Discontinuous Slope

Figure 111: Geometry of a discontinuous slope

The discontinuous slope is the upstream element of a pair of boundary elements simulating a change in slope. The corresponding downstream element is the discontinuous opening. Both are illustrated in Figure 111. The following constants have to be specified on the line beneath the *FLUID SECTION,TYPE=CHANNEL DISCONTINUOUS SLOPE card:

• the width $b$
• $S_0 = \sin (\phi_1)$ (Figure 111; if $S_0<-1$ the slope is calculated from the coordinates of the end nodes belonging to the element)
• the length $L_1$ (Figure 111; if $L_1 \le 0$ 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 reference element
• not used
• the number of the downstream discontinuous opening element
• not used

The length $L_1$ is typically small compared to the length of the adjacent channel branches. Since storage for 9 items is provided and only 8 entries are allowed per line, an extra blank line has to be provided for the ninth dummy item.

Notice that a discontinuous slope element generally has upstream channel elements attached to it. Therefore, it is always mandatory to specify an upstream reference element.

Example files: channel6.