Oscillations Of Gas Bubble Research Articles

The role of the dynamic pressure in the behavior of an oscillating gas bubble

The paper contains a preliminary study on the role that dynamic pressure might play in the dynamics of a gas bubble oscillating in a liquid. To this aim, we introduce a mathematical model, proposed under the homobaricity hypothesis and deduced from the 14-moment theory of rational extended thermodynamics through significant simplifications, that makes the equations easily integrable over long time intervals. In the presence of a gas with high bulk viscosity, relevant effects can be observed in different physical conditions: isothermal or adiabatic regimes, small amplitude oscillations, non-linear oscillations, resonances, and sonoluminescence. To make the study more realistic, we always refer to carbon dioxide gas, which on the one hand could present high values of bulk viscosity and on the other hand is known for its peculiar behaviors in the framework of cavitation and gas bubbles.

Sonoluminescence: Photon production in time-dependent analog systems

Sonoluminescence is a well-known laboratory phenomenon where an oscillating gas bubble in the appropriate environment periodically emits a flash of light in the visible frequency range. In this work, we study the system in the framework of analog gravity. We model the oscillating bubble in terms of analog geometry and propose a nonminimal coupling prescription of the electromagnetic field with the geometry. The geometry behaves as an analogous oscillating time-dependent background in which repeated flux of photons are produced in a wide frequency range through parametric resonance from quantum vacuum. Due to our numerical limitation, we could reach the frequency up to ∼105 m−1. However, we numerically fit the spectrum in a polynomial form including the observed frequency range around ∼107 m−1. Our current analysis seems to suggest that parametric resonance in analog background may play a fundamental role in explaining such phenomena in the quantum field theory framework. Published by the American Physical Society 2024

Acceleration waves in a spherical oscillating gas bubble containing a gas mixture

Acceleration waves in a spherical oscillating gas bubble containing a gas mixture

Modeling and Simulation of Parametric Nonlinear Focused Ultrasound in Three-Dimensional Bubbly Liquids with Axial Symmetry by a Finite-Element Model

This paper presents the development of a numerical model able to track in time the behavior of nonlinear focused ultrasound when interacting with tiny gas bubbles in a liquid. Our goal here is to analyze the frequency components of the waves by developing a model that can easily be adapted to the geometrical restrictions and complexities that come out in several application frameworks (sonochemistry, medicine, and engineering). We thus model the behavior of nonlinear focused ultrasound propagating in a liquid with gas bubbles by means of the finite-element method in an axisymmetric three-dimensional domain and the generalized-α method in the time domain. The model solves a differential system derived for the nonlinear interaction of acoustic waves and gas bubble oscillations. The high nonlinearity and dispersion of the bubbly medium hugely affect the behavior of the finite-amplitude waves. These characteristics are used here to generate frequency components of the signals that do not exist at the source through nonlinear mixing (parametric antenna). The ability of the model to work with complex geometries, which is the main advantage of the method, is illustrated through the simulation of nonlinear focused ultrasound in a medium excited from two spherical sources in opposite directions.

Insight into acoustic wave-driven gas bubble dynamics in Williamson's fluid

This study's motivation on the behavior of a gas bubble and surrounding fluid during the collapse phase of an acoustic wave leads to the emission of light, which can be modelled using the Rayleigh-Plesset equation. The significant contribution to the major addition to the understanding of gas bubble dynamics in viscoelastic fluids. The results of the study have the potential to impact a wide range of applications, from sonar and underwater acoustic propagation to biomedical applications and industrial operations. Understanding the dynamics of acoustic wave-driven gas bubble oscillations in non-Newtonian fluids is crucial for various applications in medical imaging, therapy, and microfluidics. The aim of this study is to discover the conditions under which these bubbles can undergo sonoluminescence, the emission of light due to the collapse of bubbles under severe sonic pressure. The complex ordinary differential equation is solved numerically, and graphs are generated to evaluates various parameters such as velocity, radius, and pressure. A comparison with the viscous case is also presented to assess the influence of Newtonian and non-Newtonian fluids. A program designed by Mathematica software (13.0) “parametric NDSolve package” is used to solve the equations. The numerical solution supports the boundary conditions, indicating stability and reliability. Notably, the study identifies distinct fluctuations in the phase and stable characteristics associated with non-Newtonian effects. Interestingly, certain fluid parameters lead to discrete group modulation of radial excursions, revealing a novel and previously unknown phenomenon. It is concluded that Higher Reynolds numbers result in turbulent flow, which causes the bubble to enlarge and increase its volume. Furthermore the pressure gradient is affected by magnetic drag force, and as size of bubble increases, required pressure gradient to counteract the drag force also increases. As the magnetic field intensity increases, the velocity of the bubble decreases. Also, considering the implications of these results, the study explores their relevance to medical ultrasonography applications.

Introducing realistic distributions of gas bubble size and inclusion aspect ratio to model the coexistence of gas hydrate and free gas

The coexisting free gas within the hydrate stability zone is recognized by laboratory and field studies. The conventional resistivity method fails to obtain hydrate saturation in the sediment with gas hydrate and free gas because both of them are electrical insulators. Hydrate saturation can be obtained from a velocity log based on a certain rock physics model. However, few studies of rock physics have been conducted on gas and hydrate coexistence. In this study, a more realistic distribution of gas bubble size and inclusion aspect ratio was introduced into an effective medium model to elucidate how such coexistence affects velocity and attenuation at a broad-band frequency. The modeling results obtained indicate that such coexistence decreases P-wave velocity at low frequencies, while increases P- and S-wave velocities at high frequencies. The velocity decrease of P-wave at low frequencies is attributed to the overwhelming effect of gas bubble vibration, while it seems not to affect P-wave velocity at high frequencies significantly. Moreover, coexisting gas hydrate and free gas may strengthen P-wave attenuation at the broad-band frequency range. It is found that the damping of oscillating gas bubbles dominates P-wave attenuation at low frequencies, while squirt flow in the porous hydrate is more likely to contribute to P-wave attenuation at high frequencies. Hydrate morphology is also a significant factor affecting P-wave velocity and attenuation at high frequencies. This research reveals that rock physics modeling can provide insight into how to characterize the coexisting gas hydrate and free gas as referring to the acoustic velocity and attenuation at seismic, sonic, and ultrasonic frequencies.

Underwater gas bubbles produced by droplet impact: Mechanism to trigger volumetric oscillations

Oscillating gas bubbles formed when droplets collide with a water surface are studied experimentally. Over a short time interval, before and after the bubble detachment, the bubble surface curvature changes drastically, causing a pulse of Laplace pressure. The leading edge of the pulse occurs before the bubble detachment, and the rear (negative) edge falls on the stage of an already closed bubble, which, like a resonator, is excited into volume oscillations on the natural frequency while simultaneously emitting an acoustic wavepacket. The amplitude and steepness of the pulse are inversely related to the size of the bubble, thereby ensuring that the dynamic parameters of the triggering pulse correspond to the natural frequency of the bubble. The release of pressure during the negative trailing edge of the pulse initiates the beginning of volumetric oscillations from the expansion phase and the acoustic packet from the positive half-wave.

Acceleration waves and oscillating gas bubbles modelled by rational extended thermodynamics

The study of acceleration waves for a rarefied polyatomic gas is carried out in planar, cylindrical and spherical geometry referring to the rational extended thermodynamics theory with 14 moments. The case of a rarefied monatomic gas is determined as a limit case, and the role of geometry and molecular degrees of freedom is investigated. In addition, the behaviour of an acceleration wave travelling inside an oscillating gas bubble is modelled by the 14-moment PDE system under adiabatic condition. We show that dissipation combined with hyperbolicity tends to inhibit shock formation, and that the dynamic pressure cannot be zero inside the oscillating bubble. This fact can produce observable effects even in the Navier–Stokes approximation, if the gas exhibits high bulk viscosity.

Gas Bubble Photonics: Manipulating Sonoluminescence Light with Fluorescent and Plasmonic Nanoparticles

Oscillations of gas bubbles in liquids irradiated with acoustic pressure waves may result in an intriguing physical phenomenon called sonoluminescence, where a collapsing bubble emits the in a broad optical spectral range. However, the intensity of the so-generated light is typically weak for practical purposes. Recently, it has been demonstrated that nanoparticles can be used to increase the efficiency of sonoluminescence, thereby enabling one to generate light that is intense enough for a number of applications in photonics, biomedicine, and materials science. In this article, we review the latest achievements in the field of nanoparticle-enhanced sonoluminescence and showcase the perspectives of their practical applications.

Complex measurement of parameters of iron ore magnetic separation based on ultrasonic methods

Purpose. To develop a method for complex ultrasonic measurement of such parameters of the iron ore slurry flow passing through the working chamber of the magnetic separator as efficiency, concentration and grade size distribution of solid-phase particles. Methodology. The research uses methods of modelling processes of ultrasonic wave propagation in the iron ore slurry. Ultrasonic wave absorption and scattering in water with solid particles and air bubbles are considered. To characterize absorption and scattering of acoustic oscillations by oscillating gas bubbles, concepts of effective cross-sections of attenuation, absorption and scattering are introduced. Findings. The dependence of the phase velocity of asymmetric Lamb waves on the wall thickness of the magnetic separator was obtained. As a result of computer simulation of the process of ultrasonic waves propagation, its time and frequency characteristics were obtained. Based on the data obtained using ultrasonic measurements, the coefficients of the Rozin-Rammler equation for the characteristics of the ore material at various points of the technological line were calculated. Originality. The proposed method of ultrasonic measurement of characteristics of the iron ore slurry in the working chamber of the magnetic separator differs from the existing ones in the fact that the Lamb wave source operates in a wide pattern and is connected by a V-shaped scheme which makes it possible to create a beam of coherent waves propagating both in the container wall (the working separator chamber) and in the measured medium (the iron ore slurry). Practical value. The practical value consists in developing an ultrasonic measuring channel scheme for determining characteristics of the iron ore slurry in the working chamber of the magnetic separator.

Acoustic, Phononic, Brillouin Light Scattering and Faraday Wave-Based Frequency Combs: Physical Foundations and Applications.

Frequency combs (FCs)—spectra containing equidistant coherent peaks—have enabled researchers and engineers to measure the frequencies of complex signals with high precision, thereby revolutionising the areas of sensing, metrology and communications and also benefiting the fundamental science. Although mostly optical FCs have found widespread applications thus far, in general FCs can be generated using waves other than light. Here, we review and summarise recent achievements in the emergent field of acoustic frequency combs (AFCs), including phononic FCs and relevant acousto-optical, Brillouin light scattering and Faraday wave-based techniques that have enabled the development of phonon lasers, quantum computers and advanced vibration sensors. In particular, our discussion is centred around potential applications of AFCs in precision measurements in various physical, chemical and biological systems in conditions where using light, and hence optical FCs, faces technical and fundamental limitations, which is, for example, the case in underwater distance measurements and biomedical imaging applications. This review article will also be of interest to readers seeking a discussion of specific theoretical aspects of different classes of AFCs. To that end, we support the mainstream discussion by the results of our original analysis and numerical simulations that can be used to design the spectra of AFCs generated using oscillations of gas bubbles in liquids, vibrations of liquid drops and plasmonic enhancement of Brillouin light scattering in metal nanostructures. We also discuss the application of non-toxic room-temperature liquid–metal alloys in the field of AFC generation.

Neural echo state network using oscillations of gas bubbles in water.

In the framework of physical reservoir computing (RC), machine learning algorithms designed for digital computers are executed using analog computerlike nonlinear physical systems that can provide energy-efficient computational power for predicting time-dependent quantities that can be found using nonlinear differential equations. We suggest a bubble-based RC (BRC) system that combines the nonlinearity of an acoustic response of a cluster of oscillating gas bubbles in water with a standard echo state network (ESN) algorithm that is well suited to forecast chaotic time series. We confirm the plausibility of the BRC system by numerically demonstrating its ability to forecast certain chaotic time series similarly to or even more accurately than ESN.

Behavior of a gas bubble separating from a cavity formed in magnetic fluid in an inhomogeneous magnetic field

In this work, we report results of the experimental study of the dynamics of a gas bubble separating from the air cavity in a magnetic fluid placed in an inhomogeneous magnetic field created by a ring magnet. Two experiments were carried out for samples with different concentrations: video recordings of the interphase boundary in a flat channel and recordings of electromagnetic vibrations caused by the gas bubble oscillations in a magnetic fluid. It is shown that the bubbles have a stable size. The respective dependencies of the bubble size on the magnetic fluid concentration and the air supply argue that it is possible to use the considered setup as a microdoser or a gas meter in microfluidics applications.

Enhancement of Mechanical Properties of Pure Aluminium through Contactless Melt Sonicating Treatment.

A new contactless ultrasonic sonotrode method was previously designed to provide cavitation conditions inside liquid metal. The oscillation of entrapped gas bubbles followed by their final collapse causes extreme pressure changes leading to de-agglomeration and the dispersion of oxide films. The forced wetting of particle surfaces and degassing are other mechanisms that are considered to be involved. Previous publications showed a significant decrease in grain size using this technique. In this paper, the authors extend this research to strength measurements and demonstrate an improvement in cast quality. Degassing effects are also interpreted to illustrate the main mechanisms involved in alloy strengthening. The mean values and Weibull analysis are presented where appropriate to complete the data. The test results on cast Al demonstrated a maximum of 48% grain refinement, a 28% increase in elongation compared to 16% for untreated material and up to 17% increase in ultimate tensile strength (UTS). Under conditions promoting degassing, the hydrogen content was reduced by 0.1 cm3/100 g.

Modeling the thermal behavior of an acoustically driven gas bubble.

Numerical simulation of an acoustically driven gas bubble is usually achieved by solving a Rayleigh-Plesset-type equation, in which the time-dependent pressure of the gas inside the bubble needs to be appropriately modeled. This is done in most existing methods by assuming a polytropic relation between the gas pressure and the bubble volume, which sometimes oversimplifies the thermal interaction between the bubble and the ambient liquid. In this paper, a model is developed aiming to perform an accurate and efficient calculation of the pressure variation in the bubble. The approach is different from that in the recent paper by the author and his collaborator which used a combination of an integral and a collocation method to solve the energy equation in the gas [Zhou and Prosperetti (2020). J. Fluid Mech. 901, R3]. The starting point of the proposed method in this paper is the gas continuity equation which is manipulated to lead to three ordinary differential equations. In this way, the thermal behavior of an oscillating gas bubble is captured at a modest coding and computational cost.

Gas-Babble Oscillations: Resonance Effects in Nonviscous and Newton Media

A linear mathematical model of forced oscillations of a gas bubble in viscous Newtonian fluid is developed in this paper. The natural frequency of oscillations of the gas bubble is found. A numerical analysis of the resonant effects of gas bubble oscillations within the media is carried out and a comparison of the obtained results with the existing classical ones for non-viscous media is discussed.

Infrasound from giant bubbles during explosive submarine eruptions

Shallow submarine volcanoes pose unique scientific and monitoring challenges. The interaction between water and magma can create violent explosions just below the surface, but the inaccessibility of submerged volcanoes means they are typically not instrumented. This both increases the risk to marine and aviation traffic and leaves the underlying eruption physics poorly understood. Here we use low-frequency sound in the atmosphere (infrasound) to examine the source mechanics of shallow submarine explosions from Bogoslof volcano, Alaska. We show that the infrasound originates from the oscillation and rupture of magmatic gas bubbles that initially formed from submerged vents, but that grew and burst above sea level. We model the low-frequency signals as overpressurized gas bubbles that grow near the water–air interface, which require bubble radii of 50–220 m. Bubbles of this size and larger have been described in explosive subaqueous eruptions for more than a century, but we present a unique geophysical record of this phenomenon. We propose that the dominant role of seawater during the effusion of gas-rich magma into shallow water is to repeatedly produce a gas-tight seal near the vent. This resealing mechanism leads to sequences of violent explosions and the release of large, bubble-forming volumes of gas—activity we describe as hydrovulcanian. During the submarine eruption of gas-rich magma into shallow water, a gas-tight seal forms, breaks and reseals, a process that results in violent explosions and the release of large gas bubbles, suggest low-frequency sound data from Bogoslof volcano, Alaska.

Interior non-uniformity of acoustically excited oscillating gas bubbles

In the present paper, the interior non-uniformity of oscillating gas bubbles in liquids under an acoustic field is theoretically investigated, as well as the temperature non-uniformity in the surrounding liquid. The pressure, the density and the temperature inside the gas bubbles are quantitatively predicted for a wide range of bubble Mach numbers. It is shown that the bubble interior non-uniformity increases significantly with the increase of the bubble Mach number. In the case of a large Mach number, the values of aforementioned paramount parameters at the bubble center are significantly larger than those at the bubble interface. Except for a very thin layer close to the bubble interface, the effects of the temperature non-uniformity in the bulk liquid could be safely ignored.

Oscillations of small bubbles and medium yielding in elastoviscoplastic fluids

We investigate the radial oscillations of small gas bubbles trapped in yield-stress fluid and driven by an acoustic pressure field. We model the rheological behavior of the yield-stress fluid using the recently developed elasto-visco-plastic (EVP) constitutive equation that takes into account the elastic and visco-plastic deformations of the material [P. Saramito, J. NonNewton. Fluid Mech. 158 (1-3) (2009) pp.154-161]. Assuming that the bubble remains spherical during the pressure driving, we reduce the problem to a set of ODEs and an integrodifferential equation, which we solve numerically for the case of two yield-stress fluids, a sot Carbopol gel and a stiffer Kaolin suspension. We find that, depending on the amplitude and frequency of the pressure field, the radial oscillations of the bubble produce elastic stresses that may or may not suffice to yield the surrounding material. We evaluate the critical amplitude of the acoustic pressure required to achieve yielding and we find a good agreement between numerical simulations and an analytical formula derived under the assumption of linear deformations. Finally, we examine the bubble oscillation amplitude for a very wide range of applied pressures both below and above the critical value to assess the impact of yielding on the bubble dynamics. This analysis could be used to identify a signature of yielding in experiments where the radial dynamics of a bubble is measured. More generally, these results can be used to rationalize the optimal conditions for pressure-induced bubble release from yield-stress fluids, which is relevant to various biomedical and industrial applications, including oil industry and food processing.

On the Stability of Oscillations of Soluble Gas Bubbles

It is shown that the bubbles of a gas solved in a liquid and performing small radial-symmetric oscillations in an acoustic field are amplitude unstable. An expression has been obtained for the increment that characterizes the rate of instability development.