Submerged Orifice
Discharge through a submerged orifice
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.
= 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
Last Modified: 10 Jan 12 @ 17:32 Page Rendered: 2022-03-14 17:46:32