Droplet impact on vibrating superhydrophobic surfaces

Weisensee, Patricia B.; Ma, Jingcheng; Shin, Young Hwan; Tian, Junjiao; Chang, Yujin; King, William P.; Miljkovic, Nenad

doi:10.1103/physrevfluids.2.103601

Cited by 57 publications

(34 citation statements)

References 42 publications

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“…This dependence of contact time on the surface phase was recently reported on the drop impact on the vibrating superhydrophobic surface. 26 In their study, however, the contact time reduction was only observed at a moderate Weber number of We = 50-60 26 since their previous study showed that the contact time was only reduced above We = 40. 25 Our measurements, however, show that the contact time can be reduced at low Weber numbers, We = 20, with a clear dependence of the contact time on the surface phase.…”

Section: B Influence Of Surface Vibrating Frequencymentioning

confidence: 80%

“…This observation coincides with the recent result that the manipulation of the surface vibration occurs when the droplet is out of phase with the vibrating flexible surface. 26 The droplet force at the second impact was estimated to be F = 1 mN [ Fig. 5(b)], which is roughly 25% of the initial impact force.…”

Section: Subsequent Impact Of the Dropletmentioning

confidence: 99%

“…When the completion of the droplet spreading was coupled to the upward motion of the surface in 50 Hz < f s < 100 Hz, the elastic energy of the surface was transferred to the kinetic energy of the droplet. 25,26 As a result, the contact time was reduced by as much as 7% compared to the rigid superhydrophobic surface. Beyond f s = 100 Hz, the contact time gradually increased since less of the stored elastic energy of the surface was transferred to the droplet.…”

Section: B Influence Of Surface Vibrating Frequencymentioning

confidence: 99%

“…The impact force of the droplet, which scales as F ∼ ρU 0 2 πD 0 2 , 23 excites the flexible surface to vibrate at its first-mode natural frequency, f s = (1/2π) √ k s /m s . [24][25][26] Here, m s is the effective mass and k s is the flexural rigidity. During spreading, the initial kinetic energy of the droplet converts to the elastic energy of the flexible surface and the surface energy of the droplet.…”

Section: Introductionmentioning

confidence: 99%

“…In this scenario, the pancake-shaped droplet is lifted off from the surface, resulting in a contact time reduction and an enhanced restitution coefficient. [24][25][26] As the natural frequency of the surface increases further, f s > f d , the time of the maximum surface deflection is less than the maximum spreading time, U spr = D 0 /U 0 . The stored elastic energy of the surface returns to the droplet and participates in the droplet spreading dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of a flexible superhydrophobic surface during a drop impact

2018

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In this study, coupled dynamic responses of flexible superhydrophobic surfaces during a drop impact were investigated with position sensing and high-speed imaging. A smooth polydimethylsiloxane surface was spray coated with commercially available superhydrophobic paint particles. The influence of initial and subsequent impacts of a water droplet on the surface dynamics was studied at various natural frequencies of the surface (50 < f s < 230 Hz) and Weber numbers (2 < We < 90). We discovered that the flexible superhydrophobic surface was deflected twice during contact of the droplet by an impact force of the droplet as well as its reaction force during recoil. The magnitude of the droplet reaction force was estimated to be comparable to the droplet impact force. As the Weber number increased, however, the influence of the droplet reaction force on the surface displacement was attenuated because of the instability of the droplet rim. The contact time of the droplet and surface dynamics were found to be dependent on the phase of the surface. The contact time was reduced as much as 7% when a completion of the droplet spreading matched to the upward motion of the surface. One of the two local minima of the surface position observed during the contact of the droplet was diminished by matching the instance of the droplet reaction force to the downward motion of the surface. This study provides new insight into the effect of the droplet reaction force on dynamics of flexible superhydrophobic surfaces.

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Section: B Influence Of Surface Vibrating Frequencymentioning

confidence: 80%

Section: Subsequent Impact Of the Dropletmentioning

confidence: 99%

Section: B Influence Of Surface Vibrating Frequencymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamics of a flexible superhydrophobic surface during a drop impact

2018

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Control of Droplet Impact through Magnetic Actuation of Surface Microstructures

Jezeršek

Kriegl

Kravanja

et al. 2023

Adv Materials Inter

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An effective method for on‐demand control over the impact dynamics of droplets on a magnetoresponsive surface is reported. The surface is comprised of micrometer‐sized lamellas from a magnetoactive elastomer on a copper substrate. The surface itself is fabricated using laser micromachining. The orientation of the lamellae is switched from edge‐on (orthogonal to the surface) to face‐on (parallel to the surface) by changing the direction of a moderate (<250 mT) magnetic field. This simple actuation technique can significantly change the critical velocities of droplet rebound, deposition, and splashing. Rebound and deposition regimes can be switched up to Weber number We < 13 ± 3, while deposition and splashing can be switched in the range of 32 < We < 52. Because a permanent magnet is used, no permanent power supply is required for maintaining the particular regime of droplet impact. The presented technology is highly flexible and enables selective fabrication and actuation of microstructures on complex devices. It has great potential for applications in soft robotics, microfluidics, and advanced thermal management.

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Icephobic materials and strategies: From bio‐inspirations to smart systems

Li,

Liu,

Zhang

et al. 2024

Droplet

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Unwanted ice formations may cause severe functional degradations of facilities and also have a negative impact on their lifespans. Avoiding and removing ice accumulation is always a hot topic in the industrial and technological field. Bionic functional surfaces have been greatly studied for several decades and have proved to be excellent candidates for passive anti‐/deicing applications. However, the drawbacks limit their potential industrial uses under harsh conditions, like low temperatures and high humidity. Most researches on bionic surfaces are focused on a certain function of natural creatures and their underlined fundamental theories are revealed by taking the interface as the static. Actually, living organisms, either plants or animals, are often sensitive and responsive to their surroundings, avoiding risks and even self‐repairing upon damage. From this prospect, a novel view of the bionic icephobic materials has been proposed in the present review, which is expected to be studied and designed by taking the biological species as a system. As two representative icephobic materials, the anti‐/deicing theories of superhydrophobic and slippery surfaces are first discussed. Further, the recent progress of smart icephobic strategies is summarized from interfaces to substrates. We aim to provide new bionic insights on designing future icephobic strategies.

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Droplet impact on vibrating superhydrophobic surfaces

Cited by 57 publications

References 42 publications

Dynamics of a flexible superhydrophobic surface during a drop impact

Dynamics of a flexible superhydrophobic surface during a drop impact

Control of Droplet Impact through Magnetic Actuation of Surface Microstructures

Icephobic materials and strategies: From bio‐inspirations to smart systems

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