| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
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.
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