CGNS logo

CFD General Notation System
Extensions


 

CGNS site pages
CGNS Home
What is CGNS?
Getting Started
Latest News
Switch to HDF5
Steering Committee
Implementations
Discussion Group
Download
Contributed Utilities
Example CGNS Files
Proposed Extensions 
FAQs

Documentation pages
Documentation Home
Papers and Slides
Meeting Minutes
User's Guide
Overview
SIDS
SIDS File Mapping
Mid-Level Library
CGIO User's Guide

CGNS Proposals for Extension (CPEX)

The CPEX is a design document or documents that describe a new feature for CGNS. The CPEX should provide a concise technical specification of the feature and a rationale for the feature. The CPEX is intended to be the primary mechanism for proposing new features and for collecting community input on an issue. The CPEX author is responsible for building consensus within the community and documenting dissenting opinions.

The CPEX editors assign CPEX numbers and change their status. All CPEX-related email should be sent to cgnstalk@lists.nasa.gov. Each CPEX must have a champion - someone who writes the CPEX, shepherds the discussions, and attempts to build community consensus around the idea. The CPEX champion must first try to determine if their idea is appropriate for a CPEX. (Small enhancements or patches may not need a CPEX.) If a CPEX is appropriate, the champion must write a proposal, following the guidelines below. A CPEX number is then assigned. This is typically followed by a period of discussion, comments, input, and consensus-building, as well as an in-depth critical review. The CGNS Steering Committee ultimately votes for or against adoption.

The proposals listed in the table below that were "not accepted" never made it to implementation, possibly because of lack of unified support, incomplete details, lack of champion involvement in the process, or because they were not generalizable to a wide enough class of problems. It is possible to resurrect and/or revise and resubmit older proposals. Some additional guidelines regarding changes or additions to the CGNS standard can be found in the CGNS Steering Committee Charter.

The CPEX should include the following informaion:

  • Name(s) and organization(s) of proposer(s)
  • E-mail contact information
  • General description of extension
  • Reason or need for extension
  • Detailed description of extension using similar documentation style found in the SIDS (LaTeX files for the SIDS are available from the Documentation Home Page - look for "LaTeX Source")
  • File Mapping description of Node Attributes, following the prescription given in existing Node Description Documentation
  • Specific example(s) of extension

In the table below, note that it is possible for a feature to be implemented in the SIDS and Filemap documentation, but not yet be implemented in the MLL software. If/when this occurs, it means that an "official" CGNS file can still be constructed with this feature, but the user must make use of means other than the MLL to accomplish it.

A primary requirement of all proposals for modifications will be to support and maintain code compatibility. No additions or changes to the CGNS standard will be adopted - without overwhelmingly compelling reasons - which invalidate existing software or data.

Note that the above CPEX work flow and requirements are new as of 09/2009, so older proposals given in the table below may be missing some of the required information.

Comments on proposals should be sent to cgnstalk@lists.nasa.gov.
 
 
 

CPEX # Scope Documentation Date first posted Date of last revision SIDS status Filemap status MLL status
0041 NGON Modification Proposals NGON-CPEX-0041-v0.10.pdf
May.05.17 July.20.17 under review --- ---
0040 Rind Plane Indexing rind_plane_indexing_5_14_2015.pdf
May.05.14 May.14.15 accepted, but not yet implemented no change required accepted, but not yet implemented
0039 Inter-Base Reference Extension CGNS-0039-Inter-Base-References1.pdf
Jan.31.14 Jan.31.14 implemented Version 3.3 no change required implemented Version 3.3
0038 Quartic Elements for High Order CGNS_P4_elem_defn2.pdf (rev)
CGNS_P4_elem_defn1.pdf (old)
Jan.07.14 Jan.10.14 implemented Version 3.3 no change required implemented Version 3.3
0037 Improvements for Multiblock Unstructured README.improv_mblk_uns.txt
CGNS-MultiBlockUnst.pdf
bump_3df_unstr_native_pw.cgns
bump_3df_unstr.cgns
bump_3df_hybrid.cgns
Aug.08.13 Sep.10.13 current version not accepted N/A N/A
0036 Cubic Elements for High Order CGNS_extended_elem_defn2.pdf Nov.05.12 Nov.13.12 implemented Version 3.2 no change required implemented Version 3.2
0035 Rigid Motion in a Family (requires CPEX #0034) CGNS-prop-ext-FamilyRigidMotion-5.pdf Feb.07.11 Feb.07.11 current version not accepted N/A N/A
0034 Multiple Families CGNS-0034-6.pdf
(Note: AdditionalFamilyName also to be added under UserDefinedData)
Feb.03.11 Nov.16.11 implemented Version 3.2 implemented Version 3.2 implemented Version 3.2
0033 Hierarchy of Families CGNS-0033-6.pdf Feb.03.11 Nov.16.11 implemented Version 3.2 implemented Version 3.2 implemented Version 3.2
0032 Rigid Motion Improvement IterativeData.pdf
FrameReference.pdf
FamilyRigidMotion.pdf (mod)
FamilyRigidMotion.pdf (old)
RigidMotion.pdf
Jul.01.08 Oct.07.08 withdrawn N/A N/A
0031 General SIDS Improvement* intro_parts_of_sids.pdf (mod)
intro_parts_of_sids.pdf (old)
parts_of_sids.pdf
Jun.09.08 Jun.09.08 implemented Version 3.1.3 implemented Version 3.1.3 implemented Version 3.1.3
0030 Regions Regions.pdf (mod)
Regions.pdf (old)
Regions_filemap.pdf
Nov.09.06 May.29.11 implemented Version 3.1.3 implemented Version 3.1.3 implemented Version 3.1.3
0029 Interface Connectivity InterpolantDonor.pdf Apr.13.07 May.22.07 implemented Version 2.5 implemented Version 2.5 implemented Version 2.5
0028 Face-Based Storage FacebasedIntro.pdf
FacebasedSIDS.pdf
Nov.09.06 Nov.09.06 not accepted N/A N/A
0027 Multiple Zone Connectivities for Time-Dependent Timedepconn.pdf
Timedepconn_filemap.pdf
Mar.08.06 Mar.08.06 implemented Version 3.1.3 implemented Version 3.1.3 implemented Version 3.1.3
0026 Face Center Connectivity Facecenter.pdf Mar.08.06 Mar.08.06 implemented Version 2.4 implemented Version 2.4 implemented Version 2.4
0025 Averaging Interfaces AveragingInterfaces.pdf Mar.08.06 Mar.08.06 not accepted N/A N/A
0024 FSI with Deformable Boundaries FSIDeformableBdy.pdf Mar.28.06 Mar.28.06 not accepted N/A N/A
0023 Rind Data for Unstructured Zones UnstructuredRind.pdf Dec.17.03 Dec.17.03 implemented Version 2.4.3 implemented Version 2.4.3 implemented Version 2.4.3
0022 Partial Connectivity Read/Write PartialConn.pdf Dec.10.03 Dec.15.03 implemented Version 2.4 implemented Version 2.4 implemented Version 2.4
0021 Connectivity Property GridConnectivityProperty.pdf Sep.25.03 Sep.25.03 implemented Version 2.4 implemented Version 2.4 implemented Version 2.4
0020 FamilyBC Extension FamilyBCExtension.pdf Sep.25.03 Sep.25.03 implemented Version 2.4 implemented Version 2.4 implemented Version 2.4
0019 UserDefined data Extension UserDefinedExtensions.pdf Apr.21.03 Apr.21.03 implemented Version 2.4 implemented Version 2.4 implemented Version 2.4
0018 BCDataSet Extension BCDataSetExtensions.pdf Apr.21.03 Apr.21.03 implemented Version 2.4 implemented Version 2.4 implemented Version 2.4
0017 Chemical Species ChemicalSpecies.pdf Oct.25.02 Oct.25.02 not accepted N/A N/A
0016 Element Regions ElementRegions.pdf Oct.25.02 Oct.25.02 not accepted N/A N/A
0015 Elemental Components ElementalComponents.pdf Oct.25.02 Oct.25.02 not accepted N/A N/A
0014 Boundary Type Extensions BCTypeExtensions.pdf Oct.25.02 Oct.25.02 not accepted N/A N/A
0013 Solution BC proposal SolutionBCproposal.pdf Jul.03.02 Jul.03.02 not accepted N/A N/A
0012 Electromagnetic proposal EMproposals.pdf Jul.03.02 Jul.03.02 implemented Version 2.4 implemented Version 2.4 implemented Version 2.4
0011 Wall Function, Periodic, Rotor/Stator WallPeriodicRS.pdf Jul.01.02 Jul.31.02 implemented Version 2.2 implemented Version 2.2 implemented Version 2.2
0010 Multi-Phase / Liquid Spray MultiPhaseExtension.pdf Dec.14.00 Dec.01.00 not accepted N/A N/A
0009 User Defined Data Arrays UserDefinedDataArrays.html
AlternateProposal.html
Nov.15.00 
Feb.02.01
Nov.15.00 
Feb.02.01
implemented Version 2.1 implemented Version 2.1 implemented Version 2.1
0008 Hierarchical Elements HierarchicalElements.pdf
Response from M.Aftosmis: hierarchicalResponse.pdf
Aug.02.00 
Dec.01.00
Aug.02.00 
Dec.01.00
not accepted N/A N/A
0007 Gravity Gravity.pdf Aug.04.99 Mar.15.00 implemented Version 2.2 implemented Version 2.2 implemented Version 2.2
0006 Rotating Coordinates RotatingCoordinates.pdf Aug.04.99 Dec.09.99 implemented Version 2.2 implemented Version 2.2 implemented Version 2.2
0005 Axisymmetry for 2D grids axisymmetry.pdf Aug.04.99 Mar.15.00 implemented Version 2.2 implemented Version 2.2 implemented Version 2.2
0004 Chemical Species Chemistry.pdf Aug.04.99 Sep.15.00 implemented Version 2.1 implemented Version 2.1 implemented Version 2.1
0003 Iterative or Time-accurate data IterativeOrTemp.pdf Aug.04.99 Mar.14.00 implemented implemented implemented
0002 Point by Point Grid Motion ArbitraryGridMotion.pdf
  see example 1
Aug.04.99 Mar.14.00 implemented implemented implemented
0001 Rigid Body Grid Motion RigidGridMotion.pdf
  see example 1
Aug.04.99 Mar.14.00 implemented implemented implemented

* For CPEX #0031, it should be noted that some aspects require significant modifications on the part of the MLL. For example, the improvement replaces the use of ElementRange and ElementList with PointRange and PointList. The methodology for accomplishing this while maintaining compatability with existing CGNS files and CGNS codes must be carefully considered prior to implementation. I.e., either the MLL must still be able to recognize, read, and translate ElementRange etc, or else ElementRange etc must still be allowed as an option (in the documentation). Therefore, this CPEX will not be added to the SIDS or Filemap documents until full implementation in the MLL is possible.
 

(Note that the CPEX is loosely patterned after the Python-based PEP (Python Enhancement Proposal). We gratefully acknowledge their well-documented methodology.)