Here, we study the water penetration dynamics through a Janus membrane with opposite wettability, i.e., (super-) hydrophobic on one side and (super-) hydrophilic on the other side, during drop impact. It is demonstrated that the penetration dynamics through the membrane consists of two temporally distinct events: dynamic pressure driven penetration dynamics on a shorter timescale and capillary pressure driven penetration dynamics on a longer timescale. For penetration under dynamic pressure, the threshold velocity for the penetration is dependent on the wettability of the impact side, such that a smaller impact velocity is required for water penetration when a water drop is impinged onto the superhydrophobic side over the superhydrophilic side. We demonstrate that this difference in the penetration dynamics upon drop impact can still be accounted for by the balance between the dynamic pressure and the capillarity pressure after adjusting the relative magnitude of the two contrasting pressures required for the penetration. Meanwhile, it is demonstrated that the penetration dynamics under capillary pressure is governed by the balance between the capillary pressure and the viscous pressure while the penetration mainly proceeds through the penetration area, which is formed during short-time penetration, showing the dynamic coupling between the two penetration dynamics. By elucidating the penetration dynamics on a Janus membrane, we believe that our results can help in designing Janus membranes for various fluidic applications such as oil–water separation, aeration, and water harvesting.

中文翻译：

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跌落冲击过程中通过Janus网格的水渗透动力学。

在这里，我们研究了具有相反润湿性的通过Janus膜的水渗透动力学，即在跌落冲击过程中，一侧的（超）疏水性，另一侧的（超）亲水性。结果表明，穿过膜的渗透动力学由两个时间上不同的事件组成：动态压力驱动的渗透动力学在较短的时间尺度上和毛细管压力驱动的渗透动力学在较长的时间尺度上。对于在动态压力下的渗透，渗透的阈值速度取决于冲击面的润湿性，使得当水滴被撞击到超亲水面上的超疏水面上时，水渗透所需的冲击速度较小。我们证明，在调节击穿所需的两个对比压力的相对大小之后，在跌落冲击时击穿动力学的这种差异仍可通过动压力和毛细压力之间的平衡来解决。同时，证明了在毛细管压力下的渗透动力学受毛细管压力和粘性压力之间的平衡支配，而渗透主要通过短时间渗透过程中形成的渗透区域进行，这表明了渗透之间的动态耦合。两种渗透动力学。通过阐明Janus膜的渗透动力学，我们相信我们的结果可以帮助设计Janus膜以用于各种流体应用，例如油水分离，曝气和集水。