Klaseboer Evert, Fong Siew Wan, Turangan Cary K, Khoo Boo Cheong, Szeri Andrew J, Calvisi Michael L, Sankin Georgy N, Zhong Pei
Institute of High Performance Computing, 1 Science Park Road, #01-01 The Capricorn, Singapore Science Park II, Singapore 117528.
J Fluid Mech. 2007;593:33-56. doi: 10.1017/S002211200700852X.
The dynamic interaction of a shockwave (modelled as a pressure pulse) with an initially spherically oscillating bubble is investigated. Upon the shockwave impact, the bubble deforms non-spherically and the flow field surrounding the bubble is determined with potential flow theory using the boundary-element method (BEM). The primary advantage of this method is its computational efficiency. The simulation process is repeated until the two opposite sides of the bubble surface collide with each other (i.e. the formation of a jet along the shockwave propagation direction). The collapse time of the bubble, its shape and the velocity of the jet are calculated. Moreover, the impact pressure is estimated based on water-hammer pressure theory. The Kelvin impulse, kinetic energy and bubble displacement (all at the moment of jet impact) are also determined. Overall, the simulated results compare favourably with experimental observations of lithotripter shockwave interaction with single bubbles (using laser-induced bubbles at various oscillation stages). The simulations confirm the experimental observation that the most intense collapse, with the highest jet velocity and impact pressure, occurs for bubbles with intermediate size during the contraction phase when the collapse time of the bubble is approximately equal to the compressive pulse duration of the shock wave. Under this condition, the maximum amount of energy of the incident shockwave is transferred to the collapsing bubble. Further, the effect of the bubble contents (ideal gas with different initial pressures) and the initial conditions of the bubble (initially oscillating vs. non-oscillating) on the dynamics of the shockwave-bubble interaction are discussed.
研究了冲击波（建模为压力脉冲）与初始呈球形振荡的气泡之间的动态相互作用。在冲击波冲击下，气泡发生非球形变形，并使用边界元法（BEM）通过势流理论确定气泡周围的流场。该方法的主要优点是其计算效率。重复模拟过程，直到气泡表面的两个相对侧相互碰撞（即沿冲击波传播方向形成射流）。计算气泡的坍塌时间、形状和射流速度。此外，基于水击压力理论估算冲击压力。还确定了开尔文冲量、动能和气泡位移（均在射流冲击时刻）。总体而言，模拟结果与碎石机冲击波与单个气泡相互作用的实验观测结果（使用处于不同振荡阶段的激光诱导气泡）相比具有优势。模拟结果证实了实验观测结果，即对于中等尺寸的气泡，在收缩阶段当气泡的坍塌时间近似等于冲击波的压缩脉冲持续时间时，会发生最强烈的坍塌，射流速度和冲击压力最高。在此条件下，入射冲击波的最大能量被传递到正在坍塌的气泡。此外，还讨论了气泡内含物（具有不同初始压力的理想气体）和气泡的初始条件（初始振荡与非振荡）对冲击波 - 气泡相互作用动力学的影响。
