Project Title:

From Design to Analysis: A Synergistic Approach to Grid and Model Geometry

94-1		02.01	6660	A		AMOUNT REQUESTED $

From Design to Analysis: A Synergistic Approach to Grid and Model 
Geometry

Abstract:

We propose designing the structured grid generator GRIDGEN's 
geometric basis so that grid geometry and CAD model geometry are 
treated identically: as rational, n-th degree polynomial curves and 
surfaces.  We also propose adding CAD-style curve and surface 
creation tools to the grid generator.  This unique approach to 
the challenge of accurate transfer of product geometry from the 
designer to the analyst will: 1) provide the analyst with a 
single code for geometry repair and grid generation, 2) enable 
the analyst to effectively repair or idealize the geometry for 
gridding, 3) enhance the grid generation process by providing 
new, CAD-style tools for grid creation, and 4) improve the 
efficiency of the grid generation software and its user 
interface.  Since grid generation is a necessary step prior to 
any CFD analysis and since complex aerospace vehicle geometry 
usually arrives at the grid generator in a form not amenable to 
analysis, the proposed work is essential to the continued use of 
CFD in aerospace design.  Since GRIDGEN is widely used at several 
NASA centers the results of the proposed research will be 
immediately useful.

Adding the proposed grid-CAD geometry engine to the GRIDGEN 
structured grid generator would have considerable commercial 
applications for any firm that obtains analysis models from CAD 
systems. Many firms are turning to computer aided engineering 
(CAE) analysis software as a means of improving their 
international competitiveness, especially in light of the recent 
downsizing trend. CAE software helps these firms decrease the 
time to market for new products and improve product quality 
through improved analyses. However, before the grid can be made 
and the analysis performed, the geometry must be changed to a 
usable form. It is this need that the proposed program fulfills. 
An aerospace application may call for editing the trailing edge 
of a wing so that is sharp. The CAD model may be of a wind tunnel 
model that purposely defined a blunt trailing edge for ease in 
milling the model. An automotive engineer may wish to fair over 
the wheel wells of a vehicle prior to an external aerodynamics 
calculation. A biomedical engineer may have to edit the curves in 
an arterial model (curves that originated from a magnetic 
resonance imaging scan). Finally, as a result of incorporating 
curve and surface creation tools, analysts without access to any 
CAD system may create a model from scratch in GRIDGEN.

KEY WORDS

MDA Engineering, Inc.
Suite 401
500 E. Border St.
Arlington, TX 76010