scholarly journals Transport of a Micro Liquid Plug in a Gas-Phase Flow in a Microchannel

Micromachines ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 423 ◽  
Author(s):  
Yutaka Kazoe ◽  
Takumi Matsuno ◽  
Ippei Yamashiro ◽  
Kazuma Mawatari ◽  
Takehiko Kitamori
Keyword(s):  
Surface Tension ◽  
Gas Phase ◽  
Inertial Force ◽  
Maximum Velocity ◽  
Size Control ◽  
Chemical Processing ◽  
Liquid Droplets ◽  
Liquid Plug ◽  
Number Ratio ◽  
Analysis And Synthesis

Micro liquid droplets and plugs in the gas-phase in microchannels have been utilized in microfluidics for chemical analysis and synthesis. While higher velocities of droplets and plugs are expected to enable chemical processing at higher efficiency and higher throughput, we recently reported that there is a limit of the liquid plug velocity owing to splitting caused by unstable wetting to the channel wall. This study expands our experimental work to examine the dynamics of a micro liquid plug in the gas phase in a microchannel. The motion of a single liquid plug, 0.4–58 nL in volume, with precise size control in 39- to 116-m-diameter hydrophobic microchannels was investigated. The maximum velocity of the liquid plug was 1.5 m/s, and increased to 5 m/s with splitting. The plug velocity was 20% of that calculated using the Hagen-Poiseuille equation. It was found that the liquid plug starts splitting when the inertial force exerted by the fluid overcomes the surface tension, i.e., the Weber number (ratio of the inertial force to the surface tension) is higher than 1. The results can be applied in the design of microfluidic devices for various applications that utilize liquid droplets and plugs in the gas phase.

scholarly journals Fabrication and Particle Size Control of Oxide Nanoparticles by Gas Phase Reaction Assisted with DC Plasma

2007 ◽  
Vol 44 (6) ◽  
pp. 447-452 ◽  
Author(s):  
Akira Watanabe ◽  
Motoharu Fujii ◽  
Masayoshi Kawahara ◽  
Takehisa Fukui ◽  
Kiyoshi Nogi
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Size Control ◽  
Oxide Nanoparticles ◽  
Phase Reaction ◽  
Dc Plasma ◽  
Gas Phase Reaction ◽  
Particle Size Control

Simulation of Impaction Between Liquid Droplet and Solid Particles Based on SPH Method

2014 ◽  
Author(s):  
Shuai Meng ◽  
Qian Wang ◽  
Rui Yang
Keyword(s):  
Surface Tension ◽  
Solid Particle ◽  
Liquid Droplet ◽  
Particle Interaction ◽  
Solid Particles ◽  
Seed Particle ◽  
Liquid Droplets ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Spray Granulation

The phenomenon of impaction between liquid droplets and solid particles is involved in many scientific problems and engineering applications, such as impaction between sprayed droplet and solid particles in limestone injection desulfurization system and the collision between a droplet of the liquid to be granulated and a seed particle in fluidized bed spray granulation process. There are a lot of factors affected this phenomenon: droplet and particle size, momentum of both liquid droplet and solid particles, materials, surface conditions of the solid particles and so on. However the experimental or numerical researches have been done mostly pay attention to Specific application or process, so the impaction phenomenon has not been through studied, for example how different factors affected the impaction process with its effect on different applications. This paper focuses on the basic issue of interaction between droplet and solid particles. Three main factors were considered: ratio of diameter between the droplet and solid particle, relative velocity and the surface tension (including the contact angle between droplet and solid particle). All the study is based on simulation using SPH (smoothed particle hydrodynamics) method, and the surface tension is simulated by particle-particle interaction.

scholarly journals Tissue pressure and cell traction compensate to drive robust aggregate spreading

2020 ◽  
Author(s):  
M. S. Yousafzai ◽  
V. Yadav ◽  
S. Amiri ◽  
M.F. Staddon ◽  
A. P. Tabatabai ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cell Aggregates ◽  
Liquid Droplets ◽  
Compensatory Mechanisms ◽  
Tissue Pressure ◽  
Comparable Rate ◽  
Compliant Substrates ◽  
Interfacial Energies ◽  
Active Liquid ◽  
Context Specific

AbstractIn liquid droplets, the balance of interfacial energies and substrate elasticity determines the shape of the droplet and the dynamics of wetting. In living cells, interfacial energies are not constant, but adapt to the mechanics of their environment. As a result, the forces driving the dynamics of wetting for cells and tissues are unclear and may be context specific. In this work, using a combination of experimental measurements and modeling, we show the surface tension of cell aggregates, as models of active liquid droplets, depends upon the size of the aggregate and the magnitude of applied load, which alters the wetting dynamics. Upon wetting rigid substrates, traction stresses are elevated at the boundary, and tension drives forward motion. By contrast, upon wetting compliant substrates, traction forces are attenuated, yet wetting occurs at a comparable rate. In this case, capillary forces at the contact line are elevated and aggregate surface tension contributes to strong outward, pressure-driven cellular flows. Thus, cell aggregates adapt to the mechanics of their environments, using pressure and traction as compensatory mechanisms to drive robust wetting.

scholarly journals Sorting Liquid Droplets by Surface Tension Using Devices with Quasi-Superamphiphobic Coatings

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 820 ◽  
Author(s):  
Yu-Ping Zhang ◽  
Di Fan ◽  
Xiu-Zhi Bai ◽  
Cheng-Xing Cui ◽  
Jun Chen ◽  
...  
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Solid Surface ◽  
Glass Slide ◽  
Liquid Droplets ◽  
Surface Tensions ◽  
Coated Nanoparticles ◽  
Tilting Angle ◽  
Time Distance ◽  
Alcoholic Strength

Any solid surface with homogenous or varying surface energy can spontaneously show variable wettability to liquid droplets with different or identical surface tensions. Here, we studied a glass slide sprayed with a quasi-superamphiphobic coating consisting of a hexane suspension of perfluorosilane-coated nanoparticles. Four areas on the glass slide with a total length of 7.5 cm were precisely tuned via ultraviolet (UV) irradiation, and droplets with surface tensions of 72.1–33.9 mN m−1 were categorized at a tilting angle of 3°. Then, we fabricated a U-shaped device sprayed with the same coating and used it to sort the droplets more finely by rolling them in the guide groove of the device to measure their total rolling time and distance. We found a correlation between ethanol content/surface tension and rolling time/distance, so we used the same device to estimate the alcoholic strength of Chinese liquors and to predict the surface tension of ethanol aqueous solutions.

Parametric Analysis of Microdroplet Formation in Co-Axial Co-Flowing Immiscible Liquids in Microtubes

2011 ◽  
Author(s):  
In-Hwan Yang ◽  
Mohamed S. El-Genk
Keyword(s):  
Finite Element Method ◽  
Surface Tension ◽  
Parametric Analysis ◽  
Jump Condition ◽  
Reynolds Numbers ◽  
Immiscible Liquid ◽  
Liquid Droplets ◽  
Immiscible Liquids ◽  
Interfacial Surface ◽  
Disperse Liquid

This paper presents numerical results of disperse liquid droplets forming in the dripping regime at the tip of a microtube into another co-flowing immiscible liquid in a coaxial microtube of larger diameter. Investigated are the effects of the interfacial surface tension, velocities and viscosities of the liquids and the diameters of the coaxial microtubes on the forming dynamics and the size of the droplet. The 2-D, transient Navier-Stockes equations, in conjunction with the momentum jump condition across the interface between the co-flowing liquids are solved using a finite element method. The solution tracks the interface and the growth of the droplet and predicts droplet size and forming frequency. The droplet’s dimensionless radius (rd*) is correlated within ± 10% in terms of the continuous liquid capillary number (Cac) and ratios of Reynolds numbers (Red/Rec) and microtube radii (Rc/Rd) of the co-flowing liquids as: rd*=0.225R*0.466/(Cac0.5)(Red/Rec).0.05

Nonlinear deformation and breakup of stretching liquid bridges

1996 ◽  
Vol 329 ◽  
pp. 207-245 ◽  
Author(s):  
X. Zhang ◽  
R. S. Padgett ◽  
O. A. Basaran
Keyword(s):  
Surface Tension ◽  
Liquid Bridge ◽  
Method Of Lines ◽  
Inertial Force ◽  
Surface Tension Force ◽  
Tension Force ◽  
Geometrical Parameters ◽  
Liquid Density ◽  
Liquid Bridges ◽  
Disk Radius

In this paper, the nonlinear dynamics of an axisymmetric liquid bridge held captive between two coaxial, circular, solid disks that are separated at a constant velocity are considered. As the disks are continuously pulled apart, the bridge deforms and ultimately breaks when its length attains a limiting value, producing two drops that are supported on the two disks. The evolution in time of the bridge shape and the rupture of the interface are investigated theoretically and experimentally to quantitatively probe the influence of physical and geometrical parameters on the dynamics. In the computations, a one-dimensional model that is based on the slender jet approximation is used to simulate the dynamic response of the bridge to the continuous uniaxial stretching. The governing system of nonlinear, time-dependent equations is solved numerically by a method of lines that uses the Galerkin/finite element method for discretization in space and an adaptive, implicit finite difference technique for discretization in time. In order to verify the model and computational results, extensive experiments are performed by using an ultra-high-speed video system to monitor the dynamics of liquid bridges with a time resolution of 1/12 th of a millisecond. The computational and experimental results show that as the importance of the inertial force – most easily changed in experiments by changing the stretching velocity – relative to the surface tension force increases but does not become too large and the importance of the viscous force – most easily changed by changing liquid viscosity – relative to the surface tension force increases, the limiting length that a liquid bridge is able to attain before breaking increases. By contrast, increasing the gravitational force – most readily controlled by varying disk radius or liquid density – relative to the surface tension force reduces the limiting bridge length at breakup. Moreover, the manner in which the bridge volume is partitioned between the pendant and sessile drops that result upon breakup is strongly influenced by the magnitudes of viscous, inertial, and gravitational forces relative to surface tension ones. Attention is also paid here to the dynamics of the liquid thread that connects the two portions of the bridge liquid that are pendant from the top moving rod and sessile on the lower stationary rod because the manner in which the thread evolves in time and breaks has important implications for the closely related problem of drop formation from a capillary. Reassuringly, the computations and the experimental measurements are shown to agree well with one another.

Blast-wave propagation in a spray

1978 ◽  
Vol 88 (4) ◽  
pp. 641-657 ◽  
Author(s):  
T. H. Pierce
Keyword(s):  
Gas Phase ◽  
Blast Wave ◽  
Wave Structure ◽  
Blast Waves ◽  
Decay Rates ◽  
Liquid Droplets ◽  
Two Phase ◽  
Number Range ◽  
Reactive Liquid ◽  
Particle Velocities

A first-order analysis is presented for the propagation of a blast wave through a dilute spray of non-reactive liquid droplets that are suspended in a non-reactive gas-phase carrier. The analysis permits straightforward computation of decay rates and internal wave structure for wave strengths in the approximate Mach number range 4 ≤ Ms ≤ 15, and loading factors (mass of spray per unit mass of carrier) less than about 0·4. The droplets must be sufficiently small to completely change phase in a distance behind the shock that is at all times negligible compared with the wave radius. Representative calculations are presented and discussed. These show more rapid decay rates and higher pressures, densities, and particle velocities in two-phase blast waves when compared against equivalent gas-phase blast waves. A simplification of the analysis for the regime of higher wave Mach numbers (strong waves) is also given, which for that case allows direct algebraic calculation of early wave characteristics.

Scattering from Gas-Phase Synthesized Particles

1989 ◽  
Vol 172 ◽  
Author(s):  
Alan J. Hurd
Keyword(s):  
Surface Tension ◽  
Gas Phase ◽  
Fiber Optics ◽  
High Purity ◽  
Rational Design ◽  
High Porosity ◽  
Phase Synthesis ◽  
Shape Distribution ◽  
Design And Optimization ◽  
Fundamental Knowledge

Rational design and optimization for the next generation of fiber optics requires fundamental knowledge of the processes at each step of production [1], not the least of which is the formation and deposition of the glass precursor particles. Currently, gas-phase synthesis dominates the industry, owing, in part, to the high purity possible for gaseous reagents. However, the production engineer has relatively little control over the microstructure of the boule from which the fiber is drawn because many complex mechanisms take part in the growth and thermophoretic deposition of the precursors. Although it is desirable, for example, to obtain a porous boule in order to facilitate the removal of deleterious hydroxyls, connected porosity is by no means guaranteed. The successful attainment of high porosity depends on a number of variables such as the size distribution [2], internal structure, shape distribution, viscosity, and surface tension of the particles at the instant of deposition.

On the Law of Spontaneous Spreading of Liquid Droplets on Solid Substrates

2002 ◽  
Author(s):  
Abdullatif M. Alteraifi ◽  
Dalia Sherif ◽  
Abdelsamie Moet
Keyword(s):  
Surface Tension ◽  
Spherical Shape ◽  
Soda Lime ◽  
Solid Substrate ◽  
Contact Radius ◽  
Soda Lime Glass ◽  
Image Analysis System ◽  
Liquid Droplets ◽  
Viscous Forces ◽  
Wide Range

Several theories deal with the spreading kinetics of liquids on solid substrate, notable amongst which is de Gennes’ law, which relates the contact radius, R, to the droplet volume, V, the surface tension, σ, and the viscosity, µ, by the equation R3m+1 = (σ/µ) t Vm and ascertains that m = 3 is “indeed expected theoretically for all cases of dry spreading”. Validity of the proposed models is examined by measurements of the spreading of a number of liquids exhibiting a wide range of surface tension and viscosity on dry soda-lime glass. The measurements used a small droplet of constant volume to minimize gravitational effects. The droplet was released near the glass surface from automatic micro syring, supported on micromanipulator. The contact radius was acquired as a function of time by an image analysis system. Analyzed in terms of de Gennes law, it was noted that the m values for silicone oils fall within the suggested variance i.e., m = 3.0±0.5. However, significant disagreements were noted in the case of other liquids, where m ranged from 5.2 to 15.0 with no correlation with the parameters included. Mechanistic considerations suggest that whereas the surface tension acts to retain the spherical shape of the droplet, interfacial tension acts to maximize the contact area whereas the viscous forces determine the kinetics. The magnitude of the difference between the interfacial and surface energies likely determines whether spreading is complete or incomplete.

Effect of atmospheric-pressure plasma irradiation on the surface tension of water

2022 ◽  
Author(s):  
Naoki Shirai ◽  
Takuma Kaneko ◽  
Yuto Takamura ◽  
Koichi Sasaki
Keyword(s):  
Surface Tension ◽  
Gas Phase ◽  
Atmospheric Pressure ◽  
Water Surface ◽  
Atmospheric Pressure Plasma ◽  
Marangoni Effect ◽  
Oh Radicals ◽  
Plasma Irradiation ◽  
Pressure Plasma ◽  
Trapping Agent

Abstract We have shown that measuring the surface tension is a useful scheme to examine the plasma-liquid interface in real-time. The surface tension was measured using a method based on the dispersion relation of an acoustic capillary wave excited on the water surface. The surface tension gradually increased with time, when the water surface was irradiated with the outside region of the spatial afterglow of an atmospheric-pressure plasma. The Marangoni effect associated with the localized increase in the surface tension was observed during the plasma irradiation. The surface tension decreased after the termination of the discharge. A correlation was found between the transient decrease in the surface tension and the variation of the OH radical density in the gas phase. No increase in the surface tension was observed in the solution containing a trapping agent for liquid-phase OH radicals. These experimental results suggest that OH radicals act to increase the surface tension. However, the behavior of the surface tension cannot be explained perfectly by considering only the action of OH radicals.

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