Orthogonalize Grid

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. In practice, this is very difficult to achieve, and thus, for most EFDC models an orthogonal deviation of less than 3^o 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 Orthogonalize Grid#Figure 1. In addition, the orthogonal deviation of a grid can be viewed from the Grid menu as shown in Orthogonalize Grid#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 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 click on the Orthogonalize grid button from the main toolbar as shown in Orthogonalize Grid#Figure 4. When this is done the entire grid will be immediately orthogonalized. Orthogonalize Grid#Figure 5 shows a change in orthogonality of the grid after applying Orthogonalize Grid.

Figure 4. Orthogonalize grid.

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 Orthogonalize Grid#Figure 6.
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 Orthogonalize Grid#Figure 7. As a result, the grid block will be immediately orthogonalized. Orthogonalize Grid#Figure 8 shows a change in orthogonality of the grid after applying Orthogonalize Grid for a grid block.

Figure 6. Select a grid block.

Figure 7. Select Orthogonalize Grid Block option.

Figure 8. Grid image after applying "Orthogonalize Grid Block"