Friction between the flowing fluid and the surface is __________ for turbulent flow.

Friction between the flowing fluid and the surface is __________ for turbulent flow.

• A. Greater
• B. Lesser
• C. Same
• D. Negligible

Answer: (A)

Friction between the flowing fluid and the surface is greater for turbulent flow. The chaotic eddies and velocity fluctuations in turbulence boost momentum transfer toward and away from the wall, raising the wall shear stress that the surface must support. This increased shear makes the frictional resistance larger than in smooth, laminar flow, where momentum transfer is dominated by molecular viscosity and the shear at the wall is comparatively smaller. In short, turbulence intensifies the near-wall momentum exchange, leading to higher surface friction.

Friction between the flowing fluid and the surface is greater for turbulent flow. The chaotic eddies and velocity fluctuations in turbulence boost momentum transfer toward and away from the wall, raising the wall shear stress that the surface must support. This increased shear makes the frictional resistance larger than in smooth, laminar flow, where momentum transfer is dominated by molecular viscosity and the shear at the wall is comparatively smaller. In short, turbulence intensifies the near-wall momentum exchange, leading to higher surface friction.