Part 6: Open Flow Channel Flashcards
Two types of channel?
Prismatic: regular cross section
Non-prismatic: irregular cross section
Laminar flow in a channel is a max of …
Re < 500
What is the turbulent flow in a channel?
Re > 12500
What is the formula for hydraulic radius?
R=A/P
Three flow classifications?
Subcritical Fr<1
Supercritical Fr>1
Critical Fr=1
If V
Subcritical
If V=c flow is _____
Critical
For V>c the flow is _______
Supercritical
What is specific energy?
The energy of flow defined with respect to the bed of the channel
T or F. E is a minimum at the critical depth
True
T or F. If the flow is uniform then dy/dx=0.
True
For uniform flow, the loss in potential energy equals…
The energy dissipated by friction
What does chezy equation consider?
Uniform flow in a channel which is sloped
Is chevys coefficient is dimensionless?
No units of (sqrt(L))/T
Manning’s coefficient reflects what?
- Roughness of the pipe
- dimensions are (T/L^1/3)
Channels of circular cross section have a unique attribute with respect too?
Max velocity and discharge
Most efficient hydraulic sections?
- semi circle
- trapezoid
- triangle
What is GVF?
Gradually varied flow
What is an occurrence of GVF?
- changes in channel geometry
- changes in channel resistance
- changes in channel slope
- existence of an obstruction(eg dam)
What are the 5 types of slopes?
Mild Fr<1 Critical Fr=1 Steep Fr>1 Horizontal So=0 Adverse So<0
How to determine slope for uniform flow?
Yn>Yc slope mild flow subcritical
Yn=Yc slope critical flow critical
Yn
What is RVF?
Rapidly varied flow
The occurrence of RVF can result from?
- Abrupt changes in channel geometry
- Interface between supercritical and subcritical
Applications of weirs?
Water treatment plants
Research
Irrigation systems
Types of weirs?
- Sharp-crested
- broad crested weir
- zero height weir
- v notch
- special types
