# Homework Help: Velocity and pipe diameter

1. Sep 17, 2009

### birddog

Hello there,

Im trying to figure this assignment question and I have hit hurdle. Can someone please help with figuring out what the velocity and pipe diameter will be??

Question:
In a plant 20m3(cubic)/h of water at 20 degrees C is to flow via gravity from a storage tank to another one. the difference in elevation is 15m and total pipe length is 50m.

I thought it would be 9.81 m/s because of gravity but that seems too fast.

2. Sep 18, 2009

### saunderson

i would give bernoulli's equation a try

$$p + \frac{1}{2} \rho v^2 + \rho g h = \rm{const}$$​

remember:

$$\dot V = \frac{v}{A}$$​

3. Sep 18, 2009

### CFDFEAGURU

Just to be technical on this.

Bernoulli's equation only works well if the viscosity of the fluid can be neglected.

Follow saunderson's post. I just wanted to throw the viscosity bit in.

Thanks
Matt

Last edited: Sep 18, 2009