TNO, P.O. Box 96864, 2509 DG, The Hague, Netherlands.
J Acoust Soc Am. 2011 Nov;130(5):3184-208. doi: 10.1121/1.3628321.
Perhaps the most familiar concepts when discussing acoustic scattering by bubbles are the resonance frequency for bubble pulsation, the bubbles' damping, and their scattering and extinction cross-sections, all of which are used routinely in oceanography, sonochemistry, and biomedicine. The apparent simplicity of these concepts is illusory: there exist multiple, sometimes contradictory definitions for their components. This paper reviews expressions and definitions in the literature for acoustical cross-sections, resonance frequencies, and damping factors of a spherically pulsating gas bubble in an infinite liquid medium, deriving two expressions for "resonance frequency" that are compared and reconciled with two others from the reviewed literature. In order to prevent errors, care is needed by researchers when combining results from different publications that might have used internally correct but mutually inconsistent definitions. Expressions are presented for acoustical cross-sections associated with forced pulsations damped by liquid shear and (oft-neglected) bulk or dilatational viscosities, gas thermal diffusivity, and acoustic re-radiation. The concept of a dimensionless "damping coefficient" is unsuitable for radiation damping because different cross-sections would require different functional forms for this parameter. Instead, terms based on the ratio of bubble radius to acoustic wavelength are included explicitly in the cross-sections where needed.
在讨论气泡的声学散射时，最熟悉的概念也许是气泡脉动的共振频率、气泡的阻尼以及它们的散射和消光截面，这些概念在海洋学、声化学和生物医学中经常使用。这些概念表面上的简单性是虚幻的：它们的组成部分存在多种，有时甚至是相互矛盾的定义。本文回顾了文献中关于无限液体介质中球形脉动气体气泡的声学截面、共振频率和阻尼因子的表达式和定义，推导出了两个“共振频率”的表达式，并与文献中另外两个进行了比较和调和。为了防止错误，研究人员在结合来自不同出版物的结果时需要小心，这些结果可能使用了内部正确但相互不一致的定义。本文还提出了与液体剪切和（常被忽略的）体膨胀或粘性阻尼、气体热扩散以及声再辐射相关的受迫脉动的声学截面表达式。无量纲“阻尼系数”的概念不适合辐射阻尼，因为不同的截面需要该参数的不同函数形式。相反，在需要的地方，截面中明确包含基于气泡半径与声波波长比的项。
