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Second Thermal and Fluids Engineering  Conference

ISSN: 2379-1748
ISBN: 978-1-56700-430-4

Hybrid MD-LBM method for fluid flow based on the continuous and discrete velocity distribution functions

Zi-Xiang Tong
Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, No.28 Xianning West Road, Xi'an, Shaanxi, 710049, P.R. China

Ming-Jia Li
Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA; Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China

Ya-Ling He
Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China

Abstract

The fluid flow in micro-/nano-scale has drawn a lot of attentions due to the development of the micro-electro-mechanical systems. The molecular dynamic (MD) simulation has been widely employed to study the flow phenomenon in micro-/nano-scale. However, the MD consumes much more computational resources than the traditional numerical methods. One way to solve this kind of problem is to use the hybrid models, in which the MD is only applied in the region where it is necessary and in the rest of the domain the continuum methods are used.
The lattice Boltzmann method (LBM) has been rapidly developed in the recent years. Based on the kinetic theory, the LBM is a mesoscopic method. Therefore, it can be a bridge between the macroscopic continuum method and the molecular methods. In the present work, a direct hybrid scheme between the MD and LBM has been established for the nano-scale fluid flow problems. The hybrid scheme is based on the velocity distribution functions. Firstly, the relations between the discrete velocity distribution functions of LBM and the continuous distribution functions of MD are derived by the Hermite expansions. The numerical examples are used to validate the relations. Then, the hybrid scheme between the MD and LBM are proposed. The Poiseuille flow and Couette flow are simulated to test the hybrid scheme. Finally, the flow past a nanotube is simulated to show the application of the hybrid method.

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