill"><span>Effects of Gravity on <span class="hlt">Bubble</span> Formation at a Plate Orifice</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Webbon, Bruce W.; Buyevich, Yu A.</p> <p>1995-01-01</p> <p>A model of the dynamic regime of <span class="hlt">gas</span> injection through a submerged plate orifice into an ideally wetting liquid is developed in the circumstance when successively detached <span class="hlt">bubbles</span> may be regarded as independent objects. Two major factors favor <span class="hlt">bubble</span> detachment: the buoyancy force and a force due to the momentum inflow into the <span class="hlt">bubble</span> with injected <span class="hlt">gas</span>. In normal and moderately reduced gravity, the first factor dominates. At relatively low flow rates, a growing <span class="hlt">bubble</span> is modeled as a spherical segment touching the orifice perimeter during the whole period of its evolution till detachment. If the flow rate exceeds a critical value, another stage of <span class="hlt">bubble</span> evolution occurs in which an almost spherical <span class="hlt">gas</span> envelope is connected with the orifice by a nearly cylindrical gaseous stem that lengthens as the <span class="hlt">bubble</span> <span class="hlt">rises</span> above the plate. The <span class="hlt">bubble</span> continues to grow until the <span class="hlt">gas</span> supply through the stem is completely cut off, after which back flow of <span class="hlt">gas</span> into the stem from the <span class="hlt">bubble</span> becomes possible. In microgravity, the second factor prevails, and the latter stage is always present irrespective of the flow rate. However, the <span class="hlt">gas</span> envelope <span class="hlt">rises</span> and the stem lengthens very slowly. This difference in the underlying physical mechanisms provides for key properties of <span class="hlt">bubble</span> growth and detachment being drastically different in appreciable and sufficiently reduced gravity. The frequency of <span class="hlt">bubble</span> formation slightly decreases with and the detachment volume is almost proportional to the <span class="hlt">gas</span> flow rate in the first case, in accordance with familiar relations. In the second case, the first variable is proportional to the flow rate whereas the second one is independent of it. Effects of other parameters, such as the orifice radius, <span class="hlt">gas</span> and liquid densities, and surface tension are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27644021','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27644021"><span>Self assembly, mobilization, and flotation of crude oil contaminated sand particles as granular shells on <span class="hlt">gas</span> <span class="hlt">bubbles</span> in water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tansel, Berrin; Boglaienko, Daria</p> <p>2017-01-01</p> <p>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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> if the <span class="hlt">bubble</span> 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 <span class="hlt">bubbles</span> 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 <span class="hlt">gas</span> <span class="hlt">bubbles</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15485086','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15485086"><span>A deep stop during decompression from 82 fsw (25 m) significantly reduces <span class="hlt">bubbles</span> and fast tissue <span class="hlt">gas</span> tensions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marroni, A; Bennett, P B; Cronje, F J; Cali-Corleo, R; Germonpre, P; Pieri, M; Bonuccelli, C; Balestra, C</p> <p>2004-01-01</p> <p>In spite of many modifications to decompression algorithms, the incidence of decompression sickness (DCS) in scuba divers has changed very little. The success of stage, compared to linear ascents, is well described yet theoretical changes in decompression ratios have diminished the importance of fast tissue <span class="hlt">gas</span> tensions as critical for <span class="hlt">bubble</span> generation. The most serious signs and symptoms of DCS involve the spinal cord, with a tissue half time of only 12.5 minutes. It is proposed that present decompression schedules do not permit sufficient <span class="hlt">gas</span> elimination from such fast tissues, resulting in <span class="hlt">bubble</span> formation. Further, it is hypothesized that introduction of a deep stop will significantly reduce fast tissue <span class="hlt">bubble</span> formation and neurological DCS risk. A total of 181 dives were made to 82 fsw (25 m) by 22 volunteers. Two dives of 25 min and 20 min were made, with a 3 hr 30 min surface interval and according to 8 different ascent protocols. Ascent rates of 10, 33 or 60 fsw/min (3, 10, 18 m/min) were combined with no stops or a shallow stop at 20 fsw (6 m) or a deep stop at 50 fsw (15 m) and a shallow at 20 fsw (6 m). The highest <span class="hlt">bubbles</span> scores (8.78/9.97), using the Spencer Scale (SS) and Extended Spencer Scale (ESS) respectively, were with the slowest ascent rate. This also showed the highest 5 min and 10 min tissue loads of 48% and 75%. The lowest <span class="hlt">bubble</span> scores (1.79/2.50) were with an ascent rate of 33 fsw (10 m/min) and stops for 5 min at 50 fsw (15 m) and 20 fsw (6 m). This also showed the lowest 5 and 10 min tissue loads at 25% and 52% respectively. Thus, introduction of a deep stop significantly reduced Doppler detected <span class="hlt">bubbles</span> together with tissue <span class="hlt">gas</span> tensions in the 5 and 10 min tissues, which has implications for reducing the incidence of neurological DCS in divers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004xmm..pres...19.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004xmm..pres...19."><span>Cluster finds giant <span class="hlt">gas</span> vortices at the edge of Earth's magnetic <span class="hlt">bubble</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>2004-08-01</p> <p> first time that vortices are actually detected. When a KHI-wave rolls up into a vortex, it becomes known as a ‘Kelvin Cat’s eye’. The data collected by Cluster have shown density variations of the electrified <span class="hlt">gas</span>, right at the magnetopause, precisely like those expected when travelling through a ‘Kelvin Cat’s eye’. Scientists had postulated that, if these structures were to form at the magnetopause, they might be able to pull large quantities of the solar wind inside the boundary layer as they collapse. Once the solar wind particles are carried into the inner part of the magnetosphere, they can be excited strongly, allowing them to smash into Earth’s atmosphere and give <span class="hlt">rise</span> to the aurorae. Cluster’s discovery strengthens this scenario but does not show the precise mechanism by which the <span class="hlt">gas</span> is transported into Earth’s magnetic <span class="hlt">bubble</span>. Thus, scientists still do not know whether this is the only process to fill up the boundary layer when the magnetic fields are aligned. For those measurements, Hasegawa says, scientists will have to wait for a future generation of magnetospheric satellites. Notes for editors The results of this investigation have appeared in today’s issue of the scientific journal Nature, in a paper entitled ‘Transport of solar wind into Earth's magnetosphere through rolled-up Kelvin-Helmholtz vortices’, by H. Hasegawa, M. Fujimoto, T.D. Phan, H. Reme, A. Balogh, M.W. Dunlop, C. Hashimoto and R. TanDokoro. More about magnetic reconnection Solar wind particles follow ‘magnetic field lines’, rather like beads on a wire. The ‘doors’ that open in Earth’s magnetosphere during oppositely aligned magnetic configurations are caused by a phenomenon called ‘magnetic reconnection‘. During this process, Earth’s field lines spontaneously break and join themselves to the Sun’s, allowing the solar wind to pass freely into Earth’s magnetosphere. Magnetic reconnections are not possible in the aligned case, however, hence the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025509','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025509"><span>Lateral line pore diameters correlate with the development of <span class="hlt">gas</span> <span class="hlt">bubble</span> trauma signs in several Columbia River fishes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morris, R.G.; Beeman, J.W.; VanderKooi, S.P.; Maule, A.G.</p> <p>2003-01-01</p> <p><span class="hlt">Gas</span> <span class="hlt">bubble</span> trauma (GBT) caused by <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubbles</span>; however, this effect has never been examined in relation to lateral line morphology. The effects of 115, 125 and 130% total dissolved <span class="hlt">gas</span> levels were evaluated on five fish species common to the upper Columbia River. Trunk lateral line pore diameters differed significantly (P<0.0001) among species (longnose sucker>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 <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> trauma. ?? 2003 Elsevier Science Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JChPh.131r4502G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JChPh.131r4502G"><span>Generalizations of the Young-Laplace equation for the pressure of a mechanically stable <span class="hlt">gas</span> <span class="hlt">bubble</span> in a soft elastic material</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goldman, Saul</p> <p>2009-11-01</p> <p>The Young-Laplace equation for the pressure of a mechanically stable <span class="hlt">gas</span> <span class="hlt">bubble</span> is generalized to include the effects of both surface tension and elastic forces of its surroundings. The latter are taken to be comprised of a soft isotropic material. Generalizations are derived for conditions of constant external pressure and constant system volume. The derived equations are formally exact for a spherical <span class="hlt">bubble</span> surrounded by a spherical shell of isotropic material, provided that the <span class="hlt">bubble</span> is sufficiently large for the surface tension to be treated macroscopically, and that the <span class="hlt">bubble</span> radius is much larger than the thickness of the <span class="hlt">bubble</span>/soft material interface. The underlying equations are also used to derive a simple expression for the Gibbs free energy of deformation of an elastic medium that surrounds a <span class="hlt">gas</span> <span class="hlt">bubble</span>. The possible relevance of this expression to some recently published ideas on decompression sickness ("the bends") is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27163253','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27163253"><span>Enriched Air Nitrox Breathing Reduces Venous <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Souday, Vincent; Koning, Nick J; Perez, Bruno; Grelon, Fabien; Mercat, Alain; Boer, Christa; Seegers, Valérie; Radermacher, Peter; Asfar, Pierre</p> <p>2016-01-01</p> <p>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 <span class="hlt">bubble</span> formation after decompression. Human volunteers underwent a first simulated dive breathing compressed air to include subjects prone to post-decompression venous <span class="hlt">gas</span> <span class="hlt">bubbling</span>. Twelve subjects prone to <span class="hlt">bubbling</span> 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 <span class="hlt">bubble</span> formation was assessed after decompression using pulmonary artery pulsed Doppler. Twelve subjects showing high <span class="hlt">bubble</span> production were included for the cross-over trial, and all completed the experimental protocol. In the randomized protocol, EAN significantly reduced the <span class="hlt">bubble</span> score at all time points (cumulative <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> scores and age or body mass index, respectively. EAN breathing markedly reduces venous <span class="hlt">gas</span> <span class="hlt">bubble</span> emboli after decompression in volunteers selected for susceptibility for intravascular <span class="hlt">bubble</span> formation. When using similar diving profiles and avoiding oxygen toxicity limits, EAN increases safety of diving as compared to compressed air breathing. ISRCTN 31681480.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4862661','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4862661"><span>Enriched Air Nitrox Breathing Reduces Venous <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Souday, Vincent; Koning, Nick J.; Perez, Bruno; Grelon, Fabien; Mercat, Alain; Boer, Christa; Seegers, Valérie; Radermacher, Peter; Asfar, Pierre</p> <p>2016-01-01</p> <p>Objective 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 <span class="hlt">bubble</span> formation after decompression. Methods Human volunteers underwent a first simulated dive breathing compressed air to include subjects prone to post-decompression venous <span class="hlt">gas</span> <span class="hlt">bubbling</span>. Twelve subjects prone to <span class="hlt">bubbling</span> 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 <span class="hlt">bubble</span> formation was assessed after decompression using pulmonary artery pulsed Doppler. Results Twelve subjects showing high <span class="hlt">bubble</span> production were included for the cross-over trial, and all completed the experimental protocol. In the randomized protocol, EAN significantly reduced the <span class="hlt">bubble</span> score at all time points (cumulative <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> scores and age or body mass index, respectively. Conclusion EAN breathing markedly reduces venous <span class="hlt">gas</span> <span class="hlt">bubble</span> emboli after decompression in volunteers selected for susceptibility for intravascular <span class="hlt">bubble</span> formation. When using similar diving profiles and avoiding oxygen toxicity limits, EAN increases safety of diving as compared to compressed air breathing. Trial Registration ISRCTN 31681480 PMID:27163253</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20854065','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20854065"><span>Inertial-Fusion-Related Hydrodynamic Instabilities in a Spherical <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Accelerated by a Planar Shock Wave</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Niederhaus, John; Ranjan, Devesh; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo; Greenough, Jeff</p> <p>2005-05-15</p> <p>Experiments studying the compression and unstable growth of a dense spherical <span class="hlt">bubble</span> in a gaseous medium subjected to a strong planar shock wave (2.8 < M < 3.4) are performed in a vertical shock tube. The test <span class="hlt">gas</span> is initially contained in a free-falling spherical soap-film <span class="hlt">bubble</span>, and the shocked <span class="hlt">bubble</span> is imaged using planar laser diagnostics. Concurrently, simulations are carried out using a compressible hydrodynamics code in r-z axisymmetric geometry.Experiments and computations indicate the formation of characteristic vortical structures in the post-shock flow, due to Richtmyer-Meshkov and Kelvin-Helmholtz instabilities, and smaller-scale vortices due to secondary effects. Inconsistencies between experimental and computational results are examined, and the usefulness of the current axisymmetric approach is evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA622256','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA622256"><span><span class="hlt">Gas</span> Control and Thermal Modeling Methods for Pressed Pellet and Fast <span class="hlt">Rise</span> Thin-Film Thermal Batteries</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2015-09-01</p> <p>ARL-TR-7464 ● SEP 2015 US Army Research Laboratory <span class="hlt">Gas</span> Control and Thermal Modeling Methods for Pressed Pellet and Fast <span class="hlt">Rise</span>...Laboratory <span class="hlt">Gas</span> Control and Thermal Modeling Methods for Pressed Pellet and Fast <span class="hlt">Rise</span> Thin-Film Thermal Batteries by Frank C Krieger and Michael S...From - To) 10/2014 to 09/2015 4. TITLE AND SUBTITLE <span class="hlt">Gas</span> Control and Thermal Modeling Methods for Pressed Pellet and Fast <span class="hlt">Rise</span> Thin-Film Thermal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5869187','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5869187"><span><span class="hlt">Gas</span> <span class="hlt">bubbling</span>-enhanced film boiling of Freon-11 on liquid metal pools. [PWR; BWR</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Greene, G.A.</p> <p>1985-01-01</p> <p>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 <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> flux on the magnitude of the stable liquid-liquid film boiling heat flux and develop a <span class="hlt">gas</span> flux-enhanced, liquid-liquid film boiling model for incorporation into the CORCON-MOD2 computer code to replace or modify the Berenson model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=GL-2002-001101&hterms=Blows&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBlows','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=GL-2002-001101&hterms=Blows&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBlows"><span>FEASTING BLACK HOLE BLOWS <span class="hlt">BUBBLES</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>A monstrous black hole's rude table manners include blowing huge <span class="hlt">bubbles</span> of hot <span class="hlt">gas</span> 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 <span class="hlt">bubbles</span> <span class="hlt">rising</span> from a dark band of dust. The other <span class="hlt">bubble</span>, 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 <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span>). 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 <span class="hlt">gas</span>, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The <span class="hlt">bubbles</span> will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this <span class="hlt">bubble</span>-blowing phase is a short-lived event. The <span class="hlt">bubble</span> is much brighter on one side of the galaxy's center because the jet smashed into a denser amount of <span class="hlt">gas</span>. The brighter <span class="hlt">bubble</span> 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 <span class="hlt">bubbles</span>. The red regions in the picture denote the hot <span class="hlt">gas</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=GL-2002-001101&hterms=blow&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblow','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=GL-2002-001101&hterms=blow&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblow"><span>FEASTING BLACK HOLE BLOWS <span class="hlt">BUBBLES</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>A monstrous black hole's rude table manners include blowing huge <span class="hlt">bubbles</span> of hot <span class="hlt">gas</span> 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 <span class="hlt">bubbles</span> <span class="hlt">rising</span> from a dark band of dust. The other <span class="hlt">bubble</span>, 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 <span class="hlt">bubbles</span> 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 <span class="hlt">bubble</span>). 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 <span class="hlt">gas</span>, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The <span class="hlt">bubbles</span> will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this <span class="hlt">bubble</span>-blowing phase is a short-lived event. The <span class="hlt">bubble</span> is much brighter on one side of the galaxy's center because the jet smashed into a denser amount of <span class="hlt">gas</span>. The brighter <span class="hlt">bubble</span> 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 <span class="hlt">bubbles</span>. The red regions in the picture denote the hot <span class="hlt">gas</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27818004','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27818004"><span>Combination and simultaneous resonances of <span class="hlt">gas</span> <span class="hlt">bubbles</span> oscillating in liquids under dual-frequency acoustic excitation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yuning; Zhang, Yuning; Li, Shengcai</p> <p>2017-03-01</p> <p>The multi-frequency acoustic excitation has been employed to enhance the effects of oscillating <span class="hlt">bubbles</span> in sonochemistry for many years. In the present paper, nonlinear dynamic oscillations of <span class="hlt">bubble</span> under dual-frequency acoustic excitation are numerically investigated within a broad range of parameters. By investigating the power spectra and the response curves of oscillating <span class="hlt">bubbles</span>, two unique features of <span class="hlt">bubble</span> oscillations under dual-frequency excitation (termed as "combination resonance" and "simultaneous resonance") are revealed and discussed. Specifically, the amplitudes of the combination resonances are quantitatively compared with those of other traditional resonances (e.g. main resonances, harmonics). The influences of several paramount parameters (e.g., the <span class="hlt">bubble</span> radius, the acoustic pressure amplitude, the energy allocation between two component waves) on nonlinear <span class="hlt">bubble</span> oscillations are demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930000662&hterms=aquaculture&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Daquaculture','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930000662&hterms=aquaculture&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Daquaculture"><span>Aerator Combined With <span class="hlt">Bubble</span> Remover</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dreschel, Thomas W.</p> <p>1993-01-01</p> <p>System produces <span class="hlt">bubble</span>-free oxygen-saturated water. <span class="hlt">Bubble</span> remover consists of outer solid-walled tube and inner hydrophobic, porous tube. Air <span class="hlt">bubbles</span> pass from water in outer tube into inner tube, where sucked away. Developed for long-term aquaculture projects in space. Also applicable to terrestrial equipment in which entrained <span class="hlt">bubbles</span> dry membranes or give <span class="hlt">rise</span> to cavitation in pumps.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033800','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033800"><span>Segregating <span class="hlt">gas</span> from melt: an experimental study of the Ostwald ripening of vapor <span class="hlt">bubbles</span> in magmas</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lautze, Nicole C.; Sisson, Thomas W.; Mangan, Margaret T.; Grove, Timothy L.</p> <p>2011-01-01</p> <p>Diffusive coarsening (Ostwald ripening) of H2O and H2O-CO2 <span class="hlt">bubbles</span> in rhyolite and basaltic andesite melts was studied with elevated temperature–pressure experiments to investigate the rates and time spans over which vapor <span class="hlt">bubbles</span> may enlarge and attain sufficient buoyancy to segregate in magmatic systems. <span class="hlt">Bubble</span> 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 <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> radius and time-1 decrease in <span class="hlt">bubble</span> 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 <span class="hlt">bubbly</span> 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 <span class="hlt">bubbles</span> that are immobile or undergoing buoyant ascent, indicate that diffusive coarsening efficiently eliminates micron-sized <span class="hlt">bubbles</span> and would produce mm-sized <span class="hlt">bubbles</span> in 102–104 years in crustal magma bodies. Once <span class="hlt">bubbles</span> 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 <span class="hlt">bubbles</span> sufficiently large for rapid ascent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JFST....3..943K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JFST....3..943K"><span>Dynamics of a Spherical Vapor/<span class="hlt">Gas</span> <span class="hlt">Bubble</span> in Varying Pressure Fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawashima, Hisanobu; Kameda, Masaharu</p> <p></p> <p>A mathematical model is developed to simulate the radial motion of cavitation <span class="hlt">bubbles</span>. The heat and mass transports including phase change are formulated precisely. In order to reduce the computational cost without loss of the important thermo-fluid phenomena, two simplifications are employed: time-dependent <span class="hlt">bubble</span> radius is described using the Rayleigh-Plesset equation; the pressure in the <span class="hlt">bubble</span> is assumed to be uniform in space. For validation of the model, the transient radial motion of an air <span class="hlt">bubble</span> in water is observed experimentally. A shock tube is used to make the sudden pressure reduction from atmospheric to below the saturated vapor pressure. The <span class="hlt">bubble</span> radius is measured by high-speed photography, in which an interferomtric laser imaging technique is used for accurate determination of the initial <span class="hlt">bubble</span> radius. The radial motion is successfully predicted by using this model. The temperature reduction at the <span class="hlt">bubble</span> wall is a predominant factor on the <span class="hlt">bubble</span> growth rate under superheated conditions, even if the liquid temperature is close to room temperature. The numerical result indicates that the growth rate is very sensitive to initial <span class="hlt">bubble</span> radius, ambient pressure, and liquid temperature.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7255550','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7255550"><span>Heat-transfer characteristics in viscous <span class="hlt">gas</span>-liquid and <span class="hlt">gas</span>-liquid-solid systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kumar, S.; Fan, L.S. . Dept. of Chemical Engineering)</p> <p>1994-05-01</p> <p>Local heat-transfer measurements are performed using a special heat-transfer probe in <span class="hlt">gas</span>-liquid and <span class="hlt">gas</span>-liquid-solid systems with viscous Newtonian liquids as the continuous phase. Effects of viscosity on <span class="hlt">bubble</span>-liquid and <span class="hlt">bubble</span>-liquid-solid interactions affecting local heat transfer are studied through heat-transfer experiments with simultaneous flow visualization in a simplified system involving single <span class="hlt">bubbles</span> or a chain of <span class="hlt">gas</span> <span class="hlt">bubbles</span> moving in viscous liquids and liquid-solid systems. Effects of viscosity on <span class="hlt">bubble</span> wake and local heat transfer are examined with reference to heat transfer in freely-<span class="hlt">bubbling</span> beds (<span class="hlt">bubble</span> columns and three-phase fluidized beds). The kinematic viscosity of the fluid greatly influences the nature of flow in the wake which affects local heat transfer in the bed. The local heat transfer decreases with the viscosity due to the rapid decay in the circulation strength of the <span class="hlt">bubble</span> wake caused by increased viscous dissipation of vorticity. Local heat transfer due to cyclic/periodic injection of <span class="hlt">bubbles</span> is significantly enhanced due to increased <span class="hlt">bubble</span>-wake interactions which rapidly accelerate <span class="hlt">bubbles</span> and increase average <span class="hlt">bubble</span> <span class="hlt">rise</span> velocity. Heat transfer in simplified liquid and liquid-solid systems with single- and chain-<span class="hlt">bubble</span> injections characterizes the local heat-transfer performance of freely-<span class="hlt">bubbling</span> beds (<span class="hlt">bubble</span> columns and three-phase fluidized beds). A mechanistic model developed accounts for the heat-transfer behavior in <span class="hlt">bubble</span> columns and three-phase fluidized beds with viscous liquids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1133527','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1133527"><span>Small <span class="hlt">Gas</span> <span class="hlt">Bubble</span> Experiment for Mitigation of Cavitation Damage and Pressure Waves in Short-pulse Mercury Spallation Targets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wendel, Mark W; Felde, David K; Sangrey, Robert L; Abdou, Ashraf A; West, David L; Shea, Thomas J; Hasegawa, Shoichi; Kogawa, Hiroyuki; Naoe, Dr. Takashi; Farny, Dr. Caleb H.; Kaminsky, Andrew L</p> <p>2014-01-01</p> <p>Populations of small helium <span class="hlt">gas</span> <span class="hlt">bubbles</span> were introduced into a flowing mercury experiment test loop to evaluate mitigation of beam-pulse induced cavitation damage and pressure waves. The test loop was developed and thoroughly tested at the Spallation Neutron Source (SNS) prior to irradiations at the Los Alamos Neutron Science Center - Weapons Neutron Research Center (LANSCE-WNR) facility. Twelve candidate bubblers were evaluated over a range of mercury flow and <span class="hlt">gas</span> injection rates by use of a novel optical measurement technique that accurately assessed the generated <span class="hlt">bubble</span> size distributions. Final selection for irradiation testing included two variations of a swirl bubbler provided by Japan Proton Accelerator Research Complex (J-PARC) collaborators and one orifice bubbler developed at SNS. <span class="hlt">Bubble</span> populations of interest consisted of sizes up to 150 m in radius with achieved <span class="hlt">gas</span> void fractions in the 10^-5 to 10^-4 range. The nominal WNR beam pulse used for the experiment created energy deposition in the mercury comparable to SNS pulses operating at 2.5 MW. Nineteen test conditions were completed each with 100 pulses, including variations on mercury flow, <span class="hlt">gas</span> injection and protons per pulse. The principal measure of cavitation damage mitigation was surface damage assessment on test specimens that were manually replaced for each test condition. Damage assessment was done after radiation decay and decontamination by optical and laser profiling microscopy with damaged area fraction and maximum pit depth being the more valued results. Damage was reduced by flow alone; the best mitigation from <span class="hlt">bubble</span> injection was between half and a quarter that of flow alone. Other data collected included surface motion tracking by three laser Doppler vibrometers (LDV), loop wall dynamic strain, beam diagnostics for charge and beam profile assessment, embedded hydrophones and pressure sensors, and sound measurement by a suite of conventional and contact microphones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25931138','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25931138"><span>Effect of Nozzle Geometry on Characteristics of Submerged <span class="hlt">Gas</span> Jet and <span class="hlt">Bubble</span> Noise.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bie, Hai-Yan; Ye, Jian-Jun; Hao, Zong-Rui</p> <p>2016-10-01</p> <p>Submerged exhaust noise is one of the main noise sources of underwater vehicles. The nozzle features of pipe discharging systems have a great influence on exhaust noise, especially on the noise produced by <span class="hlt">gas</span>-liquid two-phase flow outside the nozzle. To study the influence of nozzle geometry on underwater jet noises, a theoretical study was performed on the critical weber number at which the jet flow field morphology changes. The underwater jet noise experiments of different nozzles under various working conditions were carried out. The experimental results implied that the critical weber number at which the jet flow transformed from <span class="hlt">bubbling</span> regime to jetting regime was basically identical with the theoretical analysis. In the condition of jetting regime, the generated cavity of elliptical and triangular nozzles was smaller than that of the circular nozzle, and the middle- and high-frequency bands increased nonlinearly. The radiated noise decreased with the decrease in nozzle diameter. Combined with theoretical analysis and experimental research, three different submerged exhaust noise reduction devices were designed, and the validation tests proved that the noise reduction device with folds and diversion cone was the most effective.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/431615','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/431615"><span>The effect of pH and <span class="hlt">gas</span> composition on the <span class="hlt">bubble</span> fractionation of proteins</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>DeSouza, A.H.G.; Tanner, R.D.; Effler, W.T. Jr.</p> <p>1991-12-31</p> <p>Studies were conducted to establish the effect of the variation of environmental factors on the separation occurring in protein systems, resulting from <span class="hlt">bubble</span> fractionation in a bioreactor. The measure of separation was selected to be the separation ratio. This is defined to be the ratio of either the top or the middle position concentration in the vessel to the bottom concentration of the vessel. Invertase and Ce-amylase were the two {open_quotes}model{close_quotes} enzymes considered. It was observed that, under certain conditions, i.e., a combination of the nature of the sparging <span class="hlt">gas</span> and the medium pH, varying degrees of protein separation were achieved. The pH of the system dramatically influenced the separation. It was found that the best separation occurred at a certain pH, assumed to be at or close to the pI of the protein in question. Furthermore, it was observed that systems sparged with CO{sub 2} exhibited greater separation than systems sparged with air. In fact, in the case of invertase, almost threefold separation was observed at the top port when the solution was sparged with CO{sub 2}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19101763','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19101763"><span>Proteomics of juvenile senegal sole (Solea senegalensis) affected by <span class="hlt">gas</span> <span class="hlt">bubble</span> disease in hyperoxygenated ponds.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Salas-Leiton, E; Cánovas-Conesa, B; Zerolo, R; López-Barea, J; Cañavate, J P; Alhama, J</p> <p>2009-01-01</p> <p>Solea senegalensis is a commercial flat fish traditionally farmed in earth ponds in coastal wetlands that might also become important to more intensive aquaculture. <span class="hlt">Gas</span> <span class="hlt">bubble</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT.......206M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT.......206M"><span>Three-phase <span class="hlt">gas</span>-liquid-solid foaming <span class="hlt">bubble</span> reactors and self-lubricated transport of bitumen froth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mata, Clara E.</p> <p></p> <p>Two distinct topics in multi-phase flow of interest of the oil industry are considered in this thesis. Studies of three-phase <span class="hlt">gas</span>-liquid-solid foaming <span class="hlt">bubble</span> 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 <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> reactor by fluidizing hydrophilic particles in the <span class="hlt">bubbly</span> mixture below the foam. In this work, we fluidized hydrophobic and hydrophilic versions of two different sands in a cold slit foaming <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> reactor, which can be continuously fed with solid particles. Global <span class="hlt">gas</span>, liquid, and solid holdups were measured for given <span class="hlt">gas</span> 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 <span class="hlt">bubble</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25263044','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25263044"><span>Management of bilateral <span class="hlt">gas-bubble</span> breakthrough during femtosecond LASIK in the presence of anterior basement membrane dystrophy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ribeiro, Giovana Castilho; Krueger, Ronald R</p> <p>2014-10-01</p> <p>We describe the case of a 50-year-old woman with anterior basement membrane dystrophy and dry eyes who had femtosecond laser in situ keratomileusis (LASIK) with <span class="hlt">gas-bubble</span> breakthrough during flap creation in both eyes. The <span class="hlt">gas-bubble</span> breakthrough appeared beneath the applanation interface in advance of the leading laser edge in the right eye and behind the advancing laser edge in the left eye. The surgery was aborted and 5 days later, photorefractive keratectomy with mitomycin-C was performed in the right eye and LASIK in the left eye. When a <span class="hlt">gas-bubble</span> breakthrough extends in front of the advancing laser edge of the flap, the surgery should be aborted; surface ablation can be performed as a second-stage procedure. However, if the breakthrough occurs behind the advancing laser edge, the flap can be carefully lifted and the LASIK completed. Dr. Krueger is a consultant to Alcon Laboratories, Inc. Dr. Ribeiro has no financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22700364','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22700364"><span>Monodisperse, submicrometer droplets via condensation of microfluidic-generated <span class="hlt">gas</span> <span class="hlt">bubbles</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Seo, Minseok; Matsuura, Naomi</p> <p>2012-09-10</p> <p>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 <span class="hlt">bubbles</span> (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 <span class="hlt">gas</span> 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 <span class="hlt">gas</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/875130','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/875130"><span><span class="hlt">Bubble</span> diagnostics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Visuri, Steven R.; Mammini, Beth M.; Da Silva, Luiz B.; Celliers, Peter M.</p> <p>2003-01-01</p> <p>The present invention is intended as a means of diagnosing the presence of a <span class="hlt">gas</span> <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span> in the fluid surrounding the occlusion may form as a result of laser irradiation. This vapor <span class="hlt">bubble</span> 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 <span class="hlt">bubble</span>. Knowledge of the <span class="hlt">bubble</span> formation and lifetime yields critical information as to the maximum size of the <span class="hlt">bubble</span>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1339835','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1339835"><span>Effect of grain morphology on <span class="hlt">gas</span> <span class="hlt">bubble</span> swelling in UMo fuels – A 3D microstructure dependent Booth model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hu, Shenyang; Burkes, Douglas; Lavender, Curt A.; Joshi, Vineet</p> <p>2016-11-01</p> <p>A three dimensional microstructure dependent swelling model is developed for studying the fission <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> swelling kinetics. As an application of the model, the effect of grain morphology, fission <span class="hlt">gas</span> 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 <span class="hlt">gas</span> diffusivity (fission rate) cause the increase of swelling kinetics. Other heterogeneities such as second phases and spatial dependent thermodynamic properties including diffusivity of fission <span class="hlt">gas</span>, sink and source strength of defects could be naturally integrated into the model to enhance the model capability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JNuM..480..323H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JNuM..480..323H"><span>Effect of grain morphology on <span class="hlt">gas</span> <span class="hlt">bubble</span> swelling in UMo fuels - A 3D microstructure dependent Booth model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Shenyang; Burkes, Douglas; Lavender, Curt A.; Joshi, Vineet</p> <p>2016-11-01</p> <p>A three dimensional microstructure dependent swelling model is developed for studying the fission <span class="hlt">gas</span> 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 <span class="hlt">gas</span> <span class="hlt">bubble</span> swelling kinetics. As an application of the model, the effect of grain morphology, fission <span class="hlt">gas</span> diffusivity, and spatially 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 <span class="hlt">gas</span> diffusivity (fission rate) cause the increase of swelling kinetics. Other heterogeneities such as second phases and spatially dependent thermodynamic properties including diffusivity of fission <span class="hlt">gas</span>, sink and source strength of defects could be naturally integrated into the model to enhance the model capability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Carbon+AND+Dioxide+AND+Oxygen&pg=3&id=EJ325707','ERIC'); return false;" href="https://eric.ed.gov/?q=Carbon+AND+Dioxide+AND+Oxygen&pg=3&id=EJ325707"><span>Tiny <span class="hlt">Bubbles</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Kim, Hy</p> <p>1985-01-01</p> <p>A simple oxygen-collecting device (easily constructed from glass jars and a lid) can show <span class="hlt">bubbles</span> released by water plants during photosynthesis. Suggestions are given for: (1) testing the collected <span class="hlt">gas</span>; (2) using various carbon dioxide sources; and (3) measuring respiration. (DH)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=LID&pg=5&id=EJ325707','ERIC'); return false;" href="http://eric.ed.gov/?q=LID&pg=5&id=EJ325707"><span>Tiny <span class="hlt">Bubbles</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Kim, Hy</p> <p>1985-01-01</p> <p>A simple oxygen-collecting device (easily constructed from glass jars and a lid) can show <span class="hlt">bubbles</span> released by water plants during photosynthesis. Suggestions are given for: (1) testing the collected <span class="hlt">gas</span>; (2) using various carbon dioxide sources; and (3) measuring respiration. (DH)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000004401&hterms=Liquid+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DLiquid%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000004401&hterms=Liquid+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DLiquid%2Btheory"><span>Controlling the Mobility of the Fluid Interface of Moving <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> or Liquid Drops by Using Micellar Solutions of Surfactants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maldarelli, Charles; Papageorgiou, Demetrios</p> <p>1998-01-01</p> <p>Microgravity processes must rely on mechanisms other than buoyancy to move <span class="hlt">bubbles</span> or droplets from one region to another in a continuous liquid phase. One suggested method is thermocapillary migration in which a temperature gradient is applied to the continuous phase. A significant and as yet unresolved impediment to the use of thermocapillary migration to direct <span class="hlt">bubble</span> or drop motion is that these migrations can be significantly retarded by the adsorption onto the fluid particle surface of surface active impurities unavoidably present in the continuous or (if the particle is a liquid) droplet phases. The focus of our research was to develop a theory for remobilizing fluid particle interfaces retarded by a surfactant impurity in an effort to make more viable the use of thermocapillary migrations for the management of <span class="hlt">bubbles</span> and drops in microgravity. We postulated that a surfactant at high bulk concentration which kinetically exchanges rapidly with the surface can restore interface mobility. The scaling arguments along with a discussion of the previous literature is reviewed in the context of the scaling framework. The specific objectives of the research were twofold. The first was to prove the remobilization theory by studying a model problem. As the mechanism for remobilization is independent of the force which drives the particle, the fluid particle shape and the presence of fluid inertia, we chose the simplest model consisting of a spherical <span class="hlt">bubble</span> <span class="hlt">rising</span> steadily by buoyancy in creeping flow. We solved the hydrodynamic and surfactant transport equations for rapid kinetic exchange to demonstrate that as the concentration increases, the Marangoni retardation at first increases (the low k behavior) and then decreases (the high k behavior). The second objective was to develop a method to determine the kinetic rate constants of a surfactant molecule, since this information is necessary to select surfactants which will exchange rapidly enough relative to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000004401&hterms=mobility+theory&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmobility%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000004401&hterms=mobility+theory&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmobility%2Btheory"><span>Controlling the Mobility of the Fluid Interface of Moving <span class="hlt">Gas</span> <span class="hlt">Bubbles</span> or Liquid Drops by Using Micellar Solutions of Surfactants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maldarelli, Charles; Papageorgiou, Demetrios</p> <p>1998-01-01</p> <p>Microgravity processes must rely on mechanisms other than buoyancy to move <span class="hlt">bubbles</span> or droplets from one region to another in a continuous liquid phase. One suggested method is thermocapillary migration in which a temperature gradient is applied to the continuous phase. A significant and as yet unresolved impediment to the use of thermocapillary migration to direct <span class="hlt">bubble</span> or drop motion is that these migrations can be significantly retarded by the adsorption onto the fluid particle surface of surface active impurities unavoidably present in the continuous or (if the particle is a liquid) droplet phases. The focus of our research was to develop a theory for remobilizing fluid particle interfaces retarded by a surfactant impurity in an effort to make more viable the use of thermocapillary migrations for the management of <span class="hlt">bubbles</span> and drops in microgravity. We postulated that a surfactant at high bulk concentration which kinetically exchanges rapidly with the surface can restore interface mobility. The scaling arguments along with a discussion of the previous literature is reviewed in the context of the scaling framework. The specific objectives of the research were twofold. The first was to prove the remobilization theory by studying a model problem. As the mechanism for remobilization is independent of the force which drives the particle, the fluid particle shape and the presence of fluid inertia, we chose the simplest model consisting of a spherical <span class="hlt">bubble</span> <span class="hlt">rising</span> steadily by buoyancy in creeping flow. We solved the hydrodynamic and surfactant transport equations for rapid kinetic exchange to demonstrate that as the concentration increases, the Marangoni retardation at first increases (the low k behavior) and then decreases (the high k behavior). The second objective was to develop a method to determine the kinetic rate constants of a surfactant molecule, since this information is necessary to select surfactants which will exchange rapidly enough relative to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002ExFl...32..728M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ExFl...32..728M"><span>A new method for measuring concentration of a fluorescent tracer in <span class="hlt">bubbly</span> <span class="hlt">gas</span>-liquid flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moghaddas, J. S.; Trägårdh, C.; Kovacs, T.; Östergren, K.</p> <p>2002-06-01</p> <p>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 <span class="hlt">bubbly</span> two-phase system. Light scattering and shading effects due to the <span class="hlt">bubbles</span> 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 <span class="hlt">bubbly</span> two-phase system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.796a2041B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.796a2041B"><span><span class="hlt">Gas</span> holdup and flow regime transition in spider-sparger <span class="hlt">bubble</span> column: effect of liquid phase properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Besagni, G.; Inzoli, F.; De Guido, G.; Pellegrini, L. A.</p> <p>2017-01-01</p> <p>This paper discusses the effects of the liquid velocity and the liquid phase properties on the <span class="hlt">gas</span> holdup and the flow regime transition in a large-diameter and large-scale counter-current two-phase <span class="hlt">bubble</span> column. In particular, we compared and analysed the experimental data obtained in our previous experimental studies. The <span class="hlt">bubble</span> column is 5.3 m in height, has an inner diameter of 0.24 m, it was operated with <span class="hlt">gas</span> superficial velocities in the range of 0.004–0.20 m/s and, in the counter-current mode, the liquid was recirculated up to a superficial velocity of -0.09 m/s. Air was used as the dispersed phase and various fluids (tap water, aqueous solutions of sodium chloride, ethanol and monoethylene glycol) were employed as liquid phases. The experimental dataset consist in <span class="hlt">gas</span> holdup measurements and was used to investigate the global fluid dynamics and the flow regime transition between the homogeneous flow regime and the transition flow regime. We found that the liquid velocity and the liquid phase properties significantly affect the <span class="hlt">gas</span> holdup and the flow regime transition. In this respect, a possible relationship (based on the lift force) between the flow regime transition and the <span class="hlt">gas</span> holdup was proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23379835','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23379835"><span>Measurement of interactions between solid particles, liquid droplets, and/or <span class="hlt">gas</span> <span class="hlt">bubbles</span> in a liquid using an integrated thin film drainage apparatus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Louxiang; Sharp, David; Masliyah, Jacob; Xu, Zhenghe</p> <p>2013-03-19</p> <p>A novel device was designed to measure drainage dynamics of thin liquid films confined between a solid particle, an immiscible liquid droplet, and/or <span class="hlt">gas</span> <span class="hlt">bubble</span>. Equipped with a bimorph force sensor, a computer-interfaced video capture, and a data acquisition system, the newly designed integrated thin film drainage apparatus (ITFDA) allows for the direct and simultaneous measurements of force barrier, true film drainage time, and <span class="hlt">bubble</span>/droplet deformation under a well-controlled external force, receding and advancing contact angles, capillary force, and adhesion (detachment) force between an air <span class="hlt">bubble</span> or oil droplet and a solid, a liquid, or an air <span class="hlt">bubble</span> in an immiscible liquid. Using the diaphragm of a high-frequency speaker as the drive mechanism for the air <span class="hlt">bubble</span> or oil droplet attached to a capillary tube, this newly designed device is capable of measuring forces over a wide range of hydrodynamic conditions, including <span class="hlt">bubble</span> approach and retract velocities up to 50 mm/s and displacement range up to 1 mm. The results showed that the ITFDA was capable of measuring hydrodynamic resistance, film drainage time, and other important physical parameters between air <span class="hlt">bubbles</span> and solid particles in aqueous solutions. As an example of illustrating the versatility, the ITFDA was also applied to other important systems such as interactions between air <span class="hlt">bubble</span> and oil droplet, two air <span class="hlt">bubbles</span>, and two oil droplets in an aqueous solution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=cone&pg=5&id=EJ914739','ERIC'); return false;" href="https://eric.ed.gov/?q=cone&pg=5&id=EJ914739"><span>In Search of the Big <span class="hlt">Bubble</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Simoson, Andrew; Wentzky, Bethany</p> <p>2011-01-01</p> <p>Freely <span class="hlt">rising</span> air <span class="hlt">bubbles</span> in water sometimes assume the shape of a spherical cap, a shape also known as the "big <span class="hlt">bubble</span>". Is it possible to find some objective function involving a combination of a <span class="hlt">bubble</span>'s attributes for which the big <span class="hlt">bubble</span> is the optimal shape? Following the basic idea of the definite integral, we define a <span class="hlt">bubble</span>'s surface as…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=numerical+AND+method&pg=5&id=EJ914739','ERIC'); return false;" href="http://eric.ed.gov/?q=numerical+AND+method&pg=5&id=EJ914739"><span>In Search of the Big <span class="hlt">Bubble</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Simoson, Andrew; Wentzky, Bethany</p> <p>2011-01-01</p> <p>Freely <span class="hlt">rising</span> air <span class="hlt">bubbles</span> in water sometimes assume the shape of a spherical cap, a shape also known as the "big <span class="hlt">bubble</span>". Is it possible to find some objective function involving a combination of a <span class="hlt">bubble</span>'s attributes for which the big <span class="hlt">bubble</span> is the optimal shape? Following the basic idea of the definite integral, we define a <span class="hlt">bubble</span>'s surface as…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880025744&hterms=effects+altitude&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffects%2Baltitude','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880025744&hterms=effects+altitude&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffects%2Baltitude"><span>The effect of extended O2 prebreathing on altitude decompression sickness and venous <span class="hlt">gas</span> <span class="hlt">bubbles</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Waligora, James M.; Horrigan, David J.; Conkin, Johnny</p> <p>1987-01-01</p> <p>The purpose of this study was to determine the effect of extended O2 prebreathing on symptom and <span class="hlt">bubble</span> incidence during decompressions simulating extravehicular activity. The 38 subjects breathed O2 for a 6-hr period prior to decompression to 4.3 psi. The subjects performed upper body exercises for 6 hr. Eight subjects were exposed to the same protocol after an 8-hr prebreathe. Venous <span class="hlt">bub