Droplet coalescence on water repellant surfaces

Soft Matter ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 154-160 ◽  
Author(s):  
Youngsuk Nam ◽  
Donghyun Seo ◽  
Choongyeop Lee ◽  
Seungwon Shin
Keyword(s):  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Droplet Coalescence

We report our hydrodynamic and energy analyses of droplet coalescence on water repellent surfaces including hydrophobic, superhydrophobic and oil-infused superhydrophobic surfaces.

scholarly journals Superhydrophobic surfaces

2012 ◽  
Vol 21 (1-2) ◽  
pp. 21-32 ◽  
Author(s):  
Ioannis Karapanagiotis ◽  
Panagiotis Manoudis
Keyword(s):  
Water Repellency ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Baxter Equation ◽  
Feature Article ◽  
Surface Protection ◽  
Recent Developments ◽  
Potential Applications ◽  
Nanoparticle Composites ◽  
Potential Use

AbstractSuperhydrophobicity – also known as water repellency – has recently attracted considerable attention because of its numerous potential applications. However, the fundamental concepts and equations describing the wettability of superhydrophobic surfaces have been known since the 1940s. These concepts are reviewed and discussed in the present feature article in light of the recent developments. Furthermore, the potential use of water-repellent siloxane-nanoparticle composites for surface protection and consolidation of stones and mortars used in outdoor objects of cultural heritage is investigated. Finally, it is shown that the wettability of the composite surfaces can be predicted by the Cassie-Baxter equation.

Three dimensional aspects of droplet coalescence during dropwise condensation on superhydrophobic surfaces

Soft Matter ◽  
2011 ◽  
Vol 7 (19) ◽  
pp. 8749 ◽  
Author(s):  
Konrad Rykaczewski ◽  
John Henry J. Scott ◽  
Sukumar Rajauria ◽  
Jeff Chinn ◽  
Amy M. Chinn ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Superhydrophobic Surfaces ◽  
Dropwise Condensation ◽  
Droplet Coalescence

HOT WATER-REPELLENT SUPERHYDROPHOBIC SURFACES WITH LONG-TERM STABILITY

2021 ◽  
Author(s):  
JI SEONG CHOI ◽  
SEONG MIN KANG
Keyword(s):  
Hot Water ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Water Droplets ◽  
Long Term Stability ◽  
Cassie State ◽  
Potential Applications ◽  
Different Temperatures ◽  
Temperature Water

In this paper, we fabricate and evaluate superhydrophobic surfaces with mushroom-shaped microstructures. Using a silicon master and polymer microstructure patterning, polydimethylsiloxane (PDMS) surfaces bearing mushroom-shaped structures with five different spacing ratios are prepared and tested with water droplets of different temperatures. The fabricated PDMS surfaces demonstrate superhydrophobicity even to high-temperature water droplets with decreased surface tension. We compare the experimental data with the theoretical results calculated based on the Cassie state and Eötvös rule. Our work suggests potential applications to control wettability with liquids of various temperatures.

“Dancing Droplets”: Partial Coalescence on Superhydrophobic Surfaces

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Xiao Yan ◽  
Lezhou Feng ◽  
Leicheng Zhang ◽  
Soumyadip Sett ◽  
Longnan Li ◽  
...  
Keyword(s):  
Capture Rate ◽  
Size Control ◽  
Superhydrophobic Surfaces ◽  
Droplet Coalescence ◽  
Satellite Droplet ◽  
Visualization System ◽  
Partial Coalescence ◽  
Primary Droplet ◽  
Moving Direction ◽  
Air Cushion

Abstract Droplet coalescence has received significant attention due to its significant role in fluid mixing, microfluidics, coalescence-induced droplet jumping, and heat and mass transfer applications. Coalescence of droplets has been extensively investigated from the perspectives of hydrodynamics and energy transfer. However, the study of coalescence characteristics of size-mismatched droplets on superhydrophobic surfaces remains a challenge due to visualization difficulty, limited droplet size control, and poor droplet manipulation. Here, in order to study coalescence dynamics of droplets with arbitrary initial sizes, a droplet dispensing and visualization system was developed. To control the size of droplets, monodispersed droplets with radii of ≈20 μm were dispensed using a frequency-controlled piezoelectric pulse injector onto a superhydrophobic surface, enabling the target droplets to accumulate in volume and grow in radii. The coalescence process of droplets having radii of ≈270 and ≈780 μm was imaged at a magnification of ≈25X and capture rate of 13000 fps. Surprisingly instead of completely merging together, the size-mismatched droplets underwent partial coalescence with the development of an additional satellite droplet. Specifically, the smaller droplet gave 'birth' to a secondary satellite droplet upon coalescence with the larger primary droplet due to liquid-bridge pinch-off dynamics, after which the satellite droplet bounced off upon collision with the primary droplet due to the presence of an air cushion that blocked contact between the two droplets. Meanwhile, the primary droplet continued to oscillate while the bouncing satellite droplet returned to the surface and eventually bounced off (moving direction is identified with arrows). Our work not only presents a powerful platform capable of both controlling and visualizing droplet coalescence hydrodynamics, but also provides insights into the flow hydrodynamics of droplets undergoing partial coalescence.

scholarly journals Water-repellent and corrosion-resistance properties of superhydrophobic and lubricant-infused super slippery surfaces

RSC Advances ◽  
2017 ◽  
Vol 7 (70) ◽  
pp. 44239-44246 ◽  
Author(s):  
Fan Song ◽  
Cuiqing Wu ◽  
Hailong Chen ◽  
Qi Liu ◽  
Jingyuan Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Superhydrophobic Surfaces ◽  
Az31 Magnesium Alloy ◽  
Water Repellent ◽  
Pitcher Plants ◽  
Lotus Leaves

Inspired by lotus leaves and pitcher plants, superhydrophobic surfaces and super slippery surfaces have been fabricated to improve the characteristics of AZ31 magnesium alloy surfaces.

Characterization of water-repellent and corrosion-resistant superhydrophobic surfaces on galvanized steel

2020 ◽  
Vol 17 (6) ◽  
pp. 1537-1548
Author(s):  
Thet Htet Naing ◽  
Vishnu Rachpech ◽  
Somjai Janudom ◽  
Narissara Mahathaninwong
Keyword(s):  
Superhydrophobic Surfaces ◽  
Galvanized Steel ◽  
Water Repellent ◽  
Corrosion Resistant

Fractal pattern mediated superhydrophobic glass and metallic surfaces using PTFE particles: a generalized simple approach

2019 ◽  
Vol 43 (21) ◽  
pp. 8075-8084 ◽  
Author(s):  
Nainsi Saxena ◽  
Santanu Paria
Keyword(s):  
Real Life ◽  
Microfluidic Devices ◽  
Simple Approach ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Metallic Surfaces ◽  
Water Separation ◽  
Fractal Pattern ◽  
Oil Water Separation ◽  
Oil Water

Superhydrophobic surfaces are practically important for several real-life applications such as self-cleaning, anti-corrosion and drag reducing surfaces, non-wetting cloths, oil–water separation, water-repellent surfaces and microfluidic devices, etc.

scholarly journals A Review of Recent Advances in Superhydrophobic Surfaces and Their Applications in Drag Reduction and Heat Transfer

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 44
Author(s):  
Yu Zhang ◽  
Zhentao Zhang ◽  
Junling Yang ◽  
Yunkai Yue ◽  
Huafu Zhang
Keyword(s):  
Heat Transfer ◽  
Drag Reduction ◽  
Industrial Applications ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Fluid Viscosity ◽  
Preparation Methods ◽  
Practical Applications ◽  
Heat Transfer Efficiency ◽  
Improve Heat Transfer

Inspired by the superhydrophobic properties of some plants and animals with special structures, such as self-cleaning, water repellent, and drag reduction, the research on the basic theory and practical applications of superhydrophobic surfaces is increasing. In this paper, the characteristics of superhydrophobic surfaces and the preparation methods of superhydrophobic surfaces are briefly reviewed. The mechanisms of drag reduction on superhydrophobic surfaces and the effects of parameters such as flow rate, fluid viscosity, wettability, and surface morphology on drag reduction are discussed, as well as the applications of superhydrophobic surfaces in boiling heat transfer and condensation heat transfer. Finally, the limitations of adapting superhydrophobic surfaces to industrial applications are discussed. The possibility of applying superhydrophobic surfaces to highly viscous fluids for heat transfer to reduce flow resistance and improve heat transfer efficiency is introduced as a topic for further research in the future.

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