17.5.2. Eddy Size and Frequency

Try these first

1. 1.

   What is an eddy in fluid mechanics?

   Hint

   Think about how water swirls in a stream.

2. 2.

   What does a Reynolds number less than 2300 indicate?

   Hint

   Consider the smoothness of the flow.

3. 3.

   What definitively indicates a flow has transitioned to turbulent?

   • Reynolds number below 1000
   • Reynolds number above 4000
   • Reynolds number equals 2300

   Hint

   Consider the significance of high turbulence.

4. 4.

   True or False: Eddies smoothly transport mass in laminar flow.

   • True
   • False

   Hint

   Think about how laminar flows behave.

5. 5.

   Given a pipe flow scenario with a diameter of 0.1 m, determine the Reynolds number if the fluid has a density of 1000 kg/m³ and flows at a velocity of 5 m/s with a dynamic viscosity of 0.001 Pa.s. Is the flow laminar, transitional, or turbulent?

   Hint

   Use the formula for Reynolds number.

6. 6.

   Discuss how energy cascades from large eddies to small eddies, highlighting the role of viscosity in this process.

   Hint

   Think about the implications of size on energy.