Rayleigh-Taylor不稳定性非线性特性的数值研究

以往对于单模态Rayleigh-Taylor（RT）不稳定性非线性特性的研究主要集中于推导和测量恒定的气泡推进速度上，而缺乏对液态尖钉区域非线性动力学特性的详细分析。采用耦合的Level-Set和Volume-of-Fluid（CLSVOF）界面捕捉方法对单模态RT不稳定性的发展过程进行了精确的数值模拟，并利用模拟得到的压力场和速度场信息对RT不稳定性非线性发展阶段的稳态动力学特性进行了分析。模拟结果表明，在液态尖钉根部由于惯性力作用而引起的水平冲击流会在此处形成一个局部最大压力点，由于此处惯性力与压强梯度的平衡，位于最大压力点附近的流动最终将达到稳态。通过理论分析，确定了此稳态流动中各稳态特征参数与初始扰动波长、惯性加速度之间的关系。这些特征参数的确定有助于将经典低速射流的相关理论扩展应用到RT不稳定性诱导雾化的研究领域。

Numerical study on nonlinear characteristics of Rayleigh-Taylor instability

The research on the nonlinear dynamics of Rayleigh-Taylor (RT) before mainly focused on deducing and measuring the constant penetration velocity of the bubble and had little detailed analysis of the nonlinear dynamic characteristics in the liquid spike region. An accurate numerical simulation of the single-mode RT instability was carried out based on the coupled Level-Set and Volume-of-Fluid (CLSVOF) interface capturing method. The detailed information on the pressure fields and velocity fields was obtained. In addition, the steady-state dynamic characteristics in the nonlinear development stage were analyzed. Simulation results show that a local maximum pressure point which is caused by the horizontal impinging flow with the action of inertial force appears at the root of the spike. The dependence of the different characteristic parameters of the steady flow on the initial perturbation wavelength and the inertial acceleration is determined. This work may extend the relevant classical theories of the low speed jet to the RT instability inducing atomization field.