Solution methods for gas flow in ducts through the whole pressure regime

摘要: Abstract In vacuum technology it is frequently necessary to calculate gas flows over a wide range of pressures and flow conditions. Ideally, desirable be able conduct calculations for long short ducts large small pressure differences rates. The basic requirement general purpose calculation method combined continuum/molecular model that provides smooth transition between the regimes. Since gases are compressible generally applicable requires application thermodynamic relations. equations introduced and, in particular, form laminar conditions together with relate velocities applied boundary (not covered fluid dynamics literature). addition circular cross-section include other common shapes so discussed generalised annular rectangular cross-sections. Continuum formulas these well known but there appear no published molecular or arbitrary length. Empirical which have been developed by author presented.