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
|
|
|
Figure 30. The
mesh generated with default settings
|
|
|
-
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
.