Loss of Energy due to Sudden Enlargement

Now, the force acting on the liquid in the control volume in the direction of flow is,

By Newton's second law, the rate of change of momentum is equal force acting on the liquid, i.e.

or,                                                           (1)

Now, if h_L is the head loss between two sections ‘1' and ‘2' due to sudden enlargement, then applying Bernoulli's equation