Skip navigation links
(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)

CGNS Steering Committee

Telecon Minutes

15 March 2001
2:00pm Eastern Time

Telecon Number: (304) 345-7506, participant code: 686358

The meeting was called to order at 2:00 Eastern time. There were 14 attendees, listed below.


   Bob Bush   Pratt & Whitney
Chris Rumsey NASA Langley
Armen Darian Boeing Space
David Edwards Intelligent Light
Michel Delanaye NUMECA
John Chawner Pointwise
Greg Power USAF/AEDC
Don Roberts Amtec
Dave Schowalter Fluent
Francis Enomoto NASA Ames
Alan Shih Catalpa Research
Kevin Mack ADAPCO
Diane Poirier ICEM-CFD Engineering
Doug McCarthy Boeing Commercial

E-mail from Ray Cosner on ISO Approval Status


Due to a travel commitment, I will not be participating in the CGNS telecon
on March 15.  Here's the latest on the ISO-STEP project.

The ISO-STEP project has progressed through Gate 2 - New Work Item Proposal.
This standard has been assigned the name "AP 237: Fluid Dynamics".  We will
be producing (probably) five documents:

1) AP 237, the top-level standard for fluid dynamics data

2) Part 1xx (100-series, number not yet assigned), specialized components of
the standard applicable only to CFD.  In the future, other 100-series parts
will be produced with specializations for flight test data, wind tunnel
data, and other categories of fluid dynamics data.  These will all be
components of AP 237.

3) Part 52, generic data structures for mesh-based data - both structured
and unstructured mesh.  This will be referenced from AP 237 and Part 1xx.

4) Part 5b (50-series, number not yet assigned), general product data
management information for numerical analysis results.  This will be
referenced from AP237 and Part 1xx.

5) A "Usage Guide" which is more of a free-form document, intended to
familiarize the reader with the concepts and the implementation.  If you
ever need to become knowledgeable quickly about an ISO standard, I recommend
you start with the Usage Guide for that standard.  Not all standards have
one, however.

Drafts of all these parts exist now, except for the Usage Guide.  However,
only Parts 52 and 5b are in a state which we think could be final.  The
current drafts of AP 237 and 1xx were marked up at meetings in December and
February, and those markups have not yet been incorporated into revisions of
the documents.

Our Fluid Dynamics proposal was supported by US, UK, Sweden, Germany,
Switzerland, Australia and Japan - these I know of, and probably there were
several others that I don't yet know of because the official results of the
vote have not yet been conveyed to me.  At this stage in the process, we had
to have five "yes" votes and no "no" votes.

The next stage of the process will be to present a full draft for detailed
review.  With Parts 5b and 52, we hope to reach this point in April.  For
Part 1xx, we are shooting for the summer, and for the top-level AP 237,
sometime in the fall.

Here are some questions which have been raised.  I would ask the CGNS
Steering Committee to consider these questions.

1) Do we need to provide for rinds?  This seems like redundant information
that (a) can be easily created by an application code as needed and (b) is
related to a specific code, i.e., different codes will require different
rind characteristics (excluding the large number of codes which don't
require a rind at all).  The rind can be retained in the standard if it's
needed, but there is a desire not to include data in the standard which can
be easily recreated from other data in the standard, or data which has no
relevance except to a specific application code.

2) Does the CGNS Steering Committee have plans to extend CGNS to include
associative geometry, in a time frame that is compatible with the schedule I
have outlined above?

3) Is it necessary to identify as discrete types of structured grid blocks
the degenerate block types which include collapsed faces or edges?
Currently, all these degenerate cases are listed and given separate
identifiers but we are not sure this is needed.

4) Is there a need to include the vertex count associated with each
unstructured cell type.  This seems to be redundant information that is
easily derived.

5) Do we need the entity "index_range_OK" ?

As I indicated during my presentation to this Committee on January 9, I plan
to refer these and future questions regarding intellectual content to this
Committee, since it is my goal to keep the ISO-STEP standard as close as
possible to CGNS.

At this point, it seems possible to think of having a final, approved
international standard by perhaps late 2003 or early 2004.

Thank you for your continued support.

E-mail from Charlie Towne on Documentation Status


Sorry, but I won't be able to dial in for tomorrow's telecon.  Here's
a summary of the documentation changes since the last meeting, and the
current status.

   - The documentation web pages have been moved to the GRC web server.
     The documentation page at the CGNS web server looks basically the
     same, but links now go to the GRC server.

   - HTML versions have been added for the:

      - Overview (but the content is old and should be updated)
      - User's Guide
      - File Mapping Manual

   - The "hard-copy" versions of the Overview and File Mapping documents
     have been converted to LaTeX

   - The File Mapping Manual has been updated for consistency with the
     current version of the SIDS.

   - The Mid-Level Library documentation is being re-organized, and
     basically follows the organization used in the "Detailed CGNS Node
     Descriptions" section of the File Mapping Manual.  Both an HTML and
     LaTeX "hard-copy" version will be available.  The first cut at this
     should be ready tomorrow or Friday for review, I assume by you,
     Diane, and Chris (and anyone else who's interested enough).

Charlie Towne                   Email:  
MS 86-7                         Phone: (216) 433-5851
NASA Glenn Research Center      FAX:   (216) 977-7500
Cleveland, OH  44135-3191       WWW: