Time-Dependent Wetting Scenarios of a Water Droplet on Surface-Energy-Controlled Microcavity Structures with Functional Nanocoatings

2020 ◽  
Vol 12 (35) ◽  
pp. 39881-39891
Author(s):  
Prashant Pendyala ◽  
Hong Nam Kim ◽  
Yong-Sang Ryu ◽  
Eui-Sung Yoon
Keyword(s):  
Surface Energy ◽  
Water Droplet ◽  
Time Dependent

scholarly journals Study on contact angles and surface energy of MXene films

RSC Advances ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 5512-5520
Author(s):  
Hang Zhou ◽  
Fuqiang Wang ◽  
Yuwei Wang ◽  
Changping Li ◽  
Changrui Shi ◽  
...  
Keyword(s):  
Surface Energy ◽  
Contact Angles ◽  
Time Dependent ◽  
Wetting Behaviors

This work sheds light on the process- and time-dependent wetting behaviors and surface energy of MXene films.

Laser Beam-Hygroscopic Aerosol Interactions

1977 ◽  
Vol 99 (2) ◽  
pp. 281-286 ◽  
Author(s):  
G. E. Caledonia ◽  
J. D. Teare
Keyword(s):  
Steady State ◽  
Laser Beam ◽  
Water Droplet ◽  
Atmospheric Aerosol ◽  
Phase Shifts ◽  
Time Dependent ◽  
Small Water ◽  
Steady State Solutions

A model for the prediction of the temperature and vapor fields created about a small water droplet undergoing irradiation by a laser beam has been developed. Time-dependent and steady-state solutions of the model are discussed. Estimates of characteristic phase shifts to be expected in propagating through standard atmospheric aerosol distributions are also presented. While the model is quite general, the calculations are limited to DF laser wavelengths.

Conversion of Surface Energy and Experimental Investigation on the Self-Motion Behaviors of Liquid Droplets on Gradient Surfaces

2011 ◽  
Vol 687 ◽  
pp. 596-601
Author(s):  
Chang Song Liu ◽  
Ji Gen Zhou ◽  
Dong Mei Zheng ◽  
Yong Wan ◽  
Zhi Wen Li
Keyword(s):  
Surface Energy ◽  
Potential Energy ◽  
Interfacial Energy ◽  
Water Droplet ◽  
Gravitational Potential Energy ◽  
Horizontal Gradient ◽  
Liquid Droplets ◽  
Droplet Motion ◽  
Gradient Surfaces ◽  
Self Motion

A surface with surface energy gradient was fabricated by using a controlled photodegradation technique of a fluoroalkylsilane self-assembled monolayer (SAM) using irradiation of vacuum ultraviolet light (wavelength=172 nm). Visualization experiments were carried out to investigate the motion behaviors of water droplets on horizontal gradient surfaces. System free energy conversion was analyzed to understand the mechanics of the droplet self-motion. The results show that the liquid droplets were self-propelled to move from hydrophobic region to hydrophilic region on horizontal gradient surfaces. The motion process of the water droplet experienced an accelerating stage and a decelerating stage. The velocity of 2 mL water droplet reached to a maximum of 23.28 mm/s. In the droplet motion on the horizontal gradient surface, the deformation and spread of the droplet continuously release out the interfacial and gravitational potential energy, which offers the kinetic energy for the droplet motion. However, the released interfacial energy is three orders of magnitude larger than the released gravitational potential energy. Thus, the released interfacial energy is the main source of driven energy for the droplet motion. The theoretical analysis is consistent with the experimental results.

scholarly journals Time-dependent solutions for daily-periodic slope flows driven by surface energy budget

2021 ◽  
Author(s):  
Mattia Marchio ◽  
Sofia Farina ◽  
Dino Zardi
Keyword(s):  
Heat Flux ◽  
Surface Energy ◽  
Surface Temperature ◽  
Wind Velocity ◽  
Analytical Model ◽  
Slope Angle ◽  
Time Dependent ◽  
Fourier Series Expansion ◽  
Ambient Atmosphere ◽  
Slope Wind

<p>Diurnal wind systems generated from daytime heating and nighttime cooling of valleys and slopes are a very common feature over mountainous terrains. Despite their frequent occurrence and relevance for a variety of applications, ranging from pollutant transport to convection initiation, slope winds are far from being fully understood and still provide an open research topic.</p><p>A well-known steady-state analytical model <span>is the one</span> developed by Prandtl (1942). Then, a first time-dependent analytical model was proposed by F. Defant (1949) and later extended by Zardi and Serafin (2015). These models provide slope-normal profiles of temperature and along-slope wind velocity as a response to a sinusoidal forcing representing the surface temperature. The resulting profiles exhibit sinusoidal oscillations at every distance from the surface, although with different phase lags under different regimes, determined by different combinations of slope angle and stability of the unperturbed ambient atmosphere. As a consequence, they can not explain the observed differences between daytime upslope and nighttime downslope winds in terms of magnitude and height of the peak of wind velocity, as well as the different timing characterising nighttime, daytime, and the two reversal phases.</p><p>In the present work, the solutions derived in Zardi and Serafin (2015) are extended to include a more realistic daily-periodic surface forcing taking into account the daily evolution of the surface temperature computed on the basis of a surface energy <span>budget</span>. Incoming solar radiation is represented by means of a Fourier series expansion derived from well-established relationships taking into account latitude, day of the year, slope angle, exposition and other astronomical and atmospheric factors. Based on <span>these</span> expansions, suitable harmonic solutions are derived for the heat flux into the ground and sensible heat flux in the atmosphere, and hence for the daily evolution of slope-normal profiles of along-slope wind velocity and potential temperature.</p><p>References:</p><ul><li><span>Prandtl L. 1942. Führer durch die Strömungslehre, Chapter 5. Vieweg und Sohn: Braunschweig, Germany. </span>[English translation: Prandtl L. 1952. Mountain and valley winds in stratified air, in Essentials of Fluid Dynamics: 422–425. Hafner Publishing Company: New York, NY]</li> <li><span>Defant F. 1949. Zur Theorie der Hangwinde, nebst Bemerkungen zur Theorie der Berg- und Talwinde. </span>Arch. Meteorol. Geophys. Bioklimatol. A 1: 421–450</li> <li>Zardi D., Serafin S. 2015. An analytic solution for time‐periodic thermally driven slope flows. Q. J. R. Meteorol. Soc., 141, 1968–1974, https://doi.org/10.1002/qj.2485</li> </ul>

Fabrication of Surface Energy Gradients Using Self-Assembled Monolayer Surfaces Prepared by Photodegradation

2011 ◽  
Vol 688 ◽  
pp. 102-106 ◽  
Author(s):  
Chang Song Liu ◽  
Dong Mei Zheng ◽  
Ji Gen Zhou ◽  
Yong Wan ◽  
Zhi Wen Li
Keyword(s):  
Surface Energy ◽  
Water Droplet ◽  
Chemical Vapor ◽  
Self Assembled Monolayers ◽  
Self Assembled Monolayer ◽  
Si Substrates ◽  
Energy Gradient ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
A New Technique

A new technique, direct photodegradation of self-assembled monolayers (SAM), to obtain surface energy gradients on Si substrates was demonstrated. The gradient surface, with hydrophobic to hydrophilic gradients, was prepared by two steps: Firstly, a homogeneous fluoroalkylsilane SAM film was deposited by a chemical vapor deposition on a Si substrate. Secondly, a controlled photodegradation technique was directly applied to the homogeneous FAS-SAM surface. The surface energy gradient was then obtained due to the different intensity of photoirradiation in the different positions along the photodegraded path on the SAM surfaces. The resulting surface displayed a gradient of wettability (with the contact angle of water changing from 55° to 18°) over a distance of 4.2 mm. The water droplet was driven by surface energy gradient and spontaneously moved from the hydrophobic to hydrophilic surface. During the moving process, the water droplet accelerated firstly and then decelerated. The peak velocity was about 23.3 mm/s. The velocity is dependent on the gradient of the surface energy.

Investigation of time dependent water droplet dynamics on porous fuel cell material via synchrotron based X-ray imaging technique

2018 ◽  
Vol 97 ◽  
pp. 237-245 ◽  
Author(s):  
Paria Rahimian ◽  
Logan Battrell ◽  
Ryan Anderson ◽  
Ning Zhu ◽  
Erick Johnson ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Water Droplet ◽  
Imaging Technique ◽  
Time Dependent ◽  
Droplet Dynamics ◽  
X Ray ◽  
Cell Material ◽  
X Ray Imaging
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