open(unit=46,file=fich)
 19 write(46,'(1A26)') '# vtk DataFile Version 2.0'
 20 write(46,*) 'Flow'
 21 write(46,*) 'ASCII'
 22 write(46,*) 'DATASET STRUCTURED_GRID'
 23 write(46,*) 'FIELD FieldData 1'
 24 write(46,*) 'TIME 1 1 double'
 25 write(46,*) time
 26 write(46,*) 'DIMENSIONS' ,nc+1,mc+1,1
 27 write(46,*) 'POINTS', (nc+1)*(mc+1), 'double'
 28 write(46,*) (( nd(n,m)%center(1), nd(n,m)%center(2) , 0.0d0, n=0,nc), m=0,mc)
 29 write(46,*) 'CELL_DATA', nc*mc
 30 write(46,*) 'SCALARS rho double'
 31 write(46,*) 'LOOKUP_TABLE default'
 32 write(46,*) (( sngl( cl(n,m)%w(1) ), n=1,nc), m=1,mc)