# Post processing VOF cases with more than two phases

 In VOF problems with more than 2 phases, there is no direct variable to visualize all the three phases simultaneously. The custom field function below would help in visualizing all three phases at the same time in a three phase problem.Function = phase-1 + 2*phase-2 + 3*phase-3where phase-* is the volume fraction of each phase.When the function is displayed, all the three phases would be shown in different colors with lowest in the color scale being phase-1 and highest being phase-2.The procedure can be extended to more than 3 phases too.The following scheme can be used to create iso-surfaces in x y or z directions for visualizing the contours.;; scheme to make isosurfaces at constant x y and z directions;; n number of surfaces(define nx 5)(define ny 5)(define nz 5)(set! nx (read-integer "Number of surfaces in x direction " 5 ))(set! ny (read-integer "Number of surfaces in y direction " 5 ))(set! nz (read-integer "Number of surfaces in z direction " 5 ))(define minx (list-ref (domain-extents) 0))(define maxx (list-ref (domain-extents) 1))(define miny (list-ref (domain-extents) 2))(define maxy (list-ref (domain-extents) 3))(define minz (list-ref (domain-extents) 4))(define maxz (list-ref (domain-extents) 5))(do ((i 1 (+ i 1))) ((> i nx)) (ti-menu-load-string (format #f "surf iso-surf mix x-coord bx-~02d , , ~d ," i (+ minx (* i (/ (- maxx minx) nx))))))(do ((i 1 (+ i 1))) ((> i ny)) (ti-menu-load-string (format #f "surf iso-surf mix y-coord by-~02d , , ~d ," i (+ miny (* i (/ (- maxy miny) ny))))))(do ((i 1 (+ i 1))) ((> i nz)) (ti-menu-load-string (format #f "surf iso-surf mix z-coord bz-~02d , , ~d ," i (+ minz (* i (/ (- maxz minz) nz))))))