Discontinuous Opening

The discontinuous opening is the downstream element of the boundary element pair defining a change in channel slope. The following constants have to be specified on the line beneath the *FLUID SECTION,TYPE=CHANNEL DISCONTINUOUS OPENING card:

• the width $b$
• $S_0 = \sin (\phi_2)$ (Figure 111; if $S_0<-1$ the slope is calculated from the coordinates of the end nodes belonging to the element)
• the length $L_2$ (Figure 111; if $L_2 \le 0$ the length is calculated from the coordinates of the end nodes belonging to the element)
• the trapezoid angle $\theta$
• the grain diameter $k_s$ for the White-Colebrook law or the Manning constant $n$ for the Manning law (in the latter case the user has to specify the parameter MANNING on the *FLUID SECTION card)
• the number of the upstream discontinuous slope element.

The length $L_2$ is typically small compared to the length of the adjacent channel branches.

Example files: channel6.