Abstract
Rarefied gas flow has received wide attention due to the booming of micro/nano-electromechanical systems and aerospace engineering. Under such rarefied conditions, the frequency of intermolecular collisions is sharply reduced, so the impacts of interactions between gas molecules and the wall surface on flow states become non-negligible. Owing to the complexity of theoretical research and the poor reproducibility of experimentation, molecular dynamics simulation has developed into an effective method to study the interplay between gases and solid surfaces. In this study, molecular dynamics simulations on the scattering process of nitrogen molecules from a platinum surface are conducted in a three-dimensional system. The dependences of scattering angle distributions and momentum/energy variations on the incident velocity, angles, and surface roughness are obtained. The results of this paper are not only an attempt to reveal the mechanisms of gas–surface interactions but can also be used as necessary reference data for the development of appropriate gas–surface interaction models.
Highlights
The collision frequency between gas molecules declines dramatically, so the interactions between gas molecules and the solid surface turn into an important influential factor that affects the flow state
The research object of this article is the study of diatomic molecules, and the focus is on the impacts of the incident polar angle, velocity, and wall surface roughness on the angular distribution and momentum/energy conservations after scattering, so gas molecules will have to collide with the metal surface at a specific angle and velocity, meaning that the research aim cannot be achieved by using the sampling method
The three-dimensional molecular dynamics simulations on the scattering process of nitrogen molecules from a platinum surface by the molecular beam method are conducted in this paper
Summary
Due to the ubiquity of rarefied gas flow in micro/nanoelectromechanical systems (MEMS/NEMS), astronautics, process engineering (such as heterogeneous catalysis and gas separation membranes), and vacuum technology, the research on rarefied gas flow mechanisms has attracted much attention. Under rarefied conditions, the collision frequency between gas molecules declines dramatically, so the interactions between gas molecules and the solid surface turn into an important influential factor that affects the flow state. Andric and Jenny simulated the scattering of nitrogen molecules from a graphite surface under strong thermal non-equilibrium conditions, where the initial molecular velocities were sampled from the equilibrium Maxwellian distribution They explored the energy transfer in cases of rotational and translational excitation and established the relationship between pre- and postscattered velocity distributions. The research object of this article is the study of diatomic molecules, and the focus is on the impacts of the incident polar angle, velocity, and wall surface roughness on the angular distribution and momentum/energy conservations after scattering, so gas molecules will have to collide with the metal surface at a specific angle and velocity, meaning that the research aim cannot be achieved by using the sampling method.
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