7 Mesh Modification

void FEM_Update_mesh(FEM_Update_mesh_fn routine, int callMeshUpdated,int doWhat);
SUBROUTINE FEM_Update_mesh(routine,callMeshUpdated,doWhat)
external, INTENT(IN) :: routine
INTEGER, INTENT(IN) :: callMeshUpdated,doWhat

Reassemble the mesh chunks from each partition into a single serial mesh, and call the given routine on the assembled mesh. In this routine, which runs on processor 0, the FEM_Get and FEM_Set routines can manipulate the serial mesh. The parameter callMeshUpdated, which must be non-zero, is passed down to routine as routine(callMeshUpdated).

FEM_Get calls from driver() will only return the new mesh after a FEM_Update_mesh call where doWhat is FEM_MESH_UPDATE; otherwise FEM_Get from driver() will still return the old mesh. FEM_Update_mesh can only be called from driver; and must be called by the driver routine for every chunk.

doWhat	Numeric	Repartition?	FEM_Update_mesh
FEM_MESH_OUTPUT	0	No	driver() continues alongside routine
FEM_MESH_FINALIZE	2	No	driver() blocks until routine finishes
FEM_MESH_UPDATE	1	Yes	driver() blocks for the new partition

For example, FEM_Update_mesh(my_output_routine, k, FEM_MESH_OUTPUT) reassembles the mesh and calls a routine named my_output_routine(k) while the driver routines continue with the computation. This might be useful, for example, for writing out intermediate solutions as a single file; writing outputs from driver() is more efficient but often results in a separate file for each mesh chunk.

To block the driver routines during a call to a routine named my_finalize_routine(k), such as at the end of the computation when the drivers have no other work to do, use FEM_Update_mesh(my_finalize_routine, k, FEM_MESH_FINALIZE).

To reassemble, modify, and repartition the mesh, use FEM_Update_mesh(my_update_routine, k, FEM_MESH_UPDATE). It may be easier to perform major mesh modifications from my_update_routine(k) than the drivers, since the entire serial mesh is available to my_update_routine(k).

FEM_Update_mesh reassembles the serial mesh with an attempt to preserve the element and node global numbering. If the new mesh has the same number and type of elements and nodes, the global numbers (and hence serial mesh) will be unchanged. If new elements or nodes are added at each chunk, they will be assigned new unique global numbers. If elements or nodes are removed, their global numbers are not re-used- you can detect the resulting holes in the serial mesh since the user data associated with the deleted elements will be all zero. Generally, however, it is less error-prone to perform mesh modifications only in driver() or only in an update routine, rather than some in both.