For laminar flow in a pipe of circular cross-section, the Darcy’s friction factor f is

inversely proportional to Reynolds number and directly proportional to pipe wall roughness

directly proportional to Reynolds number and independent of pipe wall roughness

directly proportional to pipe wall roughness and independent of Reynolds number

inversely proportional to Reynolds number and indpendent of pipe wall roughness

For laminar flow in a pipe of circular cross-section, the Darcy’s f

1.	For laminar flow in a pipe of circular cross-section, the Darcy’s friction factor f is
A.	directly proportional to Reynolds number and independent of pipe wall roughness
B.	directly proportional to pipe wall roughness and independent of Reynolds number
C.	inversely proportional to Reynolds number and indpendent of pipe wall roughness
D.	inversely proportional to Reynolds number and directly proportional to pipe wall roughness
Answer» D. inversely proportional to Reynolds number and directly proportional to pipe wall roughness