We were discussing the basic difference
between orifice and mouthpiece, classification
of orifices and mouthpieces, advantages
and disadvantages of orifices, hydraulic
coefficients and also experimental process to determine the
hydraulic coefficients, in the subject of fluid mechanics, in our recent
posts.

Now we will go ahead to find out the flow through fully submerged orifices, in the subject of fluid mechanics, with the help of this post.

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Now we will go ahead to find out the flow through fully submerged orifices, in the subject of fluid mechanics, with the help of this post.

Fully submerged orifice is one which has its whole
of the outlet side submerged under liquid so that it discharges a jet of liquid
in to the liquid of the same kind.

Fully submerged orifice is also called as totally
drowned orifice. Coefficient of contraction for fully submerged orifice will be
equivalent to 1.

Let us consider the following figure displaying the
fully submerged orifice. Let us consider two points i.e. 1 and 2. Point 1 will
be in the reservoir on the upstream side of the orifice and point 2 will be at
the vena-contracta as displayed here in following figure.

H

_{1}= Height of water above the top of the orifice on the upstream side
H

_{2}= Height of water above the bottom of the orifice
H = Difference in level of water

b = Width of the orifice

C

_{d}= Coefficient of discharge
Height of water above the centre of orifice on
upstream side

= H

_{1}+ (H_{2}- H_{1})/2
= (H

_{1}+ H_{2})/2
Height of water above the centre of orifice on downstream
side

= (H

_{1}+ H_{2})/2 – H
Now we will apply the Bernoulli’s equation at 1 and
2.

Considering the term z

_{1}= z_{2}, we will have following equation as mentioned here
This is
the expression for the flow or discharge through the fully submerged orifice.

Now we
will go ahead to find out the method to determine the discharge through a partially submerged orifice, in the subject of fluid mechanics, in our next post.

Do you
have any suggestions? Please write in comment box.

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**Reference:**

Fluid
mechanics, By R. K. Bansal

Image
Courtesy: Google