Question

1. What will happen to the volumetric flowrate (m3/s) when water flows from small diamiter pipe to larger diamiter pipe? Why?

2. What will happen to the water velocity (m/s) when water flows from small diamiter pipe to larger diamiter pipe? Why?

3. Why is the presure reading on the small diamiter pipe different to that of the larger diamiter pipe?

Answer 1

1) water is an incompressible substance, so Volumetric flow rate should not change.

This can be explained easily by the continuity equation.

Here, are area of the pipe.

is the water velocity and Volume.

2) From above equation

And as water will go to higher diameter velocity will decrease.

3) From the Bernoulli's equation

Since, h = constant equation becomes

So, if water goes from region where decreases then the term will also decrease which implies that will increase in that region to satisfy the above equation.

That is why pressure reading on the smaller pipe different to that of the larger diameter pope.