Sewer Network Flow

For sewer network simulation, scenarify uses the Storm Water Management Model (SWMM). In SWMM, a sewer network is represented by nodes connected by links transmitting pipe discharges. Nodes represent either non-storage junction nodes or storage nodes with non-zero volume.

Here are some helpful links for related tasks: - For assistance with setting up a sewer network, please refer to the Sewer Network Setup guide. - For a list of supported sewer structures in Scenarify, see the Sewer Structures page. - For technical details on the sewer network implementation, refer to the SWMM User's Manual. - For more information on the coupling with the surface model, see the Bidirectional Surface–Sewer Coupling page.

1D Shallow Water Equations

Sewer network flow is governed by the time-dependent 1D Shallow Water Equations (SWEs):

\[ \partial_t A + \partial_x Q = 0 , \]

\[ \partial_t Q + \partial_x \left( \frac{Q^2}{A} + \frac{1}{2} gA^2 \right) = g A \left( S_0 - S_f - S_b \right) . \]

Here, \( A \) is the flow cross-section, \( Q \) is the discharge, and the source terms \( S_0 \), \( S_f \), and \( S_b \) represent bed slope, friction slope, and the expansion/contraction of the flow, respectively. The friction slope is computed with the Manning equation:

\[ S_f = n^2 \frac{Q |Q|}{A^{10/3}} . \]

The non-linear system of equations for all junction and storage nodes is solved iteratively using Newton-Raphson's method. The pipe flows are modeled by the Preissmann slot scheme to ensure the open channel flow transition.