scholarly journals Bubble Nucleation and Growth of Dissolved Gas in Solution Flowing across a Cavitating Nozzle

2015 ◽  
Vol 773-774 ◽  
pp. 304-308 ◽  
Author(s):  
Zhen Hong Ban ◽  
Kok Keong Lau ◽  
Mohd Sharif Azmi
Keyword(s):  
Bubble Dynamics ◽  
Bubbly Flow ◽  
Bubble Formation ◽  
Computational Modelling ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Supersaturated Solution ◽  
Computational Domain ◽  
Dissolved Gas ◽  
Growth Phenomenon

Computational modelling of dissolved gas bubble formation and growth in supersaturated solution is essential for various engineering applications, including flash vaporisation of petroleum crude oil. The common mathematical modelling of bubbly flow only caters for single liquid and its vapour, which is known as cavitation. This work aims to simulate the bubble nucleation and growth of dissolved CO2 in water across a cavitating nozzle. The dynamics of bubble nucleation and growth phenomenon will be predicted based on the hydrodynamics in the computational domain. The complex interrelated bubble dynamics, mass transfer and hydrodynamics was coupled by using Computational Fluid Dynamics (CFD) and bubble nucleation and growth model. Generally, the bubbles nucleate at the throat of the nozzle and grow along with the flow. Therefore, only the region after the throat of the nozzle has bubbles. This approach is expected to be useful for various types of bubbly flow modelling in supersaturated condition.

Nucleation and Growth of Bubble With the Effects of Solute Gas

Volume 3 ◽  
2004 ◽  
Author(s):  
Shin-Ichi Tsuda ◽  
Shu Takagi ◽  
Yoichiro Matsumoto
Keyword(s):  
Saturation Pressure ◽  
Pressure Change ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Dynamics Simulation ◽  
Pure Liquid ◽  
Dissolved Gas ◽  
High Concentration ◽  
Wrong Prediction ◽  
Solvent Molecules

Bubble nucleation and growth of formed nuclei are investigated by molecular dynamics simulation in Lennard-Jones liquid with gas impurities. For the onset of nucleation from bulk, it has been found that a dissolved gas whose interaction is very weak and whose diameter is larger than that of solvent molecules makes the action to cause composition fluctuation or local phase separation so strong that the nucleation probability predicted from pressure change becomes qualitatively wrong. It has been confirmed that this wrong prediction is generally explained by introducing the superheat ratio nondimensionalized by saturation pressure and spinodal pressure. For the growth stage of formed bubble nuclei, it is observed that the coalescence of nuclei occurs when a weak-interaction gas is dissolved at a high concentration while the competition between neighbor nuclei is dominant in the case of pure liquid.

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

2016 ◽  
Vol 193 ◽  
pp. 223-240 ◽  
Author(s):  
Sean R. German ◽  
Martin A. Edwards ◽  
Qianjin Chen ◽  
Yuwen Liu ◽  
Long Luo ◽  
...  
Keyword(s):  
Critical Size ◽  
Bubble Formation ◽  
Water Electrolysis ◽  
Surface Concentration ◽  
Bubble Nucleation ◽  
Critical Surface ◽  
Gas Bubble ◽  
Dissolved Gas ◽  
Stochastic Fluctuations ◽  
Gas Molecules

In this article, we address the fundamental question: “What is the critical size of a single cluster of gas molecules that grows and becomes a stable (or continuously growing) gas bubble during gas evolving reactions?” Electrochemical reactions that produce dissolved gas molecules are ubiquitous in electrochemical technologies, e.g., water electrolysis, photoelectrochemistry, chlorine production, corrosion, and often lead to the formation of gaseous bubbles. Herein, we demonstrate that electrochemical measurements of the dissolved gas concentration, at the instant prior to nucleation of an individual nanobubble of H2, N2, or O2 at a Pt nanodisk electrode, can be analyzed using classical thermodynamic relationships (Henry's law and the Young–Laplace equation – including non-ideal corrections) to provide an estimate of the size of the gas bubble nucleus that grows into a stable bubble. We further demonstrate that this critical nucleus size is independent of the radius of the Pt nanodisk employed (<100 nm radius), and weakly dependent on the nature of the gas. For example, the measured critical surface concentration of H2 of ∼0.23 M at the instant of bubble formation corresponds to a critical H2 nucleus that has a radius of ∼3.6 nm, an internal pressure of ∼350 atm, and contains ∼1700 H2 molecules. The data are consistent with stochastic fluctuations in the density of dissolved gas, at or near the Pt/solution interface, controlling the rate of bubble nucleation. We discuss the growth of the nucleus as a diffusion-limited process and how that process is affected by proximity to an electrode producing ∼1011 gas molecules per second. Our study demonstrates the advantages of studying a single-entity, i.e., an individual nanobubble, in understanding and quantifying complex physicochemical phenomena.

Blister-Promoted Bubble Growth in Viscous Polymer Melts

1991 ◽  
Vol 237 ◽  
Author(s):  
Ramon J. Albalák ◽  
Zehev Tadmor ◽  
Yeshayahu Talmon
Keyword(s):  
Bubble Growth ◽  
Polymer Melts ◽  
Bubble Formation ◽  
Cooling Water ◽  
Bubble Surface ◽  
Bubble Nucleation ◽  
General Mechanism ◽  
Volatile Components ◽  
Local Pressure ◽  
Growth Phenomenon

ABSTRACTResidual monomer and other low molecular weight volatile components are removed from polymer melts in a devolatilization step involving bubble formation and growth. Polymer strands containing residual volatiles were extruded into a heated and evacuated devolatilization tank and were then frozen by the flow of cooling water. They were subsequently fractured in liquid nitrogen to reveal their cross-sections and examined in a scanning electron microscope (SEM).SEM observations revealed a previously unknown growth phenomenon in which devolatilization was seen to proceed through a ‘blistering’ mechanism. We discovered that volatile bubbles growing in the melt are fed by the formation of blisters on their inner surfaces. These blisters are formed by the coalescence of a growing bubble and the many satellite micro-bubbles formed around it as it expands. We propose a general mechanism for bubble growth in which we have shown that heterogeneous bubble nucleation in the core, which is governed by the degree of superheat, plays a major role in determining the overall rate of devolatilization. Tensile stresses accompanying bubble growth may result in a local increase in superheat by reducing the local pressure in the melt. This additional superheat combined with the possible accumulation of impurities on the macrobubble surface may be sufficient to increase the nucleation rate of microbubbles in the melt adjacent to the growing bubble, resulting in the large number of blisters formed on the bubble surface.

Steady-State Cavitating Nozzle Flows With Nucleation

2005 ◽  
Vol 127 (4) ◽  
pp. 770-777 ◽  
Author(s):  
Can F. Delale ◽  
Kohei Okita ◽  
Yoichiro Matsumoto
Keyword(s):  
Steady State ◽  
Bubble Dynamics ◽  
Bubbly Flow ◽  
Bubble Radius ◽  
Stable Solution ◽  
Bubble Nucleation ◽  
Bubble Collapse ◽  
Stable Steady State ◽  
Bubbly Liquid ◽  
Nozzle Flows

Quasi-one-dimensional steady-state cavitating nozzle flows with homogeneous bubble nucleation and nonlinear bubble dynamics are considered using a continuum bubbly liquid flow model. The onset of cavitation is modeled using an improved version of the classical theory of homogeneous nucleation, and the nonlinear dynamics of cavitating bubbles is described by the classical Rayleigh-Plesset equation. Using a polytropic law for the partial gas pressure within the bubble and accounting for the classical damping mechanisms, in a crude manner, by an effective viscosity, stable steady-state solutions with stationary shock waves as well as unstable flashing flow solutions were obtained, similar to the homogeneous bubbly flow solutions given by Wang and Brennen [J. Fluids Eng., 120, 166–170, 1998] and by Delale, Schnerr, and Sauer [J. Fluid Mech., 427, 167–204, 2001]. In particular, reductions in the maximum bubble radius and bubble collapse periods are observed for stable nucleating nozzle flows as compared to the nonnucleating stable solution of Wang and Brennen under similar conditions.

scholarly journals Phase transitions from the fifth dimension

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Kaustubh Agashe ◽  
Peizhi Du ◽  
Majid Ekhterachian ◽  
Soubhik Kumar ◽  
Raman Sundrum
Keyword(s):  
Bubble Dynamics ◽  
Effective Field ◽  
Bubble Nucleation ◽  
Thin Wall ◽  
Black Brane ◽  
Composite Higgs ◽  
Fifth Dimension ◽  
Two Phases ◽  
Holographic Description ◽  
The Impact

Abstract We study the cosmological transition of 5D warped compactifications, from the high-temperature black-brane phase to the low-temperature Randall-Sundrum I phase. The transition proceeds via percolation of bubbles of IR-brane nucleating from the black-brane horizon. The violent bubble dynamics can be a powerful source of observable stochastic gravitational waves. While bubble nucleation is non-perturbative in 5D gravity, it is amenable to semiclassical treatment in terms of a “bounce” configuration interpolating between the two phases. We demonstrate how such a bounce configuration can be smooth enough to maintain 5D effective field theory control, and how a simple ansatz for it places a rigorous lower-bound on the transition rate in the thin-wall regime, and gives plausible estimates more generally. When applied to the Hierarchy Problem, the minimal Goldberger-Wise stabilization of the warped throat leads to a slow transition with significant supercooling. We demonstrate that a simple generalization of the Goldberger-Wise potential modifies the IR-brane dynamics so that the transition completes more promptly. Supercooling determines the dilution of any (dark) matter abundances generated before the transition, potentially at odds with data, while the prompter transition resolves such tensions. We discuss the impact of the different possibilities on the strength of the gravitational wave signals. Via AdS/CFT duality the warped transition gives a theoretically tractable holographic description of the 4D Composite Higgs (de)confinement transition. Our generalization of the Goldberger-Wise mechanism is dual to, and concretely models, our earlier proposal in which the composite dynamics is governed by separate UV and IR RG fixed points. The smooth 5D bounce configuration we introduce complements the 4D dilaton/radion dominance derivation presented in our earlier work.

Effect of dissolved gas on bubble formation and boiling heat transfer in forced flow boiling

2020 ◽  
Vol 2020 (0) ◽  
pp. 16B01
Author(s):  
Hiroaki NARAZAKI ◽  
Satoshi MATSUMOTO ◽  
Yutaka ABE ◽  
Akiko KANEKO
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Bubble Formation ◽  
Forced Flow ◽  
Dissolved Gas

scholarly journals Euler–Lagrange Modeling of Bubbles Formation in Supersaturated Water

2018 ◽  
Vol 2 (3) ◽  
pp. 39 ◽  
Author(s):  
Alessandro Battistella ◽  
Sander Aelen ◽  
Ivo Roghair ◽  
Martin van Sint Annaland
Keyword(s):  
Phase Transition ◽  
Numerical Models ◽  
Bubble Formation ◽  
Industrial Applications ◽  
Bubble Nucleation ◽  
Initial Growth ◽  
Depletion Effect ◽  
Nucleation Sites ◽  
Scale Modelling ◽  
Spherical Bubbles

Phase transition, and more specifically bubble formation, plays an important role in many industrial applications, where bubbles are formed as a consequence of reaction such as in electrolytic processes or fermentation. Predictive tools, such as numerical models, are thus required to study, design or optimize these processes. This paper aims at providing a meso-scale modelling description of gas–liquid bubbly flows including heterogeneous bubble nucleation using a Discrete Bubble Model (DBM), which tracks each bubble individually and which has been extended to include phase transition. The model is able to initialize gas pockets (as spherical bubbles) representing randomly generated conical nucleation sites, which can host, grow and detach a bubble. To demonstrate its capabilities, the model was used to study the formation of bubbles on a surface as a result of supersaturation. A higher supersaturation results in a faster rate of nucleation, which means more bubbles in the column. A clear depletion effect could be observed during the initial growth of the bubbles, due to insufficient mixing.

A Model of Bubble Nucleation on a Micro Line Heater

1999 ◽  
Vol 121 (1) ◽  
pp. 220-225 ◽  
Author(s):  
S.-D. Oh ◽  
S. S. Seung ◽  
H. Y. Kwak
Keyword(s):  
Bubble Formation ◽  
Three Dimensional ◽  
Bubble Nucleation ◽  
Heat Diffusion ◽  
Nucleation Theory ◽  
Molecular Cluster ◽  
Heater Surface ◽  
Calculation Results ◽  
Critical Bubble ◽  
Superheat Limit

The bubble nucleation mechanism on a cavity-free micro line heater surface was studied by using the molecular cluster model. A finite difference numerical scheme for the three-dimensional transient conduction equation for the liquid was employed to estimate the superheated volume where homogeneous bubble nucleation could occur due to heat diffusion from the heater to the liquid. Calculation results revealed that bubble formation on the heater is possible when the temperature at the hottest point in the heater is greater than the superheat limit of the liquid by 6°C–12°C, which is in agreement with the experimental results. Also it was found that the classical bubble nucleation theory breaks down near the critical point where the radius of the critical bubble is below 100 nm.

Dynamic observations of vesiculation reveal the role of silicate crystals in bubble nucleation and growth in andesitic magmas

Lithos ◽  
2018 ◽  
Vol 296-299 ◽  
pp. 532-546 ◽  
Author(s):  
P. Pleše ◽  
M.D. Higgins ◽  
L. Mancini ◽  
G. Lanzafame ◽  
F. Brun ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Bubble Nucleation

Formulation of a Mathematical Process Model for the Foaming of a Mesophase Carbon Precursor

1992 ◽  
Vol 270 ◽  
Author(s):  
S. S. Sandhu ◽  
J. W. Hager
Keyword(s):  
Process Model ◽  
Analytical Description ◽  
Nucleation And Growth ◽  
Bubble Surface ◽  
Bubble Nucleation ◽  
Mesophase Pitch ◽  
Experimental Production ◽  
Mathematical Equations ◽  
Experimental Effort ◽  
Mathematical Process

ABSTRACTMathematical equations have been formulated to guide an experimental effort to produce an open-celled mesophase pitch foam. The formulation provides an analytical description of homogeneous bubble nucleation and growth, diffusion of the blowing gas through the liquid to the bubble surface, and the average material thickness between bubbles. Implications of the formulation for the experimental production of mesophase pitch foam are discussed.

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