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Table Of Contents
Chapter 5 Working with Hydrology Commands
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3 Select the second point from the drawing.
The Orifice Calculator dialog box displays and the value of the diameter you
selected is displayed in the Diameter text box.
Specifying an Area
You can specify an area from the Orifice Calculator dialog box by selecting
points from your drawing.
NOTE
You must select the Area option under Use in the Orifice Calculator dialog
box in order to specify an area.
To specify an orifice area
1 In the Orifice Calculator dialog box, click the Select button next to the Area
box. The Orifice Calculator dialog box closes temporarily and the following
prompt is displayed:
Select polyline (or Draw):
2 Do one of the following:
n
Select a polyline in the drawing.
n
Type Draw to draw the area in the drawing. When you have drawn all but
the last segment of the polyline, type Close to close the polyline back to its
start point.
The Orifice Calculator dialog box displays and the value for the area you
selected or drew displays in the Area text box.
Calculating Weir Values
Weirs are used as outlet devices for regulating the flow of water out of detention
ponds or other water storage facilities. They can also be used as measurement
devices in streams and constricted channels. Using the weir calculators, you can
solve for the flowrate, depth of flow, weir coefficient, and height.
Autodesk Civil Design has commands you can use to design sharp-crested weirs
in three shapes: Cipolleti (trapezoidal), rectangular, and triangular.
When you enter the weir parameters, the velocity, wetted area, area, and
percent full values are also calculated for the weir. For Cipolleti and triangular
weirs, the crested length is also reported.
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.