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GridTool: A Tool for Structured and Unstructured Grid Generation
Introduction
GridTool is an interactive program for grid/geometry applications .
Most grid generation programs represent geometry
by a set of structured points which
is not consistent with the Computer Aided Design (CAD)
representation. The purpose of GridTool is to bridge the gap between
the CAD and the grid generation systems.
Computer Aided Design (CAD) tools store the geometry by set of
NonUniform Rational B-Splines which allows to represent the geometry
accurately. On other hand, most grid generation programs are designed
around the concept that the surface grids are generated on a set of
bi-linear patches (approximating the actual geometry). This type of
grid generation is quite easy to implement, and it avoids the problems
associated with complex CAD surface representations and associated
surface parameterizations. However, the resulting surface grids are
close to but not on the original CAD surfaces. Also the grid generator
requires more information about the grid that can not be easily created
in a CAD environment. GridTool bridges the gap between the CAD and grid
generation systems by: (1) bringing the accurate CAD geometry to the
grid generators, (2) creating the necessary information for grid
generator such as patch definitions and spacing requirements, (3)
providing a mechanism for checking the integrity and quality of the
CAD geometry, (4) creating the missing information, and (5) providing an
interactive environment to process very complex geometries.
GridTool is
designed primary for unstructured grid generation systems. Currently,
GridTool supports VGRID [1] and
FELISA [2] systems, and it
can be easily extended to support other unstructured grid
generation systems.
The data in GridTool is stored parametrically so that
once the problem is set up, one can modify the surfaces and the entire
set of points, curves and patches will be updated automatically.
This is very useful in a multidisciplinary design and optimization
process.
GridTool is written entirely in ANSI "C", the interface is
based on the FORMS library [3], and the graphics is based
on the GL library. The code has been tested successfully on IRIS
workstations running IRIX4.0 and above. The memory is allocated
dynamically, therefore, memory size will depend on the
complexity of geometry/grid.
GridTool data structure is based on a link-list structure which
allows the required memory to expand and contract dynamically
according to the user's data size and action.
Data structure contains several types of objects such as
points, curves, patches, sources and surfaces. At any given time, there is
always an active object which is drawn in magenta, or in their highlighted
colors as defined by the resource file which will be discussed later.
FAQ
- How can I get a copy of GridTool?
- For the SGI, fill out the online request form for GridTool
- For Mac OS X, send email to Craig Hunter
- For Linux, send email to Shahyar Pirzadeh
- How do I report my comments/suggestions/questions?
- Contact Norma Bean at
(Norma.F.Bean@nasa.gov) (757-864-5325)
- Where can I find the lastest version of this document?
-
Press here (/GridTool/GridTool_Doc.html)
- What are the system requirements to run GridTool?
- The code has been tested successfully on IRIX
workstations running IRIX4.0 and above. The memory is allocated
dynamically, therefore, memory size will depend on the
complexity of geometry/grid. Recently the GridTool software has
been ported to workstations running the MacOSX and Linux operating
systems.
- Is there an on-line help for GridTool?
- There is some limited on-line help which can be activated by pressing
the Help button in the main panel which in turn will
open a browser. As the user moves the cursor over any object in the panels,
a description of that button will be given in the browser.
Also, you use the Help button in each panel to access sections of
this document.
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