The main aims of this work are to identify, verify, and validate a smoothed particle
hydrodynamics (SPH) method for simulating long duration transient and steady-
state fluid sloshing in complex geometries. The validation will be carried out by
comparing the SPH simulations against experimental data provided by ESA/ESTEC
for transient and steady-state sloshing in a rectangular tank with a low filling ratio
and of transient sloshing in a pill-shaped tank that exhibits transition from swaying
to swirling waves.
The experimental tests proved to be extremely challenging due to the low fill
ratio of the rectangular tank and the long duration of both experiments. The main
challenge is to devise a SPH scheme that balances spatial and temporal accuracy with
an efficient computer implementation to produce accurate simulations at a reasonable
computing cost.
The investigation highlighted three issues of critical importance: the treatment of
solid boundaries in order to limit the introduction numerical errors into the system;
the application of a correct numerical dissipation scheme to reduce existing numerical
errors; and the need for a massively parallel implementation..
Careful examination of the most suitable techniques led to the adoption a cor-
rected δ-SPH scheme that provides numerical dissipation to reduce spurious pressure
oscillations, and a fixed ghost particle boundary condition to accurately impose wall
boundary conditions. The proposed SPH methods were coded in the open source
parallel code DualSPHysics.
The implementation showed significant improvements in energy conservation and
solution accuracy when compared to state-of-the-art SPH methods, and accurately
reproduced known analytical solutions to linear sloshing.
The validation against the ESA/ESTEC experimental data showed excellent
agreement between the SPH simulations and experiments, accurately reproducing
the time history of wave heights and sloshing forces as well as capturing the full
free-surface shapes. Only the careful selection of appropriate boundary conditions,
artificial dissipation and a massively parallel GPU architecture allowed to accurately
simulate these experiments.