Two-Pronged Jet Formation Caused by Droplet Impact on Anisotropic Superhydrophobic Surfaces

When a liquid droplet impacts a superhydrophobic surface with anisotropic surface patterning in the form of alternating ribs and cavities, the rebounding droplet may exhibit a unique two-pronged jet emission. Droplet impact experiments with 11 different fluids of viscosity that varied by more than three orders of magnitude were conducted, and this paper quantifies the Capillary number, Ca, and Ohnesorge number, Oh, ranges over which the two-pronged phenomenon occurs. For Oh > 0.0154, the behavior was never observed, while at lower values of Oh, the behavior occurs for an intermediate range of Ca that depends on Oh.

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Two-Pronged Jet Formation Caused by Droplet Impact on Anisotropic Superhydrophobic Surfaces

Volume 1B, Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Fundamental Issues and Perspectives in Fluid Mechanics ◽

10.1115/fedsm2013-16629 ◽

2013 ◽

Cited By ~ 1

Author(s):

John T. Pearson ◽

Daniel Maynes ◽

David Bilodeau ◽

Brent W. Webb

Keyword(s):

Superhydrophobic Surface ◽

Liquid Droplet ◽

Droplet Impact ◽

Surface Patterning ◽

Superhydrophobic Surfaces ◽

Ohnesorge Number ◽

Jet Formation ◽

Anisotropic Surface ◽

Impact Experiments ◽

Droplet Impacts

When a liquid droplet impacts a superhydrophobic surface with anisotropic surface patterning in the form of alternating ribs and cavities, the rebounding droplet may exhibit a unique two-pronged jet emission. Droplet impact experiments with eleven different fluids of viscosity that varied by more than three orders of magnitude were conducted, and this paper quantifies the Capillary number, Ca, and Ohnesorge number, Oh, ranges over which the two-pronged phenomenon occurs. For Oh > 0.0154, the behavior was never observed, while at lower values of Oh, the behavior occurs for an intermediate range of Ca that depends on Oh.

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Functional Superhydrophobic Surfaces with Spatially Programmable Adhesion

Polymers ◽

10.3390/polym12122968 ◽

2020 ◽

Vol 12 (12) ◽

pp. 2968

Author(s):

Duan-Yi Guo ◽

Cheng-Huan Li ◽

Li-Min Chang ◽

Hung-Chang Jau ◽

Wei-Chun Lo ◽

...

Keyword(s):

Superhydrophobic Surface ◽

Liquid Droplet ◽

Superhydrophobic Surfaces ◽

Patterned Surfaces ◽

Liquid Droplets ◽

Practical Applications ◽

Crystal Polymer ◽

Smart Surfaces ◽

Enhanced Raman Scattering ◽

Spatially Varying

A superhydrophobic surface that has controllable adhesion and is characterized by the lotus and petal effects is a powerful tool for the manipulation of liquid droplets. Such a surface has considerable potential in many domains, such as biomedicine, enhanced Raman scattering, and smart surfaces. There have been many attempts to fabricate superhydrophobic films; however, most of the fabricated films had uniform adhesion over their area. A patterned superhydrophobic surface with spatially controllable adhesion allows for increased functions in the context of droplet manipulation. In this study, we proposed a method based on liquid-crystal/polymer phase separation and local photopolymerization to realize a superhydrophobic surface with spatially varying adhesion. Materials and topographic structures were analyzed to understand their adhesion mechanisms. Two patterned surfaces with varying adhesion were fabricated from a superhydrophobic material to function as droplet guides and droplet collectors. Due to their easy fabrication and high functionality, superhydrophobic surfaces have high potential for being used in the fabrication of smart liquid-droplet-controlling surfaces for practical applications.

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Trapping a Hot Drop on a Superhydrophobic Surface with Rapid Condensation or Microtexture Melting

Micromachines ◽

10.3390/mi9110566 ◽

2018 ◽

Vol 9 (11) ◽

pp. 566 ◽

Cited By ~ 3

Author(s):

Samira Shiri ◽

Armela Murrizi ◽

James Bird

Keyword(s):

Critical Temperature ◽

Superhydrophobic Surface ◽

Water Drop ◽

Superhydrophobic Surfaces ◽

Temperature Threshold ◽

New Class ◽

Condensation Growth ◽

Thermal Fuse ◽

Impact Experiments ◽

Insight Into

A water drop can bounce upon impacting a superhydrophobic surface. However, on certain superhydrophobic surfaces, a water drop will stick rather than bounce if it is sufficiently hot. Here, we aim to better understand the mechanisms that can lead to this bouncing-sticking transition. Specifically, we model two potential mechanisms in which a superhydrophobic surface could trap a sufficiently hot drop within milliseconds: melting of microtextured wax and condensation of the vapor within the superhydrophobic texture. We then test these mechanisms through systematic drop impact experiments in which we independently vary the substrate and drop temperatures on a waxy superhydrophobic Nasturtium leaf. We find that, whenever the surface or the drop is above a microtexture-melting temperature, the drop sticks. Below this temperature, a critical temperature threshold for bouncing can be predicted and controlled by considering the relative timescales between condensation growth and drop residence time. We envision that these results can provide insight into the design of a new class of superhydrophobic surfaces to act as a rapid thermal fuse to prevent drops that exceed a critical temperature from bouncing onto a thermally sensitive target.

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Dynamic Impact Behavior of Water Droplet on a Superhydrophobic Surface in the Presence of Stagnation Flow

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.232.267 ◽

2012 ◽

Vol 232 ◽

pp. 267-272 ◽

Cited By ~ 4

Author(s):

Morteza Mohammadi ◽

Sara Moghtadernejad ◽

Percival J. Graham ◽

Ali Dolatabadi

Keyword(s):

Water Droplet ◽

Weber Number ◽

Contact Time ◽

Superhydrophobic Surface ◽

Superhydrophobic Surfaces ◽

Impact Behavior ◽

Stagnation Flow ◽

Dynamic Impact ◽

Air Flow Velocity ◽

Impact Experiments

The following study investigates splashing of impinging water droplets on superhydrophobic surfaces with and without the presence of a stagnation flow. Droplets were accelerated by either gravity or gravity and co-flow. By changing the height and the air flow velocity different combinations of stagnation flow and droplet velocity were created. The spreading diameter, spreading velocity and contact time were studied for different air and droplet speeds. It was clearly observed that for a fixed impact velocity (i.e. constant Weber number), the presence of the stagnation flow promotes splashing and formation of satellite droplets. Consequently, for the co-flow droplet impact experiments, the mass of the recoiled droplet is significantly smaller than that of the impinging droplet in still air.

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Fabrication of Superhydrophobic Surface by Modulating Morphology of the Organogel

Soft Matter ◽

10.1039/d0sm02182b ◽

2021 ◽

Author(s):

Jianchen Zhu ◽

Tian ren Zhang ◽

Yajie Liu ◽

Daoyi Lu ◽

Peng Zhang ◽

...

Keyword(s):

Molecular Weight ◽

Superhydrophobic Surface ◽

Superhydrophobic Surfaces ◽

Low Molecular Weight

A kind of low-molecular weight organic gelator (LMOG) bearing hydrazine linkage and end-capped by alkoxy-substituted phenyl, namely 1, 4-bis[(3, 4-bisoctyloxyphenyl)hydrozide]phenylene (BPH-8), was used to facilely fabricate superhydrophobic surfaces by drop-casting...

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Ferromagnetic Liquid Droplet on a Superhydrophobic Surface for the Transduction of Mechanical Energy to Electricity Based on Electromagnetic Induction

ACS Nano ◽

10.1021/acsnano.1c03539 ◽

2021 ◽

Author(s):

Zheng Ma ◽

Qi Wang ◽

Jingwei Ai ◽

Bin Su

Keyword(s):

Superhydrophobic Surface ◽

Electromagnetic Induction ◽

Liquid Droplet ◽

Mechanical Energy

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Stretchable dual cross-linked silicon elastomer with superhydrophobic surface and fast triple self-healing ability at room temperature

Soft Matter ◽

10.1039/d0sm02175j ◽

2021 ◽

Author(s):

Yuxing Shan ◽

shuai liang ◽

Xiangkai Mao ◽

Jie Lu ◽

Lili Liu ◽

...

Keyword(s):

Superhydrophobic Surface ◽

Room Temperature ◽

Superhydrophobic Surfaces ◽

Self Healing ◽

Wearable Electronics ◽

Actual Application ◽

Potential Applications

Abstract. Stretchable elastomers with superhydrophobic surfaces have potential applications in wearable electronics. However, various types of damage inevitably occur on these elastomers in actual application, resulting in deterioration of the...

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