Special Issue "Advances in Bubble Acoustics"

A special issue of Fluids (ISSN 2311-5521).

Deadline for manuscript submissions: closed (15 September 2018).

Special Issue Editor

Prof. Dr. Richard Manasseh
Website
Guest Editor
Swinburne University of Technology, Melbourne 3122, Australia
Interests: bubble acoustics; fluid dynamics; ocean wave-power; wave modelling and wave-induced processes; applied mathematics
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Bubble acoustics is one of the most diverse and exciting areas in fluid dynamics. Its origins date to the work of Rayleigh in the early 20th century on underwater explosions, which laid the mathematical framework predicting the volumetric oscillations of a gas bubble in liquid. Contemporary applications range from supercavitating marine vessels to the delivery of drugs across the blood-brain barrier, and from the measurement of ocean wave-breaking and industrial processes to the prediction of volcanic eruptions. Bubbles large enough to be visible naturally emit sounds on formation that are immediately familiar, whether we pour a glass of water or swim in the surf; even though linear theory may be applied, accurate prediction of the sounds of these complex flows is still elusive. Bubbles microns in size driven by ultrasound undergo nonlinear oscillations so extreme that the gas breaks down, emitting light. Ultrasonically-driven bubbles foster useful chemical and biomedical reactions, many of which remain poorly understood.

This Special Issue will be an archival collection of reviews and original research contributions on the latest developments in the theoretical, numerical and experimental understanding of all aspects of bubble acoustics. The natural sound emissions of bubbles, their response to vibrations and ultrasound, and their effects on industrial, defence, chemical and biological systems will be covered. Specific topics may include marine and industrial cavitation, passive bubble-size measurement in oceanic, industrial and geological contexts, sonochemistry, microfluidic devices, ultrasound contrast imaging, sonoporation for gene and drug delivery, cell stimulation and sonothrombolysis, and zoological studies.

Prof. Richard Manasseh
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fluids is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • bubble acoustics
  • cavitation
  • oceanic noise
  • sonochemistry
  • ultrasound contrast agents
  • microfluidics

Published Papers (7 papers)

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Research

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Open AccessArticle
Acoustics of Bubble Arrays: Role Played by the Dipole Response of Bubbles
Fluids 2018, 3(4), 95; https://doi.org/10.3390/fluids3040095 - 20 Nov 2018
Cited by 4
Abstract
A model for acoustic transmission through a 2D square crystal of R-radius bubbles with a lattice constant L was previously proposed. Assuming a purely monopole response of the bubbles, this model offers a simple analytical expression of the transmission. However, it is [...] Read more.
A model for acoustic transmission through a 2D square crystal of R-radius bubbles with a lattice constant L was previously proposed. Assuming a purely monopole response of the bubbles, this model offers a simple analytical expression of the transmission. However, it is not applicable when the bubbles are too close to each other (L/R < 5). This article proposes an extension of the model by including the dipole response of the bubbles. Comparisons with numerical and experimental results show that the new expression gives a good estimate of the concentration at which the monopole model is no longer valid, but fails at properly predicting the transmission. Full article
(This article belongs to the Special Issue Advances in Bubble Acoustics)
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Open AccessArticle
Symmetry Approach in the Evaluation of the Effect of Boundary Proximity on Oscillation of Gas Bubbles
Fluids 2018, 3(4), 90; https://doi.org/10.3390/fluids3040090 - 10 Nov 2018
Cited by 1
Abstract
The purpose of the present review is to describe the effect of an interface between media with different mechanical properties on the acoustic response of a gas bubble. This is necessary to interpret sonar signals received from underwater gas seeps and mud volcanoes, [...] Read more.
The purpose of the present review is to describe the effect of an interface between media with different mechanical properties on the acoustic response of a gas bubble. This is necessary to interpret sonar signals received from underwater gas seeps and mud volcanoes, as well as in the case of acoustic studies on the Arctic shelf where rising gas bubbles accumulate at the lower boundary of the ice cover. The ability to describe the dynamics of constrained bubble by analytical methods is related to the presence of internal symmetry in the governing equations. This leads to the presence of specific (toroidal and bi-spherical) coordinate systems in which the variables are separated. The existence of symmetry properties is possible only under certain conditions. In particular, the characteristic wavelength should be larger than the bubble size and the distance to an interface. The derived analytical solution allows us to determine how the natural frequency, radiation damping, and bubble shape depend on the distance to the boundary and the material parameters of contacting media. Full article
(This article belongs to the Special Issue Advances in Bubble Acoustics)
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Review

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Open AccessReview
Acoustic Streaming and Its Applications
Fluids 2018, 3(4), 108; https://doi.org/10.3390/fluids3040108 - 18 Dec 2018
Cited by 3
Abstract
Broadly speaking, acoustic streaming is generated by a nonlinear acoustic wave with a finite amplitude propagating in a viscid fluid. The fluid volume elements of molecules, dV, are forced to oscillate at the same frequency as the incident acoustic wave. Due [...] Read more.
Broadly speaking, acoustic streaming is generated by a nonlinear acoustic wave with a finite amplitude propagating in a viscid fluid. The fluid volume elements of molecules, d V , are forced to oscillate at the same frequency as the incident acoustic wave. Due to the nature of the nonlinearity of the acoustic wave, the second-order effect of the wave propagation produces a time-independent flow velocity (DC flow) in addition to a regular oscillatory motion (AC motion). Consequently, the fluid moves in a certain direction, which depends on the geometry of the system and its boundary conditions, as well as the parameters of the incident acoustic wave. The small scale acoustic streaming in a fluid is called “microstreaming”. When it is associated with acoustic cavitation, which refers to activities of microbubbles in a general sense, it is often called “cavitation microstreaming”. For biomedical applications, microstreaming usually takes place in a boundary layer at proximity of a solid boundary, which could be the membrane of a cell or walls of a container. To satisfy the non-slip boundary condition, the flow motion at a solid boundary should be zero. The magnitude of the DC acoustic streaming velocity, as well as the oscillatory flow velocity near the boundary, drop drastically; consequently, the acoustic streaming velocity generates a DC velocity gradient and the oscillatory flow velocity gradient produces an AC velocity gradient; they both will produce shear stress. The former is a DC shear stress and the latter is AC shear stress. It was observed the DC shear stress plays the dominant role, which may enhance the permeability of molecules passing through the cell membrane. This phenomenon is called “sonoporation”. Sonoporation has shown a great potential for the targeted delivery of DNA, drugs, and macromolecules into a cell. Acoustic streaming has also been used in fluid mixing, boundary cooling, and many other applications. The goal of this work is to give a brief review of the basic mathematical theory for acoustic microstreaming related to the aforementioned applications. The emphasis will be on its applications in biotechnology. Full article
(This article belongs to the Special Issue Advances in Bubble Acoustics)
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Open AccessFeature PaperReview
Application of Hydrodynamic Cavitation Reactors for Treatment of Wastewater Containing Organic Pollutants: Intensification Using Hybrid Approaches
Fluids 2018, 3(4), 98; https://doi.org/10.3390/fluids3040098 - 23 Nov 2018
Cited by 7
Abstract
The concentration of hazardous pollutants in the wastewater streams has to keep below a certain level in order to comply with the stringent environmental laws. The conventional technologies for wastewater treatment have drawbacks in terms of limited applicability and efficiency. Utilization of hydrodynamic [...] Read more.
The concentration of hazardous pollutants in the wastewater streams has to keep below a certain level in order to comply with the stringent environmental laws. The conventional technologies for wastewater treatment have drawbacks in terms of limited applicability and efficiency. Utilization of hydrodynamic cavitation (HC) reactors for the degradation of pollutants at large scale has shown considerable promise over last few years, due to higher energy efficiencies and low cost operation based on lower consumption of chemicals for the treatment. The present work overviews the degradation of different pollutants, such as pharmaceuticals, pesticide, phenolic derivatives and dyes, as well as the treatment of real industrial effluents using hybrid methods based on HC viz. HC/H2O2, HC/Ozone, HC/Fenton, HC/Ultraviolet irradiations (UV), and HC coupled with biological oxidation. Furthermore, based on the literature reports, recommendations for the selection of optimum operating parameters, such as inlet pressure, solution temperature, initial pH and initial pollutant concentration have been discussed in order to maximize the process intensification benefits. Moreover, hybrid methods based on HC has been demonstrated to show good synergism as compared to individual treatment approach. Overall, high energy efficient wastewater treatment can be achieved using a combined treatment approach based on HC under optimized conditions. Full article
(This article belongs to the Special Issue Advances in Bubble Acoustics)
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Open AccessReview
Microstreaming and Its Role in Applications: A Mini-Review
Fluids 2018, 3(4), 93; https://doi.org/10.3390/fluids3040093 - 17 Nov 2018
Cited by 5
Abstract
Acoustic streaming is the steady flow of a fluid that is caused by the propagation of sound through that fluid. The fluid flow in acoustic streaming is generated by a nonlinear, time-averaged effect that results from the spatial and temporal variations in a [...] Read more.
Acoustic streaming is the steady flow of a fluid that is caused by the propagation of sound through that fluid. The fluid flow in acoustic streaming is generated by a nonlinear, time-averaged effect that results from the spatial and temporal variations in a pressure field. When there is an oscillating body submerged in the fluid, such as a cavitation bubble, vorticity is generated on the boundary layer on its surface, resulting in microstreaming. Although the effects are generated at the microscale, microstreaming can have a profound influence on the fluid mechanics of ultrasound/acoustic processing systems, which are of high interest to sonochemistry, sonoprocessing, and acoustophoretic applications. The effects of microstreaming have been evaluated over the years using carefully controlled experiments that identify and quantify the fluid motion at a small scale. This mini-review article overviews the historical development of acoustic streaming, shows how microstreaming behaves, and provides an update on new numerical and experimental studies that seek to explore and improve our understanding of microstreaming. Full article
(This article belongs to the Special Issue Advances in Bubble Acoustics)
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Open AccessReview
On the Behaviour of Living Cells under the Influence of Ultrasound
Fluids 2018, 3(4), 82; https://doi.org/10.3390/fluids3040082 - 26 Oct 2018
Cited by 4
Abstract
Medical ultrasound technology is available, affordable, and non-invasive. It is used to detect, quantify, and heat tissue structures. This review article gives a concise overview of the types of behaviour that biological cells experience under the influence of ultrasound only, i.e., without the [...] Read more.
Medical ultrasound technology is available, affordable, and non-invasive. It is used to detect, quantify, and heat tissue structures. This review article gives a concise overview of the types of behaviour that biological cells experience under the influence of ultrasound only, i.e., without the presence of microbubbles. The phenomena are discussed from a physics and engineering perspective. They include proliferation, translation, apoptosis, lysis, transient membrane permeation, and oscillation. The ultimate goal of cellular acoustics is the detection, quantification, manipulation and eradication of individual cells. Full article
(This article belongs to the Special Issue Advances in Bubble Acoustics)
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Open AccessReview
Microbubble-Mediated Delivery for Cancer Therapy
Fluids 2018, 3(4), 74; https://doi.org/10.3390/fluids3040074 - 19 Oct 2018
Cited by 5
Abstract
Despite an overall improvement in survival rates for cancer, certain resistant forms of the disease still impose a significant burden on patients and healthcare systems. Standard chemotherapy in these cases is often ineffective and/or gives rise to severe side effects. Targeted delivery of [...] Read more.
Despite an overall improvement in survival rates for cancer, certain resistant forms of the disease still impose a significant burden on patients and healthcare systems. Standard chemotherapy in these cases is often ineffective and/or gives rise to severe side effects. Targeted delivery of chemotherapeutics could improve both tumour response and patient experience. Hence, there is an urgent need to develop effective methods for this. Ultrasound is an established technique in both diagnosis and therapy. Its use in conjunction with microbubbles is being actively researched for the targeted delivery of small-molecule drugs. In this review, we cover the methods by which ultrasound and microbubbles can be used to overcome tumour barriers to cancer therapy. Full article
(This article belongs to the Special Issue Advances in Bubble Acoustics)
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