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Figure 13. Merged grids.
Step 6: Create branch grids
The branch grids can be built using the similar steps as for main channel grids. Note that the intersection splines and nodes are overlaid with satisfactory precision so that Grid+ can merge grids without errors.
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Figure 14. Creating and connecting branch grids.
Step 7: Generate grids with islands
In conception, there are two methods to deal with this case. The first method involves generating a grid domain which covers the main river, the island and the branches, then the grid cells on the island will be deleted. The advantages of this approach is that it is easy and fast. However, it may result in inexact fitting of the grid borders along the river banks. The second method is to generate a grid domain for the main river and the branch only while the island is ignore. This guarantees a good fitting of the grid borders along the river banks but could be time-consuming and difficult to implement.
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Figure 22. Creating and connecting branch grids.
Step 8: Display IJ cell indices
Check the IJ cell indices of the latest updated grids by RMC on the layer, select Show Labels then select Cell I, J Indices. The I, J Indices are the displayed as in Figure 23.
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Figure 23. Displaying I, J indices.
Step 9: Generate grids for the main river branch
The identification of I, J indices is required for the determination of the dimension of the subsequent grid block. Click on the first and the last nodes of the branch to define the number of cells along the main river branch. Delete the cells inside the splines as indicated in Figure 24.
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Figure 27. Completed grids.
Step 10: Orthogonalize grids
The user can orthogonalize a grid either globally or locally. Global orthogonalization is applied for the entire gird while local orthogonalization is only applied for selected grid cells.
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Figure 29. Local orthogonalization.
Step 11. Viewing orthogonal deviation
RMC on the grid layer, go to Show Properties and select Orthogonal Deviation (Figure 30).
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Figure 31. Viewing orthogonal deviation.
Step 12: Removing in-land cells
To remove in-land cells, use the Delete node button in the main toolbar. The user can LMC on the nodes/cells which need removing (Figure 32).
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