1D Culverts
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Introduction
This post provides a modelling example for a 1D pump using a fixed flow rate and pump curve. For this example we will model a pump in two common situations (2D-2D & 1D-2D).
Pump Attributes
A pump needs to first be digitised in a 1d_nwke layer. The direction of the polyline must go from inlet to outlet as a pump is unidirectional (? Is that true). The attributes required for a pump in your 1d_nwke layer can be found within the 2015 TUFLOW manual.
In the 1d_nwk layer, the following attributes are required:
- ID = ID of the channel
- Type = "P"
- Len_or_ANA = Nominal length in m (only used for calculating nodal storage if UCS is on)
- US_Invert = Upstream invert level of the channel
- DS_Invert = Downstream invert level of the channel
- Inlet_Type = Used to specify the pump curve in the Depth Discharge database.
2D-2D Configuration
Because pumps are zero length channels they do not create automatic nodes at the upstream and downstream end. If you ran the model with just a pump polyline you will get ERROR 1353 - No NA data for Node.To remove this error you will need to digitise a node within a separate 1d nwke layer and give a nominal storage amount in the “Len_or_NA” attribute for the 1d nwke ‘Node’, see the example below.
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To connect the pump to the 2d domain you will also need to digitise an SX connection. In the figure below I have showed both the 1d node and 2d SX points as being separate from each other for illustrative purposes only – they should both be snapped to the end of the pump polyline. SX connections are required at connections to 2D domains to transfer water from the 1D node to the 2D. Without the SX connection, water will build up within the node and cause an instability.
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