Difference between revisions of "Flow through an orifice"

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Orifices are simply holes which restrict the flow of water. They may be used at the bottom end of an LID practice to add some [[flow control]].
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Orifices are simply holes which restrict the flow of water. They may be used at the bottom end of an LID practice to add some [[flow control]]:
  
 
<math>Q= B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot h}</math>
 
<math>Q= B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot h}</math>
  
 
{{Plainlist|1=Where:
 
{{Plainlist|1=Where:
*''L'' is the length of perforated pipe (m)
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*''B'' is the clogging factor (between 0.5 (for matured installation) and 1 (for a new perfectly performing orifice)),     
*''B'' is the clogging factor (between 0.5 (for matured installation) and 1 (for a new perfectly performing BMP)),     
 
 
*''C<sub>d</sub>'' is the coefficient of discharge (usually 0.61 for a plate, or 0.8 for a pipe),  
 
*''C<sub>d</sub>'' is the coefficient of discharge (usually 0.61 for a plate, or 0.8 for a pipe),  
*''A<sub>o</sub>'' is the area of the orifice (m<sup>2</sup>/m),  
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*''A<sub>o</sub>'' is the area of the orifice (m<sup>2</sup>),  
 
*''g'' is acceleration due to gravity = 9.81 m/s<sup>2</sup>, and  
 
*''g'' is acceleration due to gravity = 9.81 m/s<sup>2</sup>, and  
*''h'' is the head of water over the centre of the orifice.
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*''h'' is the head of water over the centre of the orifice (m).
 
}}
 
}}
  

Latest revision as of 19:57, 17 March 2019

Orifices are simply holes which restrict the flow of water. They may be used at the bottom end of an LID practice to add some flow control:

Where:

  • B is the clogging factor (between 0.5 (for matured installation) and 1 (for a new perfectly performing orifice)),
  • Cd is the coefficient of discharge (usually 0.61 for a plate, or 0.8 for a pipe),
  • Ao is the area of the orifice (m2),
  • g is acceleration due to gravity = 9.81 m/s2, and
  • h is the head of water over the centre of the orifice (m).

See also[edit]