Updated : Oct 29, 2019 in Education


Flow Over Notches and Weirs A notch is an opening in the side of a tank or reservoir which extends above the surface of the liquid. It is usually a device for. –As it has sharp edges, the flow over the notch is FRICTIONLESS (Ff=0). –these are generally used to measure small discharge across CANAL. WEIR: -These. The bottom edge, over which the liquid flows, is known as sill or crest of the notch and the sheet of liquid flowing over a notch (or a weir) is known as nappe or.

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Our calculation does not account for partially contracted weirs, but for most practical purposes the difference in C is inconsequential.

The bottom of the “V” should be at least 1. Feedback Privacy Policy Feedback.

Flow Over Notches and Weirs

If you compare it to the graphs shown in the references, it looks nearly identical which implies that our fits are very good. Department of the Interior, Bureau of Reclamation. The equation for flow through flw notch is obtained from the equations for rectangular and V-notches. Weir Assumptions We will assume that the velocity of the fluid approaching the weir is small so that kinetic energy can be neglected.

When the crest length of a rectangular weir is less than the width of the channel, there will be lateral contraction. Head Correction Factor, k: It may ove sharp crested but also may have a substantial width in the direction of flow – it is used as both a flow measuring device and a device to raise water levels. A jet of water from a hose exerts a force on whatever it hits. The method of determining the theoretical flow through a notch is the same as that adopted for a large orifice.


We think you have liked this presentation. Water surface downstream of the weir should be at least 0. Download ppt “Flow Over Notches and Weirs”.

V Notch Weir Discharge Calculator and Equations

As a result, the discharge through the strip will be. Published by Alessandro Illes Modified over 3 years ago. Available from Global Engineering Documents at http: My presentations Profile Feedback Log out. Introduction Weirs are typically installed in open channels such as streams to determine discharge flowrate. Consider the ovrr dimensional system in the figure below: American Society for Testing and Materials.

When the water on the downstream side of a weir rises above the level of the crest, the weir is said to be a submerged weir. Thus in this case, the effects of sides of fow weir is eliminated or suppressed.

As in the case of orifice, the actual discharge through a notch or weir can be found by multiplying the theoretical discharge by a coefficient of discharge to allow for energy losses and the contraction of the cross-section of the stream at the bottom and sides.

The lift force on an aircraft is exerted by the air moving weirx the wing. The notch angle must be between 20 o and o 0. When the length of crest of the weir is same as the width of the channel, the weir is said to be suppressed weir. The V-notch design causes small changes in discharge to have a large change in depth allowing more accurate head measurement than with a rectangular weir.


If you wish to download it, please recommend it to your friends in any social system. To make this website work, we log user data and share it with processors. The basic principle is that discharge is directly related to the water depth above the crotch bottom of the V; this distance is called head h. V-Notch Triangular Weir Calculator. Please contact us for consulting or other questions.

This is an initial check of user input. Note that the value of v 1 is obtained by nohches the discharge by the full cross sectional area of the channel itself, not that of the notch. Occurs if head is being computed and a very low Q is entered e.

A notch is an opening in the side of a measuring tank or reservoir extending above the free surface. If the bulk of the weir is thicker than 0.

The momentum equation is a statement of Newton. Input results in a negative head due to the compiler’s machine precision.