Molecular Dynamics Based Analysis of Nucleation and Surface Energy of Droplets in Supersaturated Vapors of Methane and Ethane

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Jadran Vrabec ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Droplet Size ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
First Passage Time ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Critical Droplet

Homogeneous nucleation processes are characterized by the nucleation rate and the critical droplet size. Molecular dynamics simulation is applied for studying homogeneous nucleation during condensation of supersaturated vapors of methane and ethane. The results are compared with the classical nucleation theory (CNT) and the Laaksonen–Ford–Kulmala (LFK) model that introduces the size dependence of the specific surface energy. It is shown for the nucleation rate that the Yasuoka–Matsumoto method and the mean first passage time method lead to considerably differing results. Even more significant deviations are found between two other approaches to the critical droplet size, based on the maximum of the Gibbs free energy of droplet formation (Yasuoka–Matsumoto) and the supersaturation dependence of the nucleation rate (nucleation theorem). CNT is found to agree reasonably well with the simulation results, whereas LFK leads to large deviations at high temperatures.

Molecular Dynamics Based Analysis of Nucleation and Surface Energy of Droplets in Supersaturated Vapors of Methane and Ethane

2008 ◽  
Author(s):  
Jadran Vrabec ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Size Dependence ◽  
Md Simulations ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Specific Surface Energy ◽  
Simulation Results

Molecular dynamics (MD) simulations are applied for studying homogeneous nucleation during condensation of supersaturated vapors of methane and ethane. Nucleation processes are characterized by the nucleation rate, i.e. the number of stable droplets produced per volume and time. Nucleation rates from simulations are compared to the classical nucleation theory (CNT) and a model that introduces a size dependence of the specific surface energy. CNT is found to agree well with the simulation results, deviations are throughout lower than three orders of magnitude.

Molecular Dynamics Simulation of Bubble Nucleation in Superheated Liquid

2010 ◽  
Author(s):  
Chao Liu ◽  
Xiaobo Wu ◽  
Hualing Zhang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Argon Atom ◽  
Bubble Nucleation ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Superheated Liquid ◽  
Classic Nucleation Theory

The bubble homogeneous nucleation in superheated liquid argon is studied by molecular dynamics simulation in NVT ensemble. L-J potential is adopted for the interaction of argon atom. The simulated particle numbers of argon atom is 10976. The non-dimensional size of simulated box is 27.8×27.8×27.8. The initial non-dimensional temperature and density are 0.4 and 0.51 separately. The results show that the bubble homogeneous nucleation is divided into the waiting process, the appearing process of numerous small bubble nucleuses and the aggregation process of small bubble nucleuses. By fitting simulated data, we find that the bubble nucleation rate is eight orders of magnitudes bigger than the result of classic nucleation theory. The bubble nucleation rate increases along with the increasing of density and superheated temperature, which agrees well with one of classic nucleation theory.

Molecular Dynamics Simulation of Three-Dimensional Heterogeneous Nucleation

2011 ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Three Dimensional ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Supersaturation Ratio ◽  
Seed Growth ◽  
Thermodynamic Conditions

Nanoparticle growth based on three-dimensional heterogeneous nucleation was simulated by classical molecular dynamics. To collectively observe the effects of the dimension of seeds and thermodynamic conditions, seed size and system supersaturation ratio were the factors that were examined to see if they influenced the nucleation rates. Two stages were found to exist within the system, where the first stage is from the seed growth and the second from homogeneous nucleation. The Yasuoka-Matsumoto method was used to calculate the rates. The homogeneous nucleation characteristics coincided with the classical nucleation theory, but heterogeneous nucleation showed an irregular form, which at the current state cannot not be fully understood. Kinetic analysis was also performed to calculate the critical nucleus size and better understand the seed growth characteristics. All in all, the seed effects were insignificant to the overall nucleation characteristics for this system.

Molecular Dynamics Simulation of Nano Cluster-Seed Effects on Heterogeneous Nucleation

2009 ◽  
Author(s):  
Donguk Suh ◽  
Seung-chai Jung ◽  
Woong-sup Yoon
Keyword(s):  
Molecular Dynamics ◽  
Heterogeneous Nucleation ◽  
Three Dimensional ◽  
Seed Mass ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Supersaturation Ratio ◽  
Order Of Magnitude ◽  
Nano Cluster

A three-dimensional heterogeneous nucleation is simulated by classical molecular dynamics, where the Lennard-Jones gas and solid nano cluster-seed molecules have argon and aluminum properties, respectively. All dimensions of the wall are periodic and a soft core carrier gas within the system controls the temperature rise induced by latent heat of condensation. There are three shapes of cluster-seeds being cube, rod, and sphere, three classes of masses, and the simulation took place under nine supersaturation ratios, making a total of 81 calculations. An analysis of variance was performed under a three-way layout to analyze the cluster-seed and supersaturation ratio effects on the system. For supersaturation ratios above the critical value nucleation rates were evaluated, below growth rates, and overall liquefaction rates were each defined and calculated. Results show that the supersaturation ratio dominantly controls all rates, but seed characteristics are important for the growth of the largest cluster under the critical supersaturation ratio. Overall liquefaction increases subject to an escalation of supersaturation ratio and seed mass. However, the significance of the supersaturation ratio for overall liquefaction suggests that thermal diffusion is more dominant than mass interactions for this system. Homogeneous characteristics are also compared with the heterogeneous system to find that though nucleation may occur for an insufficient supersaturation ratio when a seed is within the system, the addition of a seed does not in fact facilitate the increase in rates of the phenomena at high supersaturation ratios. Finally a comparison with the classical nucleation theory asserts a 3 to 4 order of magnitude difference, which is within the lines of deviation when it comes to theory and molecular simulations.

A study to investigate phase transitions and nucleation kinetics of nickel and copper

2016 ◽  
Vol 30 (11) ◽  
pp. 1650129 ◽  
Author(s):  
F. A. Celik ◽  
A. K. Yildiz
Keyword(s):  
Molecular Dynamics ◽  
Orientational Order ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Structural Development ◽  
Nucleation Kinetics ◽  
Embedded Atom ◽  
Bond Orientational Order ◽  
Kinetics Of

In this study, we investigate the homogeneous nucleation kinetics of copper and nickel system during cooling process using molecular dynamics simulation (MDS). The calculation is carried out for a different number of atoms consisting of 500, 2048, 8788 and 13,500 based on embedded atom method (EAM). It is observed that the melting points for the both model increases with increasing the size of systems (i.e. the number of atoms) as expected from Parrinello and Rahman MD method. The interfacial free energies and critical nucleus radius of nickel and copper are also determined by molecular dynamics, and the results are consistent with the classical nucleation theory. The structural development and phase transformation are also determined from the radial distribution function (RDF) and local bond orientational order parameters (LBOO).

Analytical Investigation on the Homogeneous Nucleation in a Mono-Component and Bi-Component Droplet

2019 ◽  
Author(s):  
Xi Xi ◽  
Hong Liu ◽  
Chang Cai ◽  
Ming Jia ◽  
Weilong Zhang
Keyword(s):  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Ambient Pressure ◽  
Analytical Investigation ◽  
Bubble Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Liquid Temperature ◽  
Wide Range ◽  
Good Agreement

Abstract The work attempts to analyze the performance of homogeneous nucleation by using the non-equilibrium thermodynamics theory and the classical nucleation theory. A nucleation rate graph was constructed under a wide range of operating temperature conditions. The results indicate that the superheat limit temperature (SLT) estimated by the modified homogeneous nucleation sub-model is in good agreement with the experimental results. The nucleation rate increases exponentially with the liquid temperature rise when the liquid temperature exceeds the SLT under atmospheric pressure. The superheated temperature needed to trigger the bubble nucleation decreases with the elevated ambient pressure.

Homogeneous nucleation of NaCl in supersaturated solutions

2021 ◽  
Author(s):  
Cintia Pulido Lamas ◽  
Jorge R. Espinosa ◽  
María Martín Conde ◽  
Jorge Ramirez ◽  
Pablo Montero de Hijes ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Homogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Approximate Approach ◽  
Seeding Method ◽  
Dynamics Simulations ◽  
Supersaturated Solutions

The Seeding method is an approximate approach to investigate nucleation that combines molecular dynamics simulations with classical nucleation theory. This technique has been successfully implemented in a broad range of...

Molecular Dynamics Simulation of Homogeneous Nucleation and Growth of Supercooled Al Liquid

NANO ◽  
2021 ◽  
Author(s):  
Tao Zhou ◽  
Zhengping Bao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Nucleation Rate ◽  
First Passage Time ◽  
Spherical Shape ◽  
Passage Time ◽  
Dynamics Simulation ◽  
Spontaneous Nucleation ◽  
Different Shapes ◽  
The Mean

Molecular dynamics simulation is used to study the spontaneous nucleation and solidification of Al liquid. According to the mean first-passage time (MFPT), the critical crystal nucleus size at 31.6% undercooling is 152 atoms, the nucleation rate is [Formula: see text][Formula: see text]m[Formula: see text][Formula: see text]s[Formula: see text]. The nucleation rate obtained by the survival probability (SP) is [Formula: see text][Formula: see text]m[Formula: see text][Formula: see text]s[Formula: see text], which is very consistent with the result obtained by MFPT. Using Johnson–Mehl–Avrami (JMA) law to analyze the growth of the two extreme conditions in the experiment, the system with the smallest average atomic volume (Run38) grows faster than the system with the largest volume (Run73). In terms of microstructure, Run38 is a lamellar (LAM) structure, and Run73 is a complex polycrystalline structure accompanied by five-fold twinning (FFT). The shapes of clusters in a given range (5–10,000 atoms) during solidification in 100 experiments were counted. The results show that no clusters are perfectly spherical, but ellipsoids are of different shapes, and the larger the ellipsoid size, the closer to a spherical shape.

Kinetic Analysis on Nanoparticle Condensation by Molecular Dynamics

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Free Energy ◽  
Kinetic Analysis ◽  
Seed Size ◽  
Homogeneous Nucleation ◽  
Cluster Formation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Seed Particle

Condensation on a cubic seed particle was simulated by classical molecular dynamics (MD). Seed size and supersaturation ratio of the system were the factors that were examined in order to observe the effects of the dimension of seeds and thermodynamic conditions. Two stages of nucleation were observed in the phenomenon, where the first stage is from the seed growth and the second from homogeneous nucleation. Therefore, the nucleation rate and growth rate were each calculated by the Yasuoka–Matsumoto (YM) method. As the seed size increased, the growth rate decreased, but there was no clear seed influence on the homogeneous nucleation characteristics. Besides, the classical nucleation theory (CNT), cluster formation free energy and kinetic analysis were conducted. The free energy in the exponential term of the classical nucleation theory and that obtained from the cluster formation free energy showed different characteristics.

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