クラウドキャビテーションの崩壊現象を利用した結石破砕法 : 第1報,クラウドキャビテーション制御手法の開発(流体工学,流体機械)

概要

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In a therapeutic ultrasound field, cavitation frequently forms a bubble cloud that consists of many microbubbles. A method to control the violent collapse of cloud cavitation is being developed. It is comprised of two frequency ultrasound forcing. The first is a higher frequency ultrasound waveform that makes cloud cavitation at the surface of the object. The second is a lower frequency waveform that produces a violent collapse of the cloud cavitation. If the phenomena is well controlled in time and space, it can be utilized for the stone crushing mechanism in lithotripsy. From a numerical simulation, the controllability of the cloud cavitation is predicted. A stable bubble cloud at the solid surface and the shock wave from the violent cloud cavitation collapse are observed by using a high-speed photography. The occurrence time of the collapsing phenomena of cloud cavitation is controlled within 100ns and the area is controlled within several hundreds micrometers. Using the present method, stones are chipped away such that scoop-like indentations are achieved.
2004-04-25