园管的稳态流 ◆p 2b|1-(-) max dpa 8 2 (3-51) Hagen-Poiseuille equation C 2TS 1616 pr:ub dp Re 摩擦系数λ=64/Re,故∫=1/4园管的稳态流       = − 2 2 1 ( ) i z b r r u u 2 8 i f d b r u dz dp L p  = − =  umax = 2ub （3-51） Hagen-Poiseuille Equation         − = −  = 2 max 2 2 1 ( ) 4 i z i r r r r u L p u  i b r r z S r u dr du i    4 = − = = Re 2 8 16 16 2 = = = = i b i b u b r u d u s f       摩擦系数＝64 / Re,故f =  / 4