Numerical modeling of Knudsen's thermal creep experiment

Abstract

In his study of thermal creep phenomena in 1910, M. Knudsen build a construction that was composed of 10 pairs of cylindrical tubes of different diameters heated at its junctions. He observed that at some conditions the construction worked as a gas compressor and he was able to obtain the pressure ratio at the ends of the device up to 10. The aim of the present work was to model the experiment using the power of modern computers and the efficient method for solving the Boltzmann kinetic equation. The computations were made for the same set of temperatures, gas pressures and geometrical parameters of the installation as in the experiment, and for molecular hydrogen with real Lenard-Jones potential and realistic rotational energy relaxation time. The Boltzmann equation was solved by the conservative projection method. The computations were carried out with the use of specially developed by the authors program-solving environment for modeling of rarefied gas flows with arbitrary geometry and real gas parameters. The obtained results are in reasonable good agreement with the experimental data. © Published under licence by IOP Publishing Ltd.