Thermal Conductivity of Water/Carbon Nanotube Composite Systems: Insights From Molecular Dynamics Simulations

2009 ◽  
Author(s):  
J. A. Thomas ◽  
R. M. Iutzi ◽  
A. J. H. McGaughey
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Effective Thermal Conductivity ◽  
Linear Response Theory ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Phonon Modes ◽  
Composite Systems ◽  
Dynamics Simulations

The effective thermal conductivity of water/carbon nanotube (CNT) composite systems is predicted using molecular dynamics simulation. Both empty and water-filled CNTs with diameters ranging from 0.83 nm to 1.26 nm are considered. Using a direct application of the Fourier law, we explore the transition to diffusive phonon transport with increasing CNT length and identify the correlation between CNT diameter and fully-diffusive thermal conductivity. Using Green-Kubo linear response theory, we explore how the thermal conductivity of water inside CNT varies with tube diameter. We predict the effective thermal conductivity of the composite systems and examine how the phonon modes in the CNT are affected by interactions with the water molecules.

Coupling Between Phonons and Fluid Particles in Water/Carbon Nanotube Systems

2009 ◽  
Author(s):  
A. J. H. McGaughey ◽  
J. A. Thomas ◽  
J. Turney ◽  
R. M. Iutzi
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Relaxation Times ◽  
Mean Free Path ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Spectral Energy ◽  
Total Thermal Conductivity ◽  
Phonon Modes

We investigate thermal transport in water/carbon nanotube (CNT) composite systems using molecular dynamics simulations. Carbon-carbon interactions are modeled using the second-generation REBO potential, water-water interactions are modeled using the TIP4P potential, and carbon-water interactions are modeled using a Lennard-Jones potential. The thermal conductivities of empty and water-filled CNTs with diameters between 0.83 nm and 1.66 nm are predicted using molecular dynamics simulation and a direct application of the Fourier law. For empty CNTs, the thermal conductivity decreases with increasing CNT diameter. As the CNT length approaches 1 micron, a length-independent thermal conductivity is obtained, indicative of diffusive phonon transport. When the CNTs are filled with water, the thermal conductivity decreases compared to the empty CNTs and transitions to diffusive phonon transport at shorter lengths. To understand this behavior, we calculate the spectral energy density of the empty and water-filled CNTs and calculate the mode-specific group velocities, relaxation times, and thermal conductivity. For the empty 1.10 nm diameter CNT, we show that the acoustic phonon modes account for 65 percent of the total thermal conductivity. This behavior is attributed to their long mean-free paths. When the CNT is filled with water, interactions with the water molecules shorten the acoustic mode mean-free path and lower the overall CNT thermal conductivity.

Thermal Conductivity of Silicon Thin Films Predicted by Molecular Dynamics Simulations and Theoretical Calculation

2011 ◽  
Vol 55-57 ◽  
pp. 1152-1155 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Boltzmann Transport Equation ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Boltzmann Transport ◽  
Silicon Thin Films ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Good Agreement

Molecular, dynamics simulation and the Boltzmann transport equation are used respectively to analyze the phonon transport in Si thin film. The MD result is in good agreement with the theoretical analysis values. The results show that the calculated thermal conductivity decreases almost linearly as the film thickness reduced and is almost independent of the temperature at the nanoscale. It was observed from the simulation results that there exists the obvious size effect on the thermal conductivity.

Molecular Dynamics Simulations of Heat Conduction in Nano-Structured Silicon

2007 ◽  
Author(s):  
Koji Miyazaki ◽  
Yoshizumi Iida ◽  
Daisuke Nagai ◽  
Hiroshi Tsukamoto
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Heat Conduction ◽  
Molecular Dynamics Simulations ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Phonon Modes ◽  
Dynamics Simulations ◽  
Si Thin Film

We carried out molecular dynamics simulations (MD) of heat conduction in Si thin film and Si films with a nano-hole to represent the nano-structure, in order to investigate the mechanism of the thermal conductivity reduction of nano-structured materials. The Stillinger-Weber potential is used in this study. Different temperatures are applied at the both sides of boundaries of the calculation domain in the z-direction, and periodic boundary conditions are applied in the x and y directions. The calculated temperature profile of a Si thin film of 10.86nm thickness is compared to that calculated by using the phonon Boltzmann transport equation (BTE). These agreed reasonably well with each other, and the phonon mean free path of Si is estimated to be several tens of nanometers. Molecular dynamics simulation of Si at the uniform temperature of 800K is also carried out. Phonon dispersion curves are calculated by using the time-space 2D Fourier transform. The phonon modes at high frequency are not present in nano-structures of Si. We discuss the mechanism of the reduction of the thermal conductivity of nano-structured material on the atomic scale.

Molecular Dynamics Simulations of Heat Conduction in Thin Film With Nano-Holes

2008 ◽  
Author(s):  
Koji Miyazaki ◽  
Daisuke Nagai ◽  
Hiroshi Tsukamoto
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Heat Conduction ◽  
Molecular Dynamics Simulations ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Phonon Modes ◽  
Dynamics Simulations ◽  
Si Thin Film

We carried out molecular dynamics simulations (MD) of heat conduction in Si thin film and Si films with a nano-hole to represent the nano-structure, in order to investigate the mechanism of the thermal conductivity reduction of nano-structured materials. The Stillinger-Weber potential is used in this study. Different temperatures are applied at the both sides of boundaries of the calculation domain in the z-direction, and periodic boundary conditions are applied in the x and y directions. The calculated temperature profile of a Si thin film of 10.86nm thickness is compared to that calculated by using the phonon Boltzmann transport equation (BTE). These agreed reasonably well with each other, and the phonon mean free path of Si is estimated to be several tens of nanometers. Molecular dynamics simulation of Si at the uniform temperature of 800K is also carried out. Phonon dispersion curves are calculated by using the time-space 2D Fourier transform. The phonon modes at high frequency are not present in nano-structures of Si. We discuss the mechanism of the reduction of the thermal conductivity of nano-structured material on the atomic scale.

Molecular Dynamics Study on Thermal Conductivity of Single-Walled Carbon Nanotubes

2009 ◽  
Author(s):  
Bingyang Cao ◽  
Quanwen Hou ◽  
Zengyuan Guo ◽  
Wusheng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Molecular Dynamics Simulations ◽  
Phonon Transport ◽  
Tube Length ◽  
Length Dependence ◽  
Dynamics Simulations ◽  
Walled Carbon Nanotubes

In this paper, we study the thermal conductivities of sing-walled carbon nanotubes (CNTs) and CNTs-based nanocomposites using molecular dynamics simulations. Length dependence of the thermal conductivity of (5, 5) carbon nanotube at 300 K and 1000 K is simulated. At room temperature the thermal conductivity shows linear length dependence with the tube length less than 40 nm, which indicates the completely ballistic transport. The thermal conductivity increases with the increase of the nanotube length, but the increase rate decreases as the length increases. It shows that the phonon transport transits from ballistic to diffusive. In the simulations, the power exponent of the thermal conductivity of carbon nanotube to the tube length decreases by decaying exponential function as the tube length increases. We also observe a decrease of the low-dimensional effects by the surrounding matters. A carbon-nanotube-atom-fixed and -activated scheme of non-equilibrium molecular dynamics simulations is put forward to extract the thermal conductivity of carbon nanotubes embedded in solid argon. Though a 6.5% volume fraction of CNTs increases the composite thermal conductivity by about twice larger than that of the pure basal material, the thermal conductivity of CNTs embedded in solids is found to be decreased by 1/8–1/5 with reference to that of pure ones. The decrease of the intrinsic thermal conductivity of the solid-embedded CNTs and the thermal interface resistance are demonstrated to be responsible for the results.

Thermal Conductivity Computation of Nanofluids by Equilibrium Molecular Dynamics Simulation: Nanoparticle Loading and Temperature Effect

2007 ◽  
Vol 1022 ◽  
Author(s):  
Suranjan Sarkar ◽  
R. Panneer Selvam
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Effective Thermal Conductivity ◽  
Copper Nanoparticles ◽  
Base Fluid ◽  
Liquid Argon ◽  
Dynamics Simulation ◽  
System Temperature ◽  
Solid Copper

AbstractA model nanofluid system of copper nanoparticles in argon base fluid was successfully modeled by molecular dynamics simulation. The interatomic interactions between solid copper nanoparticles, base liquid argon atoms and between solid copper and liquid argon were modeled by Lennard Jones potential with appropriate parameters. The effective thermal conductivity of the nanofluids was calculated through Green Kubo method in equilibrium molecular dynamics simulation for varying nanoparticle concentrations and for varying system temperatures. Thermal conductivity of the basefluid was also calculated for comparison. This study showed that effective thermal conductivity of nanofluids is much higher than that of the base fluid and found to increase with increased nanoparticle concentration and system temperature. Through molecular dynamics calculation of mean square displacements for basefluid, nanofluid and its components, we suggested that the increased movement of liquid atoms in the presence of nanoparticle was probable mechanism for higher thermal conductivity of nanofluids.

An Investigation on Thermal Conductivity of Fluid in a Nanochannel by Nonequilibrium Molecular Dynamics Simulations

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Mohammad Bagheri Motlagh ◽  
Mohammad Kalteh
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Poiseuille Flow ◽  
Driving Force ◽  
Dynamics Simulation ◽  
Nonequilibrium Molecular Dynamics ◽  
Wall Roughness ◽  
Dynamics Simulations ◽  
Effect Of Copper

Abstract In this paper, molecular dynamics simulation is used to investigate the effect of copper and argon nanochannels size on the thermal conductivity of argon. Thermal conductivity is calculated by nonequilibrium molecular dynamics (NEMD) simulation. Simulations are performed for different distances between the walls. Results for both copper and argon walls are investigated individually. Results show that the existence of argon walls has little effect on the thermal conductivity. However, the amount of it for the argon confined between the copper walls is affected by the distance between the two walls. In the same way, the effect of wall roughness on the thermal conductivity is investigated, which shows that roughness is effective only for low distances between the walls. Also, the thermal conductivity of argon under Poiseuille flow in a nanochannel is studied. The results indicate that by increasing the driving force, the thermal conductivity increases and the increase ratio is higher for larger forces.

scholarly journals Molecular Dynamics Simulations on Influence of Defect on Thermal Conductivity of Silicon Nanowires

2021 ◽  
Vol 9 ◽  
Author(s):  
Hao Li ◽  
Qiancheng Rui ◽  
Xiwen Wang ◽  
Wei Yu
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Silicon Nanowires ◽  
Surface Defects ◽  
Low Frequency ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations ◽  
The Impact

A non-equilibrium molecular dynamics simulation method is conducted to study the thermal conductivity (TC) of silicon nanowires (SiNWs) with different types of defects. The impacts of defect position, porosity, temperature, and length on the TC of SiNWs are analyzed. The numerical results indicate that SiNWs with surface defects have higher TC than SiNWs with inner defects, the TC of SiNWs gradually decreases with the increase of porosity and temperature, and the impact of temperature on the TC of SiNWs with defects is weaker than the impact on the TC of SiNWs with no defects. The TC of SiNWs increases as their length increases. SiNWs with no defects have the highest corresponding frequency of low-frequency peaks of phonon density of states; however, when SiNWs have inner defects, the lowest frequency is observed. Under the same porosity, the average phonon participation of SiNWs with surface defects is higher than that of SiNWs with inner defects.

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