Definition of Model Geometry

The definition of the model geometry is performed by the FEMGEN program module. The top-down approach used in FEMGEN means that the geometry of the model is first defined, then the mesh is generated.

The building-blocks in the geometrical model are points, lines, surfaces and bodies. These form a complete solid model where lines are defined from points, surfaces from lines, and bodies from surfaces.

The top-down approach means that only coordinates for certain key points need be entered. It is therefore very easy to modify a geometry by, for example, moving a few points. Then a new mesh can be generated which conforms to the new geometry.

Further geometric objects are sets and analytical shapes. The analytical shapes provided are planes, spheres, cylinders and cones; and these can be used for point coordinate calculation, defining intersection curves and defining the form of a surface (projection).

A set is a collection of points, lines, surfaces and bodies. It is a useful tool for many operations, especially in the replication of part of a model.