10.3 Modifying the Mesh

Once the elements in the mesh has been prepared by specifying there desired sizes, we are ready to use the actual adaptivity operations. Currently we provide delauney flip operations, edge bisect operations and edge-coarsen operations all of which are implemented in parallel, but the user has access to these wrapper functions which interlligently decide when and in which region of the mesh to use the adaptivity operations to generate a mesh with higher quality elements while achieving the desired size (which is usually average edge length per element), or it could even be the area of each element.

void FEM_ADAPT_Refine(int meshID, int qm, int method, double factor,double *sizes);
Perform refinements on the mesh specified by meshId. Tries to maintain/improve element quality by refining the mesh as specified by a quality measure qm. If method = 0, refine areas with size larger than factor down to factor If method = 1, refine elements down to sizes specified in the sizes array. In this array each entry corresponds to the corresponding element. Negative entries in sizes array indicate no refinement.

void FEM_ADAPT_Coarsen(int meshID, int qm, int method, double factor,double *sizes);
Perform refinements on the mesh specified by meshId. Tries to maintain/improve element quality by coarsening the mesh as specified by a quality measure qm. If method = 0, coarsen areas with size smaller than factor down to factor If method = 1, coarsen elements up to sizes specified in the sizes array. In this array each entry corresponds to the corresponding element. Negative entries in sizes array indicate no coarsening.

void FEM_ADAPT_AdaptMesh(int meshID, int qm, int method, double factor,double *sizes);
It has the same set of arguments as required by the previous two operations, namely refine and coarsen. This function keeps using the above two functions till we have all elements in the mesh with as close to the desired quality. Apart from using the above two operations, it also performs a mesh repair operation where it gets rid of some bad quality elements by delauney flip or coarsening as the geometry in the area demands.

int FEM_ADAPT_SimpleRefineMesh(int meshID, double targetA, double xmin, double ymin, double xmax, double ymax);
A region is defined by (xmax, xmin, ymax, ymin) and the target area to be achieved for all elements in this region in the mesh specified by meshID is given by targetA. This function only performs a series of refinements on the elements in this region. If the area is larger, then no coarsening is done.

int FEM_ADAPT_SimpleCoarsenMesh(int meshID, double targetA, double xmin, double ymin, double xmax, double ymax);
A region is defined by (xmax, xmin, ymax, ymin) and the target area to be achieved for all elements in this region in the mesh specified by meshID is given by targetA. This function only performs a series of coarsenings on the elements in this region. If the area is smaller, then no refinement is done.