Here we investigate the transition from spreading to splashing of drops with radii $R$ varying from millimeters to tens of microns impacting onto a smooth and dry partially wetting substrate at normal atmospheric conditions. Experiments show that the smaller $R$ is, the larger the impact velocity $V$ for the drop to splash needs to be but also that splash is inhibited if ${\mathrm{We}}_{\lambda }=\rho V^2\lambda /\sigma \gtrsim 0.5$, with $\sigma$, $\rho$, and $\lambda$ indicating the interfacial tension coefficient, the liquid density, and the mean free path of gas molecules. This result has been validated for two different values of the Ohnesorge number ${\mathrm{Oh}}_{\lambda }=\mu /\sqrt{\rho \lambda \sigma }$, with $\mu$ indicating the liquid viscosity, defined using only the material properties of the liquid and of the surrounding gaseous atmosphere. The underlying reason for this a priori unexpected finding results from the fact that the thin liquid film ejected after the drop touches the substrate is, under many practical conditions, $H_t\simeq \sigma /\left(\rho V^2\right)$ Riboux and Gordillo [Phys. Rev. Lett. 113, 024507 (2014)]. Then, for sufficiently large values of $V$, the thickness of the lamella becomes similar to the mean free path of gas molecules, i.e., $H_t\approx \lambda$, and, under these conditions, the splash of the drop is inhibited because the lift force causing the liquid to dewet the partially wetting solid is negligible. The spreading to splashing and the splashing to spreading transitions observed experimentally as the impact velocity is increased and the radii of the droplets is above a certain threshold value are very well predicted by the theory in G. Riboux and J. M. Gordillo [Phys. Rev. Lett. 113, 024507 (2014)] and J. M. Gordillo and G. Riboux [J. Fluid Mech. 871, R3 (2019)] once the aerodynamic lift force is set to zero for $H_t/\lambda \lesssim 2$, i.e., when ${\mathrm{We}}_{\lambda }\gtrsim 0.5$.

中文翻译：

---

较大的冲击速度可抑制微米级液滴的飞溅

在这里，我们研究了半径从液滴扩散到飞溅的过渡 $\mathrm{[R}$从几毫米到几十微米不等，在正常大气条件下会撞击到光滑干燥的部分润湿的基材上。实验表明，较小的$\mathrm{[R}$ 是，冲击速度越大 $V$ 不仅要防止飞溅，而且如果 ${\mathrm{我们}}_{\lambda }=\rho V^2\lambda /\sigma \gtrsim 0.5$， 和 $\sigma$， $\rho$， 和 $\lambda$表示界面张力系数，液体密度和气体分子的平均自由程。此结果已针对Ohnesorge数的两个不同值进行了验证${哦}_{\lambda }=\mu /\sqrt{\rho \lambda \sigma }$， 和 $\mu$表示液体粘度，仅使用液体和周围气体环境的材料特性来定义。这种先验性发现的根本原因是由于在许多实际条件下，液滴接触到基材后喷出的液体薄膜的事实，$H_{Ť}\simeq \sigma /（\rho V^2）$Riboux和Gordillo [物理学 牧师 113，024507（2014）]。然后，对于足够大的$V$，则薄片的厚度变得类似于气体分子的平均自由程，即 $H_{Ť}\approx \lambda$并且，在这些条件下，由于引起液体使部分润湿的固体润湿的升力可以忽略，因此抑制了液滴的飞溅。G. Riboux和JM Gordillo [物理。牧师 113，024507（2014）]和JM戈迪略和G. Riboux [ J.流体机甲。 871，R3（2019）]，$H_{Ť}/\lambda \lesssim 2$，即何时 ${\mathrm{我们}}_{\lambda }\gtrsim 0.5$。