关键词: 边界层, 尺度化, 数量级

Abstract: By selecting intrinsic reference scaling‚and according to some related properties of continuous function‚the magnitude of each tiny quotient in Navier-Stokes equation was determined based on some experimental materials．Then scaling analysis was carried out to make each part of the equation non-dimensional‚and the magnitude of each tiny quotient of the equation was evaluated．By removing the parts whose magnitude was less than1‚Prandtl boundary layer differential equation was induced successfully．To a certain extent‚this method discloses the mathematical and physical essence of boundary differential equation． 

Key words: boundary layer, scaling, magnitude