A.1/2 B.1/4 C.1/8 D.1/32
A.只與雷諾數(shù)有關 B.只與管壁相對粗糙度有關 C.與雷諾數(shù)和管壁相對粗糙度均有關 D.與雷諾數(shù)和管長有關
A.0.62 B.0.5 C.0.06 D.0.64