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Slice of Direct Numerical Simulation (DNS) of a flow around a block 
Use under the condition that the people who generated the data
are properly mentioned:

The data is generated by R.W.C.P. Verstappen &
A.E.P. Veldman of the university of Groningen (the Netherlands)
The technique used to generate the data is described in:
    R.W.C.P. Verstappen & A.E.P. Veldman, 1998: Spectro-consistent
    discretization of Navier-Stokes: a Challenge to RANS and LES,
    Journal of Engineering Mathematics, Vol. 34, pp. 163-179

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General description of the data format
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The format stores the geometry in a file with a .gri extention and
each timestep of the set in file with the same basename but with an 
extention consisting of the number of the timestep and a .dat extention.
The gridfile consists of a 40 byte ascii header and the (binairy) position 
data. 
The header looks like:
"SN4DB %d %d %d %d %d %f",SX,SY,SZ,NF,NT,DT

where SX,SY,SZ are the dimensions of the set, NF is the number of additional
sets, NT is the number of time steps, and DT is the timestep between two
time steps. 

The geometry is organized as a 3D array of positions each
consisting of 3 floats (=4 bytes): (px,py,pz).
It can be read as follows 

   read(file,buf,40)
   sscanf(buf,"SN4DB %d %d %d %d %d %f",SX,SY,SZ,NF,NT,DT)
   data = allocate_data(SX,SY,SZ)
   for (z = 0) z < SZ; z++)
      for (y = 0; y < SY; y++)
         for (x = 0; x < SX; x++)
            read(file,*data[z][y][x].x,4)
            read(file,*data[z][y][x].y,4)
            read(file,*data[z][y][x].z,4)


The data files are organized equally with the exception that the
number of floats depends on the number of additional datasets. 

(vx,vy,vz,a1,a2, ....an) 
   for (z = 0) z < SZ; z++)
      for (y = 0; y < SY; y++)
         for (x = 0; x < SX; x++)
            read(file,*data[z][y][x].vx,4)
            read(file,*data[z][y][x].vy,4)
            read(file,*data[z][y][x].vz,4)
            for (k=0; k< NF; k++)
                read(file,*data[z][y][x].a[k],4)



This set: block.gri
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The data set is two dimensional this therefore the SZ is set to 1.
Also its a single slice sn NT is set to 0 and DT is set to 0.0
The data files contain two extra scalar data sets the first one 
is pressure and the second is vorticity perpendicular to
the slice.