Puente Gabriela F, Urteaga Raúl, Bonetto Fabián J
Laboratorio de Cavitación y Biotecnología Instituto Balseiro/Centro Atómico Bariloche, 8400 San Carlos de Bariloche, Rio Negro, Argentina.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Oct;72(4 Pt 2):046305. doi: 10.1103/PhysRevE.72.046305. Epub 2005 Oct 10.
We performed a comprehensive numerical and experimental analysis of dissociation effects in an air bubble in water acoustically levitated in a spherical resonator. Our numerical approach is based on suitable models for the different effects considered. We compared model predictions with experimental results obtained in our laboratory in the whole phase parameter space, for acoustic pressures from the bubble dissolution limit up to bubble extinction. The effects were taken into account simultaneously to consider the transition from nonsonoluminescence to sonoluminescence bubbles. The model includes (1) inside the bubble, transient and spatially nonuniform heat transfer using a collocation points method, dissociation of O2 and N2, and mass diffusion of vapor in the noncondensable gases; (2) at the bubble interface, nonequilibrium evaporation and condensation of water and a temperature jump due to the accommodation coefficient; (3) in the liquid, transient and spatially nonuniform heat transfer using a collocation points method, and mass diffusion of the gas in the liquid. The model is completed with a Rayleigh-Plesset equation with liquid compressible terms and vapor mass transfer. We computed the boundary for the shape instability based on the temporal evolution of the computed radius. The model is valid for an arbitrary number of dissociable gases dissolved in the liquid. We also obtained absolute measurements for R(t) using two photodetectors and Mie scattering calculations. The robust technique used allows the estimation of experimental results of absolute R0 and P(a). The technique is based on identifying the bubble dissolution limit coincident with the parametric instability in (P(a),R0) parameter space. We take advantage of the fact that this point can be determined experimentally with high precision and replicability. We computed the equilibrium concentration of the different gaseous species and water vapor during collapse as a function of P(a) and R0. The model obtains from first principles the result that in sonoluminescence the bubble is practically 100% argon for air dissolved in water. Therefore, the dissociation reactions in air bubbles must be taken into account for quantitative computations of maximum temperatures. The agreement found between the numerical and experimental data is very good in the whole parameter space explored. We do not fit any parameter in the model. We believe that we capture all the relevant physics with the model.
我们对球形谐振器中声悬浮于水中的气泡内的解离效应进行了全面的数值和实验分析。我们的数值方法基于针对所考虑的不同效应的合适模型。我们将模型预测结果与在我们实验室中在整个相参数空间内获得的实验结果进行了比较，该相参数空间涵盖了从气泡溶解极限到气泡熄灭的声压范围。同时考虑了这些效应，以研究从非声致发光气泡到声致发光气泡的转变。该模型包括：(1) 在气泡内部，使用配置点法进行瞬态且空间非均匀的热传递、O₂ 和 N₂ 的解离以及非冷凝气体中蒸汽的质量扩散；(2) 在气泡界面处，水的非平衡蒸发和凝结以及由于适应系数导致的温度跃变；(3) 在液体中，使用配置点法进行瞬态且空间非均匀的热传递以及气体在液体中的质量扩散。该模型通过带有液体可压缩项和蒸汽质量传递的瑞利 - 普莱斯方程得以完善。我们根据计算得到的半径的时间演化计算了形状不稳定性的边界。该模型对于溶解在液体中的任意数量的可解离气体均有效。我们还使用两个光电探测器和米氏散射计算获得了 R(t) 的绝对测量值。所采用的稳健技术能够估算绝对 R₀ 和 P(a) 的实验结果。该技术基于确定与 (P(a),R₀) 参数空间中的参数不稳定性相一致的气泡溶解极限。我们利用了这一点可以通过实验高精度且可重复地确定这一事实。我们计算了坍塌过程中不同气态物质和水蒸气的平衡浓度，其作为 P(a) 和 R₀ 的函数。该模型从第一原理得出，对于溶解在水中的空气，在声致发光过程中气泡实际上几乎 100% 是氩气。因此，对于最高温度的定量计算，必须考虑气泡中的解离反应。在所探索的整个参数空间中，数值数据与实验数据之间的一致性非常好。我们在模型中未拟合任何参数。我们相信我们的模型捕捉到了所有相关的物理现象。
