1.8. Mixing length (lm)

Try these first

1. 1.

   What is the definition of eddy viscosity?

   Hint

   Think about how turbulence complicates a flow.

2. 2.

   What does mixing length (lm) refer to?

   Hint

   Consider what is needed for momentum exchange.

3. 3.

   What is the primary role of mixing length in turbulent flow?

   • To measure viscosity
   • To facilitate momentum exchange
   • To determine flow rate

   Hint

   Think about what allows fluid layers to interact effectively.

4. 4.

   True or False: Eddy viscosity is a constant property of all fluids.

   • True
   • False

   Hint

   Consider how turbulence changes in different scenarios.

5. 5.

   Calculate the turbulent shear stress in a pipe if the average velocity gradient is 2 m/s², and the mixing length is determined to be 0.4 m.

   Hint

   Focus on the relationship between shear stress, mixing length, and velocity gradient.

6. 6.

   Explain how disturbances in velocity affect eddy viscosity and turbulent shear stress in an open channel flow.

   Hint

   Think about how turbulence impacts flow behavior on a larger scale.