*
The ability to treat arbitrary boundary shapes is one of the most desirable
characteristics of a method for generating grids, including those about
airfoils. In a grid used for computing aerodynamic flow over an airfoil, or
any other body shape, the surface of the body is usually treated as an inner
boundary and often cannot be easily represented as an analytic function.
The GRAPE computer program was developed to incorporate a method for
generating two-dimensional finite-difference grids about airfoils and other
shapes by the use of the Poisson differential equation. GRAPE can be used
with any boundary shape, even one specified by tabulated points and including
a limited number of sharp corners. The GRAPE program has been developed to be
numerically stable and computationally fast. GRAPE can provide the
aerodynamic analyst with an efficient and consistent means of grid generation.*

*
The GRAPE procedure generates a grid between an inner and an outer boundary
by utilizing an iterative procedure to solve the Poisson differential equation
subject to geometrical restraints. In this method, the inhomogeneous terms of
the equation are automatically chosen such that two important effects are
imposed on the grid. The first effect is control of the spacing between mesh
points along mesh lines intersecting the boundaries. The second effect is
control of the angles with which mesh lines intersect the boundaries. Along
with the iterative solution to Poisson's equation, a technique of coarse-fine
sequencing is employed to accelerate numerical convergence. GRAPE program
control cards and input data are entered via the NAMELIST feature. Each
variable has a default value such that user supplied data is kept to a
minimum. Basic input data consists of the boundary specification, mesh point
spacings on the boundaries, and mesh line angles at the boundaries. Output
consists of a dataset containing the grid data and, if requested, a plot of
the generated mesh.*

This program was released by NASA through COSMIC as ARC-11379. The italicized text above is from the official NASA release.

- Go to the page of references for the Grape program.
- Download grape.zip, containing the original source code, the source code converted to modern Fortran, and several test cases.

The title GRAPE comes from **GR**ids **A**bout **P**ractically **E**verything.