The study of gas bubbles in liquid media is of importance in many areas of research. Gas bubbles are often studied using in situ measurement techniques; however, acoustic inversion techniques have also been used to extract physical properties of gas bubbles. These inversion techniques rely on existing analytical scattering models; however, these models often assume that the gas bubbles are spherical in shape and have an equivalent bubble radius, a, that is small compared to the incident acoustic wavelength (ka ≪ 1), which is not always valid. This study aims to understand how the departure from these assumptions affects the acoustic backscattering cross section, σ_bs, of non-spherical gas bubbles. Experimental estimates of σ_bs of non-spherical gas bubbles of different sizes, with ka values ranging between 0.03 and 4.4, were compared to four commonly known analytical σ_bs models. All models performed equally at predicting σ_bs for ka smaller than 0.5; however, there was no model that better predicted the experimental estimates of σ_bs for ka larger than 0.5, regardless of bubble shape. Large variabilities in the experimental estimates of σ_bs are observed for ka larger than 0.5, which are caused by the variability in bubble shape and size, as well as the bubble's orientation.

中文翻译：

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非球形气泡在0.03到4.4之间的声反向散射观测

在许多研究领域中，液体介质中气泡的研究非常重要。通常使用原位测量技术来研究气泡。然而，声学反演技术也已经用于提取气泡的物理性质。这些反演技术依赖于现有的分析散射模型。但是，这些模型通常假定气泡为球形，并且具有等效的气泡半径a，该半径比入射声波长（ka≪ 1）小，这并不总是有效的。这项研究旨在了解从这些假设出发如何影响声散射截面，σ _BS非球形气泡。的实验估计σ _BS非球形的气泡不同的尺寸，以KA值0.03和4.4之间的范围内，进行比较，以四种常用已知的分析σ _BS模型。所有型号在预测同样地执行σ _BS为KA小于0.5; 然而，没有模型，更好预测的实验估计σ _BS为KA大于0.5，而不管气泡形状。在实验估计大变异σ _BS被观察到KA 大于0.5，这是由气泡形状和大小的变化以及气泡的方向引起的。