Abstract:  

A rarefied gas flowing out of an annular exit and impinging at a vertical flat plate was studied theoretically at the free molecular flow limit. Several analytical expressions of collisionless flow property?s distributions on the plate surface were obtained by employing a constraint relation about the velocity components of gas particles leaving a nozzle of annular exit and arriving at a given spatial point outside the nozzle. These flow property distributions include density, slip velocity, temperature, pressure, shear stress, force on the plate, and heat flux. Simplified analytical results were provided and compared with the numerical results obtained by the direct sim-ulation Monte Carlo method. In general, the exact analytical solutions and the numerical ones are virtually identical.