The Three-Dimensional Multi-block Advanced Grid Generation System
(3DMAGGS)
Stephen J. Alter and Kenneth J. Weilmuenster
NASA Langley Research Center Hampton, Va. 23681-2199
May, 1993
NASA TM-108985
As the size and complexity of three dimensional volume grids
increases, there is a growing need for fast and efficient 3D
volumetric elliptic grid solvers. Present day solvers are limited by
computational speed and do not have all the capabilities such as
interior volume grid clustering control, viscous grid clustering at
the wall of a configuration, truncation error limiters and convergence
optimization residing in one code. A new volume grid generator,
3DMAGGS (Three Dimensional Multi-block Advanced Grid Generation
System), which is based on the 3DGRAPE code written by Reese
L. Sorenson of NASA Ames, has evolved to meet these needs. This is a
manual for the usage of 3DMAGGS and contains five sections, including
the motivations and usage, a GRIDGEN interface, a grid quality
analysis tool, a sample case for verifying correct operation of the
code and a comparison to both 3DGRAPE and GRIDGEN3D. Since it was
derived from 3DGRAPE, this Technical Memorandum should be used in
conjunction with the 3DGRAPE manual (TM-102224).
Single Block Three-Dimensional Volume Grids About Complex
Aerodynamic Configurations
Stephen J. Alter and Kenneth J. Weilmuenster
NASA Langley Research Center Hampton, Va. 23681-2199
November, 1993
NASA TM-108986
This paper presents an alternate approach for the generation of
volumetric grids for supersonic and hypersonic flows about complex
configurations. The method uses parametric two-dimensional block face
grid definition within the frame work of GRIDGEN2D. The incorporation
of face decomposition reduces complex shapes to simple shapes. These
simple shapes are combined to obtain the final face definition. The
advantages of this method include the reduction of overall grid
generation time through the use of vectorized computer code, the
elimination of the need to generate matching block faces, and the
implementation of simplified boundary conditions. A simple axis
symmetric grid is used to illustrate this method. In addition, volume
grids for two complex configurations, The Langley Lifting Body (HL-20)
and the Space Shuttle Orbiter are shown.
Cell Volume Control at a Surface for Three-Dimensional Grid Generation Packages
Stephen J. Alter and Kenneth J. Weilmuenster
NASA Langley Research Center Hampton, Va. 23681-2199
"Software Systems for Surface Modeling and Grid Generation" pp 273-298
April, 1992
NASA Conference Publication (CP-3143)
This paper presents an alternate method of calculating the cell size
for orthogonality control in the solution of Poisson's
three-dimensional space equations. The method provides the capability
to enforce a better initial guess for the grid distribution required
for boundary layer resolution. This grid point distribution is
accomplished by enforcing grid spacing from a grid block boundary
where orthogonality is required. The actual grid spacing or cell size
for that boundary is determined by the two or four adjacent boundaries
in the grid block definition, which are two dimensional grids. These
two dimensional grids are in turn defined by the user using insight
into the flow field and boundary layer characteristics. The adjoining
boundaries are extended using a multi-functional blending scheme, with
user control of the blending and interpolating functions to be
used. This grid generation procedure results in an enhanced
Computational Fluid Dynamics Calculation by allowing a quicker
resolution of the configuration's boundary layer and flow field and by
limiting the number of grid re-adaptations. The cell size
specification calculation has been applied to a variety of
configurations ranging from axis symmetric to complex three
dimensional configurations. Representative grids will be shown for
the Space Shuttle and the Langley Lifting Body (HL-20).
Elliptic Volume Grid Generation for Viscous Computations in Parametric Design Studies
Stephen J. Alter and F. McNeil Cheatwood
NASA Langley Research Center Hampton, Va. 23681-0001
27th AIAA Fluid Dynamics Conference, New Orleans, Louisiana
April, 1992
AIAA 96-1999
This paper presents a robust method for the generation of zonal volume
grid of design parametrics for aerodynamic configurations. The process
utilizes simple algebraic techniques with parametric splines coupled
with elliptic volume grid generation to perform parametric design
studies. Speed of the algorithm is maximized through the algebraic
methods and reduced number of grid points to be regenerated for each
design parametric without sacrificing grid quality and continuity
within the volume domain. The method is directly applicable to grid
reusability, because it modifies existing flow adapted volume grids
and enables the user to restart the CFD solution process with an
established flow field. Use of this zonal approach reduces computer
usage time to create new volume grids for design parametric studies by
an order of magnitude, as compared to current methods which require
the regeneration of an entire volume grid. A sample configuration of a
proposed Single Stage-to-Orbit Vehicle is used to illustrate an
application of this method.
The Volume Grid Manipulator (VGM): A Grid Reusability Tool
Stephen J. Alter
NASA Langley Research Center Hampton, Va. 23681-2199
April, 1997
NASA CR-97-4772
This document is a manual describing how to use the Volume Grid
Manipulation (VGM) software. The code is specifically designed to
alter or manipulate existing surface and volume structured grids to
improve grid quality through the reduction of grid line skewness,
removal of negative volumes, and adaption of surface and volume grids
to flow field gradients. The software uses a command language to
perform all manipulations thereby offering the capability of executing
multiple manipulations on a single grid during an execution of the
code. The command language can be input to the VGM code by a UNIX
style redirected file, or interactively while it is most applicable
and where the strengths of such software can be utilized. The next two
sections describe the memory management and the manipulation command
language. The following 8 sections describe simple and complex
manipulations that can be used in conjunction with one another to
smooth, adapt, and reuse existing grids for various
computations. These are accompanied by a tutorial section that
describes how to use the commands and manipulations to solve actual
grid generation problems. The last two sections are a command
reference guide and trouble shooting sections to aid in the use of the
code as well as describe problems associated with generated scripts
for manipulation control.
Complex Volume Grid Generation Through the Use of Grid Reusability
Stephen J. Alter
NASA Langley Research Center Hampton, Va. 23681-0001
AIAA 13th Computational Fluid Dynamis Conference, Snowmass, Colorado
November, 1997
AIAA 97-1987
This paper presents a set of surface and volume grid generation
techniques which reuse existing surface and volume grids. These
methods use combinations of data manipulations to reduce grid
generation time, improve grid characteristics and increas the
capabilities of existing discretization software. The manipulation
techniques utilize physical and computational domains to produce basis
functions on which to operate and modify grid character and smooth
grids using Trans-Finite Interpolation, a vector interpolation method
and parametric re-mapping technique. With these new techniques,
inviscid grids can be converted to viscous grids, multiple zone grid
adaption can be performed to improve CFD solver efficiency, and
topological changes to improve modeling of flow fields can be done
simply and quickly. Examples of these capabilities are illustrated as
applied to various configurations.
Grid Generation Techniques Utilizing the Volume Grid Manipulator
Stephen J. Alter
NASA Langley Research Center Hampton, Va. 23681-2199
29th AIAA Fluid Dynamics Conference, Albuquerque, New Mexico
June, 1998
AIAA 98-3012
This paper presents grid generation techniques available in the Volume
Grid Manipulation (VGM) code. The VGM code is designed to manipulate
existing line, surface and volume grids to improve the quality of the
data. It embodies an easy to read rich language of commands that
enables such alterations as topology changes, grid adaption and
smoothing. Additionally, the VGM code can be used to construct
simplified straight lines, splines, and conic sections that are common
curves used in the generation and manipulation of points, lines,
surfaces and volumes (i.e., grid data). These simple geometric curves
are essential in the construction of domain discretizations for
computational fluid dynamic simulations. By comparison to previously
established methods of generating these curves interactively, the VGM
code provides control of slope continuity and grid point-to-point
stretchings as well as quick changes in the controlling
parameters. The VGM code offers the capability to couple the
generation of these geometries with an extensive manipulation
methodology in a scripting language. The scripting language allows
parametric studies of a vehicle geometry to be efficiently performed
to evaluate favorable trends in the design process. As examples of the
powerful capabilities of the VGM code, a wake flow field domain will
be appended to an existing X33 VentureStar volume grid; negative
volumes resulting from grid expansions to enable flow field capture on
a simple geometry, will be corrected; and geometrical changes to a
vehicle component of the X33 VentureStar will be shown.
NASA Official Responsible for Content --
Stephen J. Alter
Last Updated November 6, 2002
Feedback on Langley Products and Services