Lattice Boltzmann study on size effect with geometrical bending on phonon heat conduction in a nanoduct

2004 ◽  
Vol 95 (3) ◽  
pp. 958-966 ◽  
Author(s):  
Wen-Shu Jiaung ◽  
Jeng-Rong Ho
Keyword(s):  
Heat Conduction ◽  
Size Effect ◽  
Lattice Boltzmann

scholarly journals Lattice Boltzmann method simulation of the gas heat conduction of nanoporous material

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3749-3756
Author(s):  
Ya Han ◽  
Shuai Li ◽  
Hai-Dong Liu ◽  
Weipeng Cui
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Lattice Boltzmann Method ◽  
Knudsen Number ◽  
Lattice Boltzmann ◽  
Size Effects ◽  
Temperature Jump ◽  
Boundary Scattering ◽  
Nanoporous Material ◽  
Boltzmann Method

In order to deeply investigate the gas heat conduction of nanoporous aerogel, a model of gas heat conduction was established based on microstructure of aerogel. Lattice Boltzmann method was used to simulate the temperature distribution and gas thermal conductivity at different size, and the size effects of gas heat conduction have had been obtained under micro-scale conditions. It can be concluded that the temperature jump on the boundary was not obvious and the thermal conductivity remained basically constant when the value of Knudsen number was less than 0.01; as the value of Knudsen number increased from 0.01 to 0.1, there was a clear temperature jump on the boundary and the thermal conductivity tended to decrease and the effect of boundary scattering increased drastically, as the value of Knudsen number was more than 0.1, the temperature jump increased significantly on the boundary, furtherly, the thermal conductivity decreased dramatically, and the size effects were significantly.

Thin Film Phonon Heat Conduction by the Dispersion Lattice Boltzmann Method

2007 ◽  
Author(s):  
Rodrigo A. Escobar ◽  
Cristina H. Amon ◽  
Amador M. Guzma´n
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Lattice Boltzmann Method ◽  
Thermal Energy ◽  
Lattice Boltzmann ◽  
Energy Transport ◽  
Time Dependent ◽  
Boltzmann Method ◽  
Thermal Energy Transport

Numerical simulations of time-dependent thermal energy transport in semiconductor thin films are performed using the Lattice Boltzmann Method applied to phonon transport. The discrete Lattice Boltzmann Method is derived from the continuous Boltzmann transport equation assuming nonlinear, frequency-dependent phonon dispersion for acoustic and optical phonons. Results indicate that the heat conduction in silicon thin films displays a transition from diffusive to ballistic energy transport as the characteristic length of the system becomes comparable to the phonon mean free path, and that the thermal energy transport process is characterized by the propagation of multiple, superimposed phonon waves. The methodology is used to characterize the time-dependent temperature profiles inside films of decreasing thickness. Thickness-dependent thermal conductivity values are computed based on steady-state temperature distributions obtained from the numerical models. It is found that reducing feature size into the subcontinuum regime decreases the thermal conductivity when compared to bulk values, at a higher rate than what was displayed by the Debye-based gray Lattice Boltzmann Method.

A Novel Approach for Lattice Boltzmann Modeling of Energy Transport

2012 ◽  
Author(s):  
Dadong Wang ◽  
Yanbao Ma
Keyword(s):  
Heat Conduction ◽  
Lattice Boltzmann ◽  
Thermal Transport ◽  
Energy Transport ◽  
Transient Heat Conduction ◽  
Mean Free Path ◽  
Boltzmann Transport ◽  
Nano Scale ◽  
Novel Approach ◽  
Boltzmann Method

It is well known that Fourier law breaks down for the prediction of heat conduction in nano-scale, where the length scale is comparable to the mean free path of energy carriers. Over the past decade, Boltzmann transport equation (BTE) has been used to predict thermal transport in dielectrics and semiconductors at micro-scale and nano-scale. In this work, a new modified gray model is obtained from BTE. The implicit lattice Boltzmann method (LBM) is developed to simulate the thermal transport process. Based on the new model, we can derive Guyer-Krumhansl equation. Transient heat conduction through a thin nano-film and hotspot self-heating in sub-micron transistors are examined. The numerical results are compared with those provided by Fourier, Cattaneo, and Guyer-Krumhansl equation.

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