Measurement of slip velocity
Overview
Recently, the interest of applying high-tech to limiting condition has been increasing. In this situation, the demand for development of rarefied gas technology is pressing. In the rarefied environment, the no-slip condition cannot work anymore, the slip velocity occurs on the wall.
At present, the research about slip velocity is concentrated on the numerical simulation since the technical obstacle. Among those, the empirical function for velocity of Pan et. al derived by DSMC and the Langmuir model of Myong et al are the most typical approach.
The velocity slip on the solid surfaces of cylindrical Couette flow is investigated experimentally for high Knudsen numbers in vacuum pressure case. The flow was developed in two concentric cylinders. The inner cylinder is rotated at a constant speed and the torque exerted on the outer cylinder was measured a function of the varying pressure. The influence of the wall roughness was also investigated. The results show the slip begins at about and the relative slip velocity of 0.16 was obtained at . It was proved that when the roughness was implemented on the outer cylinder wall, the pressure at which slip begins increased. The relative slip velocity was also changed for the same pressure comparing to the smooth surface case.
Recent Reports
- Obi, S., Jin, H., Measurement of slip velocity in annular Couette flow at high Knudsen numbers, Mechanical Engineering Congress, 2006 Japan (MECJ-06), 2006/9/18‐22
- Obi, S., Kominami, H., Nakajima, T., 2003. Indirect measurement of slip-velocity between solid wall and gas flow at high Knudsen numbers, The International Symposium on Micro-Mechanical Engineering, 339-343