Steady uniform flow Flashcards
What is steady uniform flow?
A flow where the discharge is independent of position and does not change with time
What does the continuity equation for steady flows state?
The discharge Q is independent of position x, with dQ/dx = 0
What are the main forces acting on a control volume in steady uniform flow?
Pressure forces, gravitational body force, and friction force due to wall shear stresses
How is the Chézy coefficient (C) related to flow velocity?
Chézy’s equation relates flow velocity to the slope and channel geometry using the Chézy coefficient
What does the Chézy coefficient represent?
The smoothness of the channel affects flow velocity
How does wall shear stress vary in turbulent flows?
Approximately as the square of the mean velocity
What is the Froude number and what does it indicate?
A dimensionless number indicating the ratio of flow velocity to shallow-water wave propagation velocity
What differentiates sub-critical from super-critical flow?
Sub-critical flow is controlled downstream and is tranquil, while super-critical flow is controlled upstream and is fast
What happens in a transition between sub-critical and super-critical flow?
Occurs when flow encounters increased slope or a flow control structure
How is the Froude number calculated?
Fr = U/√(gh), where U is the flow velocity and h is the hydraulic depth
What values are not know before hand?
h(x) and A(x)
What is the equation of forces for steady uniform flow?
Pressure forces + Gravitational forces - frictional forces = 0
How frictional force be calculated?
F_f=𝜏_wPL
How can velocity from Chezy coefficient be calculated?
U=C√Rs
What are typical values of C?
Typical values between 40 (rough) to 80 (very smooth)
