This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Rarefied gas flow through a micro-orifice connecting two reservoirs at small pressure differences is considered in the whole range of rarefaction by the linearized BGK kinetic model equation. The problem is computationally challenging due to the five dimensional nature of the distribution function and techniques such as parallelization and numerical schemes of low memory requirements have been applied. Results include the distributions of density, velocity, temperature, as well as flow rates. The independence of flow rate in terms of the wall surface accommodation properties is confirmed.The European Community under the contract of Association EURATOM/Hellenic Republic
