Heat Transfer, Normal Stress, and Shear Stress for a Free-Molecular Gas Impinging on Several Wall Models

摘要

An analytical study of gas-surface interactions was made in a free-molecular flow; perfectly elastic collisions between the billiard-ball molecules and the surface were assumed and the molecules were governed by a Maxwellian velocity distribution in the free-stream. Normal stress for specular reflection from a stationary boundary was increased as the square of the mass velocity normal to the boundary, while the mass velocities tangential to the boundary had no influence on the normal stress. Normal stress increased as the square of the wall velocity, when the wall velocity squared was small as compared to the local mean square random velocity. Energy was transferred into the gas as a function of the wall speed to the second and fourth powers. Pressure and heat transfer were independent of the vibration frequency. Throughout the study, energy transfer, shear stress, and normal stress were shown to be directly dependent on gas density and the mean-random velocity.