11.3.2. Velocity Distributions in Laminar and Turbulent Flows

Try these first

1. 1.

   Define wall shear stress.

   Hint

   Think about the relationship with viscosity.

2. 2.

   What is Reynolds number?

   Hint

   Consider the ratio of inertia to viscous forces.

3. 3.

   What is the primary factor used to predict if a flow is laminar or turbulent?

   • Viscosity
   • Reynolds number
   • Pressure

   Hint

   Think about what defines flow characteristics in fluid dynamics.

4. 4.

   True or False: Stream functions can exist only in the presence of irrotational flow.

   • True
   • False

   Hint

   Consider the flexibility of stream functions in flow analysis.

5. 5.

   A fluid with a viscosity of 0.89 Pa·s flows through a circular pipe of diameter 0.1 m. Calculate the wall shear stress if the average velocity is 2 m/s.

   Hint

   Use the average velocity and divide by the distance to calculate the velocity gradient.

6. 6.

   Analyze the effect of increasing the Reynolds number from 1,000 to 10,000 on the boundary layer thickness for a flat plate in a steady flow.

   Hint

   Consider the governing relation between Reynolds number and boundary layer characteristics.