Numerical Simulation of Droplet Infiltration of Micro-nano Structure in Nepenthes Slippery Zone

doi:10.3901/JME.2022.03.203

Abstract

Abstract: The Nepenthes slippery zone depends on its micro-nano structure to appear superhydrophobic wettability, which provides a biomimetic prototype for the development of superhydrophobic surface. However, the mechanism of superhydrophobic wettability has not been fully revealed, because the infiltration degree of liquid droplets to micro-nano structure of Nepenthes slippery zone has not been accurately acquired via the existing technology. The structure model of Nepenthes slippery zone (lunate cell, waxy crystal) is constructed, the structure model is meshed and the force analysis of ultrapure-water droplet is carried out. Based on the minimal energy principle, the infiltration process of ultrapure-water droplet to the Nepenthes slippery zone is numerically simulated with the Surface Evolver software, and the morphology of ultrapure-water droplet under different infiltration degree was obtained. According to the Young-Lapalace equation fitting method, theoretical contact angle of ultrapure-water droplets on the Nepenthes slippery zone was obtained, which has the values of 155.0°~155.4° under the infiltration ratio of 0.7~0.8. To verify the validity of the numerical simulation model, the contact angle of ultrapure-water droplet is measured with the optical contact angle measuring system, showing the value of 155.1°±1.3°, n=20. This contact angle is highly consistent with the theoretical contact angle obtained from the numerical simulation, indicating the infiltration ratio of ultrapure-water droplet to the Nepenthes slippery zone is 0.7~0.8. Our obtained results provide a potential method for quantitative characterization of infiltration degree produced by liquid droplet to micro-nano structure of superhydrophobic surface, and supply theoretical foundation for fully revealing the superhydrophobic mechanism of Nepenthes slippery zone, which can promote the Nepenthes slippery zone to become a biomimetic prototype used to design superhydrophobic materials.

Key words: bionic engineering, superhydrophobic surface, Nepenthes slippery zone, contact angle, numerical simulation

CLC Number:

TB17

WANG Lixin, ZHANG Shuoyan, YAN Shixing, DONG Shiyun. Numerical Simulation of Droplet Infiltration of Micro-nano Structure in Nepenthes Slippery Zone[J]. Journal of Mechanical Engineering, 2022, 58(3): 203-212.

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