What Nappe means?
Definition of nappe 1 : sheet sense 6. 2 : a large mass of rock thrust over other rocks. 3 : one of the two sheets that lie on opposite sides of the vertex and together make up a cone.
What is Nappe in math?
One of the two portions of a double cone, which is positioned apex to apex, is termed as Nappe.
What is depressed nappe?
A depressed nappe is partially ventilated, which creates negative pressure beneath the nappe. The negative pressure leads to a 6% to 7% increase in discharged water compared to a free nappe. Clinging nappes have no air beneath, and the stream flows along the face of the weir.
What is nappe in fluid?
In hydraulic engineering, a nappe is a sheet or curtain of water that flows over a weir or dam. The upper and lower water surface have well-defined characteristics that are created by the crest of a dam or weir.
What does nappe and sill mean?
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 a free nappe?
Term used in hydraulics; nappe, the underside of which is not in contact with the overflow structure and is at ambient atmospheric pressure.
What do you mean by nappe & Sill?
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 is a depressed nappe?
Where is nappe and Sill found?
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. The height above the bottom of the tank or channel is known as crest height.
What are different types of nappe?
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 aeration of nappe why it is necessary?
An arrangement for aeration under the nappe is necessary when the weir used is suppressed rectangular weir. This may require the installation of an air vent pipe through the sidewall of the channel to provide air under the nappe. If the nappe is not aerated, the weir will deliver more flow than that actual flow.
What is nappe flow?
Why is it necessary to aerate the nappe?
The Need for Nappe Aeration As the air becomes entrained, there will be less and less air under the nappe. This reduction of air under the nappe creates a pressure gradient. Ultimately the nappe collapses against the downstream face of the weir unless new air is allowed to replenish the entrained air.
What is a nappe?
Definition of nappe 1 : sheet sense 6 2 : a large mass of rock thrust over other rocks 3 : one of the two sheets that lie on opposite sides of the vertex and together make up a cone
What is the meaning of nap in geology?
[nap] noun. Geology. a large mass of rock thrust a considerable distance along a nearly horizontal fault plane or in an overturned anticlinal fold.
What is nappe Tournay?
Une aultre nappe, ouvraige de Tournay, contenant vii aulnes de long iii aulnes de large. Une riche nappe damasse de grandes fleurs, de xii aulnes quart de long et iiii de largeur.