SMS:TUFLOW Manholes

Automatic Manholes

File:TUFLOW MC 1D Auto.jpg

TUFLOW Model Control 1D showing the Automatic Manhole tab

Global manhole attributes can be set up for a TUFLOW simulation in the TUFLOW 1D model control. TUFLOW will then automatically create manholes when the following criteria are met:

• There is at least one incoming and one outgoing culvert – a culvert is a C, I or R channel.
• There are no open channels connected (ie. no bridges, weirs or any other channel that is not a culvert).
• Pit channels can be connected, but are not included in any of the calculations for determining manhole energy losses.

The following global attributes are set:

• Automatic Manholes at All Culvert Junctions – whether or not to have TUFLOW automatically create manholes.
• Manhole Type– circular, rectangular, junction, or automatically determined.
• Side Clearance – for circular manholes, the default side clearance from the side of the largest culvert to the side of the manhole chamber. For rectangular manholes, the side clearance from the side of the culvert to the side of the manhole chamber.
• Minimum Dimension – minimum diameter for circular manholes and minimum width and length for rectangular manholes.
• C Exit Coefficient – K coefficient for flow out of circular manholes.
• R Coefficient – K coefficient for flow out of rectangular manholes.
• Loss Approach – loss approach to be used (none, Engelhund, Fixed).
• K Maximum Bend/Drop – maximum K energy loss coefficient that can occur for the sum of the loss coefficients for bends and drops at a manhole when using the Engelhund approach.

Manual Manholes

The global manhole parameters can be overridden by creating manholes in a TUFLOW 1D Network coverage. Toggling on “Manhole” and selecting the “Attributes...” button in the 1D Network node properties dialog allows the user to set the following parameters for manually created manholes:

• ID – set a name for the manhole
• Type – circular, junction, rectangular
• Loss Approach – loss approach to be used (none, Engelhund, Fixed)
• Invert – bottom or bed elevation of manhole
• Flow Width – The flow width in meters (this is the diameter for circular manholes)
• Flow Length – The flow length in meters (not used for circular manholes)
• Additional Storage Surface Area – usually set to zero
• K Fixed – Set the fixed component of the calculated manhole loss coefficient
• Km – exit coefficient used by Engelhund approach
• K Bend Max – Upper limit of the combination of K theta and K drop used by Engelhund approach

If a TUFLOW 1D Network coverage has manholes defined, the manholes will be written out as their own layer when exporting TUFLOW files.

(TUFLOW Manual 2010)