Now that the part has been drawn and the volumes created, the mesh may be generated. First we will generate a simple mesh by default.
Depending on the form of the entity to be meshed, GiD performs an automatic correction of the element size. This correction option, which by default is activated, may be modified in the Meshing
card of the Preferences
window, under the option Automatic correct sizes
. Automatic correction is sometimes not sufficient. In such cases, it must be indicated where a more precise mesh is needed. Thus, in this example, we will increase the concentration of elements along the profile of the wheel by following two methods: 1) assigning element sizes around points, and 2) assigning element sizes around lines.
Generating the mesh with assignment of size around points |
- Enter view rotate angle -90 90 ESC
in the command line. This way we will have a side view.
Footnote: Another option equivalent to view rotate angle -90 90
is RotatePlane XY
,located in the mousemenu.
Figure 33. Side view of the part.
|
|
- Choose Mesh->Unstructured->Assign sizes on points
. A window appears in which to enter the element size around the point to be selected. Enter 0.7.
- Select only the points on the wheel profile (Figure 34). One way of doing this is to select the entire part and then deselect the points that form the prism hole. Press ESC
to conclude the selection process.
Figure 34. The selected points of the wheel profile
|
|
- Choose Mesh->Generate mesh
.
- A window opens asking if the previous mesh should be eliminated (Figure 35). Click Yes
. Another window appears in which the maximum element size should be entered. Leave the default value unaltered.
Figure 35
|
|
- A third window shows the meshing process. Once it has finished, click OK
to visualize the resulting mesh (Figure 36).
Figure 36. Mesh with assignment of sizes around the points on the wheel profile
|
|
- A greater concentration of elements has been achieved around the points selected.
- Choose View->Mode->Geometry
to return to the normal visualization.
Generating the mesh with assignment of size around lines |
- Open the Preferences
window, which is found in Utilities
, and select the Meshing
card. In this window there is an option called Unstructured Size Transitions
which defines the size gradient of the elements. A high gradient number means a greater concentration of elements on the wheel profile. To do this, select a gradient size of 0.8. Click Accept
.
- Choose Mesh->Reset mesh data
to delete the previously assigned sizes from section 5.2.
- Choose Mesh->Unstructured->Assign sizes on lines
. A window appears in which to enter the element size around the lines to be selected. Enter size 0.7. Select only the lines of the wheel profile (Figure 37) in the same way as in section 5.2.
Figure 37. Selected lines of the wheel profile
|
|
- Choose Mesh->Generate mesh
. A window appears asking if the previous mesh should be eliminated. Click Ok
.
- Another window opens in which the maximum element size should be entered. Leave the default value unaltered.
- A greater concentration of elements has been achieved around the selected lines. In contrast to the case in section 5.2, this mesh is more accurate since lines define the profile much better than points do (Figure 38).
Figure 38. Mesh with assignment of sizes around lines
|
|
Generating the mesh by default |
- Choose Mesh->Generate Mesh
.
- A window comes up in which to enter the maximum element size of the mesh to be generated (Figure 28). Leave the default value given by GiD unaltered and click OK
.
Figure 28. The window in which the maximum element size is entered
|
|
- A window appears showing how the meshing is progressing. Once the process is finished, another window opens with information about the mesh that has been generated (Figure 29). Click OK
to visualize the resulting mesh (Figure 30).
Figure 29. The window with information about the mesh generated
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Figure 30. The mesh generated with default settings
|
|
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- Use the Mesh->View mesh boundary
option to see only the contour of the volumes meshed without the interiors (Figure 31). This visualization mode may be combined with the various rendering methods.
Figure 31. Mesh visualized with the MeshView mesh boundary option
|
|
- Visualize the mesh generated with the various rendering options in the Render
menu, located in the mouse menu.
Figure 32. Mesh visualized with MeshView mesh boundary combined with RenderFlat.
|
|
- Choose View->Mode->Geometry
to return to the normal visualization.
NOTE
: To visualize the geometry of the model use View->Mode->Geometry
. To visualize the mesh use View->Mode->Mesh
.