Open Channel Flow Exam 1
The E-y diagram gives - depths
alternate
any pair of depths that correspond to the same specific energy for a given discharge are referred to as - depths
alternate
the depths upstream and downstream of a sluice gate on a horizontal bed are - depths
alternate
the E-y diagram is useful for seeing -
alternate depths, effect of choke when the gate depth decreases to less than the alternate depth to the initial upstream depth, the energy loss in a hydraulic jump
you - energy in a hydraulic jump
lose
for steady unform flow, use - to obtain normal depth
mannings equation
for a fixed specific energy, specific discharge is - at critical conditions
maximized
if y(0) > y(crit), the channel is -
mild
the bernoulli equation is conserving -
momentum
the saint venant equation is conserving -
momentum
the more supercritical the flow upstream of the jump, the (more/less) subcritical will be the flow downstream of the jump
more
during a vertical drop or expansion, can the system be choked?
no
what is uniform flow
no change in x
what is steady flow
no change with time
- depth is observed under uniform flow conditions
normal
in a stepped channel, the water surface and bed are - if Fr < 1
out of phase (WSE decreases when bed height increases)
simplified version of the reynold's transport theorm
rate of change of F within control volume + sum of the flow rate of F passing through the control surface
for steady uniform flow, driving gravitational force equals -
resisting frictional force
for the case of steep to mild conditions, if M(1) > M(2), the HJ will occur in the - reach
second
depths just downstream and upstream of a hydraulic jump are - depths
sequent
The M-y diagram gives - depths
sequent or conjugate
two methods to solving quantitatively gradually varied flow
simple finite difference, HEC-RAS
what is hydrologic routing
solves continuity equation (no force)
what is hydraulic routing
solves momentum and continuity (considers force)
bernoullis equation minus pressure head
specific energy
the bernoulli equation assumes -
steady and frictionless
what are the conditions of GVF
steady, nonuniform, friction
what are the three ways you can classify flow
steady/uniformness, laminar vs turbulent, flow criticality
if y(0) < y(crit), the channel is -
steep
natural examples of open channel
stream, overland flow, estuaries/coastal
- flows occurs when the flow depth is greater than y(crit)
subcritical
If Fr < 1, the flow is -
subcritical
On an E-y diagram, values above y(crit) are -
subcritical
- flows occurs when the flow depth is less than y(crit)
supercritical
If Fr > 1, the flow is -
supercritical
On an E-y diagram, values below y(crit) are -
supercritical
the energy possessed by a flow of water
total head
when does a hydraulic jump happen
transition from super to sub critical flow
when does a hydraulic jump occur
transitioning from super to sub critical
almost all natural flows are (laminar/turbulent)
turbulent
- flow does not change in depth along the direction of flow in an open channel
uniform
what type of flow does not exist in nature
unsteady uniform flow
chezys equation uses the assertion that shear stress is directly proportional to -
velocity head
what is the reynold's transport theorem
way to convert from a system definition to a control volume definition
when flowing from a steep to mild reach, what does the WSE profile look like if y(0, b, conj) > y(0, a)
y(0, a) until transition point, M3 until y(0, b, conj), HJ to y(0, b)
when flowing from a steep to mild reach, what does the WSE profile look like if y(0, b, conj) < y(0, a)
y(0, a), HJ until y(0, a, conj), S1 until transition point @ y(0,b)
when flowing from negative mild reach to a negative less mild reach, what does the WSE profile look like
y01, M2 to transition line, y02
when flowing from negative mild slope to a negative steep slope, what does the WSE profile look like
y01, M2, pass through critical when transitions from mild to steep, S2, y02
what is the eularian frame of reference
you stand still
a hydraulic choke occurs when -
E < E(crit)
case of slowly changing (with distance) non-uniform flow
GVF
for the case of steep to mild conditions, the hydraulic jump will occur in the reach that -
has the least momentum
What does "open channel flow" mean
- open = open to the atmosphere channel flow = boundaries on 3 or more sides that contain the flow
for the case of steep to mild conditions, if y(0, up) > y(0, down, seq), the HJ will occur in reach -
1 (upstream)
at critical conditions in a rectangular channel for a given specific discharge, the energy is at a minimum value and is equal to - times the critical depth
1.5
for the case of steep to mild conditions, if y(0, up) < y(0, down, seq), the HJ will occur in reach -
2 (downstream)
energy grade lines =
E + z(b)
just upstream of a sluice gate, what reach takes the WSE from normal to alternate depth of the gate height
M1 or S1
just downstream of a sluice gate, what reach takes the WSE from gate height to the sequent depth of normal
M3 or S3
given Q and geometry of channel, we want to find
Q and A or v and y
if energy is decreasing in the direction of the flow, what does that mean
S(0) > S(f)
if all energy loss in a system is from friction, then -
S(e) = S(f), cons of momentum = cons of energy
Basic finite difference is based on -
Taylor Series
what is muskinghum-cunge
blending of hydraulic and hydrologic routing
what is the driving forces of open channel flow
body force due to acceleration of gravity
GVF requires -
boundary conditions
unsteady flow requires -
boundary conditions and initial conditions
built examples of open channel flow
canal, swale, stormwater, irrigation channel
what is nonuniform flow
change in x
what is unsteady flow
change with time
chezy and manning formulas relate velocity to -
channel characteristics
the M-y diagram is useful for seeing -
conjugate depths, loss in momentum at the sluice gate
conservation of volume is called the - equation
continuity
If Fr = 1, the flow is -
critical
if y(0) = y(crit), the channel is -
critical
the depth that corresponds to the minimum specific energy for a given q
critical depth
with a kinematic wave, there is no -. just pure -.
deformation, translation
information can propagate (upstream/downstream) in a supercritical flow
downstream
what causes different GVF profiles
downstream WSE controls, slope change, obstructions/chokes
information can propagate (upstream/downstream) in a subcritical flow
downstream and upstream
for uniform flow, - is constant
energy
in a series, - is constant
flow (Q)
if the approaching flow to a choked channel is subcritical, - will occur
flow will back up
what is the lagrangian frame of reference
follows the particle
the water surface elevation of a choked systems depends on the -
froude state of the approaching flow
what is the governing equation for unsteady flow
full saint venant
types of nonuniform flow
gradually varied flow and rapidly varied flow
for steady uniform flow, - included
gravity and friction
On an E-y diagram, E must be - than E(min) for a solution to exist
greater than
in parallel, - is constant
headloss
if the approaching flow to a choked channel is supercritical, - will occur
hydraulic jump
two types of flood wave routing
hydrologic and hydraulic routing
in a stepped channel, the water surface and bed are - if Fr > 1
in phase (WSE increases when bed height increases)
On a E-y diagram, as q increases, E will - if y stays the same
increases
what is the froude number a ration of
inertial force over gravitational force OR velocity over velocity
If Fr < 1, the flow is/isnt impact by downstream
is
If Fr > 1, the flow is/isnt impact by downstream
isn't
types of hydraulic routing waves
kinematic, diffusion, dynamic
what are the two frames of reference
lagrangian and eularian