
	Applies To

	Product(s):	Bentley PondPack
	Version(s):	08.11.01.56
	Environment:	N/A
	Area:
	Original Author:	Jesse Dringoli, Bentley Technical Support Group

Problem

Original Question: Does PondPack calculate velocity from outlet structure? by TimZ

After designing an outlet structure and running the storms through it, is there a way to determine the velocity discharging from the outlet pipe/culvert?

Solution

Although velocity is not directly reported in the outlet results, you can derive it. This article assumes that the maximum velocity is of interest.

For an orifice, weir or culvert, you can use the equation V=Q/A to calculate the velocity based on the wetted area along with the flow of interest (such as the maximum flow through the outlet component). Note that if you have multiple components in your composite outlet structure , the total flow through the outlet link is not what you'd be using. You would need to look at the headwater and tailwater at the time of interest and view the flow through the orifice component at that time. This can be done after computing the outlet in the Composite Outlet dialog by following these steps:

1) click on the component of interest 2) Click the Rating Table tab 3) Select the appropriate tailwater from the dropdown, if applicable. 4) Locate the flow corresponding to the headwater of interest 5) Use V=Q/A to determine the velocity of flow through that component.

For an Orifice, you would use the full cross sectional area of the opening(s). For a weir, you would need to calculate the wetted area based on the physical cross section and headwater elevation/HGL.

For a culvert, if the downstream ID is Tailwater, you will only be able to see the "into" HGL from the upstream end of the culvert. The downstream flow depth and velocity may need to be determined externally, such as with CulvertMaster.

Alternatively, if your composite outlet link discharges into a conduit with the same cross sectional shape that you're interested in viewing the velocity in, you can graph the conduit, locate for example the maximum flow, then right click on the Conduit, choose Channel Rating table and look at the corresponding velocity for the maximum flow.

Velocity through outlet structure

Problem

Solution

See Also