in vertical falling film,the flow should be parabolic.but in fluent,how i can get this profile.there are four boundary conditions:liquid velocity inlet,liquid pressure outlet,vapor pressure inlet and wall.thanks!

Did you tried to set up velocity inlet BC with profile instead of constant value?

i try to set up parabolic velocity profile in computational domain,because i have known it.how can i finish it?

What do you mean "finish"? What problem do you have with velocity profile?

i consider a problem of vertical falling film.accroding to nusselt theory, velocity profile of film is parabolic.