Theoretical analysis on the effect of liquid droplet geometry on contact angle

2005 ◽  
Vol 235 (10-12) ◽  
pp. 1293-1301 ◽  
Author(s):  
S. Vafaei ◽  
M.Z. Podowski
Keyword(s):  
Contact Angle ◽  
Theoretical Analysis ◽  
Liquid Droplet

scholarly journals Molecular Dynamics Simulation of Wetting Behavior: Contact Angle Dependency on Water Potential Models

2021 ◽  
Vol 1 (1) ◽  
pp. 10
Author(s):  
Lukman Hakim ◽  
Irsandi Dwi Oka Kurniawan ◽  
Ellya Indahyanti ◽  
Irwansyah Putra Pradana
Keyword(s):  
Molecular Dynamics ◽  
Contact Angle ◽  
Liquid Droplet ◽  
Center Of Mass ◽  
Contact Angles ◽  
Surface Wettability ◽  
Dynamics Simulation ◽  
Potential Models ◽  
Surface Hydrophilicity ◽  
Dynamics Simulations

The underlying principle of surface wettability has obtained great attentions for the development of novel functional surfaces. Molecular dynamics simulations has been widely utilized to obtain molecular-level details of surface wettability that is commonly quantified in term of contact angle of a liquid droplet on the surface. In this work, the sensitivity of contact angle calculation at various degrees of surface hydrophilicity to the adopted potential models of water: SPC/E, TIP4P, and TIP5P, is investigated. The simulation cell consists of a water droplet on a structureless surface whose hydrophilicity is modified by introducing a scaling factor to the water-surface interaction parameter. The simulation shows that the differences in contact angle described by the potential models are systematic and become more visible with the increase of the surface hydrophilicity. An alternative method to compute a contact angle based on the height of center-of-mass of the droplet is also evaluated, and the resulting contact angles are generally larger than those determined from the liquid-gas interfacial line.

Determining Micro Droplet Profile Using Internal Reflection Interference Fringes

2020 ◽  
Author(s):  
Iltai Isaac Kim ◽  
Yang Li ◽  
Jaesung Park
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Surface Profile ◽  
Morphological Features ◽  
Internal Reflection ◽  
Sessile Droplet ◽  
Spherical Droplet ◽  
Interference Fringes ◽  
The One ◽  
Air Liquid Interface

Abstract We introduce an optical diagnostics to determine the morphological features of liquid droplet such as the thickness, the contact angle, and the dual profile using internal reflection interferometry. A coherent laser beam is internally reflected on the air/liquid interface of a sessile droplet placed on a prism-based substrate to produce an interference fringe on a screen far from the substrate. The reflected laser rays consist of the reflection from the center spherical droplet profile and the one from the lower hyperbola-like droplet profile. The reflected rays are interfered each other to form the interference fringes. Ray tracing simulation is conducted using a custom-designed computer program. The simulation shows that the interfering rays reflected near the inflection point produce the outer-most fringes of the concentric interference pattern on the screen, and the reflected rays from the apex of the spherical profile and the contact line of the lower hyperbola-like profile construct the fringes at the center of the interference patterns. The simulated results are compared with the experimental observation to show a good agreement in the number and the location of the fringes and the radius of the outer-most-fringe where the number of the fringes is dependent on the droplet thickness and the radius of the fringe depends on the contact angle of the droplet. This result provides a new measurement technique to determine the morphological features of very small microdroplet such as the thickness (< a few micron thickness), the contact angle (< a few degree), and the dual-surface profile.

Switching Time of Electrowetting-Based Devices

2009 ◽  
Author(s):  
Jiwoo Hong ◽  
Jung Min Oh ◽  
Kwan Hyoung Kang
Keyword(s):  
Theoretical Analysis ◽  
Theoretical Prediction ◽  
Switching Time ◽  
Liquid Droplet ◽  
Volume Density ◽  
Drop Volume ◽  
Rf Switches ◽  
Domain Perturbation ◽  
Fast Spreading ◽  
Electronic Display

The switching time is important factor for enhancing performance of electrowetting-based devices, such as electronic display, liquid lens, and RF switches. These devices require fast spreading, receding time of droplet. In this work, we suggested an analytical method to predict the switching time. We considered the case of a liquid droplet on an insulator-coated electrode surrounded by air. The properties of droplet such as volume, density, viscosity, and interfacial tension affects the switching time. First we explored the influence of drop volume on switching time. To predict the switching time, the dynamics of a droplet are modeled by using the domain perturbation method. It is shown that the overall dynamics is governed by P2 shape mode. Based on theoretical analysis, we introduced a parameter which represents the switching time. We compared the theoretical prediction with experimental results, and then discussed the effect of contact-line hysteresis.

scholarly journals Slippery surface based on lubricant infused hierarchical silicon nanowire film

RSC Advances ◽  
2017 ◽  
Vol 7 (88) ◽  
pp. 55812-55818 ◽  
Author(s):  
Tian Hang ◽  
Hui-Jiuan Chen ◽  
Chengduan Yang ◽  
Shuai Xiao ◽  
Guishi Liu ◽  
...  
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Silicon Nanowire ◽  
Repellent Property ◽  
Si Nanowire ◽  
Slippery Surface

Slippery surface based on lubricant infused hierarchical Si nanowire films was developed, which provided low contact angle with liquid droplet, while possessing liquid repellent property upon slight tilting.

Ring-Shaped Sessile Droplet

2011 ◽  
Author(s):  
Svyatoslav S. Chugunov ◽  
Douglas L. Schulz ◽  
Iskander S. Akhatov
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Liquid Structure ◽  
Solid Substrate ◽  
Contact Angles ◽  
Equilibrium Contact Angle ◽  
Sessile Droplet ◽  
System Equilibrium ◽  
Energy Consideration ◽  
External Forces

It is recognized that small liquid droplet placed on the solid substrate forms equilibrium contact angle that can be obtained from well-known Young’s law. Previously, deviations from Young’s law were demonstrated for the droplets exposed to external fields (gravity, electric, etc) and for the droplets on non-homogeneous substrates. This work reveals that the Young’s equilibrium contact angle can be altered by geometrical reasons only. We consider a ring-shaped droplet on a solid substrate as a test structure for our discussion. We use the global energy consideration for analysis of system equilibrium for the case of freely deposited liquid with no external forces applied. The theoretical analysis shows that steady ring-shaped liquid structure on a solid substrate does exist with contact angles on both contact lines to be different from the Young’s equilibrium contact angle.

Wettability Analysis of Orthopaedic Materials Using Optical Contact Angle Methods

2006 ◽  
Vol 309-311 ◽  
pp. 1199-1202 ◽  
Author(s):  
Abraham Salehi ◽  
Stanley Tsai ◽  
Vivek Pawar ◽  
Jeff Sprague ◽  
Gordon Hunter ◽  
...  
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Sample Surface ◽  
Contact Angles ◽  
Radius Of Curvature ◽  
Oxide Ceramic ◽  
Optical Contact ◽  
Dlc Coating ◽  
Femoral Heads ◽  
Bearing Materials

The wettability behavior of orthopaedic materials influences the fluid film layer that affects both the friction and wear of the articulating surfaces in total joint arthroplasty. This study examined the wettability of various orthopaedic bearing materials such as alumina, zirconia, cobalt chrome (CoCr), and oxidized zirconium (OxZr). Diamond-like carbon (DLC) coating on CoCr was also examined. Additionally, the effect of radius of curvature was examined using OxZr femoral heads of various diameters. The contact angle of the liquid droplet on the surface of the material was measured using a optical contact angle method. Both water and bovine serum with 20 g/L protein concentration were used during testing, with a droplet size of 0.25 -L. The droplet was dispensed from an automated syringe and brought into contact with the sample surface. The contact angle was then measured by fitting polynomial curves to the sample surface and drop geometry. Ten individual drops were analyzed on each test component, with at least three test components for each material. There were no differences in contact angles with changing head size or when using serum compared to water. The alumina, OxZr, and zirconia femoral heads all exhibited a similar contact angle, while CoCr and DLC showed significantly greater contact angles. The smaller contact angles for the oxide ceramic surfaces indicate that they tend to be more wettable than the metals, which may help explain their lower friction and superior adhesive wear performance.

Wetting Criteria of Intrinsic Contact Angle To Distinguish between Hydrophilic and Hydrophobic Micro-/Nanotextured Surfaces: Experimental and Theoretical Analysis with Synchrotron X-ray Imaging

Langmuir ◽  
2019 ◽  
Vol 35 (10) ◽  
pp. 3607-3614 ◽  
Author(s):  
Dong In Yu ◽  
Ho Jae Kwak ◽  
Chulmin Park ◽  
Chiwoong CHOI ◽  
Narayan Pandurang Sapkal ◽  
...  
Keyword(s):  
Contact Angle ◽  
Theoretical Analysis ◽  
X Ray ◽  
X Ray Imaging ◽  
Intrinsic Contact Angle

Ratchet mechanism of drops climbing a vibrated oblique plate

2017 ◽  
Vol 835 ◽  
Author(s):  
Hang Ding ◽  
Xi Zhu ◽  
Peng Gao ◽  
Xi-Yun Lu
Keyword(s):  
Contact Angle ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Contact Angle Hysteresis ◽  
Three Dimensional ◽  
Direct Numerical Simulations ◽  
Ratchet Mechanism ◽  
Wetted Area ◽  
First Time ◽  
Good Agreement

In this paper, we investigate the ratchet mechanism of drops climbing a vibrated oblique plate based on three-dimensional direct numerical simulations, which for the first time reproduce the existing experiment (Brunet et al., Phys. Rev. Lett., vol. 99, 2007, 144501). With the help of numerical simulations, we identify an interesting and important wetting behaviour of the climbing drop; that is, the breaking of symmetry due to the inclination of the plate with respect to the acceleration leads to a hysteresis of the wetted area in one period of harmonic vibration. In particular, the average wetted area in the downhill stage is larger than that in the uphill stage, which is found to be responsible for the uphill net motion of the drop. A new hydrodynamic model is proposed to interpret the ratchet mechanism, taking account of the effects of the acceleration and contact angle hysteresis. The predictions of the theoretical analysis are in good agreement with the numerical results.

Sign in / Sign up

Export Citation Format

Share Document