传热学-第五章选编.ppt

*;*;*;*;*;*;*;*;*;*;*;*;*; The Prandtl number is a measure of the relative magnitudes of the diffusivity of momentum (and thus the development of the velocity boundary layer) and the diffusivity of heat (and thus the development of the thermal boundary layer). The Pr is a fluid property, and thus its value is independent of the type of flow geometry, The Pr changes with temperature, but not pressure. ;*;*;*;*;*;*;*;*;*;*;*;*;*;*;15/10/2012;*;*;*;*;*;*;*;*;*;*;*