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Ali Hamza
Ali Hamza
Mechanical
04 Feb 2019

What are different types of flow in open channel flow??

TYPES OF FLOW IN OPEN CHANNELS

Steady and unsteady flow

Uniform and non-uniform flow

Laminar andTurbulent flow

Subcritical, critical and supercriticalflow

Laminar and Turbulent Flow: For open channels, it is defined with Reynolds No.as;Therefore,

For laminar flow: Re < 500

For Turbulentflow: Re >1000

For transitional flow: 500 < Re <1000

For laminar flow: Re < 2000

For Turbulent flow: Re > 4000

Transitional 2000 < Re < 4000

Where, 

Rh = hydraulic radius = A

If width/depth > 10 then R ≅deptℎ

Subcritical, Critical and Supercritical Flow: 

These are classified with Froude number.Froude No. (Fr) is ratio of inertial force to gravitational force of flowing fluid. 

Mathematically, Froude no.is

Fr. < 1 Flow is subcriticalflow 

Fr. = 1 Flow is criticalflow

Fr. > 1 Flow is supercriticalflow

Where, V is average velocity of flow, h is depth of flow and g is gravitational acceleration.