Heat Transfer Predictions for Micro/Nano-Channels at Atomistic Level Using Combined Molecular Dynamics and Monte Carlo Techniques

The thermal behavior of a gas confined between two parallel walls is investigated. Wall effects like hydrophobic or hydrophilic wall interactions are studied, and the effect on the heat flux and other characteristic parameters like density and temperature is shown. For a dilute gas, the dependence on gas-wall interactions of the temperature profile between the walls for the incident and reflected molecules is obtained using Molecular Dynamics. From these profiles, the effective accomodation coefficients for different interactions and different mass fluid/wall ratio are derived. We show that MC with Maxwell boundary conditions based on the accomodation coefficient gives good results for heat flux predictions when compared to pure Molecular Dynamics simulations. We use these effective coefficients to compute the heat flux predictions for a dense gas using MD and MC with Maxwell-like boundary conditions.

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Heat Transfer Predictions for Micro-/Nanochannels at the Atomistic Level Using Combined Molecular Dynamics and Monte Carlo Techniques

Journal of Heat Transfer ◽

10.1115/1.3056592 ◽

2009 ◽

Vol 131 (3) ◽

Cited By ~ 15

Author(s):

S. V. Nedea ◽

A. J. Markvoort ◽

A. A. van Steenhoven ◽

P. A. J. Hilbers

Keyword(s):

Molecular Dynamics ◽

Heat Flux ◽

Monte Carlo ◽

Boundary Conditions ◽

Accommodation Coefficient ◽

Monte Carlo Techniques ◽

Effective Coefficients ◽

Accommodation Coefficients ◽

Dynamics Simulations ◽

Wall Interactions

The thermal behavior of a gas confined between two parallel walls is investigated. Wall effects such as hydrophobic or hydrophilic wall interactions are studied, and the effect on the heat flux and other characteristic parameters such as density and temperature is shown. For a dilute gas, the dependence on gas-wall interactions of the temperature profile between the walls for the incident and reflected molecules is obtained using molecular dynamics (MD). From these profiles, the effective accommodation coefficients for different interactions and different mass fluid/wall ratio are derived. We show that Monte Carlo (MC) with Maxwell boundary conditions based on the accommodation coefficient gives good results for heat flux predictions when compared with pure molecular dynamics simulations. We use these effective coefficients to compute the heat flux predictions for a dense gas using MD and MC with Maxwell-like boundary conditions.

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Computer-Generated Structural Models for a-Si:H

MRS Proceedings ◽

10.1557/proc-141-71 ◽

1988 ◽

Vol 141 ◽

Author(s):

Laurent J. Lewis ◽

Normand Mousseau ◽

FranÇois Drolet

Keyword(s):

Molecular Dynamics ◽

Boundary Conditions ◽

Amorphous Silicon ◽

Periodic Boundary ◽

Hydrogenated Amorphous Silicon ◽

Structural Models ◽

Periodic Boundary Conditions ◽

Dynamics Simulations ◽

Hydrogenated Amorphous ◽

Good Agreement

AbstractA new algorithm for generating fully-coordinated hydrogenated amorphous silicon models with periodic boundary conditions is presented. The hydrogen is incorporated into an a-Si matrix by a bond-switching process similar to that proposed by Wooten, Winer, and Weaire, making sure that four-fold coordination is preserved and that no rings with less than 5 members are created. After each addition of hydrogen, the structure is fully relaxed. The models so obtained, to be used as input to molecular dynamics simulations, are found to be in good agreement with experiment. A model with 12 at.% H is discussed in detail.

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Vibration of Single- and Double-Layered Graphene Sheets

Journal of Nanotechnology in Engineering and Medicine ◽

10.1115/1.4003353 ◽

2011 ◽

Vol 2 (1) ◽

Cited By ~ 63

Author(s):

Behrouz Arash ◽

Quan Wang

Keyword(s):

Molecular Dynamics ◽

Boundary Conditions ◽

Molecular Dynamics Simulations ◽

Nonlocal Parameter ◽

Small Scale ◽

Graphene Sheets ◽

Elastic Model ◽

Resonant Frequencies ◽

Nonlocal Continuum Theory ◽

Dynamics Simulations

Free vibration of single- and double-layered graphene sheets is investigated by employing nonlocal continuum theory and molecular dynamics simulations. Results show that the classical elastic model overestimated the resonant frequencies of the sheets by a percentage as high as 62%. The dependence of small-scale effects, sizes of sheets, boundary conditions, and number of layers on vibrational characteristic of single- and double-layered graphene sheets is studied. The resonant frequencies predicted by the nonlocal elastic plate theory are verified by the molecular dynamics simulations, and the nonlocal parameter is calibrated through the verification process. The simulation results reveal that the calibrated nonlocal parameter depends on boundary conditions and vibrational modes. The nonlocal plate model is found to be indispensable in vibration analysis of grapheme sheets with a length less than 8 nm on their sides.

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Heat controlling in the mass-graded harmonic lattices with double-well on-site potential

International Journal of Modern Physics B ◽

10.1142/s021797921850217x ◽

2018 ◽

Vol 32 (20) ◽

pp. 1850217

Author(s):

Peng Kong ◽

Zhengzheng Wei ◽

Tao Hu ◽

Yi Tang

Keyword(s):

Molecular Dynamics ◽

Heat Flux ◽

Power Spectrum ◽

Molecular Dynamics Simulations ◽

Heat Transport ◽

Nonequilibrium Molecular Dynamics ◽

Thermal Rectification ◽

Average Temperature ◽

New Type ◽

Dynamics Simulations

Using nonequilibrium molecular dynamics simulations, we investigate thermal rectification in mass-graded lattices with a new type on-site potential which has a physical picture of the double-well. By adjusting the ratio of harmonic on-site potential and anharmonic on-site potential, we could obtain the optimal heat transport and the best thermal rectification. In addition, we observe the reversal thermal rectification by changing the ratio of on-site potential and analyzes the mechanism of thermal rectification through the power spectrum. At last, we also study the heat flux and thermal rectification in a different case of average temperature and mass gradient.

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Interface Conditions for Coupled Atomistic and Continuum Models of Solids for Dynamics Problems at Finite Temperature

MRS Proceedings ◽

10.1557/proc-978-0978-gg06-02 ◽

2006 ◽

Vol 978 ◽

Author(s):

Xiantao Li ◽

Weinan E

Keyword(s):

Molecular Dynamics ◽

Boundary Conditions ◽

Finite Temperature ◽

Langevin Equations ◽

Continuum Models ◽

Interface Conditions ◽

System Temperature ◽

Dynamics Simulations ◽

Dynamics Problems ◽

Generalized Langevin Equations

AbstractWe will present a general formalism for deriving boundary conditions for molecular dynamics simulations of crystalline solids in the context of atomistic/continuum coupling. These boundary conditions are modeled by generalized Langevin equations, derived from Mori-Zwanzig's formalism. Such boundary conditions are useful in suppressing phonon reflections, and maintaining the system temperature.

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A Study of Nanoparticle-Enhanced Heat Transfer

Volume 7: Fluid Flow, Heat Transfer and Thermal Systems, Parts A and B ◽

10.1115/imece2010-38797 ◽

2010 ◽

Author(s):

Lawrence M. Jones ◽

Timothy Sirk ◽

Eugene Brown

Keyword(s):

Heat Transfer ◽

Experimental Data ◽

Molecular Dynamics ◽

Heat Flux ◽

Nuclear Power ◽

Power Plants ◽

Md Simulations ◽

Theoretical Description ◽

Different Temperatures ◽

Dynamics Simulations

The study of the heat transfer characteristics of nanofluids, i.e. fluids that are suspensions of nanometer size particles, has gained significant attention in the search for new coolants that can effectively service a variety of needs ranging from the increasing heat transfer demands of ever smaller microelectronic devices to mitigating the effects of loss of coolant accidents in nuclear power plants. Experimental data has shown large increases in thermal conductivity and associated increases in the level of critical heat flux in nuclear reactors; however, in some cases the range of the applicability of the experimental results is uncertain and there is a lack of a theory by which this can be resolved. Complicating the theoretical description of heat transfer in nanofluids is the fact that fluids in the vicinity of the nanoparticles are a complex combination of phase transition, interfacial, and transport phenomena. This paper describes a study in which molecular dynamics simulations were used to enhance the understanding of the effect of nanoparticles on heat transfer. The molecular dynamics (MD) simulations presented here model a Lennard-Jones fluid in a channel where the walls are maintained at different temperatures. The heat flux is calculated for a variety of nanoparticle sizes and concentrations. The results are compared to experimental data in order to provide information that will more confidently bound the data and provide information that will guide the development of more comprehensive theories. We also anticipate that this work could contribute to the design of biosensors where suspended molecules are transported through micro- and nano-channels in the presence of heat transfer.

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Reflecting Boundary Conditions for Classical and Quantum Molecular Dynamics Simulations of Nonideal Plasmas

Contributions to Plasma Physics ◽

10.1002/ctpp.201500139 ◽

2016 ◽

Vol 56 (5) ◽

pp. 448-458 ◽

Cited By ~ 3

Author(s):

Y. S. Lavrinenko ◽

I.V. Morozov ◽

I. A. Valuev

Keyword(s):

Molecular Dynamics ◽

Boundary Conditions ◽

Molecular Dynamics Simulations ◽

Quantum Molecular Dynamics ◽

Nonideal Plasmas ◽

Dynamics Simulations

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On the Vibration of Single-Walled Carbon Nanocones: Molecular Mechanics Approach versus Molecular Dynamics Simulations

Shock and Vibration ◽

10.1155/2014/410783 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 4

Author(s):

R. Ansari ◽

A. Momen ◽

S. Rouhi ◽

S. Ajori

Keyword(s):

Molecular Dynamics ◽

Boundary Conditions ◽

Molecular Dynamics Simulations ◽

Natural Frequency ◽

Structural Method ◽

Covalent Bonds ◽

Carbon Nanocones ◽

Single Walled Carbon ◽

Vibrational Behavior ◽

Dynamics Simulations

The vibrational behavior of single-walled carbon nanocones is studied using molecular structural method and molecular dynamics simulations. In molecular structural approach, point mass and beam elements are employed to model the carbon atoms and the connecting covalent bonds, respectively. Single-walled carbon nanocones with different apex angles are considered. Besides, the vibrational behavior of nanocones under various types of boundary conditions is studied. Predicted natural frequencies are compared with the existing results in the literature and also with the ones obtained by molecular dynamics simulations. It is found that decreasing apex angle and the length of carbon nanocone results in an increase in the natural frequency. Comparing the vibrational behavior of single-walled carbon nanocones under different boundary conditions shows that the effect of end condition on the natural frequency is more prominent for nanocones with smaller apex angles.

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