Sloshing and energy dissipation in an egg: SPH simulations and experiments

Abstract

Tall structures, such as towers and bridges, can oscillate at excessive magnitudes when subjected to wind and earthquake loads. Liquid sloshing absorbers can be used to suppress these excessive oscillations by tuning the frequency of the sloshing to the critical frequency of the structure. Sloshing absorbers are simple structures consisting of a partially full container of liquid with a free surface. Tuning ensures that significant amounts of harmful energy can be extracted from the structure to the sloshing liquid. However, there needs to be a rapid means of dissipating this energy to avoid its returning back to the structure (then back to the liquid periodically).A hen׳s egg seems to have evolved to efficiently dissipate energy to protect its embryo using sloshing of its liquid content. Hence, the potential to implement the egg׳s unique properties as a sloshing absorber for structural control, is the main focus of this study. Numerical simulations, using Smoothed Particle Hydrodynamics (SPH), and experimental comparisons are presented in this paper. One objective is to demonstrate the ability of SPH to simulate complex free surface behaviour in three dimensions. Such a tool is then useful to identify different dissipation modes. Effects of fill volume and viscosity on the rate of dissipation, are also investigated.