scholarly journals Nonequilibrium Molecular Dynamics Simulations of Coal Ash

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 11
Author(s):  
Shi Yu ◽  
Ruizhi Chu ◽  
Xiao Li ◽  
Guoguang Wu ◽  
Xianliang Meng
Keyword(s):  
Molecular Dynamics ◽  
Temperature Dependence ◽  
Einstein Equation ◽  
Md Simulation ◽  
Coal Ash ◽  
Nonequilibrium Molecular Dynamics ◽  
Strong Temperature Dependence ◽  
Coal Ashes ◽  
Simulation Results ◽  
Dynamics Simulations

Both molecular dynamics (MD) and nonequilibrium molecular dynamics (NEMD) simulations were performed to simulate coal ashes using the Guillot-Sator model in this work. The structural and transport properties of coal ashes at high temperatures have been obtained. Superheating of coal ash system with anorthite crystal structure initial configuration has been observed for MD simulation which explains the discrepancy between previous MD simulation results and FactSage thermochemical calculations. The fluxing effects of both calcium oxide and sodium oxide have been investigated systematically through MD and NEMD simulations. Moreover, the viscosities of coal ash systems have been computed by two methods: (1) Stokes-Einstein equation; (2) NEMD simulations. Estimations of viscosities for various coal ash systems based on Stokes-Einstein equation exhibit a strong temperature dependence of viscosity, which agrees with previous experimental results. On the other hand, NEMD simulation results that showed a strong shear-thinning feature, failed to reproduce this strong temperature dependence of viscosity, possibly due to the short simulation time. Nevertheless, NEMD simulations not only provide us detailed information about atoms dynamics under shear, but also allow us to model the coal ash system far from equilibrium which cannot be accessed by thermodynamics calculation using software like FactSage.

scholarly journals Effective Determination of Coexistence Curves using Reversible-Scaling Molecular Dynamics Simulations

2000 ◽  
Vol 653 ◽  
Author(s):  
Maurice de Koning ◽  
Alex Antonelli ◽  
Sidney Yip
Keyword(s):  
Molecular Dynamics ◽  
Md Simulation ◽  
Melting Curve ◽  
Coexistence Curve ◽  
Nonequilibrium Molecular Dynamics ◽  
Computational Cell ◽  
Clapeyron Equation ◽  
Lennard Jones ◽  
Dynamics Simulations

AbstractWe present a simulation technique that allows the calculation of a phase coexistence curve from a single nonequilibrium molecular dynamics (MD) simulation. The approach is based on the simultaneous simulation of two coexisting phases, each in its own computational cell, and the integration of the relevant Clausius-Clapeyron equation starting from a known coexistence point. As an illustration of the effectiveness of our approach we apply the method to explore the melting curve in the Lennard-Jones phase diagram.

Molecular Dynamics Simulations of Uniaxial Compression of Ceria and Gadolinia Doped Ceria

2010 ◽  
Vol 152-153 ◽  
pp. 1180-1183
Author(s):  
Yun Jun Chen ◽  
Yi Sun ◽  
Zhi Wei Cui
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Elastic Modulus ◽  
Temperature Dependence ◽  
Molecular Dynamics Simulations ◽  
Uniaxial Compression ◽  
Doped Ceria ◽  
Higher Temperature ◽  
Simulation Results ◽  
Dynamics Simulations

In this paper, we investigate the mechanical properties of ceria and gadolinia doped ceria by molecular dynamics simulations. The doped concentrations and temperature dependence of yield stress and elastic modulus have been evaluated via uniaxial compression. Simulation results reveal that such properties decrease dramatically with higher temperature and doped content. In addition, the attenuated effect of doped content is more significant than that of temperature.

scholarly journals CO2 and SO2 Pressure-Driven Adsorption by 3D Graphene Nanoslits: A Molecular Dynamics Study

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Amanda Caroline Borges ◽  
Mateus H. Köhler ◽  
José Rafael Bordin
Keyword(s):  
Molecular Dynamics ◽  
Membrane Properties ◽  
Nonequilibrium Molecular Dynamics ◽  
Anthropogenic Effect ◽  
Bulk State ◽  
3D Graphene ◽  
Gas Molecules ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Pollutant Gases

Nonequilibrium molecular dynamics simulations are employed to study the adsorption and blockage properties of a 3D graphene membrane. Specifically, we are interested in the mixtures of carbon dioxide (CO2) and sulfur dioxide (SO2), two of the most relevant pollutant gases for the anthropogenic effect in global warming. We simulate cases with distinct proportion of gases in the mixture. Our results indicate that the 3D graphene slit is able to absorb 90% or more of the gas molecules. We show that this property came from the fact that both CO2 and SO2 molecules are attracted by the graphene pore, which compensates for the entropic barrier that exists when leaving the bulk state to the confined state. Also, the simulation results show that changing the interlayer separation between the graphene sheets is possible in order to change the membrane properties, from absorbent to blockage. These results help to understand the properties of 3D graphene nanoslits and their application as highly selective filters.

Computational Diagnostics for Detecting Phase Transitions During Nanoindentation

1992 ◽  
Vol 291 ◽  
Author(s):  
Susanne M. Lee ◽  
Carol G. Hoover ◽  
Jeffrey S. Kallman ◽  
William G. Hoover ◽  
Anthony J. De Groot ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Phase Transitions ◽  
Yield Strength ◽  
Amorphous Silicon ◽  
Diagnostic Tool ◽  
Structural Changes ◽  
Nonequilibrium Molecular Dynamics ◽  
Simulation Results ◽  
Diffraction Patterns ◽  
Dynamics Simulations

ABSTRACTWe study nanoindentation of silicon using nonequilibrium molecular dynamics simulations with up to a million particles. Both crystalline and amorphous silicon samples are considered. We use computational diffraction patterns as a diagnostic tool for detecting phase transitions resulting from structural changes. Simulations of crystalline samples show a transition to the amorphous phase in a region a few atomic layers thick surrounding the lateral faces of the indentor, as has been suggested by experimental results. Our simulation results provide estimates for the yield strength (nanohardness) of silicon for a range of temperatures.

Elastic Properties of Carbon Nanotubes in the Radial Direction

2005 ◽  
Vol 219 (2) ◽  
pp. 73-88 ◽  
Author(s):  
Guoxin Cao ◽  
Yuye Tang ◽  
Xi Chen
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Elastic Properties ◽  
Md Simulation ◽  
Radial Strain ◽  
Radial Pressure ◽  
Multi Walled Carbon Nanotubes ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Walled Cnts

A systematic numerical and theoretical analysis is carried out to study the radial elastic properties of single-walled, double-walled, and multi-walled carbon nanotubes (CNTs). The molecular dynamics simulations are used to study CNTs under radial pressure, and the deformation mechanisms of CNTs are explored by analysing the relationship between radial strain and strain energy. A parallel continuum model based on plane strain theory is verified by molecular dynamics (MD) simulation results in single-walled and double-walled CNTs, and extended into multi-walled CNTs that are computationally expensive for MD simulation. Good agreement is found between MD simulation results and continuum studies. The effective radial elastic moduli of CNTs are presented as a function of tube radii and the number of CNT layers. The results of this paper may be useful when analysing the mechanical integrity of CNT nanocomposites and nanofluidic components.

Seawater desalination using pillared graphene as a novel nano-membrane in reverse osmosis process: nonequilibrium MD simulation study

2018 ◽  
Vol 20 (34) ◽  
pp. 22241-22248 ◽  
Author(s):  
Sayyed Jalil Mahdizadeh ◽  
Elaheh K. Goharshadi ◽  
Golnoosh Akhlamadi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Reverse Osmosis ◽  
Simulation Study ◽  
Md Simulation ◽  
Nonequilibrium Molecular Dynamics ◽  
Seawater Desalination ◽  
Dynamics Simulations ◽  
Graphene Nanostructures

Herein, the applicability and efficiency of two types of pillared graphene nanostructures, namely, (6,6)@G and (7,7)@G, were investigated as membranes in reverse osmosis seawater desalination using extensive nonequilibrium molecular dynamics simulations.

Adsorption behavior of Cs+ ions to vermiculite demonstrated by molecular dynamics simulations

2018 ◽  
Vol 28 (01n02) ◽  
pp. 1-5
Author(s):  
Akira Takeuchi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Md Simulation ◽  
Constant Pressure ◽  
Md Simulations ◽  
Kinetic Process ◽  
Adsorption Behavior ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Cs Ions

The present paper discusses the simulation results, performed by classical molecular dynamics (MD), for vermiculite. The kinetic process of the [Formula: see text] ions in water that are adsorbed into vermiculite [Formula: see text] was investigated with classical MD simulations utilizing Coulomb and Born–Mayer–Huggins potentials. A monoclinic vermiculite crystal with a [Formula: see text] supercell was placed into 8461 molecules of water to form a rectangular supercell of [Formula: see text]. The water was placed into contact with both sides of the [Formula: see text]–[Formula: see text] planes of the vermiculite crystal, along the [Formula: see text]-axis only. The rectangular supercells, which were prepared with the vermiculite in water with and without an additional 200 [Formula: see text] ions, were simulated. The MD conditions included a constant pressure ensemble for 1 ps at a constant step of 0.1 fs. The results revealed an increase in the distances of the [Formula: see text] layers at the interface between the vermiculite and water. This increase in the separation of the [Formula: see text] layers was suitable for the uptake of [Formula: see text] ions by the vermiculite. The accelerated MD simulation which replaced the interfacial [Formula: see text] ions with [Formula: see text] ions tended to include the [Formula: see text] ions into the vermiculite by excluding the [Formula: see text] ions.

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