Original Grid: (Shuttle Orbiter)
Below is the volume grid that was obtained by using the 3DGRAPE/AL
code for volumetric discretization. The latest version of this
software utilizes a unique scheme to compute source terms on the
domain interior to control grid line cells and
intersections. Sometimes this new scheme produces an elliptic Partial
Differential Equation system that is stiff which makes obtaining a
converged solution a daunting task. One of the side effects of
stiffness is kinked grid lines as shown in the expanded view of the
initial volume grid below.
VGM Corrected and Smoothed Grid:
Utilizing the Parametric Remapping technique of the VGM
software, the region that contains the kinked grid lines can be easily
corrected. The correction is performed by following steps in reference
to the figure below:
- Compute the normalized arclength in the K-direction.
- Use Trans-Finite Interpolation on the normalized arclength for
a surface of the arclength variable where K=constant.
- Use the new computed normalized arclengths for the interior to
update the volume grid.
In reality, this procedure generates a new distribution function that
is dependent on the K-direction arclengths at the boundaries of the
region chosen. The results of this operation correct the
irregularities in the grid, as shown below.
NASA Official Responsible for Content --
Stephen J. Alter
Last Updated November 6, 2002
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