Chimera Grid Tools User's Manual

Version 2.1

March, 2010

William M. Chan, Stuart E. Rogers, Shishir A. Pandya, David L. Kao, Pieter G. Buning,

Robert L. Meakin, David A. Boger, Steven M. Nash


Contents


Introduction

Chimera Grid Tools (CGT) is a software package containing a variety of tools for the Chimera overset grid approach [1] for solving complex configuration problems. Several examples of recent computations that used Chimera Grid Tools for the creation of the grid systems are shown on Figure 1. The current procedure for performing overset CFD analysis on such configurations is outlined in Figure 2. A typical starting point is a description of the surface geometry in CAD format, while typical outputs from the process are force and moment coefficients, pressure distributions, etc. of the configuration under certain specified freestream conditions. The complete suite of tools necessary to perform such a process includes CAD tools for geometry manipulation, and geometry defects elimination, Chimera Grid Tools for grid generation and post-processing [2,3], PEGASUS [4,5], DCF-Xrays [6], (or other equivalent tool) for domain connectivity, OVERFLOW [7] for solution computation, and FOMOCO Utilities [8,9,10], or USURP [11] for force and moment computation. Individual tools used in various parts of the process are illustrated in red in Figure 2.

Figure 1: Recent Applications of Chimera Grid Tools

Space Shuttle Launch Vehicle and Attached Hardware

(Reynaldo J. Gomez, et. al., NASA Johnson Space Center)

Space Shuttle Launch Vehicle and Debris Trajectory Analyses

(Reynaldo J. Gomez, et. al., NASA Johnson Space Center)

Space Shuttle Flowliner Analysis

(Cetin Kiris, NASA Ames Research Center)

Launch Site Flame Trench Analysis

(Cetin Kiris, NASA Ames Research Center)

Subsonic Transport with Propulsion and High Lift Devices

(Stuart E. Rogers., NASA Ames Research Center)

X-38 V-131R Crew Return Vehicle

(James S. Greathouse, NASA Johnson Space Center)

RLV Baseline Turbopump

(Cetin Kiris, NASA Ames Research Center)

V-22 Tiltrotor

(Robert L. Meakin, Army Aeroflightdynamics Directorate)

Comanche

(Robert L. Meakin, Army Aeroflightdynamics Directorate)

Figure 2: Overset CFD Process and Tools

Tools in CGT can be grouped into the following categories: surface grid generation tools, volume grid generation tools, grid utilities, configuration automation scripts, utility scripts, and post-processing tools. See Table 1 below for a brief description of each tool, the category for which it resides, and access to more detailed documentation. The package is organized with the following directories:

The doc directory contains documentation and sample input files for the various grid tools and scripts, as well as a log of the changes made for each release of CGT.

The examples directory contains a suite of examples to test the tools, and also includes a self-verification tool named verify to check that the tools are running properly.

The gui directory contains files for a graphical user interface called OVERGRID [12,13] that can be used to access the various grid tools. For a user facing a new problem, it is much easier to perform grid generation with the assistance of a graphical tool for the first time. Once the gridding strategy has been identified, scripts can be constructed to generate grids for similar configurations.

The smart directory contains files for the solution monitoring and analysis reporting tool OVERSMART [14].

The include directory contains header files that are included into various source code files through use of the preprocessor.

The lib directory contains libraries of FORTRAN and C routines that are common to many of the grid tools. These routines include computation of stretching functions, computation of grid normals, projections of grids, grid topology determination and enforcement, and many others.

The scriptbin directory contains a number of Tcl scripts which can automate the building of an overset grid system following the process illustrated in Figure 2. These scripts will build input files, execute, and provide error checking for a number of programs, including: volume grid generation ( HYPGEN [15,16] and LEGRID), volume grid smoothing ( SMOGRD), domain connectivity using PEGASUS 5.0 (complete input file) or PEGSUS 4.1 (partial input file) [5], surface fringe point projection ( PROGRD), hybrid surface grid generation for force and moment computation [8,9,10], flow solution computation using OVERFLOW [7]. See the scripts manual for more details. Such scripts have been used to create complex grid systems for high-lift configurations [16].

The scriptlib directory contains a library of Tcl language script procedures that are called by some of the scripts in the scriptbin directory, and are available to the user by using the lappend auto_path scriptlib command. These procedures are also highly useful when building specific grid generation scripts.

The src directory contains the source code for the high-level batch-mode FORTRAN codes that can be run by the user.

Below is a figure showing the hierarchy of the various modules in the Chimera Grid Tools package:

Figure 3: CGT Hierarchy


Components of Chimera Grid Tools

Software modules in Chimera Grid Tools consist of a main graphical interface called OVERGRID, and a number of independent tools in the form of Fortran programs or Tcl scripts that can be called in batch mode. A brief description of each tool and access to further information is given in Table 1.

Table 1: GUI and Batch Modules in Chimera Grid Tools

OVERGRID - Graphical user interface for visualization and processing of geometry and grids, grid generation, domain connectivity and flow solver input preparation

Legend

Color Category Color Category
- Surface Grid Generation - Volume Grid Generation
- Grid Utility - Configuration Automation Script
- Utility Script - Post Processing

Program Description
autobc Automatic boundary conditions determination
boxgr Generation of stretched cartesian background grids and elliptic far-field grids
BuildIngrid Builds the INGRID file used by PEGSUS 4.1
BuildMixsuri Builds the MIXSUR/OVERINT input file from OVERFLOW input files
BuildOveri Builds the OVERFLOW input files from individual "stubs"
BuildPegi/BuildPeg5i Builds the PEGSUS 4.1/5.0 input file template (no hole boundaries for 4.1)
BuildPlot Creates a PLOT3D command file to view family and boundary condition surfaces. Can also be used in a standalone mode with just an OVERFLOW input file. Type "BuildPlot -help" for documentation on its command-line parameters.
BuildProgrdi Builds the PROGRD input file from the OVERFLOW input file information
BuildSurf Runs 'make' for each component grid to update configuration surface grids
BuildVol Creates volume grids via either makevol or boxgr
cad2srf Generate surface triangulation and edge curves from native solid CAD part
cgtclean Cleans output from most CGT tools
collar Script to create collar grids [17]
combinemx Combine any number of PLOT3D grid files into one PLOT3D multiple grid file
combinemq Combine any number of PLOT3D Q files into one PLOT3D multiple grid Q file
compx Computation of difference between two grids
conmug Auto-concatenation of multiple surface and curve grids
curvar Computation of areas bounded by one or more closed curves in an x, y, or z constant plane
extractsrf Parses MIXSUR input file to create SPLITMX/SPLITMQ inputs for just surface info
gencore Generation of H-topology volume grid inside core of a tube
genpipe Generation of constant diameter pipe surface grid from 3-D centerline curve
gen_x Domain connectivity pre-processing tool for creating object images
grided Compilation of a variety of grid editing functions for structured grids
gridinf Computes basic grid information
hypgen Generation of a hyperbolic volume grid from a single surface grid [14,15]
hypin Generation of normal spacing function for volume grids
intchk Interpolation stencil quality check using fringe point coordinates
intgrd Generation of a new surface grid onto a reference grid via interpolation
loadis Computation of sectional force coefs on components
lsect Find intersection curve between one intersector surface grid and multiple intersectee surface grids
makevol Creates a volume grid via HYPGEN/LEGRID, and runs SMOGRD using OVERFLOW input file
minterp Interpolation of single/multiple grid and solution files
mixsur Generation of hybrid surface grid for force/moment computation
oversmart Generation of solution convergence plot matrices from OVERFLOW history files
overhist Extraction of residual and flow coefficients data from OVERFLOW history files
overint Integration of force/moment and mass flow rate coefficients
overplot GUI for plotting flow coefficients and sectional Cp cuts on components
pip Mass properties calculator
plothole Creates PLOT3D command file for PEGSUS 4.1 boundaries
PreVol Builds OVERFLOW input files, config.tcl, inputs.tcl from surface grid file
p3dConvert Convert PLOT3D grid and q files and OVERFLOW-2 q files between big and little endian formats
p3dtrans Conversion of PLOT3D format for curve grids to/from 2/3-column xyz data format
progrd Projection of points onto a collection of reference grids
qinfo Report OVERFLOW and PLOT3D solution-file information
recurv Grid-point redistribution
reord Grid-point re-ordering for a single grid-line
RunPeg Runs BuildIngrid, pegsus41, and PROGRD using configuration information
sblock Partial surface domain decomposition and grid generation [18]
ScriptClean Cleans up .srf, .vol, .mvlog, etc. files for an entire configuration
scriptlib Script library containing many Tcl procedures for grid scripts
seamcr Automatic seam curve extraction and spider web grid generation [19]
seamcrt Surface curves creation on surface triangulations
setzeta Generate normal grid-spacing file zetastr.i for HYPGEN program
shftgrd Shifting/translating grid coordinates of a specified subset
smogrd Perform elliptic smoothing in selected grid subset to spread out region of fine spacing
smooth Smooth grid by performing second order smoothing
smosurf Perform grid spacing smoothing in one direction for volume grids
splitmx Extraction of arbitrary grid subsets from PLOT3D multiple grid file
splitmq Extraction of arbitrary q subsets from PLOT3D multiple grid q file
srap Perform splining, grid point redistribution and projection on curves/surfaces
str2tri Convert PLOT3D multiple structured surface panels to CART3D surface triangulation
strchk Computation and display of local stretching ratio info for grids
stretch Evaluation and display of 1D stretching functions
srf2cad Project structured surface grid back to native solid CAD part
surgrd Generation of a new surface grid onto a collection of reference grids via hyperbolic/algebraic surface grid generation [20]
Tscan Computation of cross sectional area of a triangulated object versus x, y or z
triged Compilation of a variety of grid editing functions for surface triangulations
triload Generation of line loads from surface triangulation grid and solution file
usurp Integration of force/moment and mass flow rate coefficients on overset surface grids using polygon clipping
vpro Interpolate velocity profiles from a grid and solution at specified surface normals or lines
wingcap Generation of surface grid in tip region of wing
wkcut Generation of surface grid in wake region
xinted Perform various combination functions to grid, XINTOUT and INS3D bc files
xrayed Split and combine multiple Xray files with multiple Xrays in each


Authors Information

Many people have contributed to the different parts of Chimera Grid Tools. A summary of the tools/scripts and their application is shown in Table 1. See the documentation for the individual tool to determine authorship. Questions and suggestions can be directed to the corresponding authors (see Table 2).

Table 2: Authors Contact Information

Name Affiliation E-mail address
William M. Chan # NASA Ames Research Center, TNA Branch William.M.Chan@nasa.gov
Stuart E. Rogers # NASA Ames Research Center, TNA Branch Stuart.E.Rogers@nasa.gov
Shishir A. Pandya # NASA Ames Research Center, TNA Branch Shishir.A.Pandya@nasa.gov
David L. Kao # NASA Ames Research Center, TNR Branch David.L.Kao@nasa.gov
Pieter G. Buning # NASA Langley Research Center Pieter.G.Buning@nasa.gov
Robert L. Meakin * Army Aeroflightdynamics Directorate -
David A. Boger Penn State University Applied Research Laboratory dab143@only.arl.psu.edu
Steven M. Nash * ELORET, NASA Ames Research Center, INA Branch -

# Contributors to version 2.1

* No longer working on project


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References

  1. Steger, J. L., Dougherty, F. C. and Benek, J. A., "A Chimera Grid Scheme," Advances in Grid Generation, K. N. Ghia and U. Ghia, eds., ASME FED-Vol. 5, June, 1983.

  2. Chan, W. M.," Advances in Software Tools for Pre-processing and Post-processing of Overset Grid Computations," in Proceedings of the 9th International Conference on Numerical Grid Generation in Computational Field Simulations, San Jose, California, June, 2005.

  3. Chan, W. M., CAD Interface, Strand Grid Technology, and Other New Developments in Chimera Grid Tools 2.0, Proceedings of the 8th Symposium on Overset Composite Grids and Solution Technology, Houston, Texas, October, 2006.

  4. Rogers, S. E., Suhs, N. E., Dietz, W. E., "PEGASUS 5: An Automated Preprocessor for Overset-Grid Computational Fluid Dynamics," AIAA Journal, Vol. 41, No. 6, pp. 1037-1045, 2003.

  5. Suhs, N. E., Dietz, W. E., Rogers, S. E., Nash, S. M. and Onufer, J. T., " PEGASUS User's Guide," Version 5.1c, NASA Ames Research Center, July, 2000.

  6. Meakin, R. L., "Object X-rays for Cutting Holes in Composite Overset Structured Grids," AIAA Paper 2001-2537, 2001.

  7. Nichols, R. H., Buning, P. G., "User's Manual for OVERFLOW 2.1," University of Alabama and NASA Langley Research Center, 2008.

  8. Chan, W. M.," Enhancements to the Hybrid Mesh Approach to Surface Loads Integration on Overset Structured Grids," AIAA Paper 2009-3990, June, 2009.

  9. Chan, W. M. and Buning, P. G., "Zipper Grids for Force and Moment Computation on Overset Grids," AIAA Paper 95-1681, in Proceedings of the AIAA 12th Computational Fluid Dynamics Conference, 1995.

  10. Chan, W. M. and Buning, P. G.," User's Manual for FOMOCO Utilities - Force and Moment Computation Tools for Overset Grids," NASA TM~110408, July, 1996.

  11. Boger, D. and Dreyer, J., "Prediction of Hydrodynamic Forces and Moments for Underwater Vehicles Using Overset Grids," AIAA Paper 2006-1148, 44th AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, Jan., 2006.

  12. Chan, W. M.," The OVERGRID Interface for Computational Simulations on Overset Grids," AIAA Paper 2002-3188, 32nd AIAA Fluid Dynamics Conference, St. Louis, Missouri, June, 2002.

  13. Chan, W. M.," Innovative Software Streamlines Overset Grid Generation," NAS News, Vol. 3, No. 3, May-June, 1998.

  14. Kao, D. L., Chan, W. M.," OVERSMART - A Solution Monitoring and Reporting Tool for the OVERFLOW Flow Solver," AIAA Paper 2009-3998, June, 2009.

  15. Chan, W. M. and Steger, J. L., "Enhancements of a Three-Dimensional Hyperbolic Grid Generation Scheme," Appl. Math. and Comput. 51, 181--205, 1992.

  16. Chan, W. M., Chiu, I.-T., and Buning, P. G., " User's Manual for the HYPGEN Hyperbolic Grid Generator and the HGUI Graphical User Interface," NASA TM 108791, October, 1993.

  17. Rogers, S. E., Roth, K., Nash, S. M., Baker, M. D., Slotnick, J. P., Whitlock, M., and Cao, H. V.," Advances in Overset CFD Processes Applied to Subsonic High-Lift Aircraft," AIAA Paper 2000-4216, AIAA 18th Applied Aerodynamics Conference, Denver, Colorado, August, 2000.

  18. Parks, S. J., Buning, P. G., Steger, J. L., and Chan, W. M., "Collar Grids for Intersecting Geometric Components Within the Chimera Overlapped Grid Scheme," AIAA-91-1587, Proceedings of the AIAA 10th Computational Fluid Dynamics Conference, Honolulu, HI, June 24-26, 1991.

  19. Chan, W. M. and Meakin, R. L.," Advances Towards Automatic Surface Domain Decomposition and Grid Generation for Overset Grids," AIAA Paper 97-1979, Proceedings of the AIAA 13th Computational Fluid Dynamics Conference, Snowmass, Colorado, 1997.

  20. Chan, W. M. and Gomez, R. J.," Advances in Automatic Overset Grid Generation Around Surface Discontinuities," AIAA Paper 99-3303, Proceedings of the AIAA 14th Computational Fluid Dynamics Conference, Norfolk, Virginia, 1999.

  21. Chan, W. M. and Buning, P. G., "Surface Grid Generation Methods for Overset Grids," Computers and Fluids, 24, No. 5, 509--522, 1995.

  22. Chan, W. M., Gomez, R. J., Rogers, S. E. and Buning, P. G., "Best Practices in Overset Grid Generation," AIAA Paper 2002-3191, 32nd AIAA Fluid Dynamics Conference, St. Louis, Missouri, June, 2002.

  23. Pandya, S. A., Chan, W. M., Kless, J.," Automation of Structured Overset Mesh Generation for Rocket Geometries," AIAA Paper 2009-3993, June, 2009.


Sponsors

Funding for this work has been provided by the NASA Constellation Program under the Ares, Ground Operations, and Simulation-Assisted Risk Assessment (SARA) projects; and the DOD HIARMS project. Past sponsors include the NASA CICT/CNIS Program the NASA High Performance Computing and Communications Program, the DOD High Performance Computing Modernization Program under the CHSSI CFD-4 Project, the Advanced Subsonic Technology Program, and the Space Shuttle Program.


Software Request Procedure

This software package can be requested and used by U.S. citizens and permanent residents belonging to a U.S. organization. The request can be made from

"https://www.nas.nasa.gov/cgi-bin/software/start "

Follow the links for Chimera Grid Tools and fill out an appropriate Software Usage Agreement form depending on the user's affiliation, and fax the form back to the Ames Software Release Authority (FAX: 650-604-7486).


Notices and Disclaimers

The following notices and disclaimers apply to all modules and libraries of the Chimera Grid Tools software package.

NOTICES

Chimera Grid Tools, Copyright 2004, 2007, 2010 United States Government as represented by the Administrator of the National Aeronautics and Space Administration. No copyright is claimed in the United States under Title 17, U.S. Code. All Other Rights Reserved.

Unique Surface Using Ranked Polygons (USURP) distributed under license by the Pennsylvania State Research Foundation. Portions of USURP created by David Boger are Copyright 2005 The Pennsylvania State University. All Rights Reserved.

This software may be used, copied, and provided to others only as permitted under the terms of the contract or other agreement under which it was acquired from the U.S. Government. If you have received this software for use under a Government Contract, Cooperative Agreement or Grant the software is for federal government research purposes only, and may not be further distributed to third parties. Neither title to nor ownership of the software is hereby transferred. This notice shall remain on all copies of the software.

DISCLAIMERS

THE SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SOFTWARE. IN NO EVENT SHALL THE UNITED STATES GOVERNMENT, OR ITS CONTRACTORS OR SUBCONTRACTORS, BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT, INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM, OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY, CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT OF THE RESULTS OF, OR USE OF, THE SOFTWARE or services provided hereunder. THE UNITED STATES GOVERNMENT DISCLAIMS ALL WARRANTIES AND LIABILITIES REGARDING THIRD PARTY SOFTWARE, IF PRESENT IN THE NASA GENERATED SOFTWARE, AND DISTRIBUTES IT "AS IS."

RECIPIENT AGREES TO WAIVE ANY AND ALL CLAIMS AGAINST THE UNITED STATES GOVERNMENT AND ITS CONTRACTORS AND SUBCONTRACTORS, AND SHALL INDEMNIFY AND HOLD HARMLESS THE UNITED STATES GOVERNMENT AND ITS CONTRACTORS AND SUBCONTRACTORS FOR ANY LIABILITIES, DEMANDS, DAMAGES, EXPENSES OR LOSSES THAT MAY ARISE FROM RECIPIENT'S USE OF THE SOFTWARE, INCLUDING ANY DAMAGES FROM PRODUCTS BASED ON, OR RESULTING FROM, THE USE THEREOF.

IF FURTHER RELEASE OR DISTRIBUTION OF THIS SOFTWARE OR TECHNICAL DATA DERIVED FROM THIS SOFTWARE IS PERMITTED, RECIPIENT AGREES TO OBTAIN THIS IDENTICAL WAIVER OF CLAIMS, INDEMNIFICATION AND HOLD HARMLESS AGREEMENT WITH ANY ENTITIES THAT ARE PROVIDED WITH THE SOFTWARE OR TECHNICAL DATA DERIVED FROM THE SOFTWARE.


Last modified: Tue March 09 16:26:00 2010