scholarly journals Controlling uniform patterns by evaporation of multi-component liquid droplets in a confined geometry

Soft Matter ◽  
2021 ◽  
Author(s):  
Jeongsu Pyeon ◽  
Hyoungsoo Kim
Keyword(s):  
Liquid Droplet ◽  
Liquid Droplets ◽  
Confined Geometry ◽  
Closed Chamber ◽  
Coffee Ring ◽  
Marangoni Effects

A drying multi-component liquid droplet in a confined geometry leaves a uniform dried pattern. The evaporated vapors are stagnated inside the closed chamber, which induce Marangoni effects that contribute to suppress the coffee-ring pattern.

Numerical Analysis of Influence of Roughness of Material Surface on High-Speed Liquid Droplet Impingement

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Hirotoshi Sasaki ◽  
Yuka Iga
Keyword(s):  
Numerical Analysis ◽  
High Speed ◽  
Erosion Rate ◽  
Liquid Droplet ◽  
Material Surface ◽  
Liquid Droplets ◽  
Fluid Machinery ◽  
Droplet Impingement ◽  
Surface Liquid ◽  
Droplet Impingement Erosion

This study explains why the deep erosion pits are formed in liquid droplet impingement erosion even though the droplets uniformly impinge on the entire material surface. Liquid droplet impingement erosion occurs in fluid machinery on which droplets impinge at high speed. In the process of erosion, the material surface becomes completely roughened by erosion pits. In addition, most material surface is not completely smooth and has some degree of initial roughness from manufacturing and processing and so on. In this study, to consider the influence of the roughness on the material surface under droplet impingement, a numerical analysis of droplets impinging on the material surface with a single wedge and a single bump was conducted with changing offsets between the droplet impingement centers and the roughness centers on each a wedge bottom and a bump top. As results, two mechanisms are predicted from the present numerical results: the erosion rate accelerates and transitions from the incubation stage to the acceleration stage once roughness occurs on the material surface; the other is that deep erosion pits are formed even in the case of liquid droplets impinging uniformly on the entire material surface.

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 NBR1-mediated p62-liquid droplets enhance the Keap1-Nrf2 system

2019 ◽  
Author(s):  
Pablo Sánchez-Martín ◽  
Yu-shin Sou ◽  
Shun Kageyama ◽  
Masaaki Komatsu
Keyword(s):  
Oxidative Stress ◽  
Liquid Droplet ◽  
Brca1 Gene ◽  
Droplet Formation ◽  
Receptor Protein ◽  
Liquid Droplets ◽  
Nrf2 Pathway ◽  
Selective Degradation ◽  
System A ◽  
Nrf2 Activation

Abstractp62/SQSTM1 is a multivalent protein that has an ability to cause a liquid-liquid phase separation and serves as a receptor protein that participates in cargo isolation during selective autophagy. This protein is also involved in the non-canonical activation of the Keap1-Nrf2 system, a major oxidative stress response pathway. Here we show a role of Neighbor of BRCA1 gene 1 (NBR1), an autophagy receptor structurally similar to p62/SQSTM1, in the p62-liquid droplet formation and the Keap1-Nrf2 pathway. The overexpression of NBR1 blocked selective degradation of p62/SQSTM1 through autophagy and promoted the accumulation and phosphorylation of p62/SQSTM1 in liquid-like bodies, which is required for the activation of Nrf2. NBR1 was induced in response to oxidative stress, and then the p62-mediated Nrf2 activation was up-regulated. Conversely, loss of Nbr1 suppresses not only the formation of p62/SQSTM1-liquid droplets but also p62-dependent Nrf2 activation during oxidative stress. Taken together, our results show that NBR1 mediates p62/SQSTM1-liquid droplet formation to activate the Keap1-Nrf2 pathway.

The shape evolution of liquid droplets in miscible environments

2018 ◽  
Vol 852 ◽  
pp. 422-452 ◽  
Author(s):  
Daniel J. Walls ◽  
Eckart Meiburg ◽  
Gerald G. Fuller
Keyword(s):  
Sessile Drop ◽  
Liquid Droplet ◽  
Leading Edge ◽  
Numerical Approach ◽  
Shape Evolution ◽  
Liquid Droplets ◽  
Miscible Liquids ◽  
Experimental Findings ◽  
Sessile Drops ◽  
Pendant Drops

Miscible liquids often come into contact with one another in natural and technological situations, commonly as a drop of one liquid present in a second, miscible liquid. The shape of a liquid droplet present in a miscible environment evolves spontaneously in time, in a distinctly different fashion than drops present in immiscible environments, which have been reported previously. We consider drops of two classical types, pendant and sessile, in building upon our prior work with miscible systems. Here we present experimental findings of the shape evolution of pendant drops along with an expanded study of the spreading of sessile drops in miscible environments. We develop scalings considering the diffusion of mass to group volumetric data of the evolving pendant drops and the diffusion of momentum to group leading-edge radial data of the spreading sessile drops. These treatments are effective in obtaining single responses for the measurements of each type of droplet, where the volume of a pendant drop diminishes exponentially in time and the leading-edge radius of a sessile drop grows following a power law of $t^{1/2}$ at long times. A complementary numerical approach to compute the concentration and velocity fields of these systems using a simplified set of governing equations is paired with our experimental findings.

Observations of Liquid Droplet Behavior and Oil Film Formation in O/W Type Emulsion Lubrication

1988 ◽  
Vol 110 (2) ◽  
pp. 348-353 ◽  
Author(s):  
T. Nakahara ◽  
T. Makino ◽  
K. Kyogoku
Keyword(s):  
High Speed ◽  
Liquid Droplet ◽  
Film Formation ◽  
Flat Glass ◽  
Glass Plate ◽  
Rolling Speed ◽  
Liquid Droplets ◽  
Speed Range ◽  
Oil Concentration ◽  
Inlet Zone

The behavior of liquid droplets in O/W type emulsions flowing between a flat glass plate and a metal roller was observed by means of a microscope. The behavior of the droplets introduced into the EHL film was found to be related to the streamlines of the continuous water phase in the vicinity of the inlet zone. It was observed that the oil droplets which penetrated into the EHL zone formed an oily pool (an oily film zone) containing water droplets in the inlet zone close to the EHL zone. This oily pool was a W/O emulsion rich in oil caused by phase inversion. The effects of oil concentration, emulsifier content and rolling speed on the area of the oily pool were investigated, and it was found that the extent of the oily pool was influenced by the rolling speed as well as oil concentration. The EHD film thickness was measured by means of optical interferometry with use of two wavelengths, and the measured results were compared with the calculated ones employing the starvation theory of Wolveridge et al. and the empirical equation of Wymer and Cameron for the region of the oil pool. It was found that course droplets play an important role in film formation by causing the formation of the oily pool in the low speed range. In the high speed range, however, a fine O/W emulsion forms the film.

A New Multidimensional Drift Flux Mixture Model for Gas–Liquid Droplet Two-Phase Flow

2015 ◽  
Vol 12 (04) ◽  
pp. 1540001 ◽  
Author(s):  
Zhi Shang ◽  
Jing Lou ◽  
Hongying Li
Keyword(s):  
Mixture Model ◽  
Liquid Droplet ◽  
Diffusion Flux ◽  
Water Mist ◽  
Liquid Droplets ◽  
Two Phase Flows ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model

A new multidimensional drift flux mixture model was developed to simulate gas–liquid droplet two-phase flows. The new drift flux model was modified by considering the centrifugal force on the liquid-droplets. Therefore the traditional 1D drift flux model was upgraded to multidimension, 2D and 3D. The slip velocities between the continual phase (gas) and the dispersed phase (liquid droplets) were able to calculate through the multidimensional diffusion flux velocities based on the new modified drift flux model. Through the numerical simulations comparing with the experiments and the simulations of other models on the backward-facing step and the water mist spray two-phase flows, the new model was validated.

Contact Line Pinning and Depinning Prior to Rupture of an Evaporating Droplet in a Simulated Soil Pore

2020 ◽  
Author(s):  
Partha P. Chakraborty ◽  
Melanie M. Derby
Keyword(s):  
Contact Line ◽  
Pressure Difference ◽  
Liquid Droplet ◽  
Liquid Droplets ◽  
Water Contact ◽  
Marginal Rate ◽  
Vapor Interface ◽  
Hydrophobic Pore ◽  
Contact Line Pinning ◽  
Liquid Vapor

Abstract Altering soil wettability by inclusion of hydrophobicity could be an effective way to restrict evaporation from soil, thereby conserving water resources. In this study, 4-μL sessile water droplets were evaporated from an artificial soil millipore comprised of three glass (i.e. hydrophilic) and Teflon (i.e. hydrophobic) 2.38-mm-diameter beads. The distance between the beads were kept constant (i.e. center-to-center spacing of 3.1 mm). Experiments were conducted in an environmental chamber at an air temperature of 20°C and 30% and 75% relative humidity (RH). Evaporation rates were faster (i.e. ∼19 minutes and ∼49 minutes at 30% and 75% RH) from hydrophilic pores than the Teflon one (i.e. ∼24 minutes and ∼52 minutes at 30% and 75% RH) due in part to greater air-water contact area. Rupture of liquid droplets during evaporation was analyzed and predictions were made on rupture based on contact line pinning and depinning, projected surface area just before rupture, and pressure difference across liquid-vapor interface. It was observed that, in hydrophilic pore, the liquid droplet was pinned on one bead and the contact line on the other beads continuously decreased by deforming the liquid-vapor interface, though all three gas-liquid-solid contact lines decreased at a marginal rate in hydrophobic pore. For hydrophilic and hydrophobic pores, approximately 1.7 mm2 and 1.8–2 mm2 projected area of the droplet was predicted at 30% and 75% RH just before rupture occurs. Associated pressure difference responsible for rupture was estimated based on the deformation of curvature of liquid-vapor interface.

Study on Liquid-Bridging Induced Microscale Contact of Two Liquid Droplets

2011 ◽  
Author(s):  
Yuichi Shibata ◽  
Takehiko Yanai ◽  
Osamu Okamoto ◽  
Masahiro Kawaji
Keyword(s):  
Interfacial Tension ◽  
High Speed ◽  
Liquid Droplet ◽  
Dominant Factor ◽  
Contact Method ◽  
Liquid Droplets ◽  
Pendant Drop ◽  
Drop Method ◽  
Surface And Interface ◽  
Pendant Drop Method

The field of microfluidics is developing with advances in MEMS, biotechnology and μ-TAS technologies. In various devices, interfacial energy is a dominant factor for liquid movement in a microchannel. The surface tension and interfacial tension values are necessary to analyze the liquid behavior in the microchannel. Evaluating the values of interfacial tension is especially important for multiphase flow. A pendant drop method is usually used to measure the interfacial tension, however, this method has some inconveniences. For example, the pendant drop method demands strict accuracy for measuring the droplet size when the droplet has a non-spherical shape. Moreover, it needs an accurate value of the density difference between the two liquids. In this work, a new measurement method named “Liquid-bridging Induced Micro Contact Method” has been developed to overcome the weaknesses of the existing methods. In a previous study, we obtained the interfacial tension from bridging of two liquid droplets on the tip of opposing round metal rods. In this study, we have examined the liquid-bridging of two extruded liquid droplets out of a micro glass tube. By measuring the radii of curvature of each liquid surface and interface, we calculate the Laplace pressure on the surface and interface, and derive the interfacial tension value using the Laplace equation. To prove these two methods are reliable, we have compared the results obtained in this experiment to that of the pendant drop method. As a liquid droplet comes into contact with an opposite liquid droplet the phenomenon is recorded using a CCD camera and high speed camera. The results show that the values of interfacial tension obtained from two methods are approximately the same. Therefore, the liquid-bridging induced micro contact method has been shown to be capable of interfacial tension measurements.

Imaging Analysis Enables Differentiation of the Distribution of Pharmaceutical Ingredients in Tacrolimus Ointments

2019 ◽  
Vol 73 (10) ◽  
pp. 1183-1192
Author(s):  
Mika Yoshimura Fujii ◽  
Yoshihisa Yamamoto ◽  
Tatsuo Koide ◽  
Masashi Hamaguchi ◽  
Yoshinori Onuki ◽  
...  
Keyword(s):  
Liquid Droplet ◽  
Raman Microscopy ◽  
Attenuated Total Reflection ◽  
Confocal Raman Microscopy ◽  
Liquid Droplets ◽  
Pharmaceutical Ingredients ◽  
Depth Analysis ◽  
Ft Ir ◽  
Confocal Raman ◽  
The Difference

We demonstrated the difference in the distribution state of pharmaceutical ingredients between tacrolimus (TCR) original ointment and six kinds of generic medicines. Two-dimensional imaging and depth analysis using attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy and confocal Raman microscopy were used, in addition to the evaluation of pharmaceutical properties, including spreading properties, rheological properties, and amount of solvent. The solvents, such as propylene carbonate and triacetin, in TCR ointments formed liquid droplets and dispersed in hydrocarbon oils. Waxes, white beeswax and beeswax, formed other domains. Confocal Raman microscopy could detect liquid droplet size without coalescence of that on germanium or glass surfaces. The combination of ATR FT-IR and confocal Raman imaging would be a powerful tool to reveal the size and shape of liquid droplets of pharmaceutical ingredients in semisolid formulations.

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