(CGNS Documentation Home Page)
(Steering Committee Charter)
(Overview and Entry-Level Document)
(A User's Guide to CGNS)
(Standard Interface Data Structures)
(SIDS-to-ADF File Mapping Manual)
(SIDS-to-HDF File Mapping Manual)
(Mid-Level Library)
(ADF User's Guide)
(CGNS Tools and Utilities)
(Introduction)
(Design Philosophy of Standard Interface Data Structures)
(Conventions)
(Building-Block Structure Definitions)
(Data-Array Structure Definitions)
(Hierarchical Structures)
(Grid Coordinates, Elements, and Flow Solution)
(Multizone Interface Connectivity)
(Boundary Conditions)
(Governing Flow Equations)
(Time-Dependent Flow)
(Miscellaneous Data Structures)
(Conventions for Data-Name Identifiers)
(Structured Two-Zone Flat Plate Example)
Major Differences from Previous CGNS Versions
The following items represent noteworthy alterations and additions to
the SIDS starting with the August 1999 draft document.
Version 2.0, Beta 1
The following changes were made for Version 2.0, Beta 1.
- The capability for recording unstructured zones has been
added to the SIDS.
(These changes occur throughout the document, although some
specific items are listed below.)
- The values UserDefined and Null are now allowed
for all enumeration types (throughout document).
- The following nodes are now defined (some of these also
include additional new children sub-nodes):
Family_t,
Elements_t,
ZoneType_t,
FamilyName_t,
GeometryReference_t,
FamilyBC_t.
- Under CGNSBase_t, the
IndexDimension is no longer recorded; it has been replaced
by CellDimension and PhysicalDimension.
- Under Zone_t, the
optional parameter VertexSizeBoundary has been added for
unstructured zones.
- The method for general connectivity
(GridConnectivity_t)
has been altered.
It now requires the use of either (a) PointListDonor (an
integer, for Abutting1to1 only) or (b) CellListDonor
(an integer) plus InterpolantsDonor (a real).
- The GridLocation_t
structure has been moved up one level
(from BCDataSet_t to
BC_t).
Thus, for example, if the boundary conditions are defined at
vertices (the default), then any associated dataset information
must also be specified at vertices.
- The data-name identifier
LengthReference
has been added (see also the
data-name identifier
conventions for the flowfield solution).
- The νt parameter has
been renamed ViscosityEddyKinematic, and a new parameter
ViscosityEddy, representing
μt, has been defined
(see the data-name identifier
conventions for the flowfield solution).
Version 2.0, Beta 2
The following changes were made for Version 2.0, Beta 2.
Version 2.1, Beta 1
The following changes were made for Version 2.1, Beta 1.
- A node type
UserDefinedData_t
is added for the storage of arbitrary user defined data in
Descriptor_t and DataArray_t children without the
restrictions or implicit meanings imposed on these node types at
other node locations.
- Support for multi-species flows and chemistry has been added.
New gas models have been added to the
GasModelType_t
enumeration, and
ThermalRelaxationModel_t
and ChemicalKineticsModel_t
data structures have been added for describing the thermal
relaxation and chemical kinetics models.
Additional flow solution
data-name identifiers are included.
Version 2.2, Beta 1
The following changes were made for Version 2.2, Beta 1.
- Axisymmetry_t and
RotatingCoordinates_t
nodes have been added, allowing the recording of data relevant to
axisymmetric flows and rotating coordinates.
- A Gravity_t node has
been added for storage of the gravitational vector.
- A GridConnectivityProperty_t
node has been added, allowing the recording of special properties
associated with particular connectivity patches, such as periodic
interfaces, or interfaces where the data is to be averaged in some
way prior to passing it to a neighboring interface.
- A BCProperty_t
node has been added, allowing the recording of special properties
associated with particular boundary condition patches, such as wall
function or bleed regions.
- Additional flow solution
data-name identifiers are included for variables in rotating
coordinate systems.
Version 2.3
The following changes were made for Version 2.3.
Version 2.4
The following changes were made for Version 2.4.
- GridLocation_t,
PointRange, and PointList
have been added to the
BCDataSet_t data structure,
allowing boundary conditions to be specified at locations different
from those used to defined the BC patch.
(E.g., a BC patch may be defined using vertices, with boundary
conditions applied at face centers.)
- Data structures have been added to
FlowEquationSet_t
for describing the electric field, magnetic field, and conductivity
models used for electromagnetic flows.
Corresponding recommended data-name
identifiers have also been added.
- RotatingCoordinates_t
has been added to the Family_t
data structure.
- A BCDataSet_t list
has been added to the FamilyBC_t
data structure, allowing specification of boundary condition data
arrays for CFD families.
- GridLocation_t,
PointRange, PointList,
FamilyName_t,
UserDefinedData_t,
and Ordinal have been
added to the
UserDefinedData_t
data structure.
- The DimensionalUnits_t
and DimensionalExponents_t
structures have been expanded to include units for electric
current, substance amount, and luminous intensity.
- The capability to include rind
data with unstructured grids has been added, and
Rind_t has been added to the
Elements_t structure,
allowing specification of connectivity information for rind
elements.
Version 2.5
No changes were made to the data structures for Version 2.5.
Version 3.1
The following changes were made for Version 3.1.
- Changed Null to xxxxNull and UserDefined to xxxxUserDefined, as appropriate.
- Also made sure that the xxxxNull is listed first, and the
xxxxUserDefined is listed second.