Line 1: |
Line 1: |
− | | + | 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)
| + | *''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), | + | *''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. | + | *''h'' is the head of water over the centre of the orifice (m). |
| }} | | }} |
| | | |
− | ==see Also== | + | ==See also== |
− | *[[Flow through a perforated pipe]] | + | *[[Flow through perforated pipe]] |
| | | |
| [[category: Calculations]] | | [[category: Calculations]] |