Molecular Dynamics Simulations On The Diffusivity Of Fluids Of Fluids In Porous Media

This work is financially supported by the National Major Fundamental Research and Development Project G19990433 and the National Natural Science Foundation of China Project 29977018. These projects aim to predict the enrichment and distribution of petroleum and natural gas under-earth. The traditional experience cannot investigate such complicated properties of fluid under some extreme conditions. But computer simulation can be used to help people to do research jobs.All of this work relates molecular dynamics and involves four facets. Firstly, the diffusivity of the simple mixture have been calculated, which is confined by "wet" slit pore; Secondly, the diffusivity of the mixture have been simulated, which is confined by slit three-layer silicate pore; Thirdly, the distribution of mixture fluid in the slit three-layer silicate pore have been showed; Finally, a computer cluster have been applied to calculate the velocity auto-cross function of water, which is confined by slit three-layer silicate pore.Equilibrium molecular dynamic simulations have been used to calculate the diffusivity of Argon and Krypton in macrovolume system. The calculation results have been compared with experimental data in order to test the program. The diffusivities of simple fluid mixtures of Argon and Krypton in macrovolume system have also been computed in order to verify the simulation program further. The results are in good agreement with the experimental and literature data. It can be concluded that the mixing rules are right, and the program can calculate the diffusivity successfully.And then the diffusivity of Argon, Krypton, and simple fluid mixtures of Argon and Krypton in "wet" slit porous media have been investigated at different temperatures, densities and pore widths. On the other hand, based on the Chapman-Enskog theory and Heyes relationships, two correlation models, which can describe the diffusivity of simple fluid mixtures in porous media, are proposed as a function of the reduced temperature,density and pore width. The validity of the models is evaluated by comparing the calculated diffusivity to simulation data.The diffusivities of argon and krypton mixture in slit three-layer silicate pore have been studied using equilibrium molecular dynamics simulation. Based on the result, tow kinds of models have been presented. Firstly, five experiential models in five different pore widths have been presented; Secondly, A model alike to the former part has been given. The validity of these models is evaluated by comparing the calculated diffusivity data with those from the simulation data.The adsorption phenomena for the binary mixture of water and methane confined in slit silicate has been investigated by equilibrium molecular dynamics (EMD). Most of particles are adsorbed adherent to the pore walls. The adsorptions are layered and the layered number equals to subtract 1 from reduced pore width (n=H*-\). The concentration distributions of methane formed several apices and the number of apices is up to reduced pore width (n=H*).A PC Cluster, which contains four computing nodes, based on MPI for molecular simulation has been established with Windows operating system. The efficiency of this cluster has been investigated by calculation of Argon's energy. In the calculation, the phenomena that the loading is not average, has been observed. Spatial decomposition has been improved from three facets in order to reduce negative effects.- Blocked communication replaces non-blocked communication, the result of cell decomposition is used, and overlap of copying and removing particle is used in order to reduce traffic. After modification, the program is more 28.64 percent effective. Velocity auto-correlative function of water in macrovolumn and confined in silicate is computed. The result shows that parallel MD simulation can reduce the calculating time.In this work, we have reached our aim, which looked up before this job beginning. This work will benefit consequent works, which can deeply focus on the various species and more complex pore.