Rain drop (3D) falling simulation in ANSYS FLUENT
 

I want to simulate a 3D rain drop falling on the ground. I have made a 3D spherical object having a shared topology with the computational domain in Spaceclaim. But when I simulated using all necessary settings in FLUENT, I couldn't see a slight difference in the droplet it's as it is despite making sure all things are intact. I couldn't find a single tutorial for a 3D VOF problem so kinda stuck where I am making mistake. Please help me with this.

Rain Drops
 

You do not need to create a 3D rain drop in geometry. Though it could be useful but only for initialization. To model a single rain drop, you need to use Volume of Fluid model. However, it depends on the objective of the simulation. Depending upon that, it is possible that you need to use DPM instead of VOF.

Yes, I am using VOF model but I wanted proceed with geometry creation as I want to add solidification/melting model to it afterwords. Hence I created two bodies one is water drop and other is air surrounding the drop

Solidification-Melting Model
 

Solidification-Melting model also does not require a separate geometric model of the shape, however, as I mentioned earlier, it helps in defining proper shape of the drop. In reality, drops are not spherical, rather shaped like tear drops with their tail pointing forward.