Rarefied Flows of the Monatomic Gas in a Two-Dimensional Expansion Nozzle

Rarefied transition flows are calculated for the throat Knudsen-number K_n less than 0.3 by using the direct simulation Monte Carlo method. The properties on the nozzle center-plane are as follows: (1) the mean velocity decreases with the increase of K_n, (2) the overall temperature increases with K_n, (3) the number density is barely affected by K_n and is close to the equilibrium number density, and (4) disparity in the separate temperatures increases with K_n; as the nozzle area-ratio increases, the parallel temperature and the component of normal temperature parallel to the center-plane gradually rise above the equilibrium temperature, whereas the component of normal temperature perpendicular to the center-plane drops below the equilibrium temperature.