C. For turbulent pipe flow, the pipe can be treated as hydraulically smooth if Eu* et where e is the surface roughness. Hydraulically smooth conditions means that surface roughness will not effect the...

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Extracted text: C. For turbulent pipe flow, the pipe can be treated as hydraulically smooth if Eu* et where e is the surface roughness. Hydraulically smooth conditions means that surface roughness will not effect the flow. Why is the limit set to ɛt <>