ZPG-TBL Re=2800-6650: Snapshot #254. Type: Velocity W Field
Juan Sillero

=======================================================================
            INFORMATION ABOUT THE DNS DATABASE
         (HDF5 FILES)
=======================================================================

This directory tree contain some of the restart files of a direct 
numerical simulations of fully developed ZPG Boundary Layer flow 
(Re_theta=2780-6650). Details are offered below.

The algorithm used is presented in: 

- M. P. Simens, J. Jimenez, S. Hoyas, Y. Mizuno
  "A high-resolution code for turbulent boundary layers"
  Journal of Computational Physics
  Volume 228, Issue 11, 20 June 2009, Pages 4218-4231 

- G. Borrell, J.A. Sillero, J. Jimenez 
  "A code for direct numerical simulation of turbulent boundary layers  
  at high Reynolds numbers in BG/P supercomputers" 
  Computers & Fluids, Volume 80, 10 July 2013, Pages 37-43 


The data is discussed in:

- J.A. Sillero, J. Jimenez, R.D. Moser 
  "One-point statistics for turbulent wall-bounded flows at Reynolds 
  numbers up to \delta^+pprox2000"  
  Phys. Fluids 25, 105102 


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                     STRUCTURE OF THE FILES:
-----------------------------------------------------------------------

The files are written in HDF5 format, which is supported by most of the 
mathematical programs. For programming languages, libraries can be 
downloaded for C, C++, Fortran 90, and Java interfaces.

The primitive variables {u,v,w,p} are stored in Fourier space as:
(kz,ny,nx) ---> ( Fourier - Physical -Physical )

For instance, one file contains:

Re        Dataset {1} : Inverse of the viscosity used in the code,
          which defines the scaling in which the code works.
Variable  Dataset {SCALAR} : Variable recorded "u", "v", "w" or "p".
procs     Dataset {536}  : Number of nodes used to run the simulation.
           (first element of the vector!)

cfl       Dataset {1}   : Courant–Friedrichs–Lewy condition at which the
        simulation was run. 
dt        Dataset {1}   : Time step in code units for this flow realization.
tiempo    Dataset {1}   : Time stamp in code units for this flow realization.
timeinit  Dataset {1} : Initial time stamp in code units (=0).

lx        Dataset {1}   : Defines the streamwise length Lx of the box, in code units.
ly        Dataset {1}   : Defines the wall-normal length Ly of the box, in code units.
lz        Dataset {1}   : Defines the spanwise length Lz of the box, in code units.
nx        Dataset {1}   : Number of collocation points in the streamwise direction.
ny        Dataset {1}   : Number of collocation points in the wall-normal direction.
nz2       Dataset {1}   : Half the number of complex Fourier Gallerkin modes in z-> K_z[0:nz2]

We use the 2/3 dealiasing rule in z, so the number of collocation points in those directions are 3/2 
times the number of Fourier Gallerkin modes, and the extra modes are padded with zeroes. 
                     

xout      Dataset {1}       : Location of the recycling plane.
um        Dataset {536} : Mean streamwise velocity profile in code units at the recycling
             station "xout".
y         Dataset {537} : Non-uniform grid for the wall-normal distance; in code units.
              Note that, because of the staggered grid: y=(-y1,0,y1,y2,....)
value     Dataset {15361, 536, 2730}: Primitive variable in code units. The array is stored in single-precision
           as [1:2*(nz2+1),1:Ny,1:Nx], equivalent to the complex array [Kz,Ny,Nx]
   
SKETCH: 

            ------v2------      * y(3)=y1
            |            |
   u2-----> x    o w2,p2 x -----> 
            |            |        
            |            |           
==================v1=========== * ======== y(2)=0;
            |            |        
            |            |        
   u1-----> x    o w1,p1 x ----->      
            |            |
            --------------      * y(1)=-y1


Before final publication of a paper citing these data, please check this
site (http://torroja.dmt.upm.es/turbdata/blayers/high_re) for an up-to-date reference.

Please report any problems with the data, queries or doubts to J.A. Sillero, 
sillero@torroja.dmt.upm.es