The computational 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 In practice, this is very difficult to achieve, and thus, for most EFDC models an orthogonality orthogonal deviation of under less than 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 1153859831. In addition, the orthogonal deviation of a grid can be viewed from the Grid menu as shown in Figure 2 1153859831.
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Figure 1. View orthogonal deviation of a grid from RMC's option.
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Figure 2. View orthogonal deviation of a grid from Grid menu.
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Figure 3. Orthogonal deviation of a grid.
There are two options for orthogonalizing grid: Othogonalize entire grid and Othogonalize a grid which are to orthogonalize the entire grid or to orthogonalize a grid block as described below:
Othogonalize the 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, 1153859831. When this is done the entire grid will be orthogonalized immediatelyimmediately orthogonalized. 1153859831 shows a change in orthogonality of the grid after applying Orthogonalize Grid.
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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.
Anchor Figure 5 Figure 5 Anchor Figure 6 Figure 64. Orthogonalize grid.
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Figure 5. Grid image after applying "Orthogonalize Grid"
Orthogonalize a grid block
- Select the grid layer in the Layer Control by LMC
- From the main toolbar, select the Select object button then select a grid node, hold the Shift key and select the second grid node. The grid block will be highlighted as shown 1153859831.
- Next, from Grid menu, select Orthogonalize Grid or click on the Orthogonalize grid button from the main toolbar. A further option is to select Orthogonalize Grid Block from the RMC options as shown in 1153859831. As a result, the grid block will be immediately orthogonalized. 1153859831 shows a change in orthogonality of the grid after applying Orthogonalize Grid for a grid block.
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Figure 6. Select a grid block.
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Figure 7. Select Orthogonalize Grid Block option.
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Figure 8. Grid image after applying "Orthogonalize Grid Block"