The effects of average pressure, temperature ratio, length and open area of capillaries membrane on mass flow rate in transitional regime of single stage Knudsen compressor were investigated numerically by using molecular dynamic method. Both two-dimensional and three-dimensional models were implemented in this investigation. Physical models have nano-scale pores and micro-scale tanks filled with monoatomic Argon gas. The interactions between gas molecules were modeled by using Lennard-Jones potential function. Investigations were performed in a wide range of parameters including average pressure (57 torr to 10 torr); temperature ratio (from 1.54 to 2.29); capillary’s radius (50Å to 150Å). The results were compared with analytical prediction in the literatures earlier, and qualitative agreement was observed. Moreover effect of capillaries length, observed in current work, has a qualitative agreement with experimental data. Based on the obtained results, suggestions for future studies were given.

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