# Hydraulic Coefficients: 4 important Hydraulic Coefficients You Must Know Before entering into the details of the Hydraulic Coefficients, the following definitions must be clearly understood.

Here in this post, you will come to know about some definitions and four important hydraulic coefficients. ## So, here are the Definitions to Understand

• ### Jet of Water

The Continuous Stream of Liquid, that comes out or flows out of an Orifice, is known as the “Jet of Water”.

• ### Vena Contract

When a Tank is fitted with an Orifice, the Liquid Particles, in order to Flow out through the Orifice, move towards the Orifice from all Directions.

A few of the particles first move downward, then take a turn to enter into the Orifice, and then finally Flow through it.

While taking a turn to enter the Orifice, the Liquid Particles lose some Energy.

Due to this, it is observed that the Jet after leaving the Orifice, gets contracted.

The maximum Contraction takes place at a section slightly on the downstream side of an Orifice, where the Jet of Water is more or less horizontal.

Such a section is known as the “Vena Contract”

## So, now we will see the four important Hydraulic Coefficients

These Coefficients are also known as Orifice Coefficients.

## Main Hydraulic Coefficients

• ### Coefficient of Contraction

The ratio of the Area of the Jet at Vena Contract, to the Area of the Orifice, is known as the “Coefficient of Contraction”.

Its value will vary slightly with the available Head of the liquid, size, and shape of the Orifice.

An Average Value of the Coefficient of Contraction is 0.64

• ### Coefficient of Velocity

The ratio of the Actual Velocity of the Jet at Vena Contract, to the Theoretical Velocity, is known as the “Coefficient of Velocity”.

The difference occurs between the Velocities due to Friction of the Orifice.

For the Sharp Edge Orifice, the Value of the Coefficient of Velocity increases with the Head of Water.

• ### Coefficient of Discharge

The ratio of an Actual Discharge through an Orifice to the Theoretical Discharge is known as the “Coefficient of Discharge”.

The Value of the Coefficient of Discharge varies with the Value of Coefficient of Contraction and Coefficient of Velocity.

• ### Coefficient of Resistance

The ratio of Loss of Head in the Orifice to the Head of water available at the exit of the Orifice is known as the “Coefficient of Resistance”.

The Coefficient of Resistance is generally neglected while solving numerical problems.

Hope you will understand about Hydraulic Coefficient.