4. The steps of creating the mesh#

To create the network of pipes, you must activate the Salome-Meca module SMESH.

4.1. Wire line meshing#

Create a new mesh: Mesh Create Mesh by taking as geometry parameter the group of wire elements created in the 1D geometric compound (EL_FIL in our example) with as recommended parameters:

  • Algorithm = wire discretization and

  • Hypothesis = Automatic Length

  • (in our example fineness=0.2 see figure 13).

_images/10000000000005CE0000038E3A74BD1C9E20CC15.jpg

Figure 13: Wire line mesh

4.2. Hexahedral meshing of 3D tee elements#

A hexahedral mesh of 3D tees can be created in the following way:

  • Create a new mesh: Mesh Create Mesh by taking as geometry parameter a group of 3D elements created in the 3D geometric compound (Pipe TShape_1 in our example).

  • Select Hexahedron (i, j, k) as the 3D algorithm

  • Select Quadrangle (Mapping) as 2D algorithm

  • Select Wire discretization Hypothesis Nb. Segments_1 as the 1D algorithm (by putting 10 for Number of segments for example)

  • press OK then Apply and Close.

  • Right click on the Mesh_X thus created in the construction tree then compute.

If you want to modify the discretization of the mesh in the thickness of the pipes for example, you must create a sub-mesh by clicking on Mesh Create Sub-Mesh:

  • Select the full mesh Mesh2 as the Mesh parameter,

  • as a Geometry parameter the Thickness group of Pipe TShape_1 in the Geometry tree,

  • then as 1D parameters:

  • Algorithm Wire discretization Hypothesis

  • Nb. Segments (Number of Segments 3 in our example),

  • then click on OK then on Apply and Close.

  • right click on the Mesh_X created in the construction tree

  • then compute.

The mesh shown in FIG. No. 14 is obtained, which contains 3 elements in the thickness of the pipes.

_images/1000000000000690000003E860B1E90C3B8EC4DC.jpg

Figure 14: Hexahedral mesh of a 3D tee

4.3. Meshing a 2D line#

A 2D mesh can be created in the following way:

  • Click on Mesh Create Mesh,

  • select the 2D pipe or the 2D pipe compound created with the Geometry module in the Geometry field,

  • select quadrangle mapping in the 2D Algorithm field tab

  • then in the 1D Algorithm field tab select Wire discretization Automatic Length Fineness (\(\mathrm{0,7}\) on the example figure no. 15)

_images/1000000000000690000003E825F25451D3A9A096.jpg

Figure 15: Quadrangle mesh of a 2D line

4.4. Assembling the mesh#

4.4.1. Creating mesh groups#

Mesh groups can be generated from the geometric groups created in Chapter 2.7 in the following manner:

Click on Mesh then on Create Groups from Geometry:

In the Geometry field (Elements or Nodes), select the geometric group chosen from the Geometry construction tree.

You can choose to obtain a group of elements (Elements Geometry field) or a group of nodes (Nodes Geometry field), see figure 16.

_images/1000000000000690000003E8D75F61E0C38967DB.jpg

Figure 16: Choice of geometric groups for creating a group of elements

click on Apply and close we get the group of elements corresponding to the chosen geometric group (TUY_2D in our example figure 17).

_images/1000000000000690000003E8E9A34B248B32E34B.jpg

Figure 17: Group of meshes

4.4.2. Creation of a mesh compound#

You have to click on Mesh then on Build Compound:

Select the meshes that make up the compound in the Mesh construction tree (using the shift or ctrl keys to select them).

To retrieve the existing groups in the meshes composing the compound identically in the compound, leave Unite as a parameter in the Processing identical groups field.

Click on Apply and close, we get the following mesh compound for our example figure 18:

_images/1000000000000690000003E86036CBA0E74598FA.jpg

Figure No. 18: Creation of a mesh compound

You can export this compound in MED format to be able to perform a Code_Aster calculation (File, export, Med file).