the impact travels through the bottle, thus supporting the waterhammer
theory. Pressure magnitude and the period of the main
oscillation are also well predicted by the method. The maximum
pressure of the main oscillation varies parabolically with drop
height; the samewas observed in experiments. It is also shown that
the high-frequency oscillations in the pressure histories are not
caused by numerical instability, but have a physical meaning – they
are caused by the presence of unconfined pressure waves propagating
in the fluid at high speed. The effect of the base shape on
pressure/strain histories is also investigated. It is demonstrated that
the curved base shape affects the pressure/strain pulse resulting in
a more triangular profile of smaller magnitude.
It can be concluded, from experimental and numerical findings,
that waterhammer theory explains the problem of the base drop
impact of the fluid-filled containers better than the mass-spring
model. The numerical results compare well with experimental
observations. Hence, the two-system FVM numerical procedure
applied shows a great potential for solving other impact problems
involving fluid-filled bodies having complex geometries, such as side
drop impacts, inverted drop impacts, crashes of reservoirs, and so on.