# From Mesh to Simulation & System Performances Computation

The dimensioning phase remains an essential step in the design of the electromagnetic device. This step can be reached with many approaches:
> Analytical method
> Numerical method: among these methods is the finite element method (FEM).
The principle of the FEM is based on the transformation of partial differential equations into a system of algebraic equations. In general the resolution by the FEM includes several steps. Among these steps, the mesh of the device, which corresponds to the discretization of the study device on the elements (triangles, tetrahedrons, hexahedrons…) and node on which we compute:
> Magnetic application: magnetic potential
> Electric application: electric potential
> Thermal application: temperature
In other hand, the mesh allows to compute the behavior and the performances of the system. Generally a mesh is defined by: its system coordinate; its size: typically 2D or 3D; the cell geometry: triangles, polygons, squares, 2D polyhedral, parallelepipeds, cubes in 3D and the geometry elements: line, face and volume.

Among software using the mesh to compute the performances of the study system there is Flux 2D / 3D developed by CEDRAT.  In Flux 2D and 3D, we find several options of mesh and generator mesh. The most used:

Flux 2D: 3 types of mesh generator

1. automatic: triangular and tetrahedral elements
2. mapped: quadrangular and hexahedral elements
3. linked: copy of the mesh from one face to another

Mapped mesh: 2D and 3D

Flux 3D
: 4 types mesh generators

1. automatic: triangular and tetrahedral elements
2. mapped: quadrangular and hexahedral elements
3. linked: copy of the mesh from one face to another
4. extrusive: identical mesh on extruded layers and quadrangular elements on sides

Extrusive mesh

Each type of mesh has benefits and drawbacks for more information watch the following video:

The goal is to give the user the ability to choose the mesh that best fits their application.