Mohammad Sajjad Mozaffari - High Performance Computing (HPC) Laboratory, Department of Mechanical Engineering, Ferdowsi University of Mashhad, P.O. Box ۹۱۷۷۵-۱۱۱۱, Mashhad, Iran.
Ehsan Roohi - Associate Proefssor, Department of Mechanical Eng., Ferdowsi University of Mashhad

This paper presents an investigation of flow field and the mass flow rate of rarefied gaseous flow in divergent micro/nano channels compared with the results mass flow rate of straight channels. Direct simulation Monte-Carlo (DSMC) method is used to solve rarefied flow over a wide range of Knudsen number accurately. The results show Mach number increase in straight channels and then decrease with an increase divergence angle. We observed that the mass flow rate increases with the divergence angle. The effect of channel aspect ratio (AR) is not crucial on the mass flow rate in lower Knudsen numbers. However, the mass flow rate increases with the divergence angle when Knudsen number is high. We show that enhanced thermal creep effect is the main source of the mass flow rate increase if the wall temperature gradient is increased.

DSMC, Divergent micro/nano channel, Mass flow rate, Thermal creep