The microscopic Rayleigh–Taylor instability (RTI) is studied via molecular dynamics (MD) simulation for single- and dual-mode interfaces under a strong acceleration. The growth behavior of microscopic RTI as well as the underlying regime exhibits considerable differences from the macroscopic counterpart. At a microscopic scale, the flow Reynolds number is very low and thus viscosity effect plays an important role, namely, it suppresses the growth of overall perturbation amplitude and also damps the growth of harmonics. As a result, the microscopic RTI presents a much weaker nonlinearity. Also, the motion of atoms produces random fluctuations to the evolving interface, which cause the detachment of droplets from the spike under the action of surface tension at late stages. In addition, the mode coupling behavior in dual-mode RTI at a microscopic scale is evidently different from the macroscopic counterpart, and a new prescription dominating the growth of each mode is proposed. Based on these findings, a semi-empirical model applicable to the microscopic RTI from early to late stages is developed, which gives a satisfactory prediction of the MD results.

中文翻译：

---

微观尺度上的单模和双模瑞利-泰勒不稳定性

微观瑞利-泰勒不稳定性（RTI）是通过分子动力学（MD）模拟在强加速度下对单模和双模界面进行研究的。微观RTI的生长行为以及潜在的机制与宏观RTI表现出相当大的差异。在微观尺度上，流动雷诺数非常低，因此粘度效应起着重要作用，即，它抑制了总体扰动幅度的增长，并且抑制了谐波的增长。结果，微观RTI呈现出非常弱的非线性。同样，原子的运动在演化的界面上产生随机的波动，这导致液滴在后期的表面张力作用下从尖峰上脱离。此外，在微观尺度上，双模式RTI中的模式耦合行为明显不同于宏观对应物，并提出了主导每种模式增长的新处方。基于这些发现，开发了适用于微观RTI从早期到晚期的半经验模型，该模型为MD结果提供了令人满意的预测。