22.7. Velocity Distribution and Shear Stress

Try these first

1. 1.

   Define wall shear stress.

   Hint

   Think about what causes friction in fluid flow.

2. 2.

   What shape does the velocity profile take in laminar flow?

   Hint

   Consider how layers of fluid move smoothly in laminar conditions.

3. 3.

   What does wall shear stress represent in fluid flow?

   • Frictional force
   • Velocity
   • Temperature

   Hint

   Consider what resistance the fluid faces against the pipe walls.

4. 4.

   True or False: The Moody chart is only applicable to circular pipes.

   • True
   • False

   Hint

   Think about how we can apply concepts from circular flows to other shapes.

5. 5.

   If a turbulent flow in a pipe has a Reynolds number of 4 million, and the relative roughness is 0.01, what is the friction factor using the Moody chart?

   Hint

   Study the chart closely; you will observe different zones.

6. 6.

   For a non-circular duct with a hydraulic diameter of 0.2m, if the flowing viscosity is 0.001 Pa.s at a velocity of 3m/s, calculate the wall shear stress.

   Hint

   Remember to find the density first and adjust for the hydraulic diameter.