Self-Diffusion Coefficient of Molecular Fluid in Porous Media

2011 ◽  
Vol 312-315 ◽  
pp. 417-422 ◽  
Author(s):  
Vladimir Andryuschenko ◽  
Valery Rudyak
Keyword(s):  
Porous Media ◽  
Diffusion Coefficient ◽  
Hard Sphere ◽  
The Self ◽  
Dynamics Simulation ◽  
Fluid Density ◽  
Adsorption Time ◽  
Self Diffusion ◽  
Velocity Autocorrelation ◽  
Self Diffusion Coefficient

The paper deals with the molecular-dynamics simulation of the self-diffusion of fluid molecules in porous media using the hard-sphere potential. A study is made of the velocity autocorrelation functions of the molecules and dependences of the self-diffusion coefficient on the pore sizes, po-rosity, fluid density, and adsorption time.

scholarly journals Clustering effects on the diffusion of patchy colloids in disordered porous media

2021 ◽  
Vol 24 (3) ◽  
pp. 33605
Author(s):  
M. F. Holovko ◽  
M. Ya. Korvatska
Keyword(s):  
Porous Media ◽  
Diffusion Coefficient ◽  
Hard Sphere ◽  
Distribution Functions ◽  
The Self ◽  
Self Diffusion ◽  
Disordered Porous Media ◽  
Pair Distribution Functions ◽  
Matrix Pair ◽  
Self Diffusion Coefficient

Enskog theory is extended for the description of the self-diffusion coefficient of patchy colloidal fluid in disordered porous media. The theory includes the contact values of fluid-fluid and fluid-matrix pair distribution functions that are modified to include the dependence from the so-called probe particle porosity, φ, in order to correctly describe the effects of trapping the fluid particles by a matrix. The proposed expressions for the modified contact values of fluid-fluid and fluid-matrix pair distribution functions include three terms. Namely, a hard sphere contribution obtained by us in the previous work [Holovko M. F., Korvatska M. Ya., Condens. Matter Phys., 2020, 23, 23605], the depletion contribution connected with the cluster-cluster and cluster-matrix repulsion and the intramolecular correlation inside the cluster. It is shown that the last term leads to a remarkable decrease of the self-diffusion coefficient at a low fluid density. With a decreasing matrix porosity, this effect becomes weaker. For intermediate fluid densities, the depletion contribution leads to an increase of the self-diffusion coefficient in comparison with the hard sphere fluid. For a sufficiently dense fluid, the self-diffusion coefficient strongly decreases due to a hard sphere effect. The influence of the cluster size and the type of clusters as well as of the parameters of porous media is investigated and discussed in detail.

Self Diffusion in Liquid Titanium: Quasielastic Neutron Scattering and Molecular Dynamics Simulation

2009 ◽  
Vol 289-292 ◽  
pp. 609-614 ◽  
Author(s):  
Andreas Meyer ◽  
Jürgen Horbach ◽  
O. Heinen ◽  
Dirk Holland-Moritz ◽  
T. Unruh
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Neutron Scattering ◽  
The Self ◽  
Dynamics Simulation ◽  
Self Diffusion ◽  
Quasielastic Neutron ◽  
Liquid Titanium ◽  
Quasielastic Neutron Scattering ◽  
Self Diffusion Coefficient

Self diffusion in liquid titanium was measured at 2000K by quasielastic neutron scattering (QNS) in combination with container less processing via electromagnetic levitation. At small wavenumbers q the quasielastic signal is dominated by incoherent scattering. Up to about 1.2 °A−1 the width of the quasielastic line exhibits a q2 dependence as expected for long range atomic transport, thus allowing to measure the self diffusion coefficient DTi. As a result the value DTi = (5.3± 0.2)× 10−9 m2s−1 was obtained.With a molecular dynamics (MD) computer simulation using an embedded atom model (EAM) for Ti, the self diffusion coefficient is determined from the mean square displacement as well as from the decay of the incoherent intermediate scattering function at different q. By comparing both methods, we show that the hydrodynamic prediction of a q2 dependence indeed extends up to about 1.2 °A−1. Since this result does not depend significantly on the details of the interatomic potential, our findings show that accurate values of self diffusion coefficients in liquid metals can be measured by QNS on an absolute scale.

scholarly journals Molecular dynamics study of diffusion of xenon in water at different temperatures

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Niraj Kumar ◽  
Narayan Prasad Adhikari
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Structural Properties ◽  
The Self ◽  
Dynamics Simulation ◽  
Velocity Autocorrelation Function ◽  
Arrhenius Behavior ◽  
Self Diffusion ◽  
Different Temperatures ◽  
Self Diffusion Coefficient

Molecular Dynamics simulation was performed using 2 xenon atoms as solute and 300 water molecules as solvent. We have studied the structural properties as well as transport property. As structural properties, we have determined the radial distribution function (RDF) of xenon-xenon, xenon-water, and water-water interactions. Study of RDF of xenon-xenon and oxygen-oxygen interactions of water shows that there is hydrophobic behavior of xenon in the presence of water. We have studied the self diffusion coefficient of xenon, water, and mutual diffusion coefficients of xenon in water. The self diffusion coefficient of xenon was estimated using both mean-squared displacement (MSD) and velocity autocorrelation function (VACF), while only MSD was used for water. The temperature dependence of the diffusion coefficient of xenon and water were found to follow the Arrhenius behavior. The activation energies obtained are 12.156 KJ/mole with MSD and 14.617 KJ/mole with VACF in the temperature range taken in this study.

Simulation of the Properties of 1-Ethyl-3-Methyl-Imidazolium Chloride/Chloroaluminate Ionic Liquids: Concentration and Temperature Dependence

2012 ◽  
Vol 457-458 ◽  
pp. 249-252
Author(s):  
Guo Cai Tian ◽  
Ding Wang ◽  
Ya Dong Li
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Molar Fraction ◽  
Chemical Properties ◽  
The Self ◽  
Dynamics Simulation ◽  
Imidazolium Chloride ◽  
Self Diffusion ◽  
Conductivity Increase ◽  
Self Diffusion Coefficient

Influences of the molar fractions of AlCl3and temperature on room temperature molten salts 1-ethyl-3-methyl-imidazolium Chloride /Chloroaluminate [Emim]Cl/AlCl3are studied by molecular dynamics simulation. The physical and chemical properties such as density, diffusion coefficients, viscosity, conductivity of [Emim]Cl/AlCl3with different molar fraction of AlCl3are calculated. The density is obtained as 1.1744g/cm3for [Emim]Cl, which agree well with the experimental value (1.186g/cm3). It was shown that the density and conductivity increase, whereas the viscosity decreases with the increasing of molar fraction of AlCl3. The self-diffusion coefficients of [Emim]+, Cl-and AlCl3increases and the changes of self-diffusion coefficient of AlCl3is the biggest as to molar fraction increase. It is shown that the conductivity, the self-diffusion coefficient of particles all increase, and the changes of AlCl3is the biggest with the increasing of temperature, whereas the density and viscosity reduce.

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