Efficient Simulation of Rarefied Gas Flows Through Tubes of Finite Length Based on Kinetic Model Equations

The flow of a rarefied gas through tubes of circular cross-section and finite length, driven by arbitrarily large gradients of pressure is simulated in a computationally efficient manner based on kinetic model equations. The governing Ellipsoidal model kinetic equation is discretized in the phase space by a finite difference scheme and the discrete velocity method. It is seen that good agreement is obtained with corresponding DSMC results in the literature. Due to the five-dimensional nature of the problem, various techniques have been used to reduce the computational effort. Convergence has been accelerated for small Knudsen flows using the Wynn-epsilon algorithm while memory usage optimization, grid refinement and parallelization have been introduced. Overall, a highly efficient deterministic algorithm has been developed.