Analysis of the oscillatory wetting–dewetting motion of a volatile drop during the deposition of polymer on a solid substrate

Soft Matter ◽  
2019 ◽  
Vol 15 (17) ◽  
pp. 3580-3587 ◽  
Author(s):  
Anna Zigelman ◽  
Mohammad Abo Jabal ◽  
Ofer Manor
Keyword(s):  
Theoretical Model ◽  
Contact Line ◽  
Deposition Process ◽  
Solid Substrate

We employ a theoretical model to explain the wetting–dewetting motion of the contact line by incorporating opposing evaporation and Marangoni induced flows in the deposition process.

Sharp acceleration of a macroscopic contact line induced by a particle

2017 ◽  
Vol 830 ◽  
Author(s):  
Lizhong Mu ◽  
Daichi Kondo ◽  
Motochika Inoue ◽  
Toshihiro Kaneko ◽  
Harunori N. Yoshikawa ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Surface Area ◽  
Contact Line ◽  
Late Stage ◽  
Silicone Oil ◽  
Particle Interaction ◽  
Solid Substrate ◽  
Complete Wetting ◽  
Short Time ◽  
Good Agreement

Wetting of a planar solid substrate is investigated in the presence of a macroscopic particle in the complete wetting regime. A drop of silicone oil spreads on the substrate and its macroscopic edge is incident on the particle at the late stage of spreading. The drop–particle interaction is observed in detail by shadowgraph and interferometry. Although the spreading drop edge is pinned by the particle for a short time, a sharp acceleration occurs when the liquid starts wetting the extra surface area offered by the particle and forming a meniscus. This process yields a net gain in spreading speed. A theoretical model based on the classical wetting dynamics dictated by Cox’s law is developed. It predicts that the capillary energy of the meniscus gives rise to a rapid motion of the liquid edge, showing good agreement with the dynamics observed in the experiments.

Numerical and theoretical analyses of the dynamics of droplets driven by electrowetting on dielectric in a Hele-Shaw cell

2018 ◽  
Vol 839 ◽  
pp. 468-488 ◽  
Author(s):  
Yasufumi Yamamoto ◽  
Takahiro Ito ◽  
Tatsuro Wakimoto ◽  
Kenji Katoh
Keyword(s):  
Theoretical Model ◽  
Contact Line ◽  
Three Dimensional ◽  
Simulation Method ◽  
Movement Speed ◽  
Electrowetting On Dielectric ◽  
Moving Contact Line ◽  
Moving Contact ◽  
Droplet Movement ◽  
Hele Shaw Cell

Droplet movement by electrowetting on dielectric (EWOD) in a Hele-Shaw cell is analysed theoretically and numerically. We propose a simple theoretical model for the motion, which describes well the voltage dependency of droplet speed below the saturation voltage as measured experimentally. The simulation method for numerical analyses is constructed by using the Young–Lippmann equation to represent EWOD and the generalised Navier boundary condition to represent the moving contact line in the context of the front-tracking method. With an adjusted slip parameter, the present full three-dimensional numerical simulation reproduces well the shape evolution and movement speed of droplets as observed experimentally. We verify the proposed theoretical model in numerical experiments with various shapes and voltages. Furthermore, we analyse theoretically the behaviour of the contact line at the onset of droplet motion as observed in the simulation and experiment, and we are able to estimate very well the time scale on which the contact angle changes.

Detection of Advancing Edge and Existing Length of Precursor Film Ahead Macroscopic Contact Line of Droplet Spreading on Solid Substrate

2008 ◽  
Author(s):  
Ichiro Ueno
Keyword(s):  
Contact Line ◽  
High Speed ◽  
Thin Liquid Film ◽  
Experimental Studies ◽  
Laser Interferometry ◽  
Spreading Rate ◽  
Solid Substrate ◽  
Precursor Film ◽  
Boundary Line ◽  
Droplet Spreading

The author introduces a series of experimental studies on a simple but complex wetting process; a droplet spreads on a solid substrate. The spreading droplet on the solid substrate is accompanied with the movement of a visible boundary line so-called ‘macroscopic contact line.’ Existing studies have indicated there exits a thin liquid film known as ‘precursor film’ ahead the macroscopic contact line of the droplet. The present author’s group has dedicated their special effort to detect the advancing edge of the precursor film by applying a convectional laser interferometry and a high-speed camera, and to evaluate the spreading rate of the precursor film.

scholarly journals On the distinguished limits of the Navier slip model of the moving contact line problem

2015 ◽  
Vol 772 ◽  
pp. 107-126 ◽  
Author(s):  
Weiqing Ren ◽  
Philippe H. Trinh ◽  
Weinan E
Keyword(s):  
Contact Line ◽  
Solid Substrate ◽  
Slip Condition ◽  
Slip Model ◽  
Leading Order ◽  
Slip Parameter ◽  
Navier Slip ◽  
Moving Contact Line ◽  
Moving Contact ◽  
Correct Boundary Conditions

When a droplet spreads on a solid substrate, it is unclear what the correct boundary conditions are to impose at the moving contact line. The classical no-slip condition is generally acknowledged to lead to a non-integrable singularity at the moving contact line, which a slip condition, associated with a small slip parameter, ${\it\lambda}$, serves to alleviate. In this paper, we discuss what occurs as the slip parameter, ${\it\lambda}$, tends to zero. In particular, we explain how the zero-slip limit should be discussed in consideration of two distinguished limits: one where time is held constant, $t=O(1)$, and one where time tends to infinity at the rate $t=O(|\!\log {\it\lambda}|)$. The crucial result is that in the case where time is held constant, the ${\it\lambda}\rightarrow 0$ limit converges to the slip-free equation, and contact line slippage occurs as a regular perturbative effect. However, if ${\it\lambda}\rightarrow 0$ and $t\rightarrow \infty$, then contact line slippage is a leading-order singular effect.

scholarly journals The effect of the angle of «meeting» of fullerite C60 with a solid substrate on the deposition process

2020 ◽  
pp. 90-97
Author(s):  
S. V Suvorov ◽  
A. V Severiuchin ◽  
A. V Vakhrushev
Keyword(s):  
Software Package ◽  
Molecular Crystal ◽  
Velocity Vector ◽  
Deposition Process ◽  
Solid Substrate ◽  
Interaction Process ◽  
The Body ◽  
Wear Resistant Coatings ◽  
Iron Crystal ◽  
Closed Polyhedron

Carbon forms a large number of allotropic forms, one of which is fullerene. Fullerene is a convex closed polyhedron with carbon atoms at its vertices. The most common is fullerene, consisting of 60 carbon atoms and designated - C60. In turn, fullerenes are able to agglomerate, forming a molecular crystal - fullerite. In the interaction of fullerite C60 with a solid, it is possible to deposit on the surface of the body both whole fullerite and the fullerenes that form it. The interaction process in the C60 fullerite system - the substrate of a solid, and then on - the fullerite - substrate system - is multi-parameter. So, when modeling the interaction of fullerite with a substrate, the following were taken into account: the temperature of the system - 300, 700, 1150 K; the speed of fullerite movement is 0.005, 0.01, 0.02 Å / fs. In addition, in the study, we varied the angle between the fullerite velocity vector and the normal to the contact surface of the substrate, called the “meeting angle”. An iron crystal Fe (100) was modeled as a solid body substrate, as one of the most common structural materials. Fullerite C60 was in contact with the solid substrate with its face. Computer simulation of the process of contact of fullerite C60 with the substrate was carried out in the LAMMPS software package. The main result of this study is to determine the effect of the angle of “meeting” of C60 fullerite in contact with a solid substrate, which will significantly complement the overall picture of the process of C60 fullerite deposition. In turn, this can allow the creation of various films and wear-resistant coatings on the surface of materials.

Sculpting and Aerosolizing Pinned Liquid Films With Localized Acoustic Pressures of Surface Acoustic Waves

2012 ◽  
Author(s):  
Daniel Taller ◽  
Hsueh-Chia Chang ◽  
David B. Go
Keyword(s):  
Contact Angle ◽  
Numerical Modeling ◽  
Contact Line ◽  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Surface Acoustic Waves ◽  
Liquid Films ◽  
Solid Substrate ◽  
Planar Surface ◽  
Bulk Film

Due to viscous decay, a planar surface acoustic wave (SAW) diffracting from a solid substrate into a liquid film produces a time-averaged, exponentially decaying acoustic pressure in the film. We show that if the film is pinned against a bounding wall, the localized acoustic pressure generates a sequence of surface drops at the contact line, whose dimensions decay in the same exponential manner as the localized acoustic pressure. The undulating interfacial profile near the contact line also inherits this exponential decay, such that the averaged contact angle is exponentially small. The bulk film topology and the aerosolization mechanism are hence insensitive to the wettability of the surface but are controlled only by the localized acoustic pressure and the decaying undulations it produces at the contact line. The size distribution of surface drops is collapsed under the exponential scaling that depends only on the SAW decay rate and amplitude. Numerical modeling based on the Young-Laplace equation is used to model the liquid profile and to predict two aerosolization regimes.

Precursor Film Formation Process Ahead Macroscopic Contact Line of Spreading Droplet on Smooth Substrate

2009 ◽  
Author(s):  
Ichiro Ueno ◽  
Kanji Hirose ◽  
Yusuke Kizaki ◽  
Yoshiaki Kisara ◽  
Yoshizumi Fukuhara
Keyword(s):  
Liquid Film ◽  
Contact Line ◽  
Formation Process ◽  
High Speed ◽  
Thin Liquid Film ◽  
Solid Substrate ◽  
Precursor Film ◽  
Boundary Line ◽  
Brewster Angle Microscopy ◽  
Droplet Spreading

The authors pay their special attention to formation process of wafer-thin liquid film, known as ‘precursor film,’ ahead moving macroscopic contact line of a droplet spreading on a solid substrate. The spreading droplet on the solid substrate is accompanied with the movement of a visible boundary line so-called ‘macroscopic contact line.’ Existing studies have indicated there exits a thin liquid film known as ‘precursor film’ ahead the macroscopic contact line of the droplet. The present author’s group has dedicated their special effort to detect the formation process of the precursor film by applying a convectional laser interferometry and a high-speed camera, and to evaluate the spreading rate of the precursor film. In the present study, existing length of the precursor film at a very early stage of the droplet spreading is evaluated by applying a Brewster-angle microscopy as well as the interferometer. The authors extend their attention to the advancing process of the precursor film on inclined substrate.

scholarly journals Parameter sensitivity analysis of the theoretical model of a CR-39-based direct 222Rn/220Rn progeny monitor

Nukleonika ◽  
2020 ◽  
Vol 65 (2) ◽  
pp. 95-98 ◽  
Author(s):  
Jun Hu ◽  
Masahiro Hosoda ◽  
Shinji Tokonami
Keyword(s):  
Sensitivity Analysis ◽  
Theoretical Model ◽  
Measurement Techniques ◽  
Deposition Process ◽  
Parameter Sensitivity ◽  
Parameter Sensitivity Analysis ◽  
Aerodynamic Parameters ◽  
Aerosol Parameters ◽  
Spearman’S Correlation ◽  
Attachment Process

AbstractThe deposition-based direct indoor 222Rn and 220Rn progeny measurement techniques are mostly affected by the indoor environmental conditions, such as the ventilation, concentration of condensation nuclei, and reactions with the structure and its furnishings. In this study, a theoretical model of a direct 222Rn and 220Rn progeny monitor based on allyl diglycol carbonate (ADC or CR-39) was established to analyse the factors that influence the detection process by using the parameter sensitivity analysis. The aerosol parameters contributed the highest to the variance, followed by the aerodynamic parameters. With respect to the result of the Spearman’s correlation analysis, the aerosol-related and the room-related parameters are positive, whereas the aerodynamic parameters – which affect the turbulence of indoor deposition – are negative. It means that both the attachment process and the deposition process of 222Rn and 220Rn progenies are important to the performance of the progeny monitor.

scholarly journals Effect of the internal pressure on oscillations of a cylindrical gas bubble

2020 ◽  
pp. 51-62
Author(s):  
A. A. Alabuzhev ◽  
Keyword(s):  
Contact Angle ◽  
Finite Volume ◽  
Contact Line ◽  
Incompressible Liquid ◽  
Axial Direction ◽  
Solid Substrate ◽  
Forced Oscillations ◽  
Gas Bubble ◽  
Natural Oscillations ◽  
Round Cylinder

Natural and forced oscillations of a gas bubble are studied. The bubble has the shape of a round cylinder in the state of equilibrium. It is bounded in the axial direction by two parallel solid surfaces and is surrounded by an incompressible liquid of a finite volume with a free outer surface. The entire system is under an alternating pressure field. The velocity of the contact line of three media (gas-liquid-solid substrate) is proportional to the deviation of the contact angle from the equilibrium value. The frequency of eigenmodes of a gas bubble can increase with an increase in the Hocking parameter, in contrast to the frequencies of an incompressible liquid drop, which only decrease. It is shown that radial oscillations of a cylindrical bubble are possible only in a finite volume of liquid. The effect of crossing the modes of natural oscillations is considered for the dissipative case. The amplitude-frequency characteristics are constructed for different values of the internal gas pressure. Resonance phenomena are found. It is shown that the external influence excites, first of all, volumetric oscillations of the bubble. Variations in shape are caused by the movement of the contact line. Expressions are found for the vibration amplitude in the case of a fixed contact line and a fixed contact angle.

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