Blocking module

This module provides a data structure for a blocking representation. It relies on the n-G-map model and we specifically use the 3-G-Map implementation provided by CGAL library (see https://doc.cgal.org/latest/Generalized_map/index.html).

The development of this module is in progress. The final purpose is to provide a robust and reliable curved block structure for hex blocking mesh representation.

Compilation and installation

This module is built using the global CMakeLists.txtof gmds. An extra option (WITH_CGNS) is provided to allow CGNS export. It requires then to install the adequate CGNS library.

This procedure must be described in details and the spack recipes must be updated.

Main concepts

The blocking structure is described in the class CurvedBlocking. It relies on the 3-G-map model and provide several blocking queries and gives access to the underlying 3-G-map.

The CurvedBlockingClassifierprovides the first prototype to classify a block structure onto a geometrical model.

Blocking classification

All blocking structures are classified. It means that we need to build a blocking structure from a geometrical model. Nodes, edges and faces are classified on geometrical entities.

In order to automatically classify cells, we use two parameters: - a maximal distance MD for projecting a node. If the distance to any geometrical cell is greater than MD, then the node is not moved and classified. - A snapping distance SD that is used during a correction stage. After projecting a node on a curve or a surface, we check if this node could not be snapped onto a geometrical point with a distance lower to SD.

Remark: This two parameters are use-case specific and should be automatically computed in the future.

Geometrical and topological operations

It is possible to move a node with the method CurvedBlocking::move_node. This methods takes classification into account: - A node classified onto a geometrical point cannot move; - A node classified onto a geometrical curve will be moved to the expected location then projected onto the curve; - The same behavior occurs for nodes classified on geometrical surfaces.

Two operations are available to remove a block (CurvedBlocking::remove_block), or split a series of blocks along an edge (CurvedBlocking::cut_sheet). In the second case, the obtained blocks remain glued each to others.