On the maximal spreading of impacting compound drops

2018 ◽  
Vol 854 ◽  
Author(s):  
H.-R. Liu ◽  
C.-Y. Zhang ◽  
P. Gao ◽  
X.-Y. Lu ◽  
H. Ding
Keyword(s):  
Flow Regime ◽  
Weber Number ◽  
Volume Fraction ◽  
Numerical Results ◽  
Diffuse Interface ◽  
Spreading Dynamics ◽  
The One ◽  
Compound Drops ◽  
The Impact ◽  
Good Agreement

We numerically study the impact of a compound drop on a hydrophobic substrate using a ternary-fluid diffuse-interface method, aiming to understand how the presence of the inner droplet affects the spreading dynamics and maximal spreading of the compound drop. First, it is interesting to see that the numerical results for an impacting pure drop agree well with the universal rescaling of maximal spreading ratio proposed by Lee et al. (J. Fluid Mech., vol. 786, 2016, R4). Second, two flow regimes have been identified for an impacting compound drop: namely jammed spreading and joint rim formation. The maximal spreading ratio of the compound drop is found to depend on the volume fraction of the inner droplet $\unicode[STIX]{x1D6FC}$, the surface tension ratio $\unicode[STIX]{x1D6FE}$, the Weber number and the flow regime. Moreover, we propose a universal rescaling of maximal spreading ratio for compound drops, by integrating the one for pure drops with a corrected Weber number that takes $\unicode[STIX]{x1D6FC}$, $\unicode[STIX]{x1D6FE}$ and the flow regime into account. The predictions of the universal rescaling are in good agreement with the numerical results for impacting compound drops.

scholarly journals On the effectiveness of communication strategies as non-pharmaceutical interventions to tackle epidemics

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0257995
Author(s):  
Alejandro Bernardin ◽  
Alejandro J. Martínez ◽  
Tomas Perez-Acle
Keyword(s):  
Infectious Disease ◽  
Communication Strategies ◽  
Public Affairs ◽  
The Other ◽  
Agent Based ◽  
Spreading Dynamics ◽  
The One ◽  
The Impact ◽  
Adequate Management ◽  
Pharmaceutical Interventions

When pharmaceutical interventions are unavailable to deal with an epidemic outbreak, adequate management of communication strategies can be key to reduce the contagion risks. On the one hand, accessibility to trustworthy and timely information, whilst on the other, the adoption of preventive behaviors may be both crucial. However, despite the abundance of communication strategies, their effectiveness has been scarcely evaluated or merely circumscribed to the scrutiny of public affairs. To study the influence of communication strategies on the spreading dynamics of an infectious disease, we implemented a susceptible-exposed-infected-removed-dead (SEIRD) epidemiological model, using an agent-based approach. Agents in our systems can obtain information modulating their behavior from two sources: (i) through the local interaction with other neighboring agents and, (ii) from a central entity delivering information with a certain periodicity. In doing so, we highlight how global information delivered from a central entity can reduce the impact of an infectious disease and how informing even a small fraction of the population has a remarkable impact, when compared to not informing the population at all. Moreover, having a scheme of delivering daily messages makes a stark difference on the reduction of cases, compared to the other evaluated strategies, denoting that daily delivery of information produces the largest decrease in the number of cases. Furthermore, when the information spreading relies only on local interactions between agents, and no central entity takes actions along the dynamics, then the epidemic spreading is virtually independent of the initial amount of informed agents. On top of that, we found that local communication plays an important role in an intermediate regime where information coming from a central entity is scarce. As a whole, our results highlight the importance of proper communication strategies, both accurate and daily, to tackle epidemic outbreaks.

scholarly journals Experimental and Simulation Research on the Influence of Stirring Parameters on the Distribution of Particles in Cast SiCp/A356 Composites

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Zhiyong Yang ◽  
Like Pan ◽  
Jianmin Han ◽  
Zhiqiang Li ◽  
Jialin Wang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Fluid Velocity ◽  
Axial Flow ◽  
Particle Dispersion ◽  
Numerical Results ◽  
Shearing Force ◽  
Simulation Research ◽  
Velocity Magnitude ◽  
Stirring Time ◽  
Good Agreement

Achieving the uniform distribution of reinforcement particles in MMCs is very important for the effect of stirring parameters and the flow action of the melt, which should be known. The effect of stirring parameters on the distribution of SiC particles in SiCp/A356 composites was studied by the experimental and numerical methods in this paper. The experimental results show the SiC distribution with different stirring parameters. In addition, the effects of the fluid velocity and volume fraction of SiC particle at different position of crucible on the SiC distribution were analyzed by numerical simulation. The velocity magnitude, axial velocity, and radial velocity were analyzed to explain theoretically the particle distribution. The shearing force, moments, and stirring power of the stirring rod were simulated based on CFD code. The numerical results show that the stirring temperature is lower, the shearing force is greater, the stirring time is longer, and particle dispersion gets better. On the other hand, the higher the stirring speed is, the more uniform the radial and axial flow are, and the better the particles were dispersed. The numerical results were in good agreement with the experimental data.

Numerical Simulation of Droplet Flows and Evaluation of Interfacial Area

2002 ◽  
Vol 124 (3) ◽  
pp. 576-583 ◽  
Author(s):  
T. Watanabe ◽  
K. Ebihara
Keyword(s):  
Lattice Boltzmann ◽  
Weber Number ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Force Balance ◽  
Two Phase ◽  
Critical Weber Number ◽  
Boltzmann Method ◽  
Droplet Flows ◽  
Good Agreement

Droplet flows with coalescence and breakup are simulated numerically using the lattice Boltzmann method. It is shown that the rising velocities are in good agreement with those obtained by the force balance and the empirical correlation. The breakup of droplets after coalescence is simulated well in terms of the critical Weber number. A numerical method to evaluate the interfacial area and the volume fraction in two-phase flows is proposed. It is shown that the interfacial area corresponds to the shape, the number and the size of droplets, and the proposed method is effective for numerical evaluation of interfacial area even if the interface changes dynamically.

scholarly journals Quantifying the Impact of the Covid-19 Lockdown Measures on Nitrogen Dioxide Levels throughout Europe

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 131
Author(s):  
Sverre Solberg ◽  
Sam-Erik Walker ◽  
Philipp Schneider ◽  
Cristina Guerreiro
Keyword(s):  
Nitrogen Dioxide ◽  
Temporal Trends ◽  
Measurement Data ◽  
Additive Model ◽  
Generalised Additive Model ◽  
The Difference ◽  
The One ◽  
The Impact ◽  
Good Agreement ◽  
Model Approach

In this paper, the effect of the lockdown measures on nitrogen dioxide (NO2) in Europe is analysed by a statistical model approach based on a generalised additive model (GAM). The GAM is designed to find relationships between various meteorological parameters and temporal metrics (day of week, season, etc.) on the one hand and the level of pollutants on the other. The model is first trained on measurement data from almost 2000 monitoring stations during 2015–2019 and then applied to the same stations in 2020, providing predictions of expected concentrations in the absence of a lockdown. The difference between the modelled levels and the actual measurements from 2020 is used to calculate the impact of the lockdown measures adjusted for confounding effects, such as meteorology and temporal trends. The study is focused on April 2020, the month with the strongest reductions in NO2, as well as on the gradual recovery until the end of July. Significant differences between the countries are identified, with the largest NO2 reductions in Spain, France, Italy, Great Britain and Portugal and the smallest in eastern countries (Poland and Hungary). The model is found to perform best for urban and suburban sites. A comparison between the found relative changes in urban surface NO2 data during the lockdown and the corresponding changes in tropospheric vertical NO2 column density as observed by the TROPOMI instrument on Sentinel-5P revealed good agreement despite substantial differences in the observing method.

scholarly journals Directed flow of D mesons at RHIC and LHC: non-perturbative dynamics, longitudinal bulk matter asymmetry and electromagnetic fields

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Lucia Oliva ◽  
Salvatore Plumari ◽  
Vincenzo Greco
Keyword(s):  
Electromagnetic Field ◽  
Diffusion Coefficient ◽  
D Mesons ◽  
Directed Flow ◽  
Charm Quarks ◽  
Longitudinal Asymmetry ◽  
Initial Vorticity ◽  
The One ◽  
The Impact ◽  
Good Agreement

Abstract We present a study of the directed flow v1 for D mesons discussing both the impact of initial vorticity and electromagnetic field. Recent studies predicted that v1 for D mesons is expected to be surprisingly much larger than that of light charged hadrons; we clarify that this is due to a different mechanism leading to the formation of a directed flow with respect to the one of the bulk matter at both relativistic and non-relativistic energies. We point out that the very large v1 for D mesons can be generated only if there is a longitudinal asymmetry between the bulk matter and the charm quarks and if the latter have a large non-perturbative interaction in the QGP medium. A quite good agreement with the data of STAR and ALICE is obtained if the diffusion coefficient able to correctly predict the RAA(pT), v2(pT) and v3(pT) of D meson is employed. Furthermore, the mechanism for the build-up of the v1(y) is associated to a quite small formation time that can be expected to be more sensitive to the initial high-temperature dependence of the charm diffusion coefficient.We discuss also the splitting of v1 for D0 and $$ {\overline{D}}^0 $$ D ¯ 0 due to the electromagnetic field that is again much larger than the one observed for charged particles and in agreement with the data by STAR that have however still error bars comparable with the splitting itself, while at LHC standard electromagnetic profile assuming a constant conductivity is not able to account for the huge splitting observed.

scholarly journals Effect of Blade Profile on the Performance of Wells Turbine under Unidirectional Sinusoidal and Real Sea Flow Conditions

2007 ◽  
Vol 2007 ◽  
pp. 1-9 ◽  
Author(s):  
A. Thakker ◽  
R. Abdulhadi
Keyword(s):  
Unsteady Flow ◽  
Numerical Results ◽  
Blade Profile ◽  
Flow Conditions ◽  
Wells Turbine ◽  
Hysteretic Characteristics ◽  
The One ◽  
Good Agreement

This paper presents the effect of blade profile and rotor solidity on the performance of Wells turbine operating under unidirectional unsteady flow conditions. In the study, four kinds of blade profile were selected, that is, NACA0020, NACA0015, CA9, and HSIM 15-262123-1576. The experiments have been carried out for two solidities,σ= 0.48 andσ= 0.64, under sinusoidal and irregular unsteady flow conditions based on Irish waves (site2). As a result, it was found that the preferable rotor geometry is the one with blade profile of CA9 with solidityσ= 0.64. In addition, the effect of blade profile and rotor solidity on hysteretic characteristics of the turbine has been clarified experimentally and it was found to be in good agreement qualitatively when compared to numerical results (Setoguchi et al. (2003)).

Numerical Study of Liquid-Liquid Vertical Dispersed Flows

2012 ◽  
Author(s):  
Kofi Freeman K. Adane ◽  
Syed Imran A. Shah ◽  
R. Sean Sanders
Keyword(s):  
Turbulent Flows ◽  
Volume Fraction ◽  
Numerical Study ◽  
Continuous Phase ◽  
Numerical Results ◽  
Mean Velocity ◽  
Ansys Cfx ◽  
Oil In Water ◽  
Dispersed Flows ◽  
Good Agreement

Numerical simulations of liquid-liquid dispersed flow in a vertical pipe (38mm) have been carried out using the two-fluid approach implemented in a commercial CFD code, ANSYS CFX. A dispersion of oil in water (where water is the continuous phase) was studied. Both fluids were considered as turbulent flows. The k-ε model was used for the continuous phase, with the eddy viscosity of the dispersed phase estimated from that of the continuous phase. A comparison of the present numerical results with previous experimental and numerical results in terms of volume fraction, mean velocity and turbulent kinetic energy is discussed. In general, good agreement between the simulation results and experimental measurements was observed.

scholarly journals Investigation on Hydraulic Characteristics of Turbine-Type Manhole Cover

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1530
Author(s):  
Leilei Fan ◽  
Hang Zhan ◽  
Boran Zhang ◽  
Zhiren Bao ◽  
Wuyi Wan
Keyword(s):  
Flow Regime ◽  
Water Surface ◽  
Volume Fraction ◽  
Free Flow ◽  
Urban Drainage ◽  
Hydraulic Characteristics ◽  
Physical Experiments ◽  
Flow Field Characteristics ◽  
Free Drainage ◽  
Good Agreement

Manhole cover is an important device of urban drainage infrastructures. The hydraulic characteristics of turbine-type manhole covers were studied through numerical simulations and physical experiments. The flow field characteristics and water surface were investigated. The drainage process is divided into two parts: free flow regime and submerged flow regime. Numerical and experimental results are in good agreement. It is indicated that the depth of water is constant in the later stage of unstable free drainage, while it changes with time and determines the discharge under the subsequent unstable submerged drainage condition. The influence of the depth on discharge is mainly reflected in the submerged drainage stage, in which period the discharge is linearly related to the square root of the depth. While in free flow regime, the discharge is affected by volume fraction of water with second order. The correlation between the depth and the discharge in the process of submerged flow is proposed based on dimensional harmony principle. With the characteristic of massive discharge, the design of turbine-type manhole cover provides one more choice in urban drainage construction.

Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

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