I am investigating the water-entry of a steel ball-bearing at different speeds. Ideally, I would like to model (to an extent) the forces experienced by the ball bearing as it transitions from air to water. For a free-falling ball-bearing, I would expect a sudden drop in its velocity as it transitions between fluids, before increasing (or decreasing) to reach its terminal velocity in the water.
In addition to surface tension, negligible or not, what other forces can I expect to be experienced by a sphere falling from air into water? I am aware of buoyancy and viscous drag (stokes' law and the drag equation), and air cavities which form behind the object at the boundary between fluids (which as far as I know are unpredictable mathematically). From my readings of other scientific research papers, I have become aware of specific gravity and the increase of the ball bearing's wetted area as it penetrates further below the surface of the water. What other considerations are there at the zone of transition between air and water?