Wetting Behaviours of a Single Droplet on Biomimetic Micro Structured Surfaces |
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Authors: | Y.Q.Zu Y.Y.Yan J.Q.Li Z.W.Han |
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Affiliation: | 1. Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK;2. Key Laboratory of Bionic Engineering (Ministry of Education, China), Jilin University, Changchun 130022, P. R. China |
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Abstract: | Natural surfaces with super hydrophobic properties often have micro or hierarchical structures.In this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness parameters are investigated.Atheoretical model is proposed to study wetting transitions.The results of theoretical analysis are compared with those of experimentindicating that the proposed model can effectively predict the wetting transition.Furthermore, a numerical simulationbased on the meso scale Lattice Boltzmann Method (LBM) is performed to study dynamic contact angles, contact lines, andlocal velocity fields for the case that a droplet displays on the micro structured surface.A spherical water droplet with rs= 15 μmfalls down to a biomimetic square-post patterned surface under the force of gravity with an initial velocity of 0.01 m·s-1 and aninitial vertical distance of 20 μm from droplet centre to the top of pots.In spite of a higher initial velocity, the droplet can stillstay in a Cassie state; moreover, it reaches an equilibrium state at t≈17.5 ms, when contact angle is 153.16° which is slightlylower than the prediction of Cassie-Baxter’s equation which gives θCB=154.40°. |
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Keywords: | biomimetic wetting behaviours roughness surfaces contact angle wetting transition |
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