Menu: Mesh->Edit mesh->Split elements
To split elements, select them in the usual way (see Entity selection), and then press escape (see Escape) to perform the action. Triangles can be split into triangles, quadrilaterals into two or four triangles, tetrahedra into tetrahedra, hexahedra into tetrahedra, and prisms into tetrahedra.
When splitting triangles, the new nodes can be located in the mid-edge or with an enhanced interpolation (modified Butterfly scheme) in order to obtain a smooth mesh.
When splitting quadrilaterals, if 'SymmetricalStructuredTriangles' is set, then four triangles are generated for each quadrilateral; otherwise only two triangles are created per element.
When splitting hexahedra, if 'SymmetricalStructuredTetrahedra' is set, then 24 tetrahedra are generated for each hexahedron; otherwise six tetrahedra are created per element.
If original elements are quadratic, the triangles or tetrahedra obtained are quadratic. Otherwise, if original elements are linear, the triangles or tetrahedra obtained are linear.
In the case of quadratic quadrilaterals, extra nodes are generated. These nodes are not associated with geometric entities, they have simply been obtained by interpolating mesh node coordinates.
In the case of hexahedra or prisms, all selected elements must be of the same quadratic type.
With triangles or tetrahedra, when selecting only a part of the mesh, neighbor elements will be also splitted to mantain a conformal mesh. For tetrahedra is not possible to split them if they are connected with neighbor elements of another element type (to avoid create non-conformal meshes and hanging nodes)
Note: Currently, the operation Split triangles and tetrahedra only works for linear elements.