| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 90 === In the present study a new three-dimensional boundary element method was developed to simulate the collapse of an underwater-explosion bubble. In order to verify the accuracy of the new scheme, this model was applied to determine the one-dimensional bubble pulsation. The numerical results agree well with the solutions obtained from Rayleigh-Plesset equation. After having verified the accuracy of this model, the bubble collapse in the free flow field as well as near a plane solid boundary was investigated. The velocity of the collapse-induced jet was determined and compared systematically. The numerical results show that as a bubble collapses in a free flow field, the formed jet is in the opposite direction of the gravity and the jet velocity increases with the depth of the bubble location. When the bubble collapses near a plane solid boundary, the direction of the jet depends on the gravity and the relative position of the boundary to the bubble. Under the same conditions, the jet velocity has its maximum value when the collapse occurs beneath the solid boundary; on the contrary it has the minimum value as the collapse occurs above a solid boundary.
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