2D Vs 3D VOF calculations
 

Hello,
I have carried out a 2D VOF transient calculations (in Fluent) of a heavy material droplet falling inside a water pool (2phase, droplet-water ). The rate of deformation of a droplet is deduced from the simulation, calculating the droplet surface area(which is the area of iso surface created for volume fraction of a droplet). Gradient mesh adaptation is used at the interfaces. Many cases are tried with different initial velocity of droplet
Similar calculations are repeated in 3D, and the size of the mesh cells kept same in both cases.
Finally, comparing the 2D and 3D calculations, the rate of deformation of a droplet is not coherent in both cases (higher in 3D calculations).
What could be the probable reason?
Thanks in advance!

Sachin