Patterson Colin J, Shiri Samira, Bird James C
Department of Mechanical Engineering, Boston University, Boston, MA, USA. General Electric, Aviation, Lynn, MA, USA.
J Phys Condens Matter. 2017 Feb 15;29(6):064007. doi: 10.1088/1361-648X/aa4e8a. Epub 2016 Dec 21.
Liquid drops can bounce when they impact non-wetting surfaces. Recently, studies have demonstrated that the time that the bouncing drop contacts a superhydrophobic surface can be reduced by incorporating ridged macrotextures on the surface. Yet the existing models aimed at explaining this phenomenon offer incompatible predictions of the contact time when a drop impacts multiple intersecting macrotextures, or spokes. Furthermore, it is unclear whether the effects of the macrotexture on the drop hydrodynamics extend to non-wetting surfaces in which direct contact is avoided by a thin vapor layer. Here we demonstrate that the phenomenon observed for macrotextured, superhydrophobic surfaces extends to macrotextured, wettable surfaces above the Leidenfrost temperature. We show that the number of droplets and overall residence time both depend on the number of intersecting spokes. Finally, we compare and contrast our results with mechanistic models to rationalize various elements of the phenomenon.
液滴撞击不浸润表面时会反弹。最近,研究表明,通过在表面引入脊状宏观纹理,可以减少弹跳液滴与超疏水表面接触的时间。然而,现有的旨在解释这一现象的模型,在液滴撞击多个相交宏观纹理或辐条时,对接触时间给出了相互矛盾的预测。此外,尚不清楚宏观纹理对液滴流体动力学的影响是否会延伸到通过薄蒸汽层避免直接接触的不浸润表面。在这里,我们证明,在宏观纹理化的超疏水表面上观察到的现象,会延伸到高于莱顿弗罗斯特温度的宏观纹理化的可浸润表面。我们表明,液滴数量和总停留时间都取决于相交辐条的数量。最后,我们将我们的结果与机理模型进行比较和对比,以阐明该现象的各种要素。