AVS 56th International Symposium & Exhibition
    Vacuum Technology Wednesday Sessions
       Session VT-WeM

Paper VT-WeM5
Numerical Simulation of Rarefied Gas Flows through Short Tubes Driven by a Pressure Drop

Wednesday, November 11, 2009, 9:20 am, Room J1

Session: Partical and Theoretical Aspects of Gas Dynamics
Presenter: S. Varoutis, University of Thessaly, Greece
Authors: F. Sharipov, Unuversidade Federal do Parana, Brazil
S. Varoutis, University of Thessaly, Greece
D. Valougeorgis, University of Thessaly, Greece
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Rarefied gas flows through short tubes are investigated numerically by the Direct Simulation Monte Carlo method. The flow rate and flow field were calculated as a function of the gas rarefaction, length-to-radius ratio and pressure drop. The gas rarefaction, which is inversely proportional to the Knudsen number, is varied from 0 to 2000, i.e. the free-molecular, transitional and hydrodynamic regimes are embraced. A wide range of the length-to-radius ratio, namely from 0 corresponding to the orifice up to 10 representing a sufficiently long tube, are considered. Several values of the pressure ratio between 0 and 0.7 are regarded. This pressure range covers both gas flow into vacuum and into a back ground gas. It has been found that the rarefaction parameter has the most significant effect on the flowfield characteristics, followed by the pressure drop, while the length-to-radius ratio has a rather modest impact. The effect of gas rarefaction on the choked flow and on the Mach discs at large pressure drops is discussed. A comparison of the present numerical results with available experimental data has shown a good agreement.