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Foundation ::
Aerodynamics Applications ::
GRAPE
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GRAPE
Two-Dimensional Grids About Airfoils and Other Shapes By the Use of Poisson's Equation
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Moderators:
Adopt This Application!
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SOURCE CODE AVAILABLE
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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.
GRAPE carries the NASA case number ARC-11379. It was originally released as part of the NASA COSMIC collection.
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