Posted on August 14, 2019


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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Department of the Interior, Bureau of Reclamation. Head Correction Factor, k: International Organization of Standards.

If the bulk of the weir is thicker than 0. As a result, the discharge through the strip will be. Introduction Weirs are typically installed in open channels such as streams to determine discharge flowrate. It is usually a device for measuring discharge. To make this website work, we log user data and share it with processors. This is an initial check nocthes user input.

To make further use of this equation we need an expression relating the width of flow across the weir to the depth below the free surface. Measured head h should be greater than 0. A weir is a notch on a large scale, used, for example, to measure the flow of a river, and may be sharp edged or have a substantial breadth in the direction of flow.


Water surface downstream of the weir should be at least 0. Download ppt “Flow Over Notches and Weirs”. About project SlidePlayer Terms of Service. To produce automated calculations, LMNO Engineering used a curve fitting program to obtain the equations which best fit the C and k curves.

The graph shown is from our fits.

V Notch Weir Discharge Calculator and Equations

The basic principle is that discharge is directly related to the water depth above the crotch bottom notchds the V; this distance is folw head h. The lift force on an aircraft is exerted by the air moving over the wing. Auth with social network: My presentations Profile Feedback Log out.

Standard method for open-channel flow measurement of water with thin-plate weirs. Please contact us for consulting or other questions. Share buttons are a little bit lower.

Flow Over Notches and Weirs

Note that the value of v 1 is obtained by dividing 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.

Our calculation does notcues account for partially contracted weirs, but for most practical purposes the difference in C is inconsequential. A jet of water from a hose exerts a force on whatever it hits. Units in V-notch weir calculation: It doesn’t matter how thick the weir is except where water flows over the weir through the “V.


Consider the two dimensional system in the figure below: When the crest length of a rectangular weir is less than the width of the channel, there will be lateral contraction. Our equations are shown below.

This is a satisfactory assumption for flow over a notch or weir in the side of a large reservoir, but, is the notch or weir is placed at the floe of a narrow channel, the velocity of approach to the weir will be substantial and the head h producing flow will be increased by the kinetic energy of the approaching liquid to a value.

Water flow measurement in open channels using weirs and venturi flumes – Part 1: Weir Assumptions We will assume that the velocity of the fluid approaching the weir is small so that kinetic energy can be neglected. The bottom of the “V” should be at least 1.

All of the references show similar curves for C and k vs.