Computational study of a rarefied gas flow through a long circular pipe into vacuum

The paper presents an analysis of the non-linear rarefied gas flow through a circular pipe into vacuum. The main attention is given to the case of the large length to radius ratio. The problem is studied on the basis of the numerical solution of the S-model kinetic equation. Results are compared with the available DSMC data for short tubes as well as with the asymptotic solution corresponding to the infinitely long pipe.

► Rarefied gas flow through a long circular pipe into vacuum is studied.
► Results are obtained by solving numerically the S-model kinetic equation.
► Non-dimensional mass flow rates are compared to the asymptotic solution corresponding to infinitely long pipe.
► Analysis of the flow field is given.