## Laminar Flow

**Introduction:** When the flow is laminar it is possible to use the following equation to find the head lost.

The Poiseuille equation states that for a round pipe the head lost due to friction is given by:

Flow occurs because the force across AB is more than that on AB and hence it is possible to write down the following equation.

Integrating

But when

Thus:

But:

Now the mean velocity is given by:-

The head lost due to friction is given by:

Substituting from equation:

For