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Grids - Airfoil Near-Wake Case

A series of 5 nested 2-D grids are provided for the Nakayama Model-A airfoil (with sharpened trailing edge). Each coarser grid is exactly every-other-point of the next finer grid, ranging from the finest 2241 x 385 to the coarsest 141 x 25 grid. The finest grid has minimum spacing at the wall of y=2.5 x 10^-6, 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 609 points along the wake from the airfoil trailing edge to the outflow boundary on the finest grid (39 points on the coarsest grid). The figures below show two views of the 561 x 97 grid.

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) 2241 x 385 (1025 points on airfoil surface) (gzipped) (13.0 MB)
• (2-D) 1121 x 193 (513 points on airfoil surface) (gzipped) (3.2 MB)
• (2-D) 561 x 97 (257 points on airfoil surface) (gzipped) (< 1 MB)
• (2-D) 281 x 49 (129 points on airfoil surface) (< 1 MB)
• (2-D) 141 x 25 (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:

• (3-D) 2 x 2241 x 385 (2 x 1025 points on airfoil surface) (gzipped) (17.2 MB)
• (3-D) 2 x 1121 x 193 (2 x 513 points on airfoil surface) (gzipped) (4.4 MB)
• (3-D) 2 x 561 x 97 (2 x 257 points on airfoil surface) (gzipped) (1.1 MB)
• (3-D) 2 x 281 x 49 (2 x 129 points on airfoil surface) (< 1 MB)
• (3-D) 2 x 141 x 25 (2 x 65 points on airfoil surface) (< 1 MB)

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):

• Neutral Map File for (3-D) 2 x 2241 x 385
• Neutral Map File for (3-D) 2 x 1121 x 193
• Neutral Map File for (3-D) 2 x 561 x 97
• Neutral Map File for (3-D) 2 x 281 x 49
• Neutral Map File for (3-D) 2 x 141 x 25

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 2241 x 385 (2 x 1025 points on airfoil surface) (gzipped) (12.4 MB)
• (3-D) 2 x 1121 x 193 (2 x 513 points on airfoil surface) (gzipped) (3.2 MB)
• (3-D) 2 x 561 x 97 (2 x 257 points on airfoil surface) (gzipped) (< 1 MB)
• (3-D) 2 x 281 x 49 (2 x 129 points on airfoil surface) (< 1 MB)
• (3-D) 2 x 141 x 25 (2 x 65 points on airfoil surface) (< 1 MB)

UNSTRUCTURED VERSIONS OF GRIDS

CGNS and AFLR3 Files

The unstructured versions of the same grids are all given as CGNS and AFLR3 (UGRID) files. Note that the BCs written inside these 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:

• (3-D) unstructured quad version of 2 x 2241 x 385 (2 x 1025 points on airfoil surface) (gzipped) (45.1 MB)
• (3-D) unstructured quad version of 2 x 1121 x 193 (2 x 513 points on airfoil surface) (gzipped) (11.2 MB)
• (3-D) unstructured quad version of 2 x 561 x 97 (2 x 257 points on airfoil surface) (gzipped) (2.8 MB)
• (3-D) unstructured quad version of 2 x 281 x 49 (2 x 129 points on airfoil surface) (gzipped) (< 1 MB)
• (3-D) unstructured quad version of 2 x 141 x 25 (2 x 65 points on airfoil surface) (gzipped) (< 1 MB)

Download the unstructured AFLR3 grids (gzipped) as 3-D hexahedra (quadrilaterals in x-z plane) here:

• (3-D) unstructured quad version of 2 x 2241 x 385 (2 x 1025 points on airfoil surface) (gzipped) (47.3 MB)
• (3-D) unstructured quad version of 2 x 1121 x 193 (2 x 513 points on airfoil surface) (gzipped) (11.7 MB)
• (3-D) unstructured quad version of 2 x 561 x 97 (2 x 257 points on airfoil surface) (gzipped) (3.0 MB)
• (3-D) unstructured quad version of 2 x 281 x 49 (2 x 129 points on airfoil surface) (gzipped) (< 1 MB)
• (3-D) unstructured quad version of 2 x 141 x 25 (2 x 65 points on airfoil surface) (gzipped) (< 1 MB)

All AFLR3 grids have the same mapbc file: nak_a_fine_unified_all_hex.mapbc.
 
 

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Last Updated: 03/11/2025