# Submerged Orifice

Discharge through a submerged orifice

### Key Facts

**Gyroscopic Couple**: The rate of change of angular momentum () = (In the limit).

- = Moment of Inertia.
- = Angular velocity
- = Angular velocity of precession.

**Blaise Pascal**(1623-1662) was a French mathematician, physicist, inventor, writer and Catholic philosopher.

**Leonhard Euler**(1707-1783) was a pioneering Swiss mathematician and physicist.

## Discharge Through A Wholly Drowned Orifice

When the outlet side of an orifice is beneath the surface of liquid it is known as a wholly submerged orifice as shown in fig.1. In such orifices, the coefficient of contraction is equal to one. Consider a wholly drowned orifice discharging water as shown in fig.1. Let,- = Height of water (on the upstream side) above the top of the orifice
- = Height of water (on the upstream side) above the bottom of the orifice
- = Difference between the two water levels on either side of the orifice
- = Coefficient of discharge
- = Coefficient of velocity
- = Coefficient of contraction

If depth of the drowned orifice (

*d*) is given instead of and , then in such cases the discharge through the wholly drowned orifice is:Example:

[metric]

##### Example - Discharge through a wholly drowned orifice

Problem

A drowned orifice 1.5m wide and 0.5m deep is provided in one side of a tank. Find the discharge in liters/s through the orifice, if the difference of water levels on both the sides of the orifice be 4m. Take = 0.64.

Workings

Given,

- = 1.5m
- = 0.5m
- = 4m
- = 0.64

Solution

Discharge = 4250 liters/s