scholarly journals Effect of structured surface on contact angle using Sessile Droplet method

2020 ◽  
Vol 814 ◽  
pp. 012034
Author(s):  
Biswajit Majumder ◽  
Anil Katarkar ◽  
Swapan Bhaumik
Keyword(s):  
Contact Angle ◽  
Sessile Droplet ◽  
Structured Surface ◽  
Droplet Method

scholarly journals Effect of Pesticide Addition Sequence on the Preparation of Phytosanitary Spray Solutions

2019 ◽  
Vol 37 ◽  
Author(s):  
M.F.T. RAMOS ◽  
R.T.S. SANTOS ◽  
D.P. ALMEIDA ◽  
J.F.D. VECHIA ◽  
M.C. FERREIRA
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Propionic Acid ◽  
Biological Effect ◽  
Surface Coverage ◽  
Mineral Oil ◽  
Application Rate ◽  
Physicochemical Interactions ◽  
Effect Of Treatment ◽  
Droplet Method

ABSTRACT: The addition of adjuvants to herbicide solutions is aimed at preserving or enhancing the biological effect of treatment. However, it is commonly performed without knowledge of the physicochemical interactions between products. This study aimed to assess the effects of different addition sequences of the herbicide aminopyralid + fluroxypyr and adjuvants in the preparation of phytosanitary spray solutions on the surface tension and contact angle. Two experiments were carried out with herbicide doses of 1 and 2 L ha-1 associated with the adjuvants mineral oil (MO), silicone-polyether copolymer (SIL), and a mixture of phosphatidylcholine (lectin) and propionic acid (LEC), all at a proportion of 0.3% v v-1. The application rate was 150 L ha-1. Surface tension was measured by the pendant droplet method. Contact angle was measured on the adaxial and abaxial surfaces of leaves of the pasture weed Senna obtusifolia and parafilm. Preparation sequence did not change the contact angle on any of the analyzed surfaces at a dose of 1 L ha-1 of herbicide. For the dose of 2 L ha-1, the adjuvants SIL and LEC showed a higher spreading when previously added to the herbicide. MO resulted in a higher spreading when added after the herbicide, with higher surface coverage. Therefore, the preparation sequence influences the dispersion of phytosanitary spray solutions on targets.

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.

scholarly journals The Role of Wettability on the Response of a Quartz Crystal Microbalance Loaded with a Sessile Droplet

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Brandon Murray ◽  
Shankar Narayanan
Keyword(s):  
Contact Angle ◽  
Frequency Response ◽  
Quartz Crystal Microbalance ◽  
Contact Area ◽  
Quartz Crystal ◽  
Quartz Substrate ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Decay Length ◽  
Sessile Droplet

AbstractIn this work, the interaction between a sessile droplet’s contact angle and a quartz crystal microbalance (QCM) is elucidated. We differentiate the QCM’s frequency response to changes in the droplet contact area from variations in the dynamic contact angle. This is done by developing a computational model that couples the electrical and mechanical analysis of the quartz substrate with the visco-acoustic behavior of the sessile droplet. From our analysis, we conclude that changes in the contact angle have an effect on the frequency response of the QCM when the droplet height is on the order of the viscous decay length or smaller. On the other hand, changes in the interfacial contact area of the sessile droplets have a significant impact on the frequency response of the QCM regardless of the droplet size.

scholarly journals Contact angle dynamics for evaporating droplet on contrast nano-structured surface

2019 ◽  
Vol 1382 ◽  
pp. 012104
Author(s):  
E M Bochkareva ◽  
M K Lei ◽  
N B Miskiv ◽  
S V Starinsky ◽  
V V Terekhov
Keyword(s):  
Contact Angle ◽  
Structured Surface

scholarly journals Prediction of Contact Angle of Nanofluids by Single-Phase Approaches

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4558 ◽  
Author(s):  
Nur Çobanoğlu ◽  
Ziya Haktan Karadeniz ◽  
Patrice Estellé ◽  
Raul Martínez-Cuenca ◽  
Matthias H. Buschmann
Keyword(s):  
Contact Angle ◽  
Single Phase ◽  
Substrate Surface ◽  
Droplet Surface ◽  
Force Balance ◽  
Radius Of Curvature ◽  
Geometrical Parameters ◽  
Ambient Conditions ◽  
Sessile Droplet ◽  
Droplet Shape

Wettability is the ability of the liquid to contact with the solid surface at the surrounding fluid and its degree is defined by contact angle (CA), which is calculated with balance between adhesive and cohesive forces on droplet surface. Thermophysical properties of the droplet, the forces acting on the droplet, atmosphere surrounding the droplet and the substrate surface are the main parameters affecting on CA. With nanofluids (NF), nanoparticle concentration and size and shape can modify the contact angle and thus wettability. This study investigates the validity of single-phase CA correlations for several nanofluids with different types of nanoparticles dispersed in water. Geometrical parameters of sessile droplet (height of the droplet, wetting radius and radius of curvature at the apex) are used in the tested correlations, which are based on force balance acting on the droplet surface, energy balance, spherical dome approach and empirical expression, respectively. It is shown that single-phase models can be expressed in terms of Bond number, the non-dimensional droplet volume and two geometrical similarity simplexes. It is demonstrated that they can be used successfully to predict CA of dilute nanofluids’ at ambient conditions. Besides evaluation of CA, droplet shape is also well predicted for all nanofluid samples with ±5% error.

Particle Separation inside a Sessile Droplet with Variable Contact Angle Using Surface Acoustic Waves

2016 ◽  
Vol 89 (1) ◽  
pp. 736-744 ◽  
Author(s):  
Ghulam Destgeer ◽  
Jin Ho Jung ◽  
Jinsoo Park ◽  
Husnain Ahmed ◽  
Hyung Jin Sung
Keyword(s):  
Contact Angle ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Particle Separation ◽  
Sessile Droplet

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.

Dynamics of sessile drops. Part 1. Inviscid theory

2014 ◽  
Vol 760 ◽  
pp. 5-38 ◽  
Author(s):  
J. B. Bostwick ◽  
P. H. Steen
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Dynamic Contact ◽  
Linear Operators ◽  
Sessile Droplet ◽  
Physical Reason ◽  
Spherical Cap ◽  
Static Contact ◽  
Dynamic Contact Line ◽  
Line Condition

AbstractA sessile droplet partially wets a planar solid support. We study the linear stability of this spherical-cap base state to disturbances whose three-phase contact line is (i) pinned, (ii) moves with fixed contact angle and (iii) moves with a contact angle that is a smooth function of the contact-line speed. The governing hydrodynamic equations for inviscid motions are reduced to a functional eigenvalue problem on linear operators, which are parameterized by the base-state volume through the static contact angle and contact-line mobility via a spreading parameter. A solution is facilitated using inverse operators for disturbances (i) and (ii) to report frequencies and modal shapes identified by a polar $k$ and azimuthal $l$ wavenumber. For the dynamic contact-line condition (iii), we show that the disturbance energy balance takes the form of a damped-harmonic oscillator with ‘Davis dissipation’ that encompasses the dynamic effects associated with (iii). The effect of the contact-line motion on the dissipation mechanism is illustrated. We report an instability of the super-hemispherical base states with mobile contact lines (ii) that correlates with horizontal motion of the centre-of-mass, called the ‘walking’ instability. Davis dissipation from the dynamic contact-line condition (iii) can suppress the instability. The remainder of the spectrum exhibits oscillatory behaviour. For the hemispherical base state with mobile contact line (ii), the spectrum is degenerate with respect to the azimuthal wavenumber. We show that varying either the base-state volume or contact-line mobility lifts this degeneracy. For most values of these symmetry-breaking parameters, a certain spectral ordering of frequencies is maintained. However, because certain modes are more strongly influenced by the support than others, there are instances of additional modal degeneracies. We explain the physical reason for these and show how to locate them.

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