**Subject:**Force Main Friction Loss in InfoSWMM and the Transition from Partial to Full Flow

**Swamee and Jain approximation to the Colebrook-White equation**. No matter which method you use for full flow the program will use Manning's equation to calculate the loss in the link when the link is not full (see Figure 2 for the equations used for calculating the friction loss – variable dq1 in the St Venant equation for InfoSWMM). The regions for the different friction loss equations are shown in Figure 3.

How the full pipe condition is defined in InfoSWMM - both ends have to be fullFigure 1. |

Friction equations used in SWMM 5 for a Force Main.Figure 2: |

Categories: #INFOSWMM, Force Mains, H2OMapSWMM (retired), InfoSWMM, SWMM5, Venant

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