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Turbulence Modeling Resource

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Grids - NACA 0012 Airfoil Case

NOTE: the grids provided on this page were created with a minor typo in the equation definition (see description on the 2D NACA 0012 Airfoil Validation Case Intro Page). With the typo, there is a slight order 10^-8 non-closure at the trailing edge (T.E.) (and very small influence throughout). At this time, the provided grids here have used the incorrect formula and were closed at the T.E. by setting y to be exactly 0 at x=1. However, the influence of the typo is insignificant.

Much finer grids for this NACA 0012 case (with the corrected equation definition) can be found from the: Numerical Analysis of 2D NACA 0012 Airfoil Validation Case page.

A series of 5 nested 2-D grids are provided. Each coarser grid is exactly every-other-point of the next finer grid, ranging from the finest 1793 x 513 to the coarsest 113 x 33 grid. The finest grid has minimum spacing at the wall of y=4 x 10^-7, giving an approximate average y+ between 0.1 and 0.2 over the airfoil at the Reynolds number run. The grid is stretched in the wall-normal direction, and the clustering is maintained in the wake region. The topology is a so-called "C-grid," with the grid wrapping around the airfoil from downstream farfield, around the lower surface to the upper, then back to the downstream farfield again; the grid connects to itself in a 1-to-1 fashion in the wake. There are 1025 points on the airfoil surface on the finest grid (65 points on the coarsest grid). There are 385 points along the wake from the airfoil trailing edge to the outflow boundary on the finest grid (25 points on the coarsest grid). The figures below show two views of the 449 x 129 grid.
NACA 0012 449 x 129 grid - far view
NACA 0012 449 x 129 grid - near view

Note: be sure to use double precision when reading the grids!

STRUCTURED VERSIONS OF GRIDS

PLOT3D Files

The structured PLOT3D grids are given in two different ways, as 2-D grids (x-y plane) or as 3-D grids (two identical x-z planes, separated by a distance y=1, giving one spanwise cell for all grid levels). You may use whichever is more convenient for your particular application.

Format for the structured 2D grids is PLOT3D-type, formatted, MG, 2D (nbl=1) - note that you must use double precision when reading! :

      read(2,*) nbl
      read(2,*) (idim(n),jdim(n),n=1,nbl)
      do n=1,nbl
        read(2,*) ((x(i,j,n),i=1,idim(n)),j=1,jdim(n)),
     +            ((y(i,j,n),i=1,idim(n)),j=1,jdim(n))
      enddo

Download the 2-D version of the grids in PLOT3D format here:

(2-D) 1793 x 513 (1025 points on airfoil surface) (gzipped) (15.3 MB)
(2-D) 897 x 257 (513 points on airfoil surface) (gzipped) (3.7 MB)
(2-D) 449 x 129 (257 points on airfoil surface) (gzipped) (< 1 MB)
(2-D) 225 x 65 (129 points on airfoil surface) (< 1 MB)
(2-D) 113 x 33 (65 points on airfoil surface) (< 1 MB)

Format for the structured 3D grid is PLOT3D-type, formatted, MG, 3D (nbl=1, and idim in this case is 2) - note that you must use double precision when reading! :

      read(2,*) nbl
      read(2,*) (idim(n),jdim(n),kdim(n),n=1,nbl)
      do n=1,nbl
        read(2,*) (((x(i,j,k,n),i=1,idim(n)),j=1,jdim(n)),k=1,kdim(n)),
     +            (((y(i,j,k,n),i=1,idim(n)),j=1,jdim(n)),k=1,kdim(n)),
     +            (((z(i,j,k,n),i=1,idim(n)),j=1,jdim(n)),k=1,kdim(n))
      enddo

Download the 3-D version of the grids in PLOT3D format here:

If desired, example Neutral Map Files associated with 3-D version of the grids are given here (these files specify grid indices associated with each boundary condition - see The Neutral Map File):

CGNS Files

The structured grids are also available as CGNS files (3-D versions only, with two identical x-z planes, separated by a distance y=1, giving one spanwise cell for all grid levels). Note that the BCs written inside the CGNS files are for guidance only, and may not reflect the appropriate BCs needed for your application. To read/write CGNS files, (free) software may be necessary if your pre/post-processing tools do not already handle it. See: CGNS Website for details.

Download the 3-D version of the grids in CGNS format (gzipped) here:

(3-D) 2 x 1793 x 513 (2 x 1025 points on airfoil surface) (12.3 MB)
(3-D) 2 x 897 x 257 (2 x 513 points on airfoil surface) (3.1 MB)
(3-D) 2 x 449 x 129 (2 x 257 points on airfoil surface) (< 1 MB)
(3-D) 2 x 225 x 65 (2 x 129 points on airfoil surface) (< 1 MB)
(3-D) 2 x 113 x 33 (2 x 65 points on airfoil surface) (< 1 MB)

UNSTRUCTURED VERSIONS OF GRIDS

CGNS Files

The unstructured versions of the same grids are all given as CGNS files. Note that the BCs written inside the CGNS files are for guidance only, and may not reflect the appropriate BCs needed for your application. To read/write CGNS files, (free) software may be necessary if your pre/post-processing tools do not already handle it. See: CGNS Website for details.

The unstructured grids are all given as 3-D grids (two identical x-z planes, separated by a distance y=1, giving one spanwise cell for all grid levels). They are given as hexahedra (quadrilaterals in the x-z plane). Note that duplicate gridpoints in the C-mesh wakes are removed when writing the structured grids as unstructured.

Download the unstructured CGNS grids (gzipped) as 3-D hexahedra (quadrilaterals in x-z plane) here:

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Responsible NASA Official: Ethan Vogel
Page Curator: Clark Pederson
Last Updated: 11/26/2019