Index of /channels/data/fields

[ICO]NameLast modifiedSizeDescription

[DIR]Parent Directory  -  
[DIR]re180/20-Jun-2011 13:46 -  
[DIR]re550/20-Jun-2011 13:48 -  
[DIR]re950/20-Jun-2011 14:04 -  

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-----------	       FORMAT OF THE FIELD FILES		--------------
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The files are written in standard FORTRAN-UNFORMATTED format, the endianness
of the bytes is BIG (least significant bit comes first). The file contains
three records:

RECORD #1: SOME PARAMETERS

time,Re,alp,bet,a0,mx,my,mz

time (real, 4 bytes): Cumulative time of the simulation in the field (it
should be something around four thousand for the retau=550 field).

!!!! PLEASE NOTE THAT IN THE CASE RE=950, time is a real*8 !!!!


Re (real, 4bytes): Inverse of the viscosity used in the code,
which defines the scaling in which the code works. The channel
half-width is h=!, but Re is not the bulk Reynolds number, because
the bulk velocity is not one (it is about 0.89, but you can integrate 
it exactly from the mean profiles, using the values of utau in the
master README).
(It should be Re=11180 for retau=550).

alp  (real, 4 bytes): Defines the streamwise periodicity Lx of the box as
Lx=2*pi/alp (it should be 0.25 for the retau=550 field). In the present
notation, the streamwise wavenumber of the i-th Fourier mode of a variable is
kx=alp*i, i=0,...,mx/2-1.

bet  (real, 4 bytes): Defines the spanwise periodicity Lz of the box as
Lz=2*pi/bet (it should be 0.50 for the retau=550 field). In the present
notation, the spanwise wavenumber of the k-th Fourier mode of a variable is
kz=k*bet, k= 0,...,(mz-1)/2,(mz-1)/2,......, -1

a0   (real, 4bytes): Horizontal velocity of the Galilean reference frame (it
should be 0 or 0.53)
 
mx   (int, 4bytes): Twice the number of Fourier Gallerkin modes in x.

my   (int, 4bytes): Number of Chebychev modes in y.

mz   (int, 4bytes): Number of Fourier Gallerkin modes in z.

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

RECORD #2: 00-MODES

(u00(j),w00(j),j=1,my)

u00(j) and w00(j) (real, 4bytes) are respectively the modes of the streamwise
and spanwise velocity associated to zero streamwise and spanwise wavenumbers
(infinite wavelengths), and to the j-th Chevychev polynomial.

RECORD #3: OMEGA_Y AND PHI=NABLA^2(V)

((vor(i,k,j),phi(i,k,j),i=1,mx),k=1,mz)

vor and phi are 4 bytes real arrays, and cmplx(vor(2*i-1,k,j),vor(2*i,k,j))
and cmplx(phi(2*i-1,k,j),phi(2*i,k,j)) are respectively the i-th and k-th
complex Fourier coefficients of omega_y and phi associated to the j-th
Chevychev polynomial.

This formulation is the same of Kim, Moin and Moser, (1987), Journal
of Fluid Mechanics vol 177, pp 133-166

The fields were written using a procedure similar to the following one:

c-----------------------------------------------------------------------
      subroutine escribe(mx,my,mz,time,Re,alp,bet,a0,u00,w00,vor,phi)
      integer i,j,k,mx,my,mz
      real time,Re,alp,bet,a0,u00(my),w00(my),vor(mx,mz,my),
     &     phi(mx,mz,my)
      open (20,file='field',status='unknown',form='unformatted')
      rewind(20)
      write(20) time,Re,alp,bet,a0,mx,my,mz
      write(20) (u00(j),w00(j),j=1,my)
      do j=1,my
         write(20) ((vor(i,k,j),phi(i,k,j),i=1,mx),k=1,mz)
      enddo
      close(20)
      end
c-----------------------------------------------------------------------

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For doubts about the format of the file ::            juanc@torroja.dmt.upm.es
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WARNING: THIS AREA IS UNDER CONSTRUCTION 
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last touched: 02-18-2004