Non-stationary rarefied gas flow into vacuum from a circular pipe closed at one end

The paper is devoted to the analysis of the time-dependent rarefied gas flow into vacuum from a circular pipe closed at one end. The problem is studied numerically on the basis of the S-model kinetic equation. Limiting solutions corresponding to the one-dimensional free-molecular and hydrodynamic flow regimes are also considered. The results demonstrate the dependence of flow pattern and evacuation time on the Knudsen number.