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Phase Diagram of Impacting Nanodroplets on Mesh Surfaces

Qiang Ma^1,2,3, Tuan Tran^2,*, Xiaodong Wang^1,*

1 Research Center of Engineering Thermophysics, North China Electric Power University, Beijing,102206, China
2 School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
3 Department of Architectural Engineering, Ordos Vocational College, Ordos, 017000, China

* Corresponding Authors: Tuan Tran; Xiaodong Wang. Email: ;

The International Conference on Computational & Experimental Engineering and Sciences 2024, 29(4), 1-2. https://doi.org/10.32604/icces.2024.011051

Abstract

Controlling dynamics of impacting droplets on meshes is significantly important, which attracted a lot of attention because of its great potential applications in liquid separation, self-cleaning, and water harvesting [1-3], yet the underlying physical mechanisms are not entirely revealed. Here, the impact dynamics of a nanodroplet on mesh surfaces with different wettability are studied through molecular dynamics (MD) simulations. Due to scale effects between the nano and macroscale, the impacting nanodroplets exhibit some unique dynamic characteristics [4-7]. On a superhydrophobic mesh surface, when varying the impact conditions of nanodroplets, different outcomes can occur: (i) at a small impact We, the nanodroplet is entirely captured by the mesh; (ii) increase We, part of droplets penetrate through the mesh without breaking up; (iii) above a threshold We, some satellite droplets are ejected below the surface. Based on the impacting outcomes, a phase diagram is established in the parameter space of We against the surface structure dimension. The effect of wettability on penetration is validated in a wide range of static contact angles from hydrophilic to superhydrophobic surfaces. Finally, in the phase diagram, the boundaries of different outcomes are analyzed. It is found that the existing models are not suitable here due to the enhanced viscous effect of impacting nanodroplets[8]. A theoretical model is developed to propose critical conditions for the penetration with break out, which agree well with the boundary in the phase diagram. The findings in this work provide rational design principles for regulating the controllable penetration on mesh surfaces in a wide range of applications.

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