The RJump mesher is a surface mesher that meshes patches of surfaces (in 3D space) and is able to skip the inner lines of these patches when meshing. By default, the RJump mesher skips the contact lines between surfaces that are tangent enough, and points between lines that are tangent enough. By selecting Mesh->Draw->Skip entities (Rjump)
, the entities that RJump is going to skip and the ones that it is not going to skip are displayed in different colors. In this chapter we will see the properties of this mesher.
- Select Mesh->Reset mesh data
to reset all mesh sizes introduced previously.
- A window appears advising that all the mesh information is going to be erased. Press OK
.
- Go to Utilities
and open Preferences.
Click Meshing
. In the window that appears you can choose between the three surface meshers available in GiD (RFast, RSurf and RJump). Select RJump
mesher. Click Accept
.
- Select Mesh->Generate Mesh
.
- A window opens asking if the previous mesh should be eliminated. Click Yes
.
- Another window appears in which you can enter a maximum element size. Leave the default value unaltered and click OK
. This results in a mesh where contact lines between surfaces that are tangent enough do not have nodes; contact points between lines tangent enough are also skipped when meshing (see Figure 10).
Figure 10. Mesh using the RJump mesher.
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Note that the smaller elements shown in Figure 3 do not appear in this mesh, because of the properties this mesher.Using the RJump mesher it is possible to assign sizes to different entities. As an example, select Mesh->Unstructured->Size by chordal error…
.
- GiD asks for the minimum element size. Enter 0.1.
- GiD asks for the maximum element size. Enter 10.
- Enter the chordal error. This error is the maximum distance between the element generated and the real object. Enter 0.05 and press OK
.
- Again, select Mesh->Generate Mesh
.
- A window opens asking if the previous mesh should be eliminated. Click Ok
.
- Another window appears in which you can enter a maximum element size. Leave the default value unaltered and click OK
. This results in a high concentration of elements in curved areas, without the nodes in the lines and points that mesher skips. Now our approximation is significantly improved (see Figure 11).
Figure 11. Mesh using the RJump mesher and assigning sizes by chordal error.
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Force to mesh some entity |
If there is a line or a point that the RJump mesher would usually skip, but that you wish to be meshed, you can specify the entity so that it is not skipped. As an example, we will force Rjump to mesh line number 43, in order to concentrate elements around point number 29, as it was done in chapter 2.2.
- Select Mesh->Mesh criteria->No skip->lines
, and select line number 43. Press ESC
.
- Select Mesh->Draw->Skip entities(Rjump)
to display the entities that will and will not be skipped in different colors. As is shown in Figure 12, line 43 will now not be skipped; the rest of the lines are unaffected, and RJump will either skip or mesh them according to its criteria.
Figure 12. Entities that will be skipped and not skipped using the RJump mesher.
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- Select Mesh->Unstructured->Assign size on points
. A window appears in which to enter the element size around the points to be chosen. Enter 0.1 and click Assign
.
- Select the point indicated in Figure 4 (point number 29). Press ESC
to indicate that the selection of points is finished.
- Select Mesh->Generate Mesh
.
- A window opens asking if the previous mesh should be eliminated. Click Ok
.
- Another window appears in which you can enter a maximum element size. Leave the default value unaltered and click OK
. This results in a mesh like the one obtained before (in Figure 10), but with high concentration of elements around point number 29. Note that there are nodes on line number 43 because we have forced RJump not to skip this line (see Figure 13).
Figure 13. Mesh using the RJump mesher, assigning sizes by chordal error and forcing an entity to be meshed.
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In this last example we have forced the mesher not to skip an entity, but it may be interesting in some models to allow the mesher only to skip a few entities, meshing almost all or them. In this case, a different surface mesher can be selected (in the Preferences
window). One option is the RSurf mesher which meshes everything except the entities that you ask it to skip, using the Mesh->Mesh criteria->Skip
command. Here, because RJump is not selected, no entity will be skipped automatically according to tangency with neighboring entities. The next example shows how to work with this mesher.
- Select Mesh->Reset mesh data
to reset all mesh sizes introduced previously.
- A window opens advising that all the mesh information is going to be erased. Press OK
.
- Go to Utilities
and open Preferences.
Click Meshing
. In the window that appears you can choose between the three surface meshers available in GiD (RFast, RSurf and RJump). Select the RSurf
mesher. Click Accept
.
- Select Mesh->Mesh criteria->Skip->lines
, and select lines 48 and 53. Press ESC
.
- Select Mesh->Generate Mesh
.
- A window opens asking if the previous mesh should be eliminated. Click Yes
.
- Another window appears in which you can enter a maximum element size. Leave the default value unaltered and click OK
. The result is a mesh similar to the first example obtained in chapter 2 (see Figure 2), but the smaller elements highlighted in Figure 3 do not appear because lines 48 and 53 (which were meshed before) are now skipped when meshing (see Figure 14).
Figure 14. Mesh using the RSurf mesher, with some lines skipped.
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