Crown evolution kinematics of a camellia oil droplet impacting on a liquid layer

2021 ◽  
Author(s):  
Zhongyu Shi ◽  
Guanqing Wang ◽  
Xiangxiang Chen ◽  
Lu Wang ◽  
Ning Ding ◽  
...  
Keyword(s):  
Liquid Layer ◽  
Velocity Ratio ◽  
Water Layer ◽  
Theoretical Models ◽  
Immiscible Liquid ◽  
Droplet Impact ◽  
Camellia Oil ◽  
Oil Droplet ◽  
Spreading Velocity ◽  
Average Spreading

Abstract The phenomenon of droplet impact on the immiscible liquid is encountered in a variety of scenarios in nature and industrial production. Despite the exhaustive researches, it is not fully clear how the immiscibility of the droplet with impact liquid affects the crown evolution. The present work experimentally investigates the evolution kinematics of crown formed by a normal impact of camellia oil droplet on immiscible water layer. Based on discussion of dynamic impact behaviors for three critical Weber numbers (We), the radius of crown and its average spreading velocity are compared with those of previous theoretical models to discuss their applicability to the immiscible liquid. The evolution kinematics (morphology and velocity) are analyzed by considering the effects of We and layer thickness. Furthermore, the ability of crown expansion in radical and vertical directions is characterized by a velocity ratio. The results show that our experimental crown radius still follows a square-root function of evolution time, which agrees with the theoretical predictions. The dimensionless average spreading velocity decreases with We and follows a power-law, while the dimensionless average rising velocity remains constant. The velocity ratio is shown to be linearly increasing with We, demonstrating that the rising movement in crown evolution gradually enhances with We. These results are helpful for further investigation on the droplet impact on immiscible liquid layer.

Field induced anomalous spreading, oscillation, ejection, spinning, and breaking of oil droplets on a strongly slipping water surface

2017 ◽  
Vol 199 ◽  
pp. 115-128 ◽  
Author(s):  
Sunny Kumar ◽  
Bhaskarjyoti Sarma ◽  
Ahsok Kumar Dasmahapatra ◽  
Amaresh Dalal ◽  
Dipankar Narayan Basu ◽  
...  
Keyword(s):  
Electric Field ◽  
Water Layer ◽  
Theoretical Models ◽  
Copper Anode ◽  
Lower Field ◽  
Oil Droplet ◽  
Platinum Cathode ◽  
P Application ◽  
Oil Water ◽  
Rotational Motions

Application of an electric field on an oil droplet floating on the surface of a deionized water bath showed interesting motions such as spreading, oscillation, and ejection. The electric field was generated by connecting a pointed platinum cathode at the top of the oil droplet and a copper anode coated with polymer at the bottom of the water layer. The experimental setup mimicked a conventional electrowetting setup with the exception that the oil was spread on a soft and deformable water isolator. While at relatively lower field intensities we observed spreading of the droplet, at intermediate field intensities the droplet oscillated around the platinum cathode, before ejecting out at a speed as high as ∼5 body lengths per second at even stronger field intensities. The experiments suggested that when the electric field was ramped up abruptly to a particular voltage, any of the spreading, oscillation, or ejection motions of the droplet could be engendered at lower, intermediate and higher field intensities, respectively. However, when the field was ramped up progressively by increasing by a definite amount of voltage per unit time, all three aforementioned motions could be generated simultaneously with the increase in the field intensity. Interestingly, when the aforementioned setup was placed on a magnet, the droplet showed a rotational motion under the influence of the Lorentz force, which was generated because of the coupling of the weak leakage current with the externally applied magnetic field. The spreading, oscillation, ejection, and rotation of the droplet were found to be functions of the oil–water interfacial tension, viscosity, and size of the oil droplet. We developed simple theoretical models to explain the experimental results obtained. Importantly, rotating at a higher speed broke the droplet into a number of smaller ones, owing to the combined influence of the spreading due to the centripetal force and the shear at the oil–water interface. While the oscillatory and rotational motions of the incompressible droplet could be employed as stirrers or impellers inside microfluidic devices for mixing applications, the droplet ejection could be employed for futuristic applications such as payload transport or drug delivery.

scholarly journals Perturbation Analysis of a Multiple Layer Guided Love Wave Sensor in a Viscoelastic Environment

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4533 ◽  
Author(s):  
Tao Wang ◽  
Ryan Murphy ◽  
Jing Wang ◽  
Shyam S. Mohapatra ◽  
Subhra Mohapatra ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Liquid Layer ◽  
Perturbation Analysis ◽  
Love Wave ◽  
Low Cost ◽  
Maxwell Model ◽  
Theoretical Models ◽  
Fast Response ◽  
Liquid Environment

Surface acoustic wave sensors have the advantage of fast response, low-cost, and wireless interfacing capability and they have been used in the medical analysis, material characterization, and other application fields that immerse the device under a liquid environment. The theoretical analysis of the single guided layer shear horizontal acoustic wave based on the perturbation theory has seen developments that span the past 20 years. However, multiple guided layer systems under a liquid environment have not been thoroughly analyzed by existing theoretical models. A dispersion equation previously derived from a system of three rigidly coupled elastic mass layers is extended and developed in this study with multiple guided layers to analyze how the liquid layer’s properties affect the device’s sensitivity. The combination of the multiple layers to optimize the sensitivity of an acoustic wave sensor is investigated in this study. The Maxwell model of viscoelasticity is applied to represent the liquid layer. A thorough analysis of the complex velocity due to the variations of the liquid layer’s properties and thickness is derived and discussed to optimize multilayer Surface acoustic wave (SAW) sensor design. Numerical simulation of the sensitivity with a liquid layer on top of two guided layers is investigated in this study as well. The parametric investigation was conducted by varying the thicknesses for the liquid layer and the guided layers. The effect of the liquid layer viscosity on the sensitivity of the design is also presented in this study. The two guided layer device can achieve higher sensitivity than the single guided layer counterpart in a liquid environment by optimizing the second guided layer thickness. This perturbation analysis is valuable for Love wave sensor optimization to detect the liquid biological samples and analytes.

Electrophoresis of dielectric and immiscible-liquid-layer-encapsulated colloids in aqueous media

2020 ◽  
Vol 102 (4) ◽  
Author(s):  
Binod Kumar ◽  
Simanta De ◽  
Partha P. Gopmandal ◽  
R. K. Sinha ◽  
H. Ohshima
Keyword(s):  
Liquid Layer ◽  
Aqueous Media ◽  
Immiscible Liquid

scholarly journals Biogenic gradients in algal density affect the emergent properties of spatially self-organized mussel beds

2014 ◽  
Vol 11 (96) ◽  
pp. 20140089 ◽  
Author(s):  
Quan-Xing Liu ◽  
Ellen J. Weerman ◽  
Rohit Gupta ◽  
Peter M. J. Herman ◽  
Han Olff ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Water Layer ◽  
Theoretical Models ◽  
Emergent Properties ◽  
Stable States ◽  
Mussel Beds ◽  
Self Organized ◽  
Proposed Model ◽  
Secondary Productivity

Theoretical models highlight that spatially self-organized patterns can have important emergent effects on the functioning of ecosystems, for instance by increasing productivity and affecting the vulnerability to catastrophic shifts. However, most theoretical studies presume idealized homogeneous conditions, which are rarely met in real ecosystems. Using self-organized mussel beds as a case study, we reveal that spatial heterogeneity, resulting from the large-scale effects of mussel beds on their environment, significantly alters the emergent properties predicted by idealized self-organization models that assume homogeneous conditions. The proposed model explicitly considers that the suspended algae, the prime food for the mussels, are supplied by water flow from the seaward boundary of the bed, which causes in combination with consumption a gradual depletion of algae over the simulated domain. Predictions of the model are consistent with properties of natural mussel patterns observed in the field, featuring a decline in mussel biomass and a change in patterning. Model analyses reveal a fundamental change in ecosystem functioning when this self-induced algal depletion gradient is included in the model. First, no enhancement of secondary productivity of the mussels comparing with non-patterns states is predicted, irrespective of parameter setting; the equilibrium amount of mussels is entirely set by the input of algae. Second, alternate stable states, potentially present in the original (no algal gradient) model, are absent when gradual depletion of algae in the overflowing water layer is allowed. Our findings stress the importance of including sufficiently realistic environmental conditions when assessing the emergent properties of self-organized ecosystems.

The evolution of under-ice melt ponds, or double diffusion at the freezing point

1974 ◽  
Vol 64 (3) ◽  
pp. 507-528 ◽  
Author(s):  
Seelye Martin ◽  
Peter Kauffman
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Freezing Point ◽  
Salt Water ◽  
Ice Sheet ◽  
Water Layer ◽  
Double Diffusion ◽  
Theoretical Models ◽  
Interfacial Region ◽  
Ice Melt

In an experimental and theoretical study, we model a phenomenon observed in the summer Arctic, where a fresh-water layer at a temperature of 0°C floats both over a sea-water layer at its freezing point and under an ice layer. Our results show that the ice growth in this system takes place in three phases. First, because the fresh-water density decreases upon supercooling, the rapid diffusion of heat relative to salt from the fresh to the salt water causes a density inversion and thereby generates a high Rayleigh number convection in the fresh water. In this convection, supercooled water rises to the ice layer, where it nucleates into thin vertical interlocking ice crystals. When these sheets grow down to the interface, supercooling ceases. Second, the presence of the vertical ice sheets both constrains the temperatureTand salinitysto lie on the freezing curve and allows them to diffuse in the vertical. In the interfacial region, the combination of these processes generates a lateral crystal growth, which continues until a horizontal ice sheet forms. Third, because of theTandsgradients in the sea water below this ice sheet, the horizontal sheet both migrates upwards and increases in thickness. From one-dimensional theoretical models of the first two phases, we find that the heat-transfer rates are 5–10 times those calculated for classic thermal diffusion.

Slender-body theory for the generation of micrometre-sized emulsions through tip streaming

2012 ◽  
Vol 698 ◽  
pp. 423-445 ◽  
Author(s):  
E. Castro-Hernández ◽  
F. Campo-Cortés ◽  
José Manuel Gordillo
Keyword(s):  
Differential Equation ◽  
Velocity Ratio ◽  
Immiscible Liquid ◽  
Boundary Integral ◽  
Slender Body ◽  
Physical Situation ◽  
Dimensionless Numbers ◽  
Third Order ◽  
Simple Method ◽  
Slender Body Theory

AbstractWe report experiments in which a flow rate ${Q}_{i} $ of a fluid with a viscosity ${\ensuremath{\mu} }_{i} $ discharges into an immiscible liquid of viscosity ${\ensuremath{\mu} }_{o} $ that flows in parallel with the axis of the injector. When the outer capillary number verifies the condition ${\mathit{Ca}}_{o} = {\ensuremath{\mu} }_{o} {U}_{o} / \sigma ~\geqslant ~5$, where ${U}_{o} $ and $\sigma $ indicate, respectively, the outer velocity and the interfacial tension coefficient, and if the inner-to-outer velocity ratio is such that ${U}_{i} / {U}_{o} = {Q}_{i} / (\lrm{\pi} {U}_{o} { R}_{i}^{2} )\ll 1$, with ${R}_{i} $ the inner radius of the injector, a jet is formed with the same type of cone–jet geometry as predicted by the numerical results of Suryo & Basaran (Phys. Fluids, vol. 18, 2006, p. 082102). For extremely low values of the velocity ratio ${U}_{i} / {U}_{o} $, we find that the diameter of the jet emanating from the tip of the cone is so small that drops with sizes below $1~\lrm{\ensuremath{\mu}} \mathrm{m} $ can be formed. We also show that, through this simple method, concentrated emulsions composed of micrometre-sized drops with a narrow size distribution can be generated. Moreover, thanks to the information extracted from numerical simulations of boundary-integral type and using the slender-body approximation due to Taylor (Proceedings of the 11th International Congress of Applied Mechanics, Munich, 1964, pp. 790–796), we deduce a third-order, ordinary differential equation that predicts, for arbitrary values of the three dimensionless numbers that control this physical situation, namely, ${\mathit{Ca}}_{o} $, ${\ensuremath{\mu} }_{i} / {\ensuremath{\mu} }_{o} $ and ${U}_{i} / {U}_{o} $, the shape of the jet and the sizes of the drops generated. Most interestingly, the influence of the geometry of the injector system on the jet shape and drop size enters explicitly into the third-order differential equation through two functions that can be easily calculated numerically. Therefore, our theory can be used as an efficient tool for the design of new emulsification devices.

A numerical analysis of air entrapment during droplet impact on an immiscible liquid film

2020 ◽  
Vol 124 ◽  
pp. 103175 ◽  
Author(s):  
Firoozeh Yeganehdoust ◽  
Reza Attarzadeh ◽  
Ida Karimfazli ◽  
Ali Dolatabadi
Keyword(s):  
Numerical Analysis ◽  
Liquid Film ◽  
Immiscible Liquid ◽  
Droplet Impact ◽  
Air Entrapment

scholarly journals Skimming impacts and rebounds of smoothly shaped bodies on shallow liquid layers

2020 ◽  
Vol 124 (1) ◽  
pp. 41-73
Author(s):  
Ryan A. Palmer ◽  
Frank T. Smith
Keyword(s):  
Shallow Water ◽  
Liquid Layer ◽  
Contact Point ◽  
Water Layer ◽  
Small Time ◽  
The Body ◽  
Body Motion ◽  
Water Model ◽  
Initial Contact ◽  
Trailing Edge

Abstract Investigated in this paper is the coupled fluid–body motion of a thin solid body undergoing a skimming impact on a shallow-water layer. The underbody shape (the region that makes contact with the liquid layer) is described by a smooth polynomic curve for which the magnitude of underbody thickness is represented by the scale parameter C. The body undergoes an oblique impact (where the horizontal speed of the body is much greater than its vertical speed) onto a liquid layer with the underbody’s trailing edge making the initial contact. This downstream contact point of the wetted region is modelled as fixed (relative to the body) throughout the skimming motion with the liquid layer assumed to detach smoothly from this sharp trailing edge. There are two geometrical scenarios of interest: the concave case ($$C<0$$ C < 0 producing a hooked underbody) and the convex case ($$C > 0$$ C > 0 producing a rounded underbody). As C is varied the rebound dynamics of the motion are predicted. Analyses of small-time water entry and of water exit are presented and are shown to be broadly in agreement with the computational results of the shallow-water model. Reduced analysis and physical insights are also presented in each case alongside numerical investigations and comparisons as C is varied, indicating qualitative analytical/numerical agreement. Increased body thickness substantially changes the interaction structure and accentuates inertial forces in the fluid flow.

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