DISPLAY.DIC  21 June 1998
 
*********************************************************************
 
DISPLAY was written especially for the output of the FLOW program,
and has some features that will only work with such output.

However, DISPLAY can be used with other programs, assuming that

  You use a 3, 4 or 6 node finite element;

  At each node, you have values of U, V, and P.


If this is true, then you need to write out two kinds of files:


An element file:

  The element file contains, for each element, a list of the
  nodes that make it up.  The information about each element
  is written on a separate line of the file.

  A program for doing this might look like:


      subroutine wrtell(nelem,npe,node)

      integer nelem
      integer npe

      integer i
      integer j
      integer node(npe,nelem)

      open(unit=1,file='ell.dat',status='unknown')

      do j=1,nelem
        write(1,*)(node(i,j),i=1,npe)
      enddo

      close(unit=1)

      return
      end

  or

      subroutine wrtelj(nelem,npe,node)

      integer nelem
      integer npe

      integer i
      integer j
      integer node(npe,nelem)

      open(unit=1,file='elj.dat',status='unknown')

      write(1,*)nelem
      write(1,*)npe
      do j=1,nelem
        write(1,*)(node(i,j),i=1,npe)
      enddo

      close(unit=1)

      return
      end


  The element file only has to be created once for a given problem.


One or more "node" files

  Each node file contains the values of data at all the nodes.  
  For a time dependent problem, these values will change on each 
  time step, and so a new copy of this file might be created
  each step (with a different name each time).


  A routine for doing this might look like this:


      subroutine wrtnod(np,p,u,v,xc,yc)

      integer np

      integer i
      real p(np)
      real u(np)
      real v(np)
      real xc(np)
      real yc(np)

      open(unit=2,file='nod.dat',status='unknown')

      do i=1,np
        write(2,*)xc(i),yc(i),u(i),v(i),p(i)
      enddo

      close(unit=2)

      return
      end


  Here XC and YC are the X and Y coordinates, U and V the 
  horizontal and vertical velocities, and P the pressure,
  at a particular node. 

  If your program has more time steps, you would write out
  the files 'node02.dat', and so on.

Here is a very simple (NPE must be 6) LEE element data file "ell.dat":

  1  2  3  4  5  6

Here is a very simple (NPE=3) JEFF element data file "elj.dat":

  4
  3
  1  4  6
  4  2  5
  6  5  3
  5  6  4

Here is a simple node file "nod.dat" that can be used with either element file:

  (x)  (y)  (u)  (v)  (p)

  0.0  0.0  0.0  0.0  0.0
  0.0  2.0 -2.0  0.0  4.0 
  2.0  0.0  0.0  2.0  4.0
  0.0  1.0 -1.0  0.0  1.0
  1.0  1.0 -1.0  1.0  2.0
  1.0  0.0  0.0  1.0  1.0

Once you have set up these files, you can run DISPLAY, and
use the commands:

  DE
  ell.dat
  DN
  nod.dat

or, for JEFF files,

  DJE
  elj.dat
  DJN
  nod.dat

Then the program will read in your data and be ready to try
to graph it.