The accuracy of a model is increased when the orthogonality of a grid is optimized. A perfect grid would have all cells perpendicular to the boundary lines. This is very difficult to achieve and thus for most EFDC models an orthogonality of under 3o is recommended. The orthogonalization tool is used to reduce the orthogonal deviation of a grid.
To view the orthogonal deviation of a grid, LMC on the grid layer in the Layer Control then RMC on that grid layer to show RMC's options, select Show Properties/Orthogonal Deviation as shown in Figure 1. In addition, the orthogonal deviation of a grid can be viewed from the Grid menu as shown in Figure 2.
Figure 1 View orthogonal deviation of a grid from RMC's option.
Figure 2 View orthogonal deviation of a grid from Grid menu.
Figure 3 Orthogonal deviation of a grid.
There are two options for orthogonalizing grid: Othogonalize entire grid and Othogonalize grid block as described below:
Othogonalize entire grid
- Select the grid layer in the Layer Control by LMC
- From Grid menu, select Orthogonalize Grid or the user can click on the Orthogonalize grid button from the main toolbar as shown in Figure 4. As a result, the entire grid will be orthogonalized immediately.
Figure 3 Orthogonal deviation of a grid.
If a global operation is selected the entire grid will be orthogonalized immediately. If a local operation is selected, the user must define two grid nodes and the area of the grid limited by the two points will be orthogonalized. Orthogonalize 1D feature is similar to the Orthogonalize Local option but is only applicable for a 1D grid region. In case the feature is applied for an improper grid region, a warning message will appear.
The change in grid orthogonality before and after applying Orthogonalize Global are shown in Figure 2 and Figure 3. It may be seen in the first image that the average orthogonality is 20.3. In the second image, after CVLGrid has automatically reduced the orthogonalization, it is only 2.6.
The change in grid orthogonality before and after applying Orthogonalize Local are shown in Figure 4 and Figure 5.
The change in grid orthogonality before and after applying Orthogonalize 1D are shown in Figure 6 and Figure 7.
Othogonalize grid block
Figure 1 Select a grid segment to highlight.