Non-Equilibrium Molecular Dynamics Approach for Nano-Electro-Mechanical Systems: Nano-Fluidics and Its Applications

2005 ◽  
Author(s):  
Changsung Sean Kim
Keyword(s):  
Molecular Dynamics ◽  
Three Dimensional ◽  
Liquid Argon ◽  
Homogeneous System ◽  
Navier Stokes ◽  
Charged Droplet ◽  
Wall Boundary Conditions ◽  
Wide Range ◽  
Non Equilibrium Molecular Dynamics ◽  
Non Equilibrium

A three-dimensional non-equilibrium molecular dynamics code has been developed and evaluated to provide fundamental understandings of nano-fluidics at molecular level. Intermolecular energy and force between fluid-fluid and fluid-wall particles were all included. Molecular dynamics results were verified by simulating both homogeneous and heterogeneous flows in a nano-tube and then compared with the classical Navier-Stokes solution with non-slip wall boundary conditions. At equilibration state, the macroscopic parameters were calculated using the statistical calculation. Liquid argon fluids within platinum walls were simulated for a homogeneous system. Also positively charged particles are mixed with water-like solvent particles to investigate the non-Newtonian behavior of the heterogeneous fluid. For an electrowetting phenomenon, a positive charged droplet moving on the negative charged ultra thin film was successfully simulated and compared with a macroscopic experiment. Nano-jetting mechanism was identified by simulating droplet ejection, breakup, wetting, and drying process in a consequent manner. In addition, conceptual nano/micropumps using electrowetting phenomenon are simulated. The present molecular dynamics approach showed its promising capability for the wide range of NEMS/MEMS applications

Electric field-controlled semiconductor nanorod assembly in solution: mechanistic insights from non-equilibrium molecular dynamics

2015 ◽  
Vol 93 (8) ◽  
pp. 888-890 ◽  
Author(s):  
Niall J. English
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
Electric Fields ◽  
Self Assembly ◽  
Zero Field ◽  
Wide Range ◽  
Non Equilibrium Molecular Dynamics ◽  
Applied Fields ◽  
Preferential Alignment ◽  
Non Equilibrium

Non-equilibrium molecular dynamics (MD) of small, charged cadmium selenide nanorods have been carried out in the absence and presence of static applied electric fields. In the absence of applied fields, it was found that opposite dipolar alignment (antiferromagnetic) was achieved, along with self-assembly of the nanorods. However, in the case of induced electrophoresis in applied fields, the rods approached each other less readily, while at and above a field intensity of 0.05 V/Å, preferential alignment with the field was achieved for all rods, in contrast to the zero-field case. These results have implications for electric field-mediated control of nanorod assembly in solution, of key importance in a wide range of areas from photovoltaics to energy storage.

scholarly journals Transport Properties of the Lennard-Jones Truncated and Shifted Fluid from Non-equilibrium Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Martin P. Lautenschläger ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Simulation Method ◽  
Self Diffusion ◽  
Lennard Jones ◽  
Wide Range ◽  
Data Correlations ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations ◽  
Good Agreement ◽  
Non Equilibrium

The thermal conductivity λ, shear viscosity η, and self-diffusion coefficient D of the Lennard-Jones fluid truncated and shifted at the cut-off radius rc=2.5σ (LJTS fluid) are determined for a wide range of liquid and supercritical states (T*=[0.6,10.0] and ρ*=[0.2,1.2]). The simulations are carried out using a non-equilibrium molecular dynamics (NEMD) method that was introduced recently and in which two gradients are applied simultaneously. It is shown that the two-gradient method is well-suited for studies of liquid and supercritical states. Data for λ, η, and D for about 350 state points are reported. Two variants of the simulation method, which differ in the accuracy and efficiency, are explored and found to yield consistent data. Correlations for λ, η, and Dρ of the LJTS fluid are provided. The data and the correlations are compared to literature data of Lennard-Jones (LJ) type fluids and good agreement is observed. The truncation of the LJ potential causes a slight increase in D, while it has no significant effect on λ and η.

A Theoretical Study of the Temperature Gradient Effect on the Soret Coefficient in n-Pentane/n-Decane Mixtures Using Non-Equilibrium Molecular Dynamics

2020 ◽  
Vol 45 (4) ◽  
pp. 319-332
Author(s):  
Xiaoyu Chen ◽  
Ruquan Liang ◽  
Yong Wang ◽  
Ziqi Xia ◽  
Lichun Wu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Temperature Gradient ◽  
Thermal Gradient ◽  
Linear Response ◽  
Theoretical Study ◽  
Soret Coefficient ◽  
Thermal Gradients ◽  
Gradient Effect ◽  
Non Equilibrium Molecular Dynamics ◽  
Non Equilibrium

AbstractThe effect of the temperature gradient on the Soret coefficient in n-pentane/n-decane (n-C5/n-C10) mixtures was investigated using non-equilibrium molecular dynamics (NEMD) with the heat exchange (eHEX) algorithm. n-Pentane/n-decane mixtures with three different compositions (0.25, 0.5, and 0.75 mole fractions, respectively) and the TraPPE-UA force field were used in computing the Soret coefficient ({S_{T}}) at 300 K and 1 atm. Added/removed heat quantities (ΔQ) of 0.002, 0.004, 0.006, 0.008, and 0.01 kcal/mol were employed in eHEX processes in order to study the effect of different thermal gradients on the Soret coefficient. Moreover, a phenomenological description was applied to discuss the mechanism of this effect. Present results show that the Soret coefficient values firstly fluctuate violently and then become increasingly stable with increasing ΔQ (especially in the mixture with a mole fraction of 0.75), which means that ΔQ has a smaller effect on the Soret coefficient when the temperature gradient is higher than a certain thermal gradient. Thus, a high temperature gradient is recommended for calculating the Soret coefficient under the conditions that a linear response and constant phase are ensured in the system. In addition, the simulated Soret coefficient obtained at the highest ΔQ within three different compositions is in great agreement with experimental data.

The Extension of a Solution-Adaptive Three-Dimensional Navier–Stokes Solver Toward Geometries of Arbitrary Complexity

1993 ◽  
Vol 115 (2) ◽  
pp. 283-295 ◽  
Author(s):  
W. N. Dawes
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Wide Range ◽  
Nozzle Guide Vane ◽  
Recent Developments ◽  
Nozzle Guide

This paper describes recent developments to a three-dimensional, unstructured mesh, solution-adaptive Navier–Stokes solver. By adopting a simple, pragmatic but systematic approach to mesh generation, the range of simulations that can be attempted is extended toward arbitrary geometries. The combined benefits of the approach result in a powerful analytical ability. Solutions for a wide range of flows are presented, including a transonic compressor rotor, a centrifugal impeller, a steam turbine nozzle guide vane with casing extraction belt, the internal coolant passage of a radial inflow turbine, and a turbine disk cavity flow.

scholarly journals NON-EQUILIBRIUM MOLECULAR DYNAMICS USED TO OBTAIN SORET COEFFICIENTS OF BINARY HYDROCARBON MIXTURES

2015 ◽  
Vol 32 (3) ◽  
pp. 683-698 ◽  
Author(s):  
F. A. Furtado ◽  
◽  
A. J. Silveira ◽  
C. R. A. Abreu ◽  
F. W. Tavares ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrocarbon Mixtures ◽  
Non Equilibrium Molecular Dynamics ◽  
Non Equilibrium
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