Types of flow in open channel

1. HYDRAULICS
CONTENT-
TYPES OF FLOW IN OPEN CHANNEL

2. OPEN CHANNEL -
 Open Channel Flow is defined as fluid flow with a
free surface open to the atmosphere. Examples
include streams, rivers and culverts not flowing full.

3. TYPES OF FLOW IN OPEN CHANNELS
1. Steady and Unsteady Flow
2. Uniform Flow and Non-Uniform Flow
3. Laminar Flow and Turbulent Flow
4. Critical, Sub-Critical and Super - Critical Flow

4. STEADY AND UNSTEADY FLOW
 In an open channel flow, if the flow parameters
such as depth of flow, the velocity of flow and
the rate of flow at a particular point on the fluid do
not change with respect to time, then it is called as
steady flow.
 For Steady Flow-
dv/dt = 0 dQ/dt =
0
dy/dt = 0

5. UNSTEADY FLOW
 at any point on the open channel flow,if the flow
parameters like depth of flow, the velocity of flow
and rate of flow do change their value with respect
to time, then it is called as an unsteady flow.
 It is hence given by :
dv/dt ,dQ/dt and dy/dt not equal to Zero

6. 2. UNIFORM FLOW
 The flow in the channel is said to be uniform, if, for
a given length of the channel, the velocity of flow,
the depth of flow remains constant.
 For Uniform flow
dy/dS = 0 ; dv/dS=0;

7. NON-UNIFORM FLOW
 In a Non-uniform flow, the flow parameters like
velocity, depth of flow, etc do not remain constant
for a given length of the channel.
 For Non-Uniform flow
dy/dS and dv/dS not equal to zero
 The Non-uniform flow can be again defined as
Rapidly varying flow (R.V.F) and Gradually Varied
Flow (G.V.F).
 In the case of R.V.F, the depth of flow rapidly
changes over a smaller length of the channel. It
rises up suddenly for a short length and settles
back.
 While in a G.V.F, the depth of flow changes
gradually over a longer length of the channel.

8. LAMINAR FLOW & TURBULENT FLOW
 Laminar and turbulent flow in open channel flow is
defined based on the Reynolds Number, Re. The
Reynolds number is given by the relation:
 If the Reynolds number Re is less than 500 or 600, then
the flow is called laminar flow. If the Reynolds number
is more than 2000, then the flow is said to be turbulent.

9. 4. CRITICAL, SUB-CRITICAL AND SUPER -
CRITICAL FLOW
 The open channel flow is categorized as critical or
sub-critical or super-critical based on the Froude
number Fe. Froude number is given by the relation:

10. CRITICAL, SUB-CRITICAL AND SUPER -
CRITICAL FLOW
 Open channel flow is Sub-critical if the Froude
number is less than 1. Sub-Critical open channel
flow is also defined as a tranquil or streaming
flow.
 An open channel flow with a Froude number equal
to one is a critical flow.
 Super-critical flow in open channel has a Froude
number greater than 1. A supercritical flow is also
termed as rapid flow or torrential flow or
shooting flow.

11. Thank You !