Droplet impacting on solid or liquid film is a ubiquitous phenomenon in relevant processes such as spray cooling and inkjet printing on primer layers. In this study, the dynamics of water droplets impacting a solid substrate covered by a silicon oil film is investigated under the influences of the surface wettability of the dielectrowetting substrate (69.3°-117.4°) and the thickness of the silicon oil film (7.79–21.8 μm) at . A phase diagram is established, which reflects the relationships between the impact dynamic behavior, equilibrium contact angle, and the oil film thickness. The maximum spreading factor and maximum out-of-plane height for rebound of sub-droplet behaviors was smaller than 13 % and greater than 3 times than those droplet deposition behaviors, respectively. Finally, the retraction dynamics of the droplet after reaching its maximum spreading diameter is analyzed and discussed based on retraction rate through the force balance at the three-phase contact line. Results of the study indicate that the surface wettability of the dielectrowetting substrate and thickness of the silicon oil film significantly affect the impact dynamics of water droplets on a solid substrate covered by the silicone oil film, especially in the retraction stage. This study sheds new light on controlling the dynamic impact of the droplets on silicon oil films, which is of importance to the control or optimization of processes such as inkjet printing on a primer layer.

中文翻译：

---

水滴对油覆盖介电润湿基材的冲击动力学：油膜厚度和表面润湿性的影响

液滴撞击固体或液体薄膜是喷涂冷却和底漆层喷墨打印等相关工艺中普遍存在的现象。在本研究中，研究了在介电润湿基底的表面润湿性（69.3°-117.4°）和硅油膜的厚度（7.79– 21.8微米）在。建立了相图，反映了冲击动态行为、平衡接触角和油膜厚度之间的关系。子液滴行为回弹的最大扩散因子和最大面外高度分别小于液滴沉积行为的13%和大于3倍。最后，通过三相接触线处的力平衡，基于回缩速率对液滴达到最大铺展直径后的回缩动力学进行了分析和讨论。研究结果表明，介电润湿基底的表面润湿性和硅油膜的厚度显着影响水滴对硅油膜覆盖的固体基底的冲击动力学，特别是在回缩阶段。这项研究为控制液滴对硅油膜的动态影响提供了新的思路，这对于控制或优化底漆层上的喷墨印刷等工艺非常重要。