The Maximum Spreading Factor for Polymer Nanodroplets Impacting a Hydrophobic Solid Surface

2019 ◽  
Author(s):  
Yi-Bo Wang ◽  
Xiao-Dong Wang ◽  
Yan-Ru Yang ◽  
Min Chen
Keyword(s):  
Solid Surface ◽  
Spreading Factor ◽  
Maximum Spreading

scholarly journals The effects of surface tension on the spreading ratio during the impact of multiple droplets onto a hot solid surface

2018 ◽  
Vol 197 ◽  
pp. 08016
Author(s):  
Rafil Arizona ◽  
Teguh Wibowo ◽  
Indarto Indarto ◽  
Deendarlianto Deendarlianto
Keyword(s):  
Surface Tension ◽  
Ethylene Glycol ◽  
Solid Surface ◽  
High Speed ◽  
Frame Rate ◽  
Stainless Steel Surface ◽  
Droplet Spreading ◽  
Secondary Droplets ◽  
The Impact ◽  
Maximum Spreading

The impact between multiple droplets onto hot surface is an important process in a spray cooling. The present study was conducted to investigate the dynamics of multiple droplet impact under various surface tensions. Here, the ethylene glycol with compositions of 0%, 5%, and 15% was injected through a nozzle onto stainless steel surface as the multiple droplet. The solid surface was heated at the temperatures of 100 °C, 150 °C, and 200 °C. To observe the dynamics of multiple droplets, a high speed camera with the frame rate of 2000 fps was used. A technique of image processing was developed to determine the maximum droplet spreading ratio. As the result, the surface tension contributes significantly to maximum spreading ratio. As the droplet surface tension decreases, the maximum spreading ratio increases. The maximum spreading ratio appears when the percentage of the ethylene glycol is 15% at the temperature of 150°C. From the visual observation, it is shown that a slower emergence of secondary droplets (droplet splashing) is carried out under a lower surface tension. Hence, surface tension plays an important role on the behavior of emerging secondary droplets. Furthermore, results of the experiments are useful for the validation of available previous CFD models.

scholarly journals Droplet Impact on the Super-Hydrophobic Surface with Micro-Pillar Arrays Fabricated by Hybrid Laser Ablation and Silanization Process

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 765 ◽  
Author(s):  
Zhenyan Xia ◽  
Yuhe Xiao ◽  
Zhen Yang ◽  
Linan Li ◽  
Shibin Wang ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Hydrophobic Surface ◽  
Solid Surfaces ◽  
Geometrical Parameters ◽  
Generation Process ◽  
Sliding Angle ◽  
Spreading Factor ◽  
Pillar Arrays ◽  
Surface Morphologies ◽  
Maximum Spreading

A super-hydrophobic aluminum alloy surface with decorated pillar arrays was obtained by hybrid laser ablation and further silanization process. The as-prepared surface showed a high apparent contact angle of 158.2 ± 2.0° and low sliding angle of 3 ± 1°. Surface morphologies and surface chemistry were explored to obtain insights into the generation process of super-hydrophobicity. The main objective of this current work is to investigate the maximum spreading factor of water droplets impacting on the pillar-patterned super-hydrophobic surface based on the energy conservation concept. Although many previous studies have investigated the droplet impacting behavior on flat solid surfaces, the empirical models were proposed based on a few parameters including the Reynolds number (Re), Weber number (We), as well as the Ohnesorge number (Oh). This resulted in limitations for the super-hydrophobic surfaces due to the ignorance of the geometrical parameters of the pillars and viscous energy dissipation for liquid flow within the pillar arrays. In this paper, the maximum spreading factor was deduced from the perspective of energy balance, and the predicted results were in good agreement with our experimental results with a mean error of 4.99% and standard deviation of 0.10.

scholarly journals Study of the effect of surface wettability on droplet impact on spherical surfaces

2020 ◽  
Vol 15 (3) ◽  
pp. 414-420 ◽  
Author(s):  
Xiaohua Liu ◽  
Kaimin Wang ◽  
Yaqin Fang ◽  
R J Goldstein ◽  
Shengqiang Shen
Keyword(s):  
Contact Angle ◽  
Impact Velocity ◽  
Droplet Impact ◽  
Surface Wettability ◽  
Spreading Factor ◽  
Curvature Ratio ◽  
Spherical Surfaces ◽  
The Impact ◽  
Maximum Spreading ◽  
Effect Of Surface

Abstract The effect of surface wettability on droplet impact on spherical surfaces is studied with the CLSVOF method. When the impact velocity is constant, with the increase in the contact angle (CA), the maximum spreading factor and time needed to reach the maximum spreading factor (tmax) both decrease; the liquid film is more prone to breakup and rebound. When CA is constant, with the impact velocity increasing, the maximum spreading factor increases while tmax decreases. With the curvature ratio increasing, the maximum spreading factor increases when CA is between 30 and 150°, while it decreases when CA ranges from 0 to 30°.

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