The Effect of Model Internal Flexibility Upon NEMD Simulations of Viscosity
نویسندگان
چکیده
The influence of model flexibility upon simulated viscosity was investigated. NEMD simulations of viscosity were performed on seven pure fluids using three different models for each: one with rigid bonds and angles, one with flexible angles and rigid bonds, and one with flexible bonds and angles. Three nonpolar fluids (propane, n-butane and isobutane), two moderately polar fluids (propyl chloride and acetone), and two strongly polar fluids (methanol and water) were studied. Internal flexibility had little effect upon the simulated viscosity of nonpolar fluids. While model flexibility did affect the simulated viscosity of the polar fluids, it did so principally by allowing a density-dependent change in the dipole moment of the fluid. By using a rigid model with the same geometry and dipole moment as the average flexible molecule at the same density, it was shown that the direct effect of flexibility is small even in polar fluids. It was concluded that internal model flexibility does not enhance the accuracy of viscosities obtained from NEMD simulations as long as the appropriate model geometry is used in the rigid model for the desired simulation density.
منابع مشابه
Effect of bilayer flexibility and medium viscosity on separation of liposomes upon stagnation
Liposomes are widely used as drug delivery systems in different forms including osmotic pumps, infusion and IV injection. In spite of these, there is no data available about their behavior under convective flow (e.g. infusion or osmotic pumps) and upon stagnation in such drug delivery systems. As a part of a series of investigations in this area, the present study investigates the effects of vi...
متن کاملAUA model NEMD and EMD simulations of the shear viscosity of alkane and alcohol systems
The viscosities of alkanes (propane, isobutane, nonane), alcohols (ethanol, propanol, isopropanol, 2-butanol) and isopropanol + nonane mixtures were calculated using non-equilibrium and equilibrium molecular dynamics (NEMD and EMD) simulation methods. The nonane, isopropanol and nonane + isopropanol mixture simulations were performed in response to the First Industrial Simulation Challenge. Int...
متن کاملShear viscosity of molten alkali halides from equilibrium and nonequilibrium molecular-dynamics simulations.
The shear viscosity of molten NaCl and KCl was calculated through equilibrium (EMD) and nonequilibrium molecular-dynamics (NEMD) simulations in the canonical (N,V,T) ensemble. Two rigid-ion potentials were investigated, namely, the Born-Mayer-Huggins-Tosi-Fumi potential and the Michielsen-Woerlee-Graaf-Ketelaar potential with the parameters proposed by Ladd. The NEMD simulations were performed ...
متن کاملRheological Behavior of Water-Ethylene Glycol Based Graphene Oxide Nanofluids
Traditionally water-ethylene glycol mixture based nanofluids are used in cold regions as a coolant in the car radiators. In the present study, the rheological properties of water-ethylene glycol based graphene oxide nanofluid are studied using Non-Equilibrium Molecular Dynamics (NEMD) method at different temperatures, volume concentrations, and shear rates. NEMD simulations are perfor...
متن کاملOn the relationship between two-body and three-body interactions from nonequilibrium molecular dynamics simulation
Nonequilibrium molecular dynamics ~NEMD! simulations are performed for argon at different strain rates using accurate two-body and three-body intermolecular potentials. The contributions of twoand three-body interactions to the configurational energy of argon at different strain rates are reported. The NEMD data indicate that there is the same simple relationship between twoand three-body inter...
متن کامل