Model Generation

Creating a Model
Using interactive software such as Modview, a basic model of the domain can be generated in a reasonable amount of time because only an outline of the boundaries is needed at this point; further subdivision of this relatively coarse frame is performed automatically by a separate program.

Creating Nodes
Nodes are specified by entering their coordinates.

1	2	3

Adding Edges		Adding Faces
Edges are specified by selecting their endpoint nodes.		Three to four edges determine a face.

4	5	6

Reducing the size of the Domain
To create the narrow model, we started out with the original wide model and moved the lateral boundaries closer to the plane of symmetry, reducing its width (and total volume) by one-half.
1	2	3

4	5	6

Original Model	Narrow Model
140 nodes 203 edges 88 faces	130 nodes 183 edges 77 faces

Result: the Model File
For each:	Lists:
Node Number	X-coord.	Y-coord.	Z-coord.	Refinement Value
Edge	Nodes that determine the edge
Face	Nodes at vertices			RNG Value
The refinement value, specified for each node by the user, is used during the surface mesh generation phase to determine the mesh element size in the neighborhood of the node. Small elements (and more resolution) can be requested at nodes where the solution is likely to be more complex. The RNG (Reference Node Group) value is used by the simulation software to keep track of which boundary conditions must be applied on each face. For instance, all the faces that together make up the free surface will have the same RNG number. Faces on the river bed will have a different RNG number, and so on.

Surface Mesh Generation