Study on the pondermotive action of an ultrasonic wave

声辐射压力通常被解释为作用在声场中的物体上的时间平均压力，其导致移动物体的单向力。本文的研究目的是从根本上揭示动态效应的机理，以往对声辐射压力的讨论是区分在普通实验条件下所经历的朗之万辐射压力和在封闭容器壁上所经历的瑞利辐射压力。此外，还有各种不同的辐射压理论，每一种理论都包含逻辑上的跳跃和不必要的假设。特别是对于后者，一个理论估计与另一个理论估计相差200%，而且没有人用实验证明这些理论。也就是说，这个理论仍然处于某种混乱状态。本文首先统一了朗之万辐射压理论，并证明了辐射压是由障碍物表面振动引起的张量，从而统一了朗之万辐射压的张量性质.其次，我们证明了朗之万辐射压是瑞利辐射压的一种特殊情况，迄今为止，瑞利辐射压一直被看作是一种纯压力，揭示了张量性质。在瑞利辐射压力的情况下，由于声波的非线性引起的介质膨胀效应是不可忽略的。因此，Rayleigh辐射压力定义中“封闭容器”的表述需要重新考虑，本文的理论消除了传统辐射压力理论中的模糊性，证明了辐射压力在一般情况下是张量性质。

The acoustic radiation pressure is customarily interpreted as the time-averaged pressure acting on an object in a sound field, which results in a unidirectional force that moves the object. The purpose of the present research is to get behind the mechanism of the dynamic effect fundamentally.Historically, the acoustic radiation pressure has been discussed in distinction between the Langevin radiation pressure experienced in ordinary experimental conditions and the Rayleigh radiation pressure experienced on the wall of a closed vessel. Furthermore there are variant theories of the respective radiation pressure, and each of them contains leaps in logic and unnecessary assumptions. As for the latter, in particular, one theoretical estimate differs from another by a factor of 200%, and nobody has proved the theories experimentally. That is to say the theory remains in a state of some confusion. In the present research, therefore, we attempt to develop a unified theory that covers both the Rayleigh and the Langevin radiation pressure.For a start, we unify the theory of the Langevin radiation pressure which is complicated in regard to the origin of tensor properties, and prove that the radiation pressure is tensor as a result that the surface of an obstacle vibrates. Next, we prove that the Langevin radiation pressure is a special case of the Rayleigh radiation pressure, which being looked upon a pure pressure up to now reveals tensor properties. In the case of the Rayleigh radiation pressure, the effect of medium expansion caused by nonlinearity of sound waves cannot be disregarded. Consequently, the expression "a closed vessel" in the definition of the Rayleigh radiation pressure needs to be reconsidered.The present theory eliminates ambiguity in the traditional theory of radiation pressure over and it is proved that radiation pressure is tensor properties in general.