relative roughness
Raised specifically refers to the rough wall height (absolute roughness) e and the ratio of pipe diameter d, ie e / d, is a dimensionless number.
In laminar flow, the flow system of parallel flow, no vortex generation, so the coefficient of friction and roughness of the wall has nothing to do. However, in turbulence, the roughness of the wall friction coefficient has a significant influence. The greater the roughness, the greater the impact. |
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