Molecular Dynamics Simulation on Micro Couette Flow of Nanofluids

2011 ◽  
Vol 284-286 ◽  
pp. 658-661
Author(s):  
Wen Zheng Cui ◽  
Min Li Bai ◽  
Ji Zu Lv ◽  
Xiao Jie Li
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Heat Transfer Enhancement ◽  
Couette Flow ◽  
Liquid Argon ◽  
Visual Observation ◽  
Solid Surfaces ◽  
Dynamics Simulation ◽  
Transfer Enhancement ◽  
Base Liquid

This research applied molecular dynamics method to micro Couette flow of nanofluids, in order to examine the absorption layer near solid surfaces, and propose mechanisms of heat transfer enhancement due to flow. The model of nanofluids consisted of 4 nm Cu nanoparticles and liquid argon as base liquid, Lennard-Jones potential function was adopted to deal with the interactions between atoms. Through visual observation and analysis, it was found that the even-distributed liquid argon atoms near solid surfaces could be seemed as a reform to base liquid and had contributed to heat transfer enhancement. In the process of Couette flow, nanoparticles were rotating and vibrating besides moving translationally. The micro-motions of nanoparticles could disturb the continuity of fluid and strengthen partial flow nearby nanoparticles, and enhance heat transfer in nanofluids.

scholarly journals On the Microscopic Flow Characteristics of Nanofluids by Molecular Dynamics Simulation on Couette Flow

2012 ◽  
Vol 5 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Wenzheng Cui ◽  
Minli Bai ◽  
Jizu Lv ◽  
Xiaojie Li
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Heat Transfer Enhancement ◽  
Couette Flow ◽  
Flow Characteristics ◽  
Dynamics Simulation ◽  
Shear Direction ◽  
Transfer Enhancement ◽  
Microscopic Flow

Adding a small amount of nanoparticles to conventional fluids (nanofluids) has been proved to be an effective way for improving capability of heat transferring in base fluids. The change in micro structure of base fluids and micro motion of nanoparticles may be key factors for heat transfer enhancement of nanofluids. Therefore, it is essential to examine these mechanisms on microscopic level. The present work performed a Molecular Dynamics simulation on Couette flow of nanofluids and investigated the microscopic flow characteristics through visual observation and statistic analysis. It was found that the even-distributed liquid argon atoms near solid surfaces of nanoparticles could be seemed as a reform to base liquid and had contributed to heat transfer enhancement. In the process of Couette flow, nanoparticles moved quickly in the shear direction accompanying with motions of rotation and vibration in the other two directions. When the shearing velocity was increased, the motions of nanoparticles were strengthened significantly. The motions of nanoparticles could disturb the continuity of fluid and strengthen partial flowing around nanoparticles, and further enhanced heat transferring in nanofluids.

Molecular Dynamics Simulation on the Effect of Micro-Motions of Nanoparticles in Heat Transfer Enhancement of Nanofluids

2016 ◽  
Author(s):  
Chengzhi Hu ◽  
Minli Bai ◽  
Jizu Lv ◽  
Yuyan Wang
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Shear Flow ◽  
Flow Field ◽  
Heat Transfer Enhancement ◽  
Base Fluid ◽  
Dynamics Simulation ◽  
Wall Region ◽  
Transfer Enhancement

The flow and heat transfer characteristics of nanofluids in the near-wall region were studied by non-equilibrium molecular dynamics simulation. The nanofluid model consisted of one spherical copper nanoparticle and argon atoms as base liquid. The effective thermal conductivity (ETC) of nanofluids and base fluid in shear flow fields were obtained. The ETC was increased with the increasing of shear velocity for both base fluid and nanofluids. The heat transfer enhancement of nanofluids in the shear flow field (v≠0) is better than that in the zero-shear flow field (v=0). By analyzing the flow characteristics we proved that the micro-motions of nanoparticles were another mechanism responsible for the heat transfer enhancement of nanofluids in the flow field. Based on the model built in the paper, we found that the thermal properties accounted for 52%–65% heat transfer enhancement and the contribution of micro-motions is 35%–48%.

Numerical Study of Nanofluids Flow Characteristics Using LES–Lagrange Method and Molecular Dynamics Simulation

2013 ◽  
Author(s):  
Chengzhi Hu ◽  
Peng Heng ◽  
Minli Bai ◽  
Jizu Lv ◽  
Yuyan Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Heat Transfer Enhancement ◽  
Flow Characteristics ◽  
Dynamics Simulation ◽  
Turbulent Intensity ◽  
Transfer Enhancement ◽  
Lagrange Method ◽  
Turbulent Characteristics ◽  
Flow Activity

In order to reveal the mechanisms of heat transfer enhancement in nanofluids from the flow characteristics, this paper firstly used LES (Large eddy simulation)–Lagrange method to simulate the turbulent flow of nanofluids through a straight circular tube. It has been observed that nanoparticles would move up and down and sideways besides main flowing. The turbulent characteristics of nanofluids have been changed greatly in comparison with pure water: the turbulent intensity and Reynolds stress are enhanced obviously; there are more vortexes in the flow field. These flow characteristics of nanofluids can effectively strengthen the transport of momentum, mass and energy, which is the main reason for heat transfer enhancement in nanofluids. It is also found that nanofluids containing smaller diameter nanoparticles have higher turbulent intensity and flow activity. The flow characteristics of nanofluids are sensitive to the changes of smaller diameter nanoparticle size. While using different nanoparticle materials, the flow characteristics of nanofluids have a little change. At last, to verify the aforesaid views, the flow behaviors of nanofluids in the near wall region and main flow region have been simulated by molecular dynamics.

Molecular Dynamics Simulation of Pool Boiling Heat Transfer of Nanofluids on Rough Walls

2017 ◽  
Author(s):  
Xunyan Yin ◽  
Minli Bai ◽  
Chengzhi Hu ◽  
Jizu Lv
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Boiling Heat Transfer ◽  
Heating Temperature ◽  
Pool Boiling ◽  
Liquid Argon ◽  
Dynamics Simulation ◽  
Pool Boiling Heat Transfer ◽  
Rough Walls

Molecular dynamics simulation was performed to investigate pool boiling heat transfer of nanofluids on rough walls. Nanoparticle movement was calculated to investigate the physical mechanisms of boiling heat transfer. The simulated system consisted of four regions: vapor argon, liquid argon, solid copper, and copper nanoparticles, and three cases were considered: base fluids (case A), nanoparticles far from the wall (case B), and nanoparticles near the wall (case C). Boiling heat transfer was enhanced by the addition of nanoparticles, and the enhancement increased with increasing heating temperature. Case C showed that nanoparticles were adsorbed on the nonevaporated film and did not move with the fluids. Thus, nanoparticles enhanced heat and energy transfer between the wall and fluids. Case B showed that nanoparticles moved randomly in the fluid area, which enhanced heat transfer within the fluid.

scholarly journals Heat transfer enhancement and torque reduction by traveling wave-like blowing and suction in turbulent Taylor-Couette flow

2021 ◽  
Vol 16 (1) ◽  
pp. JTST0003-JTST0003
Author(s):  
Hiroya MAMORI ◽  
Koji FUKUDOME ◽  
Kohei OGINO ◽  
Naoya FUKUSHIMA ◽  
Makoto YAMAMOTO
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Couette Flow ◽  
Traveling Wave ◽  
Transfer Enhancement ◽  
Taylor Couette ◽  
Taylor Couette Flow
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