• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.5
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• pp.382-391
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• 2008

A simple analytical model of rarefied channel flow is developed to predict the compression ratio in a helical drag pump. If the surface velocity is zero, the model reduces to a capillary leaks. Predictions of our model agree well with the Knudsen's data for capillary leaks in transition flow, in addition to giving a good account of the Knudsen minimum. Also, the present results are compared with experimental data, and good agreement is obtained over the entire pressure range from molecular to slip flow.