[Nek5000-users] How to identify boundary faces ?

[nek5000-users at lists.mcs.anl.gov]

Hello
I want to identify boundary faces to set their boundary condition type.
Following some of the examples, I created the following function. To find
the location of the face, I need to know the coordinates (xf,yf) of the
face center using which I can figure out where the face lies. Is this
possible to find ?

Thanks
praveen

C=======================================================================
      subroutine usrdat2

      include 'SIZE'
      include 'TOTAL'

      parameter(XTOL=1e-10)
      character*3 cbv
      integer e, f
      real xmin, xmax, ymax

      xmin = -5.0
      xmax = +10.0
      ymax =  3.0

c set boundary conditions
      do e = 1,nelt
         do f = 1,2*ndim
            cbv = cbc(f,e,1)
            if (cbv.ne.'E  ') then       ! This is boundary edge
c TODO: Get mid-point coordinate of face f = (xf,yf)
               if(abs(xf-xmin).lt.XTOL)then
                   cbc(f,e,1) = 'v  '   ! inlet
               else if(abs(xf-xmax).lt.XTOL)then
                   cbc(f,e,1) = 'O  '   ! outlet
               else if(abs(yf-ymax).lt.XTOL)then
                   cbc(f,e,1) = 'SYM'   ! top wall
               else
                   cbc(f,e,1) = 'W  '   ! bottom wall
               endif
            endif
         enddo
      enddo

      return
      end
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