CFmesh format for parallel I O

COOLFluiD has its own file format, named "CFmesh", for parallel I/O of mesh and solution. Only one CFmesh file is needed to start a simulation and only one CFmesh file will be created as output. This means that all info appearing in the file (e.g. counts, IDs) are global. In order to start a simulation from a different format (e.g. CGNS, Gmsh, GAMBIT, TECPLOT), suitable converters to the CFmesh format must be implemented (if not available yet).

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The CFmesh format is available in two versions: ASCII and binary (recent addition). The latter is highly recommended for 3D simulations, since the corresponding I/O algorithms can be up to 3 orders of magnitude faster in parallel.

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Here follows a detailed description of the ASCII format. The file works with keywords, all starting with a "!". The same string keywords and file structure (including spaces after keywords) is kept also in the binary format, while integer and flops are replaced by corresponding binary entries, instead.

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The header includes some versioning info.

!COOLFLUID_VERSION 2013.9 (COOLFluiD version)

!COOLFLUID_SVNVERSION 15166M (SVN revision number)

!CFMESH_FORMAT_VERSION 1.3 (CFmesh format version)

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Then, some global counts follow.

!NB_DIM 2 (spatial dimension of the problem: can be 1,2 or 3)

!NB_EQ 4 (number of equations, i.e. number of independent variables)

!NB_NODES 1670 0 (number of mesh vertices and a "0" kept for backward compatibility)

!NB_STATES 3178 0 (number of state vectors and a "0" kept for backward compatibility)

!NB_ELEM 3178 (number of elements, i.e. cells)

Note: in a mesh with isoparametric elements (e.g. P1-P1 FEM), !NB_NODES = !NB_STATES, otherwise (e.g. in FVM), !NB_NODES differs from !NB_STATES.

Note: In a mesh for cell-centered FVM !NB_STATES = !NB_ELEM 3178.

!NB_ELEM_TYPES 1 (number of element types: it is >1 for hybrid 2D and 3D meshes)

!GEOM_POLYORDER 1 (order of the polynomials for the geometric representation)

!SOL_POLYORDER 1 (order of the polynomials for the solution representation)

Note: In a mesh for cell-centered FVM !SOL_POLYORDER 0.

!ELEM_TYPES Triag (list of the element type names: "Line", "Triag", "Quad", "Tetra", "Pyram", "Prism", "Hexa").

!NB_ELEM_PER_TYPE 3178 (list of numbers of elements per element type)

!NB_NODES_PER_TYPE 3 (list of numbers of nodes per element type)

!NB_STATES_PER_TYPE 3 (list of numbers of state vectors per element type)

Note: In a mesh for cell-centered FVM !NB_STATES_PER_TYPE 1.

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Connectivity data for elements follow.

!LIST_ELEM (list of element-node and element-state connectivities)
38 39 40 0 (node IDs followed by state IDs in each line, 3 + 1 in this FVM example)
0 158 159 1 (node IDs followed by state IDs in each line, 3 + 1 in this FVM example)
...

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Then, data for Topological Region Sets (TRS) and Topological Regions (TR) are provided.

!NB_TRSs 2 (number of boundary super patches, a.k.a. TRSs, in the mesh)

!TRS_NAME SuperOutlet (name of the first TRS coming from the original mesh generator file)

!NB_TRs 3 (number of boundary patches, a.k.a. TRs, in which current TRS is divided)

!NB_GEOM_ENTS 40 40 40 (list of numbers of geometric entities per TR)

!GEOM_TYPE Face (type of the geometric entity)

!LIST_GEOM_ENT (list of geometric entity connectivities)

2 1 0 159 1 (number of nodes -2- and number of states -1- for this face, node IDs followed by state IDs in each line)

2 1 1 0 7 (number of nodes -2- and number of states -1- for this face, node IDs followed by state IDs in each line)

...

!TRS_NAME SuperInlet (second TRS coming from the original mesh generator file)

!NB_TRs 1

!NB_GEOM_ENTS 40

!GEOM_TYPE Face

!LIST_GEOM_ENT

...

Note: in the case of a FVM mesh (as in the example), the single state ID which is provided for boundary faces is the neighboring cell ID.

Note: in the case of a P1-P1 FEM mesh, 2 node IDs and 2 state IDs must be provided for each face. The previous example becomes:

2 2 0 159 0 159

2 2 1 0 1 0

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Coordinates of mesh vertices.

!LIST_NODE (list of the node coordinates: !NB_DIM entries per line)

2.50000000000000e-02 0.00000000000000e+00 (x,y for nodeID 0)

5.00000000000000e-02 0.00000000000000e+00 (x,y for nodeID 1)

...

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Values of the state entries, i.e. solution unknowns from which a simulation can be restarted.

!LIST_STATE 0 (list of the states followed by an integer: 0 means without solution, 1 means with solution)

Only if !LIST_STATE 1 is given, the solution follows (!NB_EQ entries per line):

3.50000000000e-01 5.00000000000e+02 0.00000000000e+00 1.00000000000e-03

3.80000000000e-01 5.10000000000e+02 0.00000000000e+00 1.00000000000e-03

...

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The files always ends with the !END keyword.