scholarly journals Molecular Dynamics Investigation on Thermal Conductivity and Photon Behaviors of Graphene With Sierpinski Carpet Fractal Defects

2022 ◽  
Vol 9 ◽  
Author(s):  
Wei Yu ◽  
Yongjing Wu ◽  
Xiangxiang Shao ◽  
Xiwen Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Numerical Results ◽  
Sierpinski Carpet ◽  
Defective Graphene ◽  
Underlying Mechanisms ◽  
Non Equilibrium Molecular Dynamics ◽  
Sierpiński Carpet ◽  
Blockage Effect

The thermal conductivity (TC) of graphene with Sierpinski carpet fractal (SCF) and regular carpet (RC) defects is numerically studied by the non-equilibrium molecular dynamics (NEMD) method. The influences of porosity, fractal levels, and types of defects on the TC of graphene are clarified, and the underlying mechanisms of phonon behaviors are uncovered. The numerical results indicate that the defects in graphene induce the atoms that have the heat transfer blockage effect, and thus, the TC of defective graphene decreases with increasing porosity. With the increase in fractal levels, more atoms have the heat transfer blockage effect, which induces the TC of graphene with SCF defects to sharply decrease. Moreover, compared with the graphene with RC defects, more atoms participate in the heat transfer blockage under the graphene with SCF defects, which leads to the lower TC of graphene with SCF defects.

A Molecular Dynamics Study of Thermal Conductivity in Nanocomposites via the Phonon Wave Packet Method

2009 ◽  
Author(s):  
Zhiting Tian ◽  
Sang Kim ◽  
Ying Sun ◽  
Bruce White
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Wave Packet ◽  
Molecular Dynamics Simulations ◽  
Phonon Scattering ◽  
Flow Direction ◽  
Normal Incidence ◽  
Material Interfaces ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations

The phonon wave packet technique is used in conjunction with the molecular dynamics simulations to directly observe phonon scattering at material interfaces. The phonon transmission coefficient of nanocomposites is examined as a function of the defect size, thin film thickness, orientation of interface to the heat flow direction. To generalize the results based on phonons in a narrow frequency range and at normal incidence, the effective thermal conductivity of the same nanocomposite structure is calculated using non-equilibrium molecular dynamics simulations for model nanocomposites formed by two mass-mismatched Ar-like solids and heterogeneous Si-SiCO2 systems. The results are compared with the modified effective medium formulation for nanocomposites.

Thermal Performance of Sierpinski Carpet Fractal Fins in a Forced Convection Environment

2016 ◽  
Author(s):  
David Calamas ◽  
Daniel Dannelley ◽  
Gyunay Keten
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Forced Convection ◽  
Thermal Performance ◽  
Reynolds Numbers ◽  
Unit Mass ◽  
Thermal Testing ◽  
Sierpinski Carpet ◽  
Fractal Pattern ◽  
Sierpiński Carpet

When certain fractal geometries are used in the design of fins or heat sinks the surface area available for heat transfer can be increased while system mass can be simultaneously decreased. The Sierpinski carpet fractal pattern, when utilized in the design of an extended surface, can provide more effective heat dissipation while simultaneously reducing mass. In order to assess the thermal performance of fractal fins for application in the thermal management of electronic devices an experimental investigation was performed. The first four fractal iterations of the Sierpinski carpet pattern, used in the design of extended surfaces, were examined in a forced convection environment. The thermal performance of the Sierpinski carpet fractal fins was quantified by the following performance metrics: efficiency, effectiveness, and effectiveness per unit mass. The fractal fins were experimentally examined in a thermal testing tunnel for a range of Reynolds numbers. As the Reynolds number increased, the fin efficiency, effectiveness and effectiveness per unit mass were found to decrease. However, as the Reynolds number increased the Nusselt number was found to similarly increase due to higher average heat transfer coefficients. The fourth iteration of the fractal pattern resulted in a 6.73% and 70.97% increase in fin effectiveness and fin effectiveness per unit mass when compared with the zeroth iteration for a Reynolds number of 6.5E3. However, the fourth iteration of the fractal pattern resulted in a 1.93% decrease in fin effectiveness and 57.09% increase in fin effectiveness per unit mass when compared with the zeroth iteration for a Reynolds number of 1.3E4. The contribution of thermal radiation to the rate of heat transfer was as high as 62.90% and 33.69% for Reynolds numbers of 6.5E3 and 1.3E4 respectively.

Thermal conductivity of silicon using reverse non-equilibrium molecular dynamics

2018 ◽  
Vol 123 (20) ◽  
pp. 205104 ◽  
Author(s):  
Mohamed S. El-Genk ◽  
Khaled Talaat ◽  
Benjamin J. Cowen
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Non Equilibrium Molecular Dynamics ◽  
Non Equilibrium

Effects of Stone-Wales Defects on the Thermal Conductivity of Carbon Nanotubes

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Li Wei ◽  
Feng Yanhui ◽  
Peng Jia ◽  
Zhang Xinxin
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Temperature Profile ◽  
Defect Position ◽  
Non Equilibrium Molecular Dynamics ◽  
Increasing Temperature ◽  
Dynamics Method

The thermal conductivity of carbon nanotubes with Stone-Wales (SW) defects was investigated using non-equilibrium molecular dynamics method. The defect effects were analyzed by the temperature profile and local thermal resistance of the nanotubes with one or more SW defects and further compared with perfect tubes. The influences of the defect concentration, the length, the chirality and the radius of tubes and the ambient temperature were studied. It was demonstrated that a sharp jump in the temperature profile occurred at defect position due to a higher local thermal resistance, thus dramatically reducing the thermal conductivity of the nanotube. As the number of SW defects increases, the thermal conductivity decreases. Relative to the chirality, the radius has greater effects on the thermal conductivity of tubes with SW defects. With the similar radius, the thermal conductivity of armchair nanotube is higher than that of zigzag one. The shorter nanotube is more sensitive to the defect than the longer one. Thermal conductivity of the nanotube increases with ambient temperature, reaches a peak, and then decreases with increasing temperature.

Thermal conductivity and interfacial Thermal Resistance Behavior for the Polyaniline (C3N)– boron carbide (BC3) Heterostructure

2021 ◽  
Author(s):  
Arian Mayelifartash ◽  
Mohammad Ali Abdol ◽  
Sadegh Sadeghzadeh
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Resistance ◽  
Boron Carbide ◽  
Molecular Dynamics Simulations ◽  
Thermal Conductance ◽  
Interfacial Thermal Resistance ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations ◽  
Non Equilibrium

In this paper, by employing non-equilibrium molecular dynamics simulations (NEMD), the thermal conductance of hybrid formed by polyaniline (C3N) and boron carbide (BC3) in both armchair and zigzag configurations has...

scholarly journals Investigation of Interface Thermal Resistance between Polymer and Mold Insert in Micro-Injection Molding by Non-Equilibrium Molecular Dynamics

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2409
Author(s):  
Can Weng ◽  
Jiangwei Li ◽  
Jun Lai ◽  
Jiangwen Liu ◽  
Hao Wang
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Injection Molding ◽  
Thermal Resistance ◽  
Mold Insert ◽  
Micro Injection Molding ◽  
Interface Resistance ◽  
Interface Thermal Resistance ◽  
Packing Pressure ◽  
Non Equilibrium Molecular Dynamics

Micro-injection molding has attracted a wide range of research interests to fabricate polymer products with nanostructures for its advantages of cheap and fast production. The heat transfer between the polymer and the mold insert is important to the performance of products. In this study, the interface thermal resistance (ITR) between the polypropylene (PP) layer and the nickel (Ni) mold insert layer in micro-injection molding was studied by using the method of non-equilibrium molecular dynamics (NEMD) simulation. The relationships among the ITR, the temperature, the packing pressure, the interface morphology, and the interface interaction were investigated. The simulation results showed that the ITR decreased obviously with the increase of the temperature, the packing pressure and the interface interaction. Both rectangle and triangle interface morphologies could enhance the heat transfer compared with the smooth interface. Moreover, the ITR of triangle interface was higher than that of rectangle interface. Based on the analysis of phonon density of states (DOS) for PP-Ni system, it was found that the mismatch between the phonon DOS of the PP atoms and Ni atoms was the main cause of the interface resistance. The frequency distribution of phonon DOS also affected the interface resistance.

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