# Swamee-Jain Equation

on . Posted in Fluid Dynamics

Swamee-Jain Equation, also called Swamee-Jain formula or Swamee-Jain method, is used in the field of civil engineering and fluid mechanics.  It is used to calculate the flow of water in an open channel, specifically for determining the flow rate of water in a rectangular channel or a trapezoidal channel.  The Swamee-Jain equation provides a convenient way to estimate the flow rate in open channels without the need for complex and time consuming calculations.  It is especially useful for engineers and hydrologists involved in designing and analyzing drainage systems, culverts, and various hydraulic structures.

Manning's roughness coefficient depends on the type of channel material, channel geometry, and other factors affecting flow resistance.  It is usually determined empirically for a given channel or can be estimated based on established values for common channel materials and conditions.

The Swamee-Jain equation simplifies the process of calculating flow rates in open channels and is commonly used in hydraulic engineering applications, including the design and analysis of stormwater drainage systems, rivers, and canals.  However, it's essential to ensure that the appropriate values for channel geometry, roughness coefficient, and other parameters are used for accurate results.

### swamee-jain equation formula

$$f = 0.25 \;/\; [\; log \; (\; (\epsilon \;/\; 3.7\;d) + ( 5.74 \;/\; Re^{0.9})\; ) \; ]^2$$
Symbol English Metric
$$f$$ = friction factor $$dimensionless$$
$$\epsilon$$  (Greek symbol epsilon) = absolute roughness $$in$$ $$mm$$
$$d$$ = inside diameter of pipe $$in$$ $$mm$$
$$Re$$ = Reynolds number $$dimensionless$$