The tool extracts either lines in case of a 2D bulk mesh as input or quads/triangles in case of a 3D bulk mesh as input. The input mesh can be given either in the vtu or msh format. Since the algorithm uses the element surface normals a correct node ordering of the element nodes is required.
ExtractBoundary -i [<file name of input mesh>] [-o <file name of output mesh>] [--face-property-name <string>] [--element-property-name <string>] [--node-property-name <string>]
The data arrays added to the boundary mesh by using the options
--face-property-name (default value ‘bulk_face_ids’),
--element-property-name (default value ‘bulk_element_ids’), and
--node-property-name (default value ‘bulk_node_ids’) are used in other tools (for instance in ComputeNodeAreasFromSurfaceMesh) and are required for flux calculations during a simulation run of OpenGeoSys.
ExtractBoundary -i square_1x1_quad.vtu -o square_1x1_quad_border.vtu
In the figure above the square mesh consists of 16 cells/elements. The numbers in the cells are the cell IDs. The generated boundary grid consists of the somewhat thicker and colored line elements.
ExtractBoundary -i square_1x1_tri.vtu -o square_1x1_tri_border.vtu
In the figure above the square mesh consists of 32 triangle shaped cells. The numbers in the tri are the cell IDs. The generated boundary grid consists of the somewhat thicker and colored line elements.