Discharge over Broad-Crested Weir Calculator

✖The Coefficient of Discharge or efflux coefficient is the ratio of the actual discharge to the theoretical discharge.ⓘ Coefficient of Discharge [C_d]			+10% -10%
✖The Length of Weir is the of the base of weir through which discharge is taking place.ⓘ Length of Weir [L_w]			+10% -10%
✖The Head of Liquid is the height of a liquid column that corresponds to a particular pressure exerted by the liquid column from the base of its container.ⓘ Head of Liquid [H]			+10% -10%

✖Discharge Weir is the rate of flow of a liquid.ⓘ Discharge over Broad-Crested Weir [Q]

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Formula

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Discharge over Broad-Crested Weir

Formula

Q = 1.705 \cdot C d \cdot L w \cdot H^{\frac{3}{2}}

Example

1078.337 m³/s = 1.705 \cdot 0.8 \cdot 25 m \cdot {10 m}^{\frac{3}{2}}

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Discharge over Broad-Crested Weir Solution

STEP 0: Pre-Calculation Summary

Formula Used

Discharge Weir = 1.705*Coefficient of Discharge*Length of Weir*Head of Liquid^(3/2)
Q = 1.705*C_d*L_w*H^(3/2)
This formula uses 4 Variables

Variables Used

Discharge Weir - (Measured in Cubic Meter per Second) - Discharge Weir is the rate of flow of a liquid.
Coefficient of Discharge - The Coefficient of Discharge or efflux coefficient is the ratio of the actual discharge to the theoretical discharge.
Length of Weir - (Measured in Meter) - The Length of Weir is the of the base of weir through which discharge is taking place.
Head of Liquid - (Measured in Meter) - The Head of Liquid is the height of a liquid column that corresponds to a particular pressure exerted by the liquid column from the base of its container.

STEP 1: Convert Input(s) to Base Unit

Coefficient of Discharge: 0.8 --> No Conversion Required
Length of Weir: 25 Meter --> 25 Meter No Conversion Required
Head of Liquid: 10 Meter --> 10 Meter No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

Q = 1.705*C_d*L_w*H^(3/2) --> 1.705*0.8*25*10^(3/2)

Evaluating ... ...

Q = 1078.33668211742

STEP 3: Convert Result to Output's Unit

1078.33668211742 Cubic Meter per Second --> No Conversion Required

FINAL ANSWER

1078.33668211742 ≈ 1078.337 Cubic Meter per Second <-- Discharge Weir

(Calculation completed in 00.004 seconds)

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Home » Physics » Fluid Mechanics » Notches and Weirs » Mechanical » Discharge » Discharge over Broad-Crested Weir

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Created by Maiarutselvan V

PSG College of Technology (PSGCT), Coimbatore

Maiarutselvan V has created this Calculator and 300+ more calculators!

Verified by Vinay Mishra

Indian Institute for Aeronautical Engineering and Information Technology (IIAEIT), Pune

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< Discharge Calculators

Time Required to Empty Reservoir

Go Total Time Taken = ((3*Area of Weir)/(Coefficient of Discharge*Length of Weir*sqrt(2*[g])))*(1/sqrt(Final Height of Liquid)-1/sqrt(Initial Height of Liquid))

Time Required to Empty Tank with Triangular Weir or Notch

Go Total Time Taken = ((5*Area of Weir)/(4*Coefficient of Discharge*tan(Angle A/2)*sqrt(2*[g])))*(1/(Final Height of Liquid^(3/2))-1/(Initial Height of Liquid^(3/2)))

Head of Liquid above V-notch

Go Head of Liquid = (Theoretical Discharge/(8/15*Coefficient of Discharge*tan(Angle A/2)*sqrt(2*[g])))^0.4

Head of Liquid at Crest

Go Head of Liquid = (Theoretical Discharge/(2/3*Coefficient of Discharge*Length of Weir*sqrt(2*[g])))^(2/3)

Discharge over Broad-Crested Weir Formula

Discharge Weir = 1.705*Coefficient of Discharge*Length of Weir*Head of Liquid^(3/2)
Q = 1.705*C_d*L_w*H^(3/2)

What is broad-crested weir?

Broad crested weirs are robust structures that are generally constructed from reinforced concrete and which usually span the full width of the channel. They are used to measure the discharge of rivers and are much more suited for this purpose than the relatively flimsy sharp-crested weirs.

What are the types of weirs based on shape of the crest?

It is of four types they are, sharp-crested weir, broad- crested weir, narrow-crested weir, and ogee-shaped weir.

How to Calculate Discharge over Broad-Crested Weir?

Discharge over Broad-Crested Weir calculator uses Discharge Weir = 1.705*Coefficient of Discharge*Length of Weir*Head of Liquid^(3/2) to calculate the Discharge Weir, Discharge over Broad-crested Weir is determined by the geometry of the weir and the head of water above the weir crest. The broad-crested weir is a type of flow control structure commonly used in open channel hydraulics. Discharge Weir is denoted by Q symbol.

How to calculate Discharge over Broad-Crested Weir using this online calculator? To use this online calculator for Discharge over Broad-Crested Weir, enter Coefficient of Discharge (C_d), Length of Weir (L_w) & Head of Liquid (H) and hit the calculate button. Here is how the Discharge over Broad-Crested Weir calculation can be explained with given input values -> 51.76016 = 1.705*0.8*25*10^(3/2).

FAQ

What is Discharge over Broad-Crested Weir?

Discharge over Broad-crested Weir is determined by the geometry of the weir and the head of water above the weir crest. The broad-crested weir is a type of flow control structure commonly used in open channel hydraulics and is represented as Q = 1.705*C_d*L_w*H^(3/2) or Discharge Weir = 1.705*Coefficient of Discharge*Length of Weir*Head of Liquid^(3/2). The Coefficient of Discharge or efflux coefficient is the ratio of the actual discharge to the theoretical discharge, The Length of Weir is the of the base of weir through which discharge is taking place & The Head of Liquid is the height of a liquid column that corresponds to a particular pressure exerted by the liquid column from the base of its container.

How to calculate Discharge over Broad-Crested Weir?

Discharge over Broad-crested Weir is determined by the geometry of the weir and the head of water above the weir crest. The broad-crested weir is a type of flow control structure commonly used in open channel hydraulics is calculated using Discharge Weir = 1.705*Coefficient of Discharge*Length of Weir*Head of Liquid^(3/2). To calculate Discharge over Broad-Crested Weir, you need Coefficient of Discharge (C_d), Length of Weir (L_w) & Head of Liquid (H). With our tool, you need to enter the respective value for Coefficient of Discharge, Length of Weir & Head of Liquid and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

How many ways are there to calculate Discharge Weir?

In this formula, Discharge Weir uses Coefficient of Discharge, Length of Weir & Head of Liquid. We can use 3 other way(s) to calculate the same, which is/are as follows -

Discharge Weir = (0.405+0.003/Head of Liquid)*Length of Weir*sqrt(2*[g])*Head of Liquid^(3/2)
Discharge Weir = (0.405+0.003/(Head of Liquid+Head Due to Velocity of Approach))*Length of Weir*sqrt(2*[g])*(Head of Liquid+Head Due to Velocity of Approach)^(3/2)
Discharge Weir = 2/3*Coefficient of Discharge*(Length of Weir-0.2*Head of Liquid)*sqrt(2*[g])*Head of Liquid^(3/2)

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