─ 2.2. Meshing Parameters
In the PO module, the mesh generation is a required step that is performed immediately before simulating. In the Meshing Parameters window, represented in Figure 15, the following options are available.
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Number of processors: to set the number of processors for the meshing process
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Meshing strategy:
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Regular Meshing: The size of the generated elements is selected by the user. Regular meshing is the common algorithm used in other modules such as MoM. It provides a mesh of triangles of similar sizes with a distribution as uniform as possible. It enables the user to set the exact size edge of the triangles to be generated, given in lambda units. However, a huge number of mesh elements may results when the geometry contains large surfaces.
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Multilevel: Use Multilevel to generate the mesh automatically in several sequenced steps. This option is usually more efficient (in terms of runtime) than the common mesh generation option, so it is selected by default. However, there may be minor differences between the meshes obtained with and without the Multilevel mode.
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Edge size: Desired size for the edge of the elements, in wavelengths.
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Curvature Meshing: The size of the generated elements is automatically computed in the meshing process. However, it depends on the global bounding box of the targets, their curvatures, and the Distance error and Surface error (lambda) parameters. This technique provides a non-regular mesh with patches generated to discretize the curvatures and edges of the geometry with a quasi-adaptative method. The generated meshes usually are less dense than the ones provided with the Regular Meshing strategy. The curvature meshing has been developed with the aim of solving the limitations that uniform meshes may cause in PO and GTD-PO modules. By using this technique, the planar surfaces are discretized with the minimum number of triangles that is possible; and the curved surfaces are discretized in a set of flat triangles. The criterion of curvature meshing converts the curved surfaces in planar triangles meshes where the maximum deviation between any planar triangle and the original surfaces is lower than the wavelength multiplied by the Surface Error factor.
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Distance error: increasing this parameter creates a denser mesh in planar surfaces (smaller size of elements)
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Surface error (lambda): decreasing this parameter creates a denser mesh in curved surfaces (smaller size of elements)
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Automatic Meshing: The size of the generated elements is automatically computed by the meshing algorithm. Automatic Meshing method just simplifies the geometry with a low-density mesh of regular triangles with an automatically computed size. It is only recommended for simplest cases where the user does not know what can be the optimal setting up.
For this case, it is interesting to use the Regular Meshing option, in order to obtain a regular mesh of the geometry. As the simulation frequency is high, a good mesh will be obtained with edge size = 2.0 lambda, as shown in Figure 13.
Figure 13: Meshing parameters.
Figure 14 shows the mesh obtained for each geometry, dihedral, trihedron and cavity, respectively.
Figure 14: Mesh for the dihedral, trihedron and cavity.
This example has been meshed in a personal computer by using 4 processors and requiring approximately 1.2 GB of RAM and 1 second to obtain a mesh of about 100 elements for the dihedral, 150 elements for the trihedron and 2250 elements for the cavity.
