Molecular Dynamics Simulation Of Nanochannel Flow

With the development of modern science and nanotechnology, the behavior of nanoscale fluid has been attracting more and more attention. In this thesis, an investigation based on three types of nanochannel, including slit, pore and a simplified model of microvessel wall, was carried out by using molecular dynamics (MD) simulation.Firstly, a comprehensive investigation on the density properties of confined fluid in nano slit was carried out, in which the density properties was comprehensively investigated by MD simulation, mainly focusing on the effect of channel width, average density and potential on density distribution. And the effect of density distribution on fluid flux was also considered. It was found that: density distribution depends on channel width /average density/potential. No matter nanoscale or macroscale, density oscillation always exists near the wall. With the increase of channel width, oscillation amplitude/length will become stable. The bigger average fluid density, the longer oscillation length. For WCA/LJ fluid, oscillation length is several molecular diameter long. The attraction force takes more effect on density distribution, compared with repulsive part.Furthere more, fluid behavior in nanopore was investigated, focusing on the effect of external force/wall-fluid interaction. We mainly pay attention to density and velocity distribution. At the same time, a comparison between the flow flux of different average fluid density was also carried out. It was shown that, the fluid of lower average density corresponds to bigger flux. Then the effect of wall roughness of sinusoidal type on flow was considered, which demonstrated that velocity can be apparently suppressed by wall roughness and the effect is stronger for weaker wall-fluid interaction. We also established a simplified model to trace the movement of nano particle, and found the wall-fluid interaction takes effect and the particle will be adsorbed to the wall when the wall-fluid interaction is weak.Finally, the structure of microvessel wall was simplified and the permeable characteristics of nano-particle in microvessel wall were investigated by molecular dynamics simulation. The study is focused on the effect of particle size on transport properties. Traces of particles with different radius was recorded and compared. The result shows size effect must be considered when considering the problem of microvessel permeability. To our knowledge, we reproduce the transport of colloidal particles in the presence of fiber matrix for the first time, which is helpful to understand drug delivery in microvessel.