Question

At what flow rate might turbulence begin to develop in a 0.280 m diameter water main? Assume a 20°C temperature and a Reynolds number of 2000. (Use 1.005 10-3 (N/m2) · s for the viscosity of water.)

Answer 1

Reynolds number determine whether the flow of fluid is laminar or turbulent. For the flow of fluid in water main of uniform radius is given as,

Where,

• is the Reynolds number
• is the density of water at 20 degree Celsius
•    is the velocity of fluid
•    is the radius of tube or water main
•    is the viscosity of water

Flow rate Q is defined as the volume of fluid passing through the area per unit time t with velocity v and is given as,

Where, A is the area of tube

Given:-

• 
• 
• 
• 
• 

Now, solve above equations for velocity v.

Put this value of velocity in flow rate equation, we get,

So at this flow rate the turbulence begin to develop in water main.