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Table Of Contents
Chapter 5 Working with Hydrology Commands
524
2 From the Solve For list, select the value you want to calculate. The available
values are: Flowrate, Width, Depth of Flow, Velocity Coefficient, and Discharge
Coefficient.
NOTE
Do not enter the value for which you are solving. For example, if you select
Flowrate in this step, leave the Flowrate text box at 0. After you enter the
other values, the program solves for the Flowrate.
3 In the Flowrate box, type a flow rate value for the weir.
4 In the Width box, type a wetted width (T value) for the weir.
5 In the Depth of Flow box, type a depth of flow value.
6 In the Height box, type a height for the weir.
7 In the Cv box, type the velocity coefficient.
You can also click Select to display the Velocity Coefficients dialog box and
select a coefficient. For more information, see Specifying a Cv Value in this
chapter.
NOTE
The weir coefficients that are provided with Autodesk Civil Design are
samples only. You must determine the weir coefficient based on the
geometry of the weir you are designing.
8 In the Cd box, type a discharge coefficient.
The computed values for the weir display at the bottom left of the dialog box.
The box at the top right area displays a graphic of the currently defined weir.
This information is for display only and cannot be edited.
NOTE
If the data you entered has an error, the weir graphic image does not
display. Check for an error message at the bottom of the dialog box.
9 Click OK to exit the dialog box.
Cipolleti Weir Formulas
The Cipolleti Weir calculator uses the following formula to calculate the flow
rate:
7KJ&&4
YG
where:
Q = Design flow rate
C
d
=
Discharge coefficient
C
v
= Velocity coefficient
g = Acceleration due to gravity (32.174 ft/s
2
or 9.807 m/s
2
)
T = Wetted width of the weir
h
1
= height of weir