论文标题

可取性和润湿性:界面张力如何影响液滴对薄膜的影响

Miscibility and wettability: how interfacial tension influences droplet impact onto thin wall films

论文作者

Bernard, R., Baumgartner, D., Brenn, G., Planchette, C., Weigand, B., Lamanna, G.

论文摘要

在实验中研究了在液滴撞击对薄壁膜上的混杂性和液体润湿性的影响。尽管液体特性和影响条件相似,但仍观察到溅起极限的差异,冠延长和上升阶段的持续时间。这些差异与液滴/壁膜液体对的界面张力有关,这与它们的可交解性和润湿性有关。更确切地说,通过计算冠表能量,我们表明在液滴和壁膜之间的界面中存储的能量(如果有的话)不可忽略不计,并且会导致较小的牙冠扩展,并且需要更多的动能才能引发溅出。同样,通过计算所有表面和界面张力的修改后的毛细血管时间,我们表明界面张力充当不可忽略的后退力,从而降低了上升阶段的持续时间。如果考虑到运动中液体的变化,则该上升阶段的动力学对于不同的壁膜厚度得到了很好的捕获。总体而言,液滴/壁膜相互作用可以看作是惯性毛细血管系统,在撞击过程中,液滴和壁膜之间的界面张力在能量的存储和皇冠动力学中起着重要作用。此外,该分析强调,粘性损失已经在冠延长阶段已经产生了显着效果,它通过消耗了几乎一半的初始能量,以使液滴撞击到薄壁膜上,并且很可能通过通过阻尼来影响毛细管时间尺度。

The influence of miscibility and liquid wettability during droplet impact onto thin wall films is investigated experimentally. Despite similar liquid properties and impact conditions, differences in the splashing limit, the crown extension and the duration of the ascending phase are observed. These differences are related to the interfacial tension of the droplet/wall-film liquid pairs, which is linked to their miscibility and wettability. More precisely, by calculating the crown surface energy, we show that the energy stored in the interface between droplet and wall-film (if any) is not negligible and leads to smaller crown extensions and the need of more kinetic energy to initiate splashing. Similarly, by calculating a modified capillary time taking into account all surface and interfacial tensions, we show that the interfacial tension acts as a non-negligible recoiling force, which reduces the duration of the ascending phase. The dynamics of this ascending phase is well captured for different wall-film thicknesses if accounting for the variations of the liquid masses in movement. Overall, droplet/wall-film interactions can be seen as inertio-capillary systems where the interfacial tension between droplet and wall film plays a significant role in the storage of energy and in the crown kinetics during the impact process. Besides, this analysis highlights that viscous losses have already a significant effect during the crown extension phase, by dissipating almost half of the initial energies for droplet impact onto thin wall films, and most likely by influencing the capillary time scale through damping.

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