# GRAPE: 2-D

**GRAPE v. 107**

**Overview**

The GRAPE code (GRids about Airfoils using Poisson’s Equation) is an elliptic grid generator originally intended for isolated airfoils. The code was written by Reece Sorenson at NASA Ames Research Center, and was modified by Rod Chima at NASA Glenn to allow generation of periodic C-type grids for turbomachinery blades. Turbomachinery grids generated with GRAPE can be used directly with the RVCQ3D CFD code.

**Applications**

- Axial compressors and turbines
- Centrifugal impellers and radial diffusers (no splitters)
- Pumps
- Linear cascades
- Isolated airfoils
- Supports all options in Sorenson’s original code

**Grid Types**

The geometry input to GRAPE is completely general. If you can generate coordinates for your geometry, GRAPE can probably put put a grid around it.

- C-grids around blades
- C- and O-grids around airfoils

**Features**

- Arbitrary specification of inner and outer boundary points
- Several options for reclustering boundary points
- Interior points are generated as a solution of a Poisson equation.
- Forcing terms in the Poisson equation maintain grid spacing and angles at the boundaries.
- Version 107 uses new monotone splines for accurate geometry definition.

**Input and output**

- Namelist input
- Airfoils are input in a Cartesian (x,y) coordinate system.
- Turbomachinery blades are input in a cylindrical (m,rbar*theta) system, where m is the arc length along the surface and rbar is a mean radius.
- Grid files are written as binary data in standard PLOT3D format
- Grid files can be read directly by RVCQ3D.
- Minimal printed output

**Computer and graphics requirements**

GRAPE requires a Fortran 90 compiler and CFD visualization software for use. Click the button below for more information.

Computers & Graphics Button – Link to popup – https://www.grc.nasa.gov/WWW/5810/rvc/CandG.htm

**GRAPE, RVCQ3D, TCGRID, and SWIFT**

**The sites linked below are outside the NASA domain and are not endorsed by NASA.**

**Computer requirements**

All codes are supplied as Fortran source code and require a Fortran 90 compiler for use. The Cray, Compaq, GNU, Intel, and SGI compilers have all been used successfully. The codes are usually run on Linux systems, but will run on a PC or Mac. Parallel processing is available on multi-core computers using OpenMP directives. Check the Fortran Store for information on Fortran compilers.

**Graphical output**

No graphical output is provided with these codes, but access to some CFD visualization software is required to view and evaluate the grids and solutions. Grid and solution files are in standard PLOT3D format and can be read directly and plotted with the public-domain CFD visualization tool PLOT3D, or the commercial tools FieldView, TecPlot, or EnSight CFD. Check the following websites for information on CFD visualization software.

PLOT3D | https://software.nasa.gov/software/ARC-14400-1 |

TecPlot: | http://www.tecplot.com |

FieldView: | http://www.ilight.com |

EnSight CFD: | http://www.ensightcfd.com/ |