Liquid Holdup Calculations/solving using paraview for openfoam

Hello All,

Performed interFoam based multiphase flow two sets of calculations.
Set.1: The liquid is flowing from the top to bottom in packing
Set.2: Liquid is flowing from top to bottom and simultaneously Gas is flowing from bottom to top (Counter-Current flow modeling).

Now, I have post-process data from which I want to calculate the liquid holdup in both sets, how to do that? How to do that in paraview and extract the values?
Also, extract the data of film thickness of the liquid, how to do that?
please let me know!
Thanks.

Regards,

Ash Kot