Menu: Mesh->Edit mesh
GiD offers you several options for modifying an existing mesh. All modifications will be lost when the mesh is generated again.
Mesh Menu>Edit mesh>Create node
This tool allow the manual creation of mesh nodes, entering its x,y,z coordinates.
Mesh Menu>Edit mesh>Move node
Menu: Mesh->Edit mesh->Move node
By using this command, an existing node is selected and moved. The new position is entered in the usual way (see Point definition).
Mesh Menu>Edit mesh>Move nodes z raster
Move the z coordinate of the nodes to the value interpolated by a raster file (an image with color encoding the z of each pixel)
Mesh Menu>Edit mesh>Create element
This tool allows the manual creation of mesh elements, entering its connectivities (nodes must be previously created).
For cartesian meshes, it is only needed to specify the nodes of two opposite corners. Multiple elemenst will be created to fill all cells between the two corners.
Mesh Menu>Edit mesh>Split elements
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.
Mesh Menu>Edit mesh>Smooth elements
Menu: Mesh->Edit mesh->Smooth elements
To smooth elements, select them in the usual way (see Entity selection), and then press escape (see Escape) to perform the action.
Currently only triangles, tetrahedra and hexahedra can be smoothed.
In the case of tetrahedra and hexahedra, element connectivity is preserved after the smoothing; however, with triangle elements this may be modified during the smoothing process.
In case of triangles, sharp edges can be preserved in the smoothing process. User can set the maximum angle to be considered as sharp by the 'TolAngle' option in the contextual menu (Mouse operations).
All selected elements must be of the same quadratic type.
Mesh Menu>Edit mesh>Collapse
Menu: Mesh->Edit mesh->Collapse
The Collapse function converts coincident entities, i.e. entities that are close each other, into one.
It is possible to collapse edges, nodes, elements or the whole mesh.
- Collapse mesh collapses all the nodes of the mesh.
- Collapse edges joins nodes that are connected by edges shorter than the Import Tolerance value.
- Collapse nodes asks you to select some nodes. Nodes closer together than the Import Tolerance value are collapsed.
- Collapse elements asks you to select some elements. Then, the nodes of these elements that are closer together than the Import Tolerance value are collapsed.
Note: Entities belonging to a frozen layer (see Layers and groups (only Preprocessing)) are not checked when collapsing.
Mesh Menu>Edit mesh>Delete
Menu: Mesh->Edit mesh->Delete
To delete elements or nodes, select them in the usual way (see Entity selection ), and then press escape (see Escape ) to perform the action.
If the 'Also lower entities' check option is set then are deleted the selected entities and also its dependencies if possible (if are not shared by undeleted entities)
Note: It is possible to filter the selection, e.g. to select only triangles but not quadrilaterals (see Selection window (only Preprocessing) ).
Note: Only lonely nodes (nodes of the mesh that do not belong to any element) can be deleted.
Mesh Menu>Edit mesh>Nodes-grid quadrilaterals
To create a grid of quadrilaterals from a cloud of 3D nodes. The user will be asked for the cell size
The z of the grid will be extrapolated averaging a collection of neighbor nodes
Mesh Menu>Edit mesh>Triangles-grid quadrilaterals
To create a grid of quadrilaterals from a cloud of 3D triangles. The user will be asked for the cell size
The z of the grid will be get from the triangle where the grid corner is projected (in 2D), or from a close node.