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.
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Select Mesh
Reset mesh data to
reset all mesh sizes introduced previously.
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A window appears advising that all the mesh information is going to be erased.
Press OK .
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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
.
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Select Mesh
Generate Mesh .
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A window opens asking if the previous mesh should be eliminated. Click Yes
.
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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… .
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GiD asks for the minimum element size. Enter 0.1.
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GiD asks for the maximum element size. Enter 10.
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Enter the chordal error. This error is the maximum distance between the element
generated and the real object. Enter 0.05 and press OK .
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Again, select Mesh
Generate Mesh
.
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A window opens asking if the previous mesh should be eliminated. Click Ok
.
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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
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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.
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Select Mesh
Mesh criteria
No
skip
lines , and select line
number 43. Press ESC .
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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 .
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Select the point indicated in Figure 4 (point number 29). Press ESC to
indicate that the selection of points is finished.
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Select Mesh
Generate Mesh .
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A window opens asking if the previous mesh should be eliminated. Click Ok
.
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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.
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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 .
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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 .
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Select Mesh
Mesh criteria
Skip
lines
, and select lines 48 and 53. Press ESC .
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Select Mesh
Generate Mesh .
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A window opens asking if the previous mesh should be eliminated. Click Yes
.
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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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