Sealed Nodes

Manholes and basins can be defined as 'sealed'. If they are defined as sealed, then water will not flow onto the surface. Instead, the water enters a narrow slot comparable to the slot on closed cross sections.

The narrow slot is simulated with a sealed cover that gradually contracts to a slot with a diameter of \(w_{slot}^{2}\) times the node diameter, where \(w_{slot}\) is the width of a slot cover at infinite height. The contraction happens gradually, starting 0.25m (default value) below ground level.

Mathematically, the sealed cover enters the node equations (see Section A.2.2) only through the calculation of the surface area in the node. For a sealed cover the surface area is

\[ A_{fl} = A_{fl,node}\left[\left(1 - w_{slot}\right)e^{\frac{6\left(H - H_{gl} - 0.25\right)}{D}} - w_{slot}\right] \]

Equation: Flow area for a sealed node cover, contracting from a narrow slot as water level rises.

where D is the diameter of the node just below the cover.