Question
Why does MIKE 21 FM claim that part of my dike structure is located at a boundary?
Answer
A dike needs to be placed in such a way that flow can pass from one side of the structure to the other. When the programme calculates the discharge that is affected by the dike, it aligns the structure to the nearest cell faces and derives the flow across the dike by the water levels in the two adjacent elements, see shown in Fig. 1.
Fig. 1 - Dike located at element face with applied water levels
It may happen that the nearest cell face is a boundary face if the polyline describing the dike is close to a boundary. In this case the dike is not placed on a face between two elements. See example in Fig. 1
Fig. 2 - These images show a dike located within the domain (black solid line), but where the mesh resolution causes two of the affected elements faces (red dotted line) to be located at a boundary.
If a dike section is placed at a boundary face it will not come into action and influence the flow.
FURTHER INFORMATION & USERFUL LINKS
Manuals and User Guides
User Guide. MIKE 21 Flow Model FM. Hydrodynamic Module. User Guide