. To mesh volumes with a structured mesh, select the option Mesh->Structured->Volumes->Assign number of cells.
. Select volumes 1 and 2 and press ESC.
. A window appears in which to enter the number of divisions that the lines to be selected will have. Enter 6 and click Assign.
. Select lines of both volumes parallel to the X and Z axes. GiD automatically selects all the lines in each volume parallel to these in order to create the structured mesh. Press ESC.
. Another window appears in which to enter the number of divisions on the lines. Divide the lines parallel to the Y axis into 8 segments. Enter 8 and click Assign.
. Select an edge of volume 1 or 2 parallel to the Y axis and press ESC . Again, the line-division window comes up. Since we have already finished the assignments, click Close.
. For structured volumes, GiD generates tetrahedron meshes by default, but hexahedron structured meshes can also be assigned. Let's assign the element type that we wish to volume 1 and 2. Select Mesh->Element type->Tetrahedra,then select volume number 2 and press ESC. Select Mesh->Element type->Hexahedra, then select volume number 1 and press ESC.
. Select Mesh->Generate mesh.
. A window appears asking whether the previous mesh should be eliminated. Click Yes.
. Another window comes up in which to enter the maximum element size. Leave the default value unaltered and click OK . The result is the mesh shown in Figure 9.
. GiD can obtain volume structured meshes made of hexahedra, tetrahedra or prisms. As can be seen in Figures 9 and 10, there are two kinds of tetrahedron structured mesh: the one shown in Figure 9 is obtained when the option Utilities->Preferences->Meshing->Symmetrical structured->tetrahedra is set. If this option is not set, the mesh presented in Figure 10 is produced (with fewer nodes than if using the previous option;also, it is not topologically symmetrical).
