What is nappe in notch?
The sheet of water flowing through a notch or over a weir is known as nappe or vein. The bottom edge of the notch or the top of a weir over which water flows is known as sill or crest.
What is nappe or vein?
What is ventilation of weir?
In such a case, some air is trapped beneath the weir. This air is carried away by the flowing water, which results in creating a negative pressure beneath the nappe. The negative pressure drags the lower side of the nappe towards the surface of the weir wall. Such holes are called ‘Ventilation’ of a weir.
What does nappe and sill mean?
While the stream of water discharged by an orifice is called a jet, the sheet of water discharged by a notch or weir is called a nappe or vein. The upper surface of the notch or weir over which the water flows is called the Crest or Sill.
What nappe means?
nappe, in geology, large body or sheet of rock that has been moved a distance of about 2 km (1.2 miles) or more from its original position by faulting or folding.
What is nappe flow?
In hydraulic engineering, a nappe is a sheet or curtain of water that flows over a weir or dam. Both structures have different features that characterize how a nappe might flow through or over impervious concrete structures.
Why is ventilation of weir required?
Ventilation of notch or weirs: The air below the nappe and the walls are trapped. This air gradually carried along with flowing water and the pressure between the nappe and wall is reduced below atmospheric pressure. Eventually negative pressure is developed and as a result, the nappe starts to depress.
What is Crest in weir?
The weir crest is the upstream element of a pair of boundary elements simulating a weir. The corresponding downstream element is the weir slope.
What does nappe mean in cooking?
Building up your kitchen vocab arsenal Nappe is a consistency of a liquid or a sauce thick enough to coat your favorite stirring spoon and hold the shape of your tongue as you lick it.
What is nappe of the cone?
A cone has two identically shaped parts called nappes. One nappe is what most people mean by “cone,” and has the shape of a party hat. Conic sections are generated by the intersection of a plane with a cone. If the plane is parallel to the axis of revolution (the y -axis), then the conic section is a hyperbola.
What do you mean by Nappe?
What is the difference between a weir and a nape?
If the nappe discharges into the air, the weir has free discharge. If the discharge is partly under water, the weir is submerged or drowned. Types of Weirs. A weir with a sharp upstream corner or edge such that the water springs clear of the crest is a sharp-crested weir.
Where does the nappe stretch in a rectangular weir?
In a suppressed rectangular weir, the nappe stretches from channel wall to channel wall. On the downstream side of the weir, the air under the nappe will become entrained in the nappe as it passes over it as it spills into the downstream channel.
What are the different types of nappes?
There are three types of nappe that form over the crest of a weir, depending on the air ventilation structure of a weir: free nappes, depressed nappes, and clinging nappes. A free nappe, which is ventilated to maintain atmospheric pressure below, does not come into contact with the underside of the weir.
What is the purpose of nappe aeration?
The Need for Nappe Aeration In a suppressed rectangular weir, the nappe stretches from channel wall to channel wall. On the downstream side of the weir, the air under the nappe will become entrained in the nappe as it passes over it as it spills into the downstream channel.