Wu Shengji, Zuo Zhigang, Stone Howard A, Liu Shuhong
State Key Laboratory of Hydroscience and Engineering, Department of Thermal Engineering, Tsinghua University, 100084 Beijing, China.
Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Phys Rev Lett. 2017 Aug 25;119(8):084501. doi: 10.1103/PhysRevLett.119.084501.
We document experimentally four different interactions of a laser-induced bubble and a free-settling particle, with different combinations of the geometric and physical parameters of the system. Our force balance model shows that four nondimensional factors involving the particle radius a, the maximum bubble radius R_{max}, the initial separation distance l_{0} between the particle center and the bubble center, the fluid viscosity μ_{f}, and the particle and fluid densities ρ_{p} and ρ_{f}, respectively, in detail l_{0}/R_{max}, a/R_{max}, ρ_{p}/ρ_{f}, and μ^{*}=μ_{f}T_{c}/ρ_{f}R_{max}^{2}, where T_{c}=0.915R_{max}sqrt[ρ_{f}/(p_{∞}-p_{v})], influence the particle-bubble dynamics, and reasonably predict the maximum particle velocity and the limiting condition when the particle starts to "bounce off" the bubble during bubble growth. In particular, we also discover the high-speed ejection of the particle, and a cavity behind the particle, in cases when initially the particle is in very close proximity to the bubble. These observations offer new insights into the causal mechanism for the enhanced cavitation erosion in silt-laden water.
我们通过实验记录了激光诱导气泡与自由沉降颗粒的四种不同相互作用，这些相互作用具有系统几何和物理参数的不同组合。我们的力平衡模型表明，四个无量纲因素分别涉及颗粒半径a、最大气泡半径R_max、颗粒中心与气泡中心之间的初始分离距离l_0、流体粘度μ_f以及颗粒和流体密度ρ_p和ρ_f，具体为l_0/R_max、a/R_max、ρ_p/ρ_f以及μ* = μ_fT_c/ρ_fR_max^2，其中T_c = 0.915R_max√[ρ_f/(p_∞ - p_v)]，影响颗粒 - 气泡动力学，并合理预测了颗粒的最大速度以及在气泡生长过程中颗粒开始从气泡“反弹”时的极限条件。特别是，我们还发现，在最初颗粒非常靠近气泡的情况下，颗粒会高速喷射以及在颗粒后方形成一个空洞。这些观察结果为含沙水中空化侵蚀增强的因果机制提供了新的见解。
