scholarly journals The effect of nanoparticle size and nanoparticle aggregation on the flow characteristics of nanofluids by molecular dynamics simulation

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988948 ◽  
Author(s):  
Lingling Bao ◽  
Chaoyang Zhong ◽  
Pengfei Jie ◽  
Yan Hou
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Velocity Profile ◽  
Flow Characteristics ◽  
Maximum Velocity ◽  
Velocity Profiles ◽  
Dynamics Simulation ◽  
Nanoparticle Size ◽  
Nanoparticle Aggregation ◽  
Nanoparticle Sizes

Molecular dynamics simulation is used to investigate the flow characteristics of Cu–Ar nanofluids considering the influence of nanoparticle size and nanoparticle aggregation. Nanofluids viscosity is calculated by equilibrium molecular dynamics based on Green–Kubo equation. Results demonstrate that the viscosity of nanofluids decreases with the increase of nanoparticle size. In addition, nanoparticle aggregation results in the increase of the nanofluids viscosity. Compared with nanoparticle size, nanoparticle aggregation has a larger impact on viscosity. Nanofluids flowing in parallel-plate nanochannels are simulated. The velocity profiles are studied through three nanoparticle sizes (11.55, 14.55, and 18.33 Å) and four nanoparticle aggregate configurations. Results show that the velocity profile of 14.55 Å nanoparticle size is larger than that of other two nanoparticle sizes. As for four nanoparticles, the nanoparticles clustering as a line leads to the maximum velocity profile, while the nanoparticles clustering as a cube causes the minimum velocity profile. Compared with viscosity, nanoparticle aggregation has a greater effect on the velocity profile. When the nanoparticles are evenly distributed, the influence of viscosity on velocity profiles is dominant. Otherwise, the aggregation, aggregate configuration, and distribution of nanoparticles have a dominant impact on the flow characteristics of nanofluids.

Dynamical Behavior and Flow Mechanism of Fluid in Nanochannel by Molecular Dynamics Simulation

2009 ◽  
Author(s):  
Juanfang Liu ◽  
Chao Liu ◽  
Qin Li
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamical Behavior ◽  
Velocity Profiles ◽  
The Other ◽  
Dynamics Simulation ◽  
Nonequilibrium Molecular Dynamics ◽  
Interfacial Region ◽  
Flow Mechanism ◽  
Bulk Fluid

The flow properties and dynamical behavior of fluid in a nanochannel were investigated by nonequilibrium molecular dynamics simulation. First of all, the locale distribution of molecules in the channel is found to be strongly inhomogeneous compared to the bulk fluid. In the vicinity of the wall, portion of the fluid molecules are absorbed on the surface of wall due to the strong interaction of the atoms between the wall and liquid, so that the fluid density in the contact region would be much larger than one of the bulk fluid. But in the other region, the local density value approaches one of the bulk fluids with the increasing distance from the wall. This oscillatory behavior of density resulted in different motion behavior of molecules in the different region of nanochannel. The molecular behavior in the interfacial region is remarkably different from those of fluid atoms in the center of channel and wall atoms, which posses both the motion properties of bulk liquids and a solid atom. At the molecular level, macroscopic continuum hypothesis failed, that is, the results predicted by the Navier-Stoke equations deviate from the simulation data adopted by molecular dynamics simulation. In the paper, the velocity profiles for the channels with different width were plotted, which demonstrated that the time-averaged velocity profiles was not quadratic when the channel width was less than 10 molecular diameters. But on the other cases, the velocity profiles will agree well with the analytical solution based on the NS theory. The molecular dynamics simulation method can withdraw the important microscopical information from the simulation process, which benefit to analyze the flow mechanism at such length scale channel.

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.

Abnormal change of melting points of gold nanoparticles confined between two-layer graphene nanosheets

RSC Advances ◽  
2016 ◽  
Vol 6 (110) ◽  
pp. 108343-108346 ◽  
Author(s):  
Gang Wang ◽  
Nanhua Wu ◽  
Jinjian Wang ◽  
Jingling Shao ◽  
Xiaolei Zhu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Gold Nanoparticles ◽  
Molecular Dynamics Simulation ◽  
Melting Temperature ◽  
Graphene Nanosheets ◽  
Dynamics Simulation ◽  
Nanoparticle Size ◽  
Melting Points ◽  
Layer Graphene ◽  
Reasonable Explanation

A molecular dynamics simulation demonstrated that the melting temperature of gold nanoparticles confined in two-layer graphene nanosheets was indicated to decrease with nanoparticle size and a reasonable explanation is provided.

scholarly journals Molecular Dynamics Simulation of Nanoscale Channel Flows with Rough Wall Using the Virtual-Wall Model

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Xiaohui Lin ◽  
Fu-bing Bao ◽  
Xiaoyan Gao ◽  
Jiemin Chen
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Gas Flow ◽  
Roughness Element ◽  
Fluid Velocity ◽  
Flow Characteristics ◽  
Rough Wall ◽  
Dynamics Simulation ◽  
Low Density ◽  
Wall Model

Molecular dynamics simulation is adopted in the present study to investigate the nanoscale gas flow characteristics in rough channels. The virtual-wall model for the rough wall is proposed and validated. The computational efficiency can be improved greatly by using this model, especially for the low-density gas flow in nanoscale channels. The effect of roughness element geometry on flow behaviors is then studied in detail. The fluid velocity decreases with the increase of roughness element height, while it increases with the increases of element width and spacing.

Molecular dynamics investigation on the deliquescence of NH4Cl and NH4NO3nanoparticles under atmospheric conditions

RSC Advances ◽  
2015 ◽  
Vol 5 (48) ◽  
pp. 38345-38353 ◽  
Author(s):  
Hamed Akbarzadeh ◽  
Amir Nasser Shamkhali ◽  
Mohsen Abbaspour ◽  
Sirous Salemi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Nanoparticle Size ◽  
Atmospheric Conditions

In this study, the deliquescence of NH4Cl and NH4NO3nanoparticles under atmospheric conditions was modeled by molecular dynamics simulation in order to investigate the effects of nanoparticle size and temperature on their deliquescence process.

Sign in / Sign up

Export Citation Format

Share Document