Rob
Ansys Employee

I've had a chat with a colleague, and I now have to be careful in how I explain anything!

This links to the comment in the paper regarding harmonics. If the sloshing frequency gets into/out of phase with the vertical displacement you could get enhanced/damped free surface movement. So, vessel dimensions, fill level, motion profile, viscosity, density etc need to be checked. The Fluent solver should get the answer right, but getting the exact input parameters might be difficult. This also assumes the mesh and time resolution are fine enough to not aid damping.