Generating a 2D mesh

Step-by-step guide

In this tutorial, a 2D mesh is generated in a 2D zone with previously defined 2D boundaries. An important part of this process is understanding the validation process and the mesh log.

1. Open the 2D River Model network and 2D Ground Model on the GeoPlan.

With the 2D boundaries defined and set up, the 2D zone can be meshed.

2. On the GeoPlan Tools toolbar, click the Select tool.
3. On the GeoPlan, select the 2D zone.
4. From the Model menu, select Meshing > Mesh 2D Zones.

In the Mesh 2D Zones dialog, external files, layers, or polygons could be selected for use as voids, break lines, or walls within the mesh, but for this tutorial, keep all three of these options set to None.

5. From the Database, drag the 2D Ground Model into the Mesh 2D Zones dialog and drop it into the Ground Model group box.

6. Click OK to mesh the 2D zone.

Note that this process is similar to running a simulation.

7. Click OK to create the job.

Prior to mesh generation, the data used for creating the mesh is validated. The mesh log for the job contains any error messages, which must be corrected before the mesh can be generated.

It is possible to generate multiple meshes at the same time for different 2D zones. If any changes are made to objects within the 2D zone, a new mesh must be generated for changes to take effect and to simulate that version of the model.

8. From the Window menu, select Job control window.

This displays the status of the mesh job. Once the 2D mesh is generated, the row turns green.

9. In the Job Control window, in the Status column, click Mesh ready to open the Manage mesh results dialog.

10. With 2D Zone selected, click Show log to view details for the mesh, including any warnings, the minimum triangle area and the number of triangles and elements.

Errors may be generated if:

• Mesh zones or roughness zones overlap.
• All vertices of a mesh element lie within an undefined area of the ground model, which means that the ground level of the element cannot be determined.

If there are warnings:

• Mesh is still created.
• Mesh log contains output from meshing process and any validation warnings.
• May be generated if polygon boundaries or walls intersect each other.
• Resolve by editing object geometry, using polygon and polyline editing tools to snap and insert vertices.

11. In the manage mesh results dialog, click Load Mesh.

12. Click Close.

The mesh job is automatically removed from the Job control window and the 2D mesh is loaded into the model.

13. Zoom into an area of the GeoPlan to see the 2D elements that are now generated.
14. Select Network > Clear ground model to make the mesh easier to see.

15. Using the Select tool, double-click an area of the 2D zone.
16. In the Multiple Selection popup, select the [element: ID] item.

17. Click OK.

Information for the selected element appears. The ground level for a mesh element is calculated by sampling the ground model within the 2D triangles that make up the element, and then taking the average of the sample point levels. This is used to calculate a single elevation for each element.

18. After viewing the information, click Close.
19. Click the Validate tool to make sure there are no errors in the network.
20. Click OK.
21. Click Commit changes to database to save the changes.
22. Add a comment, such as “2D mesh created”.
23. Click OK.