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From X-Planes to JSF. Gridgen Delivers.

The U.S. Postal Service's X-Plane Express Mail Stamps ($14.40 and $4.05) feature images of the X-15 aircraft from NASA computational fluid dynamic (CFD) simulations. The $14.40 stamp shows color contours of the simulated flowfield against a mesh to illustrate the vehicle aerodynamics. It just so happens that NASA engineers generated the mesh for this CFD simulation using Pointwise's Gridgen meshing software.

This USPS Express Mail stamp shows a CFD grid generated using Pointwise's Gridgen software. +
X-Planes Stamp

Dr. William T. Jones, NASA Langley Research Center recalls the computations this way. "This work was done in the early 1990's as part of an effort to provide comparisons with experimental data. Jim Penland (NASA LaRC Retired) requested that a scale wind tunnel model of the X-15 be scanned to reproduce the geometry numerically. From that structured surface and volume grids were generated (Gridgen) and flow solutions were calculated via CFL3D."

Dr. Jones also made the following remarks at the First Day of Issue ceremony on 17 March 2006 at the Virginia Air and Space Museum in Hampton, Virginia. "The images selected for use on the stamps are far more than pretty colorful pictures. These images actually depict the true physics of the air flow around the X-15 as modeled by the CFL3D flow solver. The legacy that is CFL3D started at NASA Langley in the early 1980's. CFL3D remains a cornerstone for CFD research around the world. The ideas set forth in the development of CFL3D have served as the basis for additional software development efforts within the government, industry, and academia. The software has grown through the years to pioneer and incorporate many of the key advances in the field of CFD. "

"For this simulation, a 12 inch model of the X-15 was measured using a laser digitizing scanner. From the measurements, a mesh was created and the flow of air at supersonic speeds was computed using CFL3D. Computations were used to supplement the wealth of experimental data available for this vehicle. The Priority Mail stamp represents the X-15 surface pressures. Red is high and blue is low. The Express Mail stamp adds off-body pressures on a portion of the spatial mesh used in the computation. "

"NASA Langley has always been at the forefront of CFD research, be it development of state-of-the-art software like CFL3D, contribution to commercial software products, or construction of advanced algorithms and methodologies. Many exciting challenges remain as the demand for greater accuracy, efficiency, automated mesh adaptation, and the need to advance simulations in time while tracking configuration changes becomes commonplace. Langley's rich history in the field aeronautics research is self evident and is a source of pride to the dedicated men and women who work there. So it is with great honor that we present today an example of but one work product of many contributed by NASA Langley Research Center."

The images below illustrate the process of creating the CFD solution used on the stamp and are from http://geolab.larc.nasa.gov/cgi-bin/Bene/SubGallery.pl?x15.

X-15 Model
Start from a scale wind tunnel model of the X-15
X-15 Scan
Reproduce the geometry numerically using a 3D digital scanner.
X-15 Grid
Generate a structured grid on and around the geometry using Gridgen.
X-15 Flowfield
Compute the flow field using CFL3D.
X-15 Final Image
Create an image worthy of a postage stamp.