Transition Gas Flow Between Two Parallel Plates with a Slit-Type Obstacle of Various Geometry by Event-Driven Molecular Dynamics Simulation

Abstract

In this study, pressure-driven flow through a slit-type obstacle with various lengths (L) and heights (H) placed in between two parallel plates was investigated by Event-Driven Molecular Dynamics (EDMD) simulation. Mach number, temperature and pressure distributions were obtained along the channel in the transition regime. The change in these macroscopic properties and flow rate were examined for different cases created by changing Knudsen number (Kn) of the flow, the geometry of the slit and the outlet/inlet pressure ratio of the flow. Collision of gas molecules with plates and the obstacle were modeled with diffusive reflection boundary condition. The flow rate showed a sudden change in the transition regime and significant differences in the molecular regime depending on the pressure ratio. Except for the Kn, H and L dimensions were found to be effective in Mach disc formation. Pressure drops at the exit of the slit were shaped differently in normalized pressure profiles depending on Kn, H and L dimensions. In addition, the structure of the vortices formed at the entrance and exit of the slit varies depending on Kn. Some of the results obtained were confirmed to be consistent with similar studies in the literature. © 2025 Elsevier B.V., All rights reserved.