Rectangular Weir Flow Rate Calculator

Rectangular Weir Flow Rate Calculator
Rectangular Weir Flow Rate Calculator Results
Flow Rate (Q)= m3/s
[ 4 Votes ]

Example Formula

The formula to calculate the flow rate (Q) over a rectangular weir can be given as:

Q = Cd × L × H3/2
  1. Q: This is the flow rate over the rectangular weir.
  2. Cd: This is the discharge constant, which accounts for the effects of fluid viscosity and edge sharpness on flow over the weir. It is typically provided or experimentally determined.
  3. L: This represents the width of the rectangular weir.
  4. H: This is the head on the weir, or the height of the fluid above the weir crest.

Who wrote/refined the formula

The flow rate over a rectangular weir can be calculated using principles of fluid mechanics and the laws of hydrostatics. The refinement of these principles and their application to practical problems like weir flow calculation has been the collective work of numerous scientists and engineers over the centuries. One prominent figure in fluid mechanics is Daniel Bernoulli, who contributed significantly to the understanding of fluid behavior.

Real Life Application

Calculating the flow rate over a rectangular weir is crucial in various real-life scenarios, particularly in water management systems. For example, in a wastewater treatment plant, rectangular weirs are often used to regulate the flow of water. Also, in agricultural irrigation and hydrological studies, this calculation is important to manage water resources effectively.

Key individuals in the discipline

Daniel Bernoulli and his contributions to fluid dynamics play a significant role in our understanding of fluid behavior and the development of related formulas. Engineers and scientists in the field of environmental engineering and hydrology have also contributed significantly to the practical applications of these concepts, refining them to suit real-world scenarios.

Interesting Facts

  1. The rectangular weir is one of the simplest types of weirs used for flow measurements, primarily due to its simplicity in design and the ease of flow calculation.
  2. The use of weirs for flow measurement dates back to ancient civilizations, demonstrating the long history of humanity's interaction with water resources.
  3. The principles used in flow rate calculation have broader applications in fluid mechanics, contributing to advancements in fields such as aerodynamics and hydraulics.


Understanding the flow rate over a rectangular weir and the associated calculations helps us better manage and utilize our water resources. It underscores the importance of fluid mechanics in our daily lives and its impact on environmental engineering and hydrology.

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