We investigate acoustic levitation in a vertical standing wave in an attempt to understand the basic physical mechanism responsible for this phenomenon. We find that a description in terms of a simple pressure force leads to the prediction of stable equilibria that occur slightly below the anti-nodes of the standing pressure wave. We then demonstrate that such a prediction is at odds with experimental data, which show that levitating particles come to rest slightly below the nodes of the standing pressure wave. Finally, we outline a theoretical approach based on fluid dynamics that correctly predicts the locations of the levitating particles, which leads to a simple qualitative description for this fascinating phenomenon.

中文翻译：

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声悬浮和声辐射力

我们在垂直驻波中研究声悬浮，以试图了解引起这种现象的基本物理机制。我们发现，用简单的压力进行描述可以预测稳定平衡，该平衡发生在驻压波的波腹以下。然后，我们证明了这样的预测与实验数据不一致，实验数据表明悬浮粒子停留在驻压波节点的下方。最后，我们概述了一种基于流体动力学的理论方法，该方法可以正确预测悬浮粒子的位置，从而对这种引人入胜的现象进行简单的定性描述。