Pressure drop and heat transfer rates are ______ for turbulent flow.

• A. Weaker
• B. Stronger
• C. Unchanged
• D. Variable

Answer: (B)

Turbulent flow enhances transport processes because chaotic eddies mix momentum and energy much more effectively than smooth, orderly flow. This increases friction losses at the walls and boosts the rate at which heat is carried away or toward the surface.

For pressure drop, the wall shear stress is higher in turbulence due to these eddies and constant mixing, so the friction factor is larger and more energy is dissipated as the fluid moves through the pipe. That means a greater pressure drop per unit length than in laminar flow.

For heat transfer, turbulence thins and disrupts the thermal boundary layer near surfaces, raising the convective heat transfer coefficient. With a higher h, the rate of heat transfer Q = hAΔT increases for the same surface area and temperature difference.

So, both the pressure drop and the heat transfer rate are stronger in turbulent flow.