- Open channel flow
Open-Channel Flow, a branch of Hydraulics, is a type of liquid flow within a conduit with a free surface, known as a channel. The other type of flow within a conduit is pipe flow. These two types of flow are similar in many ways, but differ in one important respect; the free surface. Open-channel flow has a free surface, whereas pipe flow does not.
Classifications of Flow
Open-channel flow can be classified and described in various ways based on the change in flow depth with respect to time and space. The fundamental type of flow dealt with in open-channel hydraulics.
- Time as the Criterion
- Steady Flow – The depth of flow does not change over time, or if it can be assumed to be constant during the time interval under consideration.
- Unsteady Flow - The depth of flow does change with time.
- Space as the Criterion
- Uniform Flow – The depth of flow is the same at every section of the channel. Uniform flow can be steady or unsteady, depending on whether or not the depth changes with time, (although unsteady uniform flow is rare).
- Varied Flow - The depth of flow changes along the length of the channel. Varied flow technically may be either steady or unsteady (although unsteady varied flow is a practically impossible condition).
- Varied flow can be further classified as either rapidly or gradually varied.
- Rapidly varied flow - The depth changes abruptly over a comparatively short distance. Rapidly varied flow is known as local phenomenon. Examples are the hydraulic jump and the hydraulic drop.
- Gradually varied flow – The depth changes over a long distance.
- Continuous flow - The discharge is constant throughout the reach of the channel under consideration. This is often the case with steady flow. This flow is considered continuous and therefore can be described using the continuity equation for continuous steady flow.
- Spatially varied or discontinuous flow - The discharge of a steady flow is nonuniform along a channel. This happens when water enters and/or leaves the channel along the course of flow. An example of flow entering a channel would be a road side gutter. An example of flow leaving a channel would be an irrigation channel. This flow can be described using the continuity equation for continuous unsteady flow requires the consideration of the time effect and includes a time element as a variable.
Summary of the Classification of Open-Channel Flow
- Steady Flow
- Uniform Flow
- Varied Flow
- Gradually Varied flow
- Rapidly varied flow
- Unsteady flow
- Unsteady Uniform Flow (rare)
- Unsteady Flow (“unsteady varied flow” should be here, but it is a practically impossible condition, so it is known simply as unsteady flow)
- Gradually Varied Unsteady flow
- Rapidly varied Unsteady flow
States of Flow
The behavior of open channel flow is governed by the effects of viscosity and gravity relative to the inertial forces of the flow. Surface tension has a minor contribution, but does not play a significant enough role in most circumstances to be a governing factor. Depending on the effect of viscosity relative to inertia, as represented by the Reynolds number, the flow can be either laminar, turbulent, or transitional.
Fields of study
Types of fluid flow
Other Related Articles
- hydraulic jump
- Manning Formula
Chow, V. T. (2008). Open-channel hydraulics. Caldwell, New Jersey: Blackburn Press.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Dimensionless momentum-depth relationship in open-channel flow — Contents 1 Momentum in Open Channel Flow 1.1 What is Momentum? 1.2 Momentum in a Rectangular Channel 1.3 Why is Momentum Important? … Wikipedia
Dimensionless Specific Energy Diagrams for Open Channel Flow — Contents 1 Energy Equations 2 Example 3 Choke Conditions 4 Dimensionless Diagram 5 References … Wikipedia
Flow measurement — is the quantification of bulk fluid movement. Flow can be measured in a variety of ways. Positive displacement flow meters acumulate a fixed volume of fluid and then count the number of times the volume is filled to measure flow. Other flow… … Wikipedia
Channel blockers — are chemical substances, ranging from ions to complex organic molecules, that bind inside the pore of an ion channel and block the flow of ions through that channel. A subset of channel blockers, known as open channel blockers have access to… … Wikipedia
Channel (Chinese medicine) — Channel (zh stp|p=jīngluò|s=经络|t=經絡), also known as meridian, in traditional Chinese medicine, is the common name of vessel (zh stp|s=经脉|t=經脈|p=jīngmài, also known as channel) and collaterals (zh stp|s=络脉|t=絡脈|p=luòmài). It is the path of running … Wikipedia
channel — chan|nel1 W2S3 [ˈtʃænl] n ▬▬▬▬▬▬▬ 1¦(television)¦ 2¦(for getting information/goods etc)¦ 3¦(sea/river)¦ 4¦(water)¦ 5¦(radio)¦ 6¦(in a surface)¦ 7¦(way to express yourself)¦ ▬▬▬▬▬▬▬ [Date: 1300 1400; : Old French; … Dictionary of contemporary English
Open-high-low-close chart — An OHLC chart, with a moving average and Bollinger bands superimposed. An open high low close chart (also OHLC chart, or simply bar chart) is a type of chart typically used to illustrate movements in the price of a financial instrument over time … Wikipedia
critical flow — Open channel flow with Froude Number equal to unity . See also Froude number … Lexicon of Cave and Karst Terminology
rapid flow — Open channel flow with a Froude number greater than unity . See also Froude number … Lexicon of Cave and Karst Terminology
tranquil flow — Open channel flow with Froude number smaller than unity  … Lexicon of Cave and Karst Terminology