# How to design and find out the size of rectangular open channel in Hydraulic Engineering

This construction video provides some useful tricks on how to design or find out the most economical segment toward rectangular open channel.

Open Channel Flow is described as fluid flow containing a free surface open to the atmosphere. The instances are streams, rivers and culverts not flowing full.

The video provides solution to the following problem :-

problem:--Find the most economical X-section of a rectangular channel to carry 0.3𝑚^3/sec of water when channel bed slope is 1:1000. assume chezy’s constant, C=60

In the solution provided, chezy’s formula as well as some condition of economical section is applied to obtain the size of the channel.

The Chezy formula is applicable to pipes having turbulent flow. In fluid dynamics, the Chézy formula defines the mean flow velocity of steady, turbulent open channel flow.

The formula is given as

• {\displaystyle v=C{\sqrt {R\,i}},\,}where
• {\displaystyle v}ν denotes average velocity [m/s],
• {\displaystyle C}C denotes Chezy's coefficient [m½/s],
• {\displaystyle R}R is the hydraulic radius (~ water depth) [m], and
• {\displaystyle i}i is the bottom slope [m/m].