Molecular Dynamics Simulation on Effect of Nanoparticle Aggregation on Transport Properties of a Nanofluid1

2012 ◽  
Vol 3 (2) ◽  
Author(s):  
Hongbo Kang ◽  
Yuwen Zhang ◽  
Mo Yang ◽  
Ling Li
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Transport Properties ◽  
Periodic Boundary Condition ◽  
Md Simulation ◽  
Periodic Boundary ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Nanoparticle Aggregation ◽  
Nanoparticle Cluster

Effect of nanoparticle aggregation on the transport properties that include thermal conductivity and viscosity of nanofluids is studied by molecular dynamics (MD) simulation. Unlike many other MD simulations on nanofluids which have only one nanoparticle in the simulation box with periodic boundary condition, in this work, multiple nanoparticles are placed in the simulation box which makes it possible to simulate the aggregation of the nanoparticles. Thermal conductivity and viscosity of the nanofluid are calculated using Green–Kubo method and results show that the nanoparticle aggregation induces a significant enhancement of thermal conductivity in nanofluid, while the increase of viscosity is moderate. The results also indicate that different configurations of the nanoparticle cluster result in different enhancements of thermal conductivity and increase of viscosity in the nanofluid.

Molecular Dynamics Simulation of Thermal Conductivity and Viscosity of a Nanofluid: Effect of Nanoparticle Aggregation

2011 ◽  
Author(s):  
Hongbo Kang ◽  
Yuwen Zhang ◽  
Mo Yang ◽  
Ling Li
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Thermophysical Properties ◽  
Dynamics Simulation ◽  
Significant Enhancement ◽  
Nanoparticle Aggregation ◽  
Cluster Result ◽  
Non Equilibrium Molecular Dynamics ◽  
Nanoparticle Cluster

Effect of nanoparticle aggregation on the thermal conductivity and viscosity of nanofluids is studied by molecular dynamics simulation in this work. Thermal conductivity and viscosity of the nanofluid are calculated using Green-Kubo method and results show that the nanoparticle aggregation induces a significant enhancement of thermal conductivity in nanofluid, while the increase of viscosity is moderate. The results also indicate that different configurations of the nanoparticle cluster result in different enhancements of thermal conductivity and increase of viscosity in the nanofluid. The differences between equilibrium molecular dynamics (EMD) approach and non-equilibrium molecular dynamics (NEMD) approach in obtaining the thermophysical properties of nanofluids are also discussed.

STUDY OF AFFINITIES BETWEEN SINGLE-WALLED NANOTUBE AND EPOXY RESIN USING MOLECULAR DYNAMICS SIMULATION

2006 ◽  
Vol 05 (01) ◽  
pp. 131-144 ◽  
Author(s):  
JIHUA GOU ◽  
BIN FAN ◽  
GANGBING SONG ◽  
AURANGZEB KHAN
Keyword(s):  
Molecular Dynamics ◽  
Epoxy Resin ◽  
Md Simulation ◽  
Average Distance ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Repulsive Interaction ◽  
Curing Agent ◽  
Single Walled Nanotubes ◽  
Simulation Results

In the processing of carbon nanotube/polymer composites, the interactions between the nanotube and polymer matrix will occur at the molecular level. Understanding their interactions before curing is crucial for nanocomposites processing. In this study, molecular dynamics (MD) simulations were employed to reveal molecular interactions between (10, 10) single-walled nanotube and two kinds of epoxy resin systems. The two kinds of resin systems were EPON 862/EPI-CURE W curing agent (DETDA) and DGEBA (diglycidylether of bisphenol A)diethylenetriamine (DETA) curing agent. The MD simulation results show that the EPON 862, DETDA and DGEBA molecules had strong attractive interactions with single-walled nanotubes and their molecules changed their conformation to align their aromatic rings parallel to the nanotube surface due to π-stacking effect, whereas the DETA molecule had a repulsive interaction with the single-walled nanotubes. The interaction energies of the molecular systems were also calculated. Furthermore, an affinity index (AI) of the average distance between the atoms of the resin molecule and nanotube surface was defined to quantify the affinities between the nanotubes and resin molecules. The MD simulation results show that the EPON 862/EPI-CURE W curing agent system has good affinities with single-walled nanotubes.

Establishing a data-based scattering kernel model for gas–solid interaction by molecular dynamics simulation

2021 ◽  
Vol 928 ◽  
Author(s):  
Zijing Wang ◽  
Chengqian Song ◽  
Fenghua Qin ◽  
Xisheng Luo
Keyword(s):  
Machine Learning ◽  
Molecular Dynamics ◽  
Md Simulation ◽  
Rarefied Gas ◽  
Interaction Model ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Rarefied Gas Flows ◽  
Accommodation Coefficients ◽  
Scattering Kernel

Scattering kernel models for gas–solid interaction are crucial for rarefied gas flows and microscale flows. However, most existing models depend on certain accommodation coefficients (ACs). We propose here to construct a data-based model using molecular dynamics (MD) simulation and machine learning. The gas–solid interaction is first modelled by 100 000 MD simulations of a single gas molecule reflecting on the wall surface, which is fulfilled by GPU parallel technology. The results showed a correlation of the reflection velocity with the incidence velocity in the same direction, and also revealed correlations that may exist in different directions, which are neglected by the traditional gas–solid interaction model. Inspired by the sophisticated Cercignani–Lampis–Lord (CLL) model, two improved scattering kernels were constructed to better reproduce the probability density of velocity determined from MD simulation. The first one adopts variable ACs which depend on the incidence velocity and the second one combines three CLL-like kernels. All the parameters in the improved kernels are automatically chosen by the machine learning method. Compared with the numerical experiments of a molecular beam, the reconstructed scattering kernels are basically consistent with the MD results.

Molecular Dynamics Simulation of Thermal Conductivity of Diamondoid Crystals

2007 ◽  
Vol 1022 ◽  
Author(s):  
Ming Hu ◽  
Sergei Shenogin ◽  
Pawel Keblinski ◽  
Arun Majumdar
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Md Simulations ◽  
Building Blocks ◽  
Dynamics Simulation ◽  
Diamond Structure ◽  
Intramolecular Bonding ◽  
Hydrocarbon Molecules ◽  
Intermolecular Bonding

AbstractHydrocarbon molecules with diamond structure, called diamondoids have gain considerable interest as promising nanoscale building blocks. Very large mismatch between strong, covalent intramolecular bonding and weak intermolecular bonding suggests interesting phonon related properties for diamondoid crystal. We use molecular dynamics (MD) simulations to examine thermal transport of diamondoid crystals. In particular, thermal conductivity of small molecule adamantine and larger molecule pentamantane crystal is studied by equilibrium and non-equilibrium MD. The thermal conductivity of both materials is low, but comparable with that characterizing fullerene crystal.

Study of Helium Bubble Induced Hardening in BCC-Fe by Molecular Dynamics Simulation

2019 ◽  
Vol 944 ◽  
pp. 378-386
Author(s):  
Li Xia Jia ◽  
Xin Fu He ◽  
Shi Wu ◽  
Dong Jie Wang ◽  
Han Cao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Edge Dislocation ◽  
Reasonable Agreement ◽  
Md Simulation ◽  
Md Simulations ◽  
Defect Size ◽  
Dynamics Simulation ◽  
Helium Bubble ◽  
Increasing Temperature ◽  
Critical Resolved Shear Stress

The interaction between an moving edge dislocation and helium bubble was studied in BCC-Fe using Molecular dynamics（MD）simulation. Edge dislocation passed the bubble via cut mechanism. A step with a length of b is left on both sides of the bubble after dislocation left away. The influence of simulation temperature, defect size and He/V ratio in bubble on critical resolved shear stress (CRSS) for dislocation to shear bubble were investigated. The CRSS increases with increasing defect sizes, and decreases with increasing temperature. When He/V ratio is at the range of 0-1, CRSS depends weakly on the He/V ratio. The estimated obstacle strength of helium bubble based on MD simulations is acceptable and reasonable agreement with one deduced from the dispersion barrier-hardening model applied to experimental results.

Synthesis and molecular dynamics simulation of hyperbranched poly(amine-ester)/neodymium nanocomposites

2016 ◽  
Vol 23 (1) ◽  
pp. 53-60
Author(s):  
Zunli Mo ◽  
Xiaobo Zhu ◽  
Yanzhi Liu ◽  
Ruibin Guo
Keyword(s):  
Molecular Dynamics ◽  
Hyperbranched Polymer ◽  
Md Simulation ◽  
Md Simulations ◽  
Canonical System ◽  
Dynamics Simulation ◽  
Static And Dynamic Characteristics ◽  
Transmission Electron ◽  
Hyperbranched Poly ◽  
The Stability

AbstractFully atomistic molecular dynamics (MD) simulations were employed to examine the static and dynamic characteristics of hyperbranched poly(amine-ester) (HPAE). In this work, use of G2, G3, and G4 HPAE as a template and stabilizer to prepare HPAE/neodymium (Nd) nanocomposites was studied. The results of transmission electron microscopy showed that Nd particles were deposited on the surface of HPAE within nanoscales, the size of nanoparticles was uniform, and there was better dispersion with high generation of hyperbranched polymer. Virtual Materiale software was applied to research the MD simulation of HPAE/Nd nanocomposites. The stability of the system and mechanism was studied from the perspective of molecular structure and energy change in canonical system (constant NVT). G4 HPAE is more suitable for use as template and stabilizer in MD simulation, which is consistent with experimental results.

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