Damping Constants of Pulsating Bubbles
01 May 1970-Journal of the Acoustical Society of America (Acoustical Society of America)-Vol. 47, pp 1469-1470
TL;DR: In this article, the damping constants of resonant bubbles are extended to the off-resonance case and it is shown that thermal damping is important for bubbles driven below resonance, and radiation damping for those above resonance.
Abstract: Results obtained by Devin [J. Acoust. Soc. Amer. 31, 1654–1667 (1959)] for the damping constants of resonant bubbles are extended to the off‐resonance case. Calculated results show for the range of conditions considered that thermal damping is important for bubbles driven below resonance, and radiation damping is important for those above resonance.
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TL;DR: A theoretical model is developed for some acoustic properties, particularly the scatter and absorption, of this contrast agent, considering the individual microspheres as air bubbles surrounded by a thin shell, and it is concluded that the model correlates well with these acoustic measurements.
512 citations
TL;DR: It is concluded that the shell strongly alters the acoustic behavior of the bubbles: the stiffness and viscosity of the particles are mainly determined by the encapsulating shell, not by the air inside.
Abstract: A model for the oscillation of gas bubbles encapsulated in a thin shell has been developed. The model depends on viscous and elastic properties of the shell, described by thickness, shear modulus, and shear viscosity. This theory was used to describe an experimental ultrasound contrast agent from Nycomed, composed of air bubbles encapsulated in a polymer shell. Theoretical calculations were compared with measurements of acoustic attenuation at amplitudes where bubble oscillations are linear. A good fit between measured and calculated results was obtained. The results were used to estimate the viscoelastic properties of the shell material. The shell shear modulus was estimated to between 10.6 and 12.9 MPa, the shell viscosity was estimated to between 0.39 and 0.49 Pas. The shell thickness was 5% of the particle radius. These results imply that the particles are around 20 times more rigid than free air bubbles, and that the oscillations are heavily damped, corresponding to Q-values around 1. We conclude that the shell strongly alters the acoustic behavior of the bubbles: The stiffness and viscosity of the particles are mainly determined by the encapsulating shell, not by the air inside.
422 citations
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01 Aug 1974
TL;DR: In this paper, a review of Gas Hydrates with Implication for Ocean Sediments is presented, where the authors discuss pathways and environmental requirements for biogenic gas production in the Ocean.
Abstract: Pathways and Environmental Requirements for Biogenic Gas Production in the Ocean.- Depth Distributions of Gases in Shallow Water Sediments.- Methane and Carbon Dioxide in Coastal Marsh Sediments.- Hydrocarbon Gas (Methane) in Canned Deep Sea Drilling Project Core Samples.- Dissolved Gases in Cariaco Trench Sediments: Anaerobic Diagenesis.- Isotopic Analysis of Gas from the Cariaco Trench Sediments.- The Origin and Distribution of Methane in Marine Sediments.- Geothermal Gases.- The Nature and Occurrence of Clathrate Hydrates.- Review of Gas Hydrates with Implication for Ocean Sediments.- Occurrence of Natural Gas Hydrates in Sedimentary Basins.- Experiments on Hydrocarbon Gas Hydrates in Unconsolidated Sand.- Effects of Gas Hydrates in Sediments.- Acoustics and Gas in Sediments: Applied Research Laboratories (ARL) Experience.- Gas Bubbles and the Acoustically Impenetrable, or Turbid, Character of Some Estuarine Sediments.- In Situ Indications of Gas Hydrate.- Pagoda Structures in Marine Sediments.- List of Contributors.
310 citations
TL;DR: Zero-thickness interface models are developed to describe the encapsulation of microbubble contrast agents with rheological parameters such as surface tension, surface Dilatational viscosity, and surface dilatational elasticity to characterize a widely used microbubbles based ultrasound contrast agent.
Abstract: Zero-thickness interface models are developed to describe the encapsulation of microbubble contrast agents. Two different rheological models of the interface, Newtonian (viscous) and viscoelastic, with rheological parameters such as surface tension, surface dilatational viscosity, and surface dilatational elasticity are presented to characterize the encapsulation. The models are applied to characterize a widely used microbubble based ultrasound contrast agent. Attenuation of ultrasound passing through a solution of contrast agent is measured. The model parameters for the contrast agent are determined by matching the linearized model dynamics with measured attenuation data. The models are investigated for its ability to match with other experiments. Specifically, model predictions are compared with scattered fundamental and subharmonic responses. Experiments and model prediction results are discussed along with those obtained using an existing model [Church, J. Acoust. Soc. Am. 97, 1510 (1995) and Hoff et al., J. Acoust. Soc. Am. 107, 2272 (2000)] of contrast agents.
269 citations
TL;DR: In this article, a mainly theoretical review of the physical aspects of the behavior of bubbles in sound fields is presented, including an equation for the radial motion, including the effects of liquid compressibility.
198 citations