A Condition Monitoring for Collapsing Bubble Mechanism for Sonoluminescence and Sonochemistry

2015 ◽  
Vol 7 (2) ◽  
Author(s):  
Ali Alhelfi ◽  
Bengt Sundén
Keyword(s):  
Acoustic Waves ◽  
Bubble Dynamics ◽  
Stokes Equations ◽  
Current Model ◽  
Computation Time ◽  
Acoustic Cavitation ◽  
Full Potential ◽  
Bubble Oscillation ◽  
Cavitation Phenomenon ◽  
Wide Range

The acoustic cavitation phenomenon is a source of energy for a wide range of applications such as sonoluminescence and sonochemistry. The behavior of a single bubble in liquids is an essential study for acoustic cavitation. The bubbles react with the pressure forces in liquids and reveal their full potential when periodically driven by acoustic waves. As a result of extreme compression of the bubble oscillation in an acoustic field, the bubble produces a very high pressure and temperature during collapse. The temperature may increase many thousands of Kelvin, and the pressure may approach up to hundreds of bar. Subsequently, short flashes can be emitted (sonoluminescence) and the high local temperatures and pressures induce chemical reactions under extreme conditions (sonochemistry). Different models have been presented to describe the bubble dynamics in acoustic cavitation. These studies are done through full numerical simulation of the compressible Navier–Stokes equations. This task is very complex and consumes much computation time. Several features of the cavitation fields remain unexplained. In the current model, all hydrodynamics forces acting on the bubble are considered in the typical solution. Bubble oscillation and its characteristics under the action of a sound wave are presented in order to improve and give a more comprehensive understanding of the phenomenon, which is considered to have a significant role in different areas of science and technology.

A Direct Numerical Simulation of the Unsteady Development of a Deformable Rising Bubble in a Quiescent Liquid

2008 ◽  
Author(s):  
Alpana Agarwal ◽  
C. F. Tai ◽  
J. N. Chung
Keyword(s):  
Weber Number ◽  
Bubble Dynamics ◽  
Stokes Equations ◽  
Control Volume ◽  
Density Ratio ◽  
Simulation Method ◽  
Liquid Pool ◽  
Accurate Information ◽  
Two Phase ◽  
Wide Range

An accurate finite-volume based numerical method for the simulation of an isothermal two-phase flow, consisting of a deformable bubble rising in a quiescent, unbounded liquid, is presented. This direct simulation method is built on a sharp interface concept and developed on an Eulerian, Cartesian fixed grid with a cut-cell scheme and marker points to track the moving interface. The unsteady Navier-Stokes equations in both liquid and gas phases are solved separately. The mass continuity and momentum flux conditions are explicitly matched at the true phase boundary to determine the interface shape and movement of the bubble. The highlights of this method are that it utilizes a combined Eulerian-Lagrangian approach, and is capable of treating the interface as a sharp discontinuity. A fixed underlying grid is used to represent the control volume. The interface, however, is denoted by a separate set of marker particles which move along with the interface. A quadratic curve fitting algorithm with marker points is used to yield smooth and accurate information of the interface curvatures. This numerical scheme can handle a wide range of density and viscosity ratios. The bubble is assumed to be spherical and at rest initially, but deforms as it rises through the liquid pool due to buoyancy. Additionally, the flow is assumed to be axisymmetric and incompressible. The bubble deformation and dynamic motion are characterized by the Reynolds number, the Weber number, the density ratio and the viscosity ratio. The effects of these parameters on the translational bubble dynamics and shape are given and the physical mechanisms are explained and discussed. Results for the shape, velocity profile and various forces acting on the bubble are presented here as a function of time until the bubble reaches terminal velocity. The range of Reynolds numbers investigated is 1 < Re < 100, and that of Weber number is 1 < We < 10.

The Influence of Acoustic Cavitation to Microscopic Material Removal in Polishing Process Based on Vibration of Liquid: A Numerical Study

2006 ◽  
Vol 532-533 ◽  
pp. 301-304 ◽  
Author(s):  
Zhong Ning Guo ◽  
Zhi Gang Huang ◽  
Xin Chen
Keyword(s):  
Material Removal ◽  
High Speed ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Dissipative Particle Dynamics ◽  
Thermal Conditions ◽  
Acoustic Cavitation ◽  
Ultrasonic Frequency ◽  
Polishing Process ◽  
Cavitation Phenomenon

In Polishing Process based on Vibration of Liquid (PVL), abrasive particles driven by polishing liquid will brush and etch workpiece to achieve material removal. Because the liquid is vibrated in ultrasonic frequency, polishing process will be greatly affected by cavitation phenomenon. The critical thermal conditions and high-speed liquid jet produced by bubble dynamics may damage workpiece. A refined Dissipative Particle Dynamics method is applied to study the effect of acoustic cavitation on PVL. Validity of the numerical simulation is tested according to experimental results.

scholarly journals Modeling Acoustic Cavitation Using a Pressure-Based Algorithm for Polytropic Fluids

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 69 ◽  
Author(s):  
Fabian Denner ◽  
Fabien Evrard ◽  
Berend van Wachem
Keyword(s):  
Finite Volume ◽  
Acoustic Waves ◽  
Bubble Dynamics ◽  
Acoustic Cavitation ◽  
Test Cases ◽  
Linear System Of Equations ◽  
Finite Volume Discretization ◽  
Liquid Systems ◽  
Confined Domains ◽  
Fully Coupled

A fully coupled pressure-based algorithm and finite-volume framework for the simulation of the acoustic cavitation of bubbles in polytropic gas-liquid systems is proposed. The algorithm is based on a conservative finite-volume discretization with collocated variable arrangement, in which the discretized governing equations are solved in a single linear system of equations for pressure and velocity. Density is described by the polytropic Noble-Abel stiffened-gas model and the interface between the interacting bulk phases is captured by a state-of-the-art algebraic Volume-of-Fluid (VOF) method. The new numerical algorithm is validated using representative test-cases of the interaction of acoustic waves with the gas-liquid interface as well as pressure-driven bubble dynamics in infinite and confined domains, showing excellent agreement of the results obtained with the proposed algorithm compared to linear acoustic theory, the Gilmore model and high-fidelity experiments.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

scholarly journals Enhanced Bilosomal Properties Resulted in Optimum Pharmacological Effects by Increased Acidification Pathways

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1184
Author(s):  
Armin Mooranian ◽  
Thomas Foster ◽  
Corina M Ionescu ◽  
Daniel Walker ◽  
Melissa Jones ◽  
...  
Keyword(s):  
Bile Acids ◽  
Biological Effects ◽  
Cellular Respiration ◽  
Full Potential ◽  
Protective Effects ◽  
Pharmacological Effects ◽  
Β Cells ◽  
Positive Effects ◽  
Wide Range ◽  
Anti Inflammatory

Introduction: Recent studies in our laboratory have shown that some bile acids, such as chenodeoxycholic acid (CDCA), can exert cellular protective effects when encapsulated with viable β-cells via anti-inflammatory and anti-oxidative stress mechanisms. However, to explore their full potential, formulating such bile acids (that are intrinsically lipophilic) can be challenging, particularly if larger doses are required for optimal pharmacological effects. One promising approach is the development of nano gels. Accordingly, this study aimed to examine biological effects of various concentrations of CDCA using various solubilising nano gel systems on encapsulated β-cells. Methods: Using our established cellular encapsulation system, the Ionic Gelation Vibrational Jet Flow technology, a wide range of CDCA β-cell capsules were produced and examined for morphological, biological, and inflammatory profiles. Results and Conclusion: Capsules’ morphology and topographic characteristics remained similar, regardless of CDCA or nano gel concentrations. The best pharmacological, anti-inflammatory, and cellular respiration, metabolism, and energy production effects were observed at high CDCA and nano gel concentrations, suggesting dose-dependent cellular protective and positive effects of CDCA when incorporated with high loading nano gel.

scholarly journals Mineral Physicochemistry Underlying Feature-Based Extraction of Mineral Abundance and Composition from Shortwave, Mid and Thermal Infrared Reflectance Spectra

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 347
Author(s):  
Carsten Laukamp ◽  
Andrew Rodger ◽  
Monica LeGras ◽  
Heta Lampinen ◽  
Ian C. Lau ◽  
...  
Keyword(s):  
Mineral Exploration ◽  
Relevant Information ◽  
Ore Deposits ◽  
Reflectance Spectra ◽  
Full Potential ◽  
Infrared Reflectance ◽  
Vibrational Modes ◽  
Diagnostic Features ◽  
Wide Range ◽  
Mineral Assemblages

Reflectance spectroscopy allows cost-effective and rapid mineral characterisation, addressing mineral exploration and mining challenges. Shortwave (SWIR), mid (MIR) and thermal (TIR) infrared reflectance spectra are collected in a wide range of environments and scales, with instrumentation ranging from spaceborne, airborne, field and drill core sensors to IR microscopy. However, interpretation of reflectance spectra is, due to the abundance of potential vibrational modes in mineral assemblages, non-trivial and requires a thorough understanding of the potential factors contributing to the reflectance spectra. In order to close the gap between understanding mineral-diagnostic absorption features and efficient interpretation of reflectance spectra, an up-to-date overview of major vibrational modes of rock-forming minerals in the SWIR, MIR and TIR is provided. A series of scripts are proposed that allow the extraction of the relative intensity or wavelength position of single absorption and other mineral-diagnostic features. Binary discrimination diagrams can assist in rapidly evaluating mineral assemblages, and relative abundance and chemical composition of key vector minerals, in hydrothermal ore deposits. The aim of this contribution is to make geologically relevant information more easily extractable from reflectance spectra, enabling the mineral resources and geoscience communities to realise the full potential of hyperspectral sensing technologies.

Molecular markers and antioxidant activity in berry crops: Genetic diversity analysis

2012 ◽  
Vol 92 (6) ◽  
pp. 1121-1133 ◽  
Author(s):  
S. C. Debnath ◽  
Y. L. Siow ◽  
J. Petkau ◽  
D. An ◽  
N. V. Bykova
Keyword(s):  
Genetic Diversity ◽  
Antioxidant Activity ◽  
Molecular Markers ◽  
Molecular Techniques ◽  
Diversity Analysis ◽  
Full Potential ◽  
Genetic Diversity Analysis ◽  
Wide Range ◽  
Berry Crops ◽  
Improvement Programs

Debnath, S. C., Siow, Y. L., Petkau, J., An, D. and Bykova, N. V. 2012. Molecular markers and antioxidant activity in berry crops: Genetic diversity analysis. Can. J. Plant Sci. 92: 1121–1133. An improved understanding of important roles of dietary fruits in maintaining human health has led to a dramatic increase of global berry crop production. Berry fruits contain relatively high levels of vitamin C, cellulose and pectin, and produce anthocyanins, which have important therapeutic values, including antitumor, antiulcer, antioxidant and anti-inflammatory activities. There is a need to develop reliable methods to identify berry germplasm and assess genetic diversity/relatedness for dietary properties in berry genotypes for practical breeding purposes through genotype selection in a breeding program for cultivar development, and proprietary-rights protection. The introduction of molecular biology techniques, such as DNA-based markers, allows direct comparison of different genetic materials independent of environmental influences. Significant progress has been made in diversity analysis of wild cranberry, lowbush blueberry, lingonberry and cloudberry germplasm, and in strawberry and raspberry cultivars and advanced breeding lines developed in Canada. Inter simple sequence repeat (ISSR) markers detected an adequate degree of polymorphism to differentiate among berry genotypes, making this technology valuable for cultivar identification and for the more efficient choice of parents in the current berry improvement programs. Although multiple factors affect antioxidant activity, a wide range of genetic diversity has been reported in wild and cultivated berry crops. Diversity analysis based on molecular markers did not agree with those from antioxidant activity. The paper also discusses the issues that still need to be addressed to utilize the full potential of molecular techniques including expressed sequence tag-polymerase chain reaction (EST-PCR) analysis to develop improved environment-friendly berry cultivars suited to the changing needs of growers and consumers.

Layered Manufacturing: Challenges and Opportunities

2002 ◽  
Vol 758 ◽  
Author(s):  
Khershed P. Cooper
Keyword(s):  
Science Research ◽  
Scientific Activity ◽  
Layered Manufacturing ◽  
Full Potential ◽  
Local Composition ◽  
Photosensitive Polymers ◽  
Wide Range ◽  
Challenges And Opportunities ◽  
Future Direction

ABSTRACTLayered Manufacturing (LM) refers to computer-aided manufacturing processes in which parts are made in sequential layers relatively quickly. Parts that are produced by LM can be formed from a wide range of materials such as photosensitive polymers, metals and ceramics in sizes from a centimeter to a few meters with sub-millimeter feature resolutions. LM has found use in diverse areas including biomedical engineering, pharmaceuticals, aerospace, defense, electronics and design engineering. The promise of LM is the capability to make customized complex-shaped functional parts without specialized tooling and without assembly. LM is still a few years away from fully realizing its promise but its potential for manufacturing remains high. A few of the fundamental challenges in materials processing confronting the community are improving the quality of the surface finish, eliminating residual stress, controlling local composition and microstructure, achieving fine feature size and dimensional tolerance and accelerating processing speed. Until these challenges are met, the applicability of LM and its commercialization will be restricted. Sustained scientific activity in LM has advanced over the past decade into many different areas of manufacturing and has enabled exploration of novel processes and development of hybrid processes. The research community of today has the opportunity to shape the future direction of science research to realize the full potential of LM.

SiC Semiconductor Applications - An Air Force Perspective

1996 ◽  
Vol 423 ◽  
Author(s):  
L. S. Rea
Keyword(s):  
Air Force ◽  
Device Performance ◽  
Full Potential ◽  
Materials Development ◽  
Device Development ◽  
Performance Requirements ◽  
Wide Range ◽  
The Status ◽  
Performance Results ◽  
High Temperature Electronic

AbstractThe Department of Defense (DoD) is investing in the development of Silicon Carbide (SiC) for a wide range of applications. Over the past year, SiC technology has demonstrated excellent device performance results for power devices, high temperature electronic devices and microwave devices. The materials growth and processing technology for SiC is now at a level of sufficient maturity to support substantial device development efforts. While there is still considerable materials and device research required for SiC to achieve it's full potential, the fundamental technology has been proven for several critical applications. A perspective on some Air Force device performance requirements will be presented. The status of SiC materials development, material limits to advances in device performance and issues relating to supporting technology will also be discussed.

Sign in / Sign up

Export Citation Format

Share Document