空化单气泡外围压强分布

Pressure distribution outside a single cavitation bubble

通过数值计算非线性谐振的气泡外围流场中的Navier Stokes方程 ,给出详细的空化单气泡外围压强分布 .数值计算发现当气泡处于压缩相 ,那些最大半径比较大的气泡 ,其外围紧邻气泡壁处出现负压区 ,这将使气泡在这段时间处于力的非稳定平衡点 .计算还发现 ,当气泡接近它的最小半径处 ,气泡外围形成很薄的高压区 ,这个高压区域随后向外传播 ,这就形成冲击波 .分析表明 ,冲击波对Mie散射法测量气泡最小半径有一定影响 ,但不是主要影响 .

Shape instabilities and diffusive instability are generally employed to investigate the stability of a single sonoluminescencing bubble, but the effect of the pressure outside a cavitation bubble is seldom studied. This paper particularly gives the pressure distribution outside a nonlinear resonance bubble by solving the Navier-Stokes equation outside the bubble. Numerical simulation shows that a negative pressure region appears in the vicinity of the bubble wall for those bubbles with a larger maximum radius, when the bubble is in its compressed phase, and which makes the bubble in the position of unstable equilibrium. We find that when the collapsing bubble approaches its minimum radius, a high pressure layer just outside the bubble is generated which gradually moves outward and subsequently forms a shock wave. Analysis indicates that the shock wave affects the measurement of the minimum radius of the bubble by Mie scattering; however, the effect is not dominant.