4.2. Turbulent flow in smooth pipes

Try these first

1. 1.

   What flow regime is indicated by a Reynolds number above 4000?

   Hint

   Think about the range provided for laminar and turbulent flow.

2. 2.

   In turbulent flow, how does velocity behave close to the pipe wall?

   Hint

   Consider the effect of viscosity and adhesion to the wall.

3. 3.

   What is the threshold Reynolds number indicating turbulent flow?

   • 1000
   • 2000
   • 4000

   Hint

   Recall the commonly accepted values for laminar versus turbulent transitions.

4. 4.

   True or False: The velocity in a turbulent flow at the wall is always positive.

   • True
   • False

   Hint

   Consider what happens at the boundary where the fluid meets the wall.

5. 5.

   A cylindrical pipe of diameter 10 cm has turbulent flow with a velocity at 1 cm from the wall being 40% more than at 4 cm. Calculate the roughness height using Nikuradse's findings.

   Hint

   Set up equations based on velocity differences at the specified distances.

6. 6.

   Given a fluid with properties leading to a Reynolds number of 2500, convert the conditions to exhibit turbulent flow by altering the velocity or viscosity. What adjustments would lead to this change?

   Hint

   Use the formula for Reynolds number: Re = (Density * Velocity * Diameter) / Viscosity.