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Last Updated: Wednesday, 10-Feb-2021 10:13:52 EST
This document provides some guidelines on the
documentation of the validation cases. The objective is consistency in
the reporting of validation results. Further the guidelines will allow
a comparison of conclusions drawn from a variety of studies.
The
following guidelines are intended for all validation cases; however,
the level of detail of information
may vary according to whether the case is an
example, verification, or validation case.
The proper level of detail will be indicated below.
An example
requires more of a step-by-step instruction on the procedure for
performing an analysis. At a minimum this requires brief descriptions
of problem and a single common grid (*.cgd) file and an input data
(*.dat) file for showing users how to run with a certain feature of the
WIND code.
A verification
case requires a description of the problem along with information
on the computation procedures, computer system, list files, convergence
histories, and some flow properties. The intent is to be able to
determine if WIND continues to give consistent or improved results
after being installed on a new system or modified.
A validation case requires complete
documentation to examine the
performance and accuracy of WIND. This includes examination of the
sensitivity to variations in the grid density, turbulence models, and
other input parameters.
Documentation Format
The desired format for the documentation is
HTML documents for posting on the
Archive. If someone is running a
case, but is not familiar with HTML, they may write an ASCII
text file. The webmaster will then
create the HTML document. See the
File Naming Conventions for information on naming the document
files.
Documentation Guidelines
The structure of the documentation guideline
is to follow closely the Validation Process. The following are sections that should be
included in the document.
Title
At the top of the document should be a short, but descriptive title.
-
Orienting Image
An image of the grid and / or flow field is useful for orienting
the reader as to the general nature of the validation case. For
display on the Web, use the JPEG (*.jpg) or GIF (*.gif) graphics
file formats.
-
Problem Description
This should be one to two brief paragraphs describing the scope of
the flow conditions, geometry, computational features, and flow
properties examined in this test case. If a table is appropriate, then
include it. Indicate the basis (analytical, computational,
experimental) for the comparison of the computed results. Cite
references if the validation case is based on reported work.
-
Download tar File
Include a link to a compresses tar file that contains all of
the files in the archive for the validation case that can be
downloaded. See the File Naming
Conventions for information on naming the compressed tar file.
-
Geometry Model
The details on the definition of the flow domain and boundary
geometry should be included. Enough information should be provided so
that a reader may reconstruct the flow domain. For simple geometries,
a description may be adequate. A figure may be helpful. For complex
geometries a link to a file of coordinates or CAD file (IGES file) or
references to original documents could be included.
-
Grid Topology, Spacing, and Density
This section discusses the grid topology used for the case and
includes the number and types of blocks (H-block, O-block, Chimera,
abutting, etc...). The size of the grid in each block should be
listed, preferably in tabular form. Grid generation and quality
parameters, such as wall spacing and stretching ratio should be
reported. Comment on how the grid was generated with respects to the
grid generation package. If a Fortran code was written to generate the
grid, perhaps the source code can be linked as part of the validation
case. If so, indicate the values of any inputs. For viscous flows,
comment on how the wall spacing was determined, preferably with the
discussion of the value of y+ for the first grid point off the wall.
The common grid (*.cgd) file should be listed as a link. If a series
of grids were used as part of a Grid
Convergence Study, they should be listed in tabular form. See the
File Naming Conventions document on
suggestions for nameing files. A figure of the grid and / or parts of
it may be helpful for describing the topology, quality, or density. If
a PLOT3D grid was converted to a common grid (*.cgd) file, make a link
to the CFCNVT command file. See the
File Naming Conventions for information on naming this command
file.
-
Initial and Boundary Conditions
This section contains a description of the initial flow field and
flow boundary conditions to be imposed with respect to the flow
domain. A tabular form is suggested if there is significant
information. If a Fortran program was written to create the initial
solution, this could be part of the archive and a link established to
the source code file. Include links to CFCNVT and GMAN command files.
See the File Naming
Conventions for information on naming these command files.
-
Computation Strategy
The computational strategy for obtaining the computed flow field
should be described. This includes indicating whether space-marching
or time-marching is used and if turbulence or chemistry is modeled.
Further such things as the algorithms and acceleration techniques
used can be discussed. This section could be included with the next
section on the discussion of the input data file. Also to be discussed
is the use of distributed processing.
-
Input Parameters and Files
This section discusses the input parameters used in the input data
(*.dat) file. These input parameters generally coorrespond to the
desired computational strategy. For an example, one should
include more detailed discussion of the inputs for each keyword and
choice of input parameters as they relate to the physical problem
and/or the operation of the WIND code. If more than one input data
file is used, then a tabular form is suggested indicating various
values of parameters and why the parameters were varied. Indicate what
other files (*.cfl, *.chm, *.mpc) were created for the computations and
provide links to access them.
-
Computation
This section discusses how the computations were performed. The
version of WIND used should be indicated. If modifications to the
source code were used, these should be indicated. A discussion of the
computer system (CPU, number of processors, and operating system)
should be included. If distributed processing was used, the
multi-processing command (*.mpc) file should be referenced. The output
should be written to a list (*.lis) file.
The convergence properties of the computation for steady-state
problems should be discussed along with the manner in which it was
determined that it was time to stop the computation. If applicable,
plots of the residual history should be included. Indicate if several
segments of computation were needed and indicate if any input
parameters were changed between each segment. The utility RESPLT can
be used to create plot files of the residuals and other information in
the list files. Command files with names of the form
(resplt.run.#.com) should be written (see the File Naming Convention for information on
naming archive files). These files should be made available to
explicitly indicate how the residual data was determined. This is
especially important for the example cases. If turbulence is modeled
using a one or two-equation model, the convergence of the turbulence
quantities should be discussed. Comment on other flow properties that
were monitored (i.e. mass flow, thrust) as part of evaluating
convergence.
-
Post-Processing
This section discusses post-processing to obtain the flow field
properties of interest from the computation. The program CFPOST should
be used to obtain information on the flowfield from the common files
(*.cgd and *.cfl). Command files with names of the form
(cfpost.run.#.com) should be written (see the File Naming Convention for information on
naming archive files) and made available to explicitly indicate how the
flow field information was obtained. This is especially important for
the example cases. Indicate how these flow properties were computed.
If CFPOST was used, include links to command files that generated the
flow properties and / or displays. If Fortran codes were written for
post-processing, then include links to the source and include as part
of the archive. Show figures of flow contours to give an overall view
of the flow field.
-
Comparisons of the Results
This section examines the comparison between the computed results
and analytical, computational, and / or experimental results.
Differences should be noted and reasons for differences should be
stated. Include links to files containing analytical, computational,
or experimental data. Include plots of comparisons.
-
Sensitivity Studies
This section discusses the results of sensitivity studies.
Foremost, should be a Grid Convergence
Study to examine how the solution changes with grid density. The
validity of flow properties is resiquite on the condition that grid
convergence has been established. The Grid
Convergence Index (GCI) Method of Roach should be followed to
ensure consistent report of the results of a grid convergence study.
For viscous, turbulent flow computations, the sensitivity to the
choice of turbulence model should be reported. If significant
differences exist, one should comment on which turbulence model
performs the best for the flow field. If no data exists for forming a
basis of the comparison, then one should make a selection based on the
historic validity of the turbulence model for other unit problems (i.e.
if massive flow separation exists, it is likely that the k-epsilon
model probably gives the more correct answer than the Baldwin-Lomax
model).
-
References
Any references cited in the document should be listed. If the
reference is already in the Bibliography
then a link is sufficient. If a reference should be in the Bibliography, the information can be passed
to the Validation Team Coordinators for
inclusion.
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Log and Contact Information
Information on the person performing the validation case should be
included. This should include name, email address (and/or postal
address), and phone number. If more than one person was involved
in running the case or the case was run at different dates by different
people, a log should be created in tabular form indicating which
person performed which runs. The sections above can be added to by
each successive person with appropriate discussion indicating the uniqueness
of the runs.