hi, i have some doubt about the meaning of volume fraction. Since i have a round pipe with the flow of water and air, after the iteration, i got my result. For the water volume fraction phase contour, i got a contour of different layer of water volume fraction with the corresponding value. Can anybody can explain what the feature of different layer of water volume fraction is indicated? (eg. a contour for water volume fraction with four layer: bottom=0.7, next layer up=0.5, next layer up=0.2, top=0.1)

Try redisplaying the volume fraction contours with the 'LEVELS' section in the display menu set to 2 - you then only get the two phases displayed with no gradational change between them. Also, if you are using VOF, check which scheme you are employing, as some display the phase boundary quite diffuse. I found 'Geo-reconstruct' to be pretty good.