Abstract
Along with the developments of the Micro Electro Mechanical Systems (MEMS), the Knudsen number, which is the non-dimensional parameter for rarefaction, of the flow inside such systems becomes large. In these high Knudsen number flows, a gas-surface interaction has become important. To illustrate the gas-surface interaction, an accommodation coefficient α is widely used as an empirical parameter. The tangential momentum accommodation coefficient (TMAC), one of the accommodation coefficients, has close relation to the pressure loss through a micro channel. Therefore, TMAC is an important coefficient for micro flow analyses. To obtain TMAC experimentally, the mass flow rate measurements in microtubes were carried out using the constant volume method. Since the mean Knudsen number was less than 0.3, the velocity slip boundary condition is applicable. The results obtained experimentally were analyzed in frame of the Navier-Stokes equation associated with the second order velocity slip boundary condition. Then the slip coefficient of the boundary condition was obtained, and finally TMAC was determined.
