INFLUENCE OF THE FINITE LENGTH EFFECT ON THERMAL CREEP FLOW IN RAREFIED GAS

This study analyzes the influence of finite-length effects on thermally induced flow in a rarefied monatomic gas between two stationary coaxial cylinders. Using the Direct Simulation Monte Carlo method, thermoacoustic waves induced by a sudden inner-cylinder temperature shock are examined under four axial boundary conditions: diffuse, adiabatic, symmetric, and periodic. Results reveal a transient regime, where thermoacoustic waves propagate and reflect depending on boundary type, and a steady-state regime, where temperature, density, and velocity profiles stabilize. Axial boundaries significantly affect wave dynamics, dissipation, and flow structure, particularly at intermediate and radial positions. The findings emphasize the importance of accurate boundary modeling in rarefied gas dynamics for applications in microscale devices, vacuum systems, and aerospace technologies.