Exam 2 Flashcards
Uniform Flow
No change in velocity over a distance
Steady Flow
No change in velocity over time
hydraulic Radius
Area/wetted perimeter (Wp)
Hydraulic Depth
Area/B (top width)
Continuity equation
Q = Q
F =?
P*A
P = ?
gamma *Hc
Normal Depth
The equilibrium depth
The equation used to derive manning equations
Chezy Equation
Assumptions for uniform depth
a fixed geometry
a fixed flow rate
fixed roughness coefficient
fixed slope
What are alternate depths
Two depths with the same specific energy
Specific Energy
The total energy in the flow at a cross-section when Function of its kinetic and potential energy terms when you use the bottom of the channel as a datum
Critical depth
the depth that critical flow occurs
Critical flow
Flow with minimum energy, froudes number = 1
Subcritical flow
Froudes <1
Deep water and slow
Supercritical flow
Froudes > 1
Shallow water and fast
Specific Energy Equation
E = y + (v^2)/2*g
Froudes Equation
Fr = V/sqrt(g * D)
D = A / B
B= top width
Total Energy H =
E (specific energy) + z (height of ground from datum)
Hydraulic choke point
occurs when insufficient energy in a channel to pass over constriction
Water backs up until gains enough energy to pass over at critical depth
What causes a hydraulic jump
supercritical flow runs into deep subcritical flow downstream
Sequent or conjugate depths
Two depths with the same specific force
Specific force equation
F = (Q^2)/(gA) +A(y-bar)
(ft^3)
y bar is the centroid
What is a weir?
Is a low damn or overflow structure across an open channel
Weirs force critical depth to occur at the weir
The purpose is to control water and prevent flooding
