STATIC SHAPE AND INSTABILITY OF AN ACOUSTICALLY LEVITATED LIQUID-DROP
STATIC SHAPE AND INSTABILITY OF AN ACOUSTICALLY LEVITATED LIQUID-DROP
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DOI：
10.1063/1.858192
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发表时间：
1991-11-01
期刊：
影响因子：
--
通讯作者：
WANG, TG
中科院分区：
文献类型：
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作者：
LEE, CP;ANILKUMAR, AV;WANG, TG
据观察，强烈的声场可以通过辐射压力将悬浮的液滴彻底压平，从而打碎悬浮的液滴。 使用高速摄影观察到，对于低粘度液体，在高声强下，液滴的中央膜上会出现波纹。 在较高强度下，膜可能会通过从其不稳定的波纹中发射卫星液滴而雾化。 对于一般粘度，它也可能像雨伞一样向上弯曲并破碎，或者可能像片材一样水平膨胀并破碎。 使用扁平水滴的不喜欢模型对这种现象进行了研究，发现与观察结果具有良好的定性一致性。 人们认为，在低粘度下，波纹是由声压驱动的膜振动激发的参数不稳定性产生的毛细波。 当膜变得很薄以至于振动足够强烈时就会发生雾化。 对于任何粘度，振动都会导致静压的伯努利校正，从而不稳定。 由于伯努利效应，当现有平衡对于膜的径向振荡不稳定时，就会发生屈曲。 此外，扁平水滴边缘的辐射应力（即吸应力）也会不稳定，导致水平膨胀和随后的破裂。
There have been observations that an intense sound field can break up a liquid drop in levitation by flattening it drastically through radiation pressure. Using high-speed photography, it is observed that, for a low-viscosity liquid, at a high sound intensity, ripples appear on the central membrane of the drop. At a higher intensity, the membrane may atomize by emitting satellite drops from its unstable ripples. For a general viscosity, it might also buckle upward like an umbrella and shatter, or might simply expand horizontally like a sheet and shatter. Using a dislike model for the flattened drop, the phenomenon was studied and good qualitative agreement with the observations was found. It is believed that at low viscosity, the ripples are capillary waves generated by the parametric instability excited by the membrane vibration, which is driven by the sound pressure. Atomization occurs whenever the membrane becomes so thin that the vibration is sufficiently intense. For any viscosity, the vibration leads to a Bernoulli correction in the static pressure, which is destabilizing. Buckling occurs when an existent equilibrium is unstable to a radial oscillation of the membrane because of the Bernoulli effect. Besides, the radiation stress at the rim of the flattened drop, being a suction stress, is also destabilizing, leading to the horizontal expansion and the subsequent breakup.