A gradually varied flow (GVF) profile is a plot of water depth versus distance along the channel as the water depth gradually achieves normal depth . ... A GVF profile is also known as a water depth profile, backwater calculation, and non-uniform flow computation. It is for steady state flows (discharge remains constant).
What is gradually varied flow in open channel?
Gradually-varied flow (GVF) is a steady non-uniform flow in an open channel with gradual changes in its water surface elevation . The evaluation of GVF profiles under a specific flow discharge is very important in hydraulic engineering.
What is gradually varied flow and rapidly varied flow?
In Chapter 4, we discussed uniform flowin which the flow depth remains constant with distance. ... As we discussed in Chapter 1, such flows are called gradually varied flows if the rate of variation of depth with respect to distance is small , and rapidly varied flows if the rate of variation is large.
What are the kind of gradually varied flow?
A steady non-uniform flow in a prismatic channel with gradual changes in its water- surface elevation is named as gradually-varied flow (GVF). The backwater produced by a dam or weir across a river and drawdown produced at a sudden drop in a channel are few typical examples of GVF.
What do you mean by GVF?
When not flowing full, water surface profiles within a culvert are generally calculated using equations that describe Gradually Varied Flow (GVF) conditions. A GVF profile is also known as a water depth profile and applies to steady-state, or constant flow, conditions. ...
What causes gradually varied flow?
path of flow may cause the uniform flow in a channel to become gradually or rapidly varied flow.
What are the assumptions in gradually varied flow computation?
Assumptions of Gradually Varied Flow
The slope of the channel/canal is very small. The vertical depth is considered from the bottom . The pressure distribution is hydrostatic because the curvature of streamlines is small. Manning’s and Chezy’s formula is valid for the computation of velocity.
Can rapidly varied flow be steady?
Both gradually varied and rapidly varied unsteady flows are possible , and the same general rules for analysis apply as for steady flow. The zones of rapidly varied flow must be isolated before analysis under the 1-D flow assumption; thus, the method of analysis for steady and unsteady flow is the same in this respect.
What are the types of open channel flow?
- 1 Steady Flow. Flow is said to be steady when discharge does not change along the course of the channel flow.
- 2 Unsteady Flow. Flow is said to be steady when discharge changes with time.
- 3 Uniform flow. ...
- 4 Gradually Varied Flow. ...
- 5 Rapidly Varied Flow. ...
- 6 Spatially Varied Flow.
What is a critical depth?
Definitions. Critical Flow: The variation of specific energy with depth at a constant discharge shows a minimum in the specific energy at a depth called critical depth at which the Froude number has a value of one. Critical depth is also the depth of maximum discharge , when the specific energy is held constant.
Is gradually varied flow steady?
Explanation: Gradually varied flow is steady non-uniform because the velocity of water remains constant at a specified point, but it changes from one point to another point.
What is steady flow?
A steady flow is the one in which the quantity of liquid flowing per second through any section, is constant . ... The exact term use for this is mean steady flow. Steady flow may be uniform or non-uniform. Uniform flow. A truly uniform flow is one in which the velocity is same at a given instant at every point in the fluid ...
What do you mean by hydraulic jump?
Hydraulic jump, Sudden change in water level , analogous to a shock wave, commonly seen below weirs and sluice gates where a smooth stream of water suddenly rises at a foaming front. The fact that the speed of water waves varies with wavelength and with amplitude leads to a wide variety of effects.
What are the types of flow profile?
Flow profiles are classified by the slope of the channel (So), yn, and yc. There are five slope classifications designated by the letters C, M , S, A, and H ( critical, mild, steep, adverse, and horizontal ) respectively.
What is called afflux in gradually varied flow?
If the depth of flow in a channel changes gradually over a long length of a channel the flow is said to be gradually varied flow. ... Afflux is defined as the maximum increase in water level due to obstruction in the path of flow of water . 5.
What is the difference between GVF and RVF?
Rapidly Varied Flow (RVF) is a significant change in water depth or velocity of flow over a short distance. ... Gradually Varied Flow ( GVF ) is the flow where the water depth changes gradually over a large distance. Hydraulic jump is an example of rapidly varied flow, where the liquid level rises suddenly.
