A dynamical system involving the decaying test of a partially filled liquid tank is analyzed in the present paper. This analysis is relevant for the design of aircraft fuel tanks, where the wings' structural dynamics are influenced by the complexity and the violence of the internal flow generated when atmospheric turbulence or gust is encountered. The study of this kind of system is performed in order to understand the extra energy dissipation caused by the confined fluid, and the interacting force between the fluid and the tank resulting from the vertical sloshing. A complete non-dimensional analysis of the problem in terms of additional damping has been performed, and the dependency on the most relevant non-dimensional numbers has been monitored. A coupled numerical simulation where both the tank and the fluid are combined has been used to study the system, and their results are compared to previous experiments. A smoothed particle hydrodynamics model, extensively validated in the sloshing literature, is used to calculate the magnitude and frequency of the vertical force between the fluid and the tank. The extra dissipation of the tank's mechanical energy caused by the fluid action is quantified for a particular configuration with constant filling level and a wide range of non-dimensional numbers. The sensitivity of the extra damping to the variation of the non-dimensional numbers is evaluated, and the most relevant ones are compared to the equivalent experimental tests. Results show that the numerical tool developed is able to capture the different phenomena involved and can be used to determine the influence of the different phenomena happening in violent vertically excited flows.

In Part I of this series [Marrone et al., Numerical study on the dissipation mechanisms in sloshing flows induced by violent and high-frequency accelerations. I. Theoretical formulation and numerical investigation, Phys. Rev. Fluids 6, 114801 (2021)], a theoretical formulation and the numerical model were developed in order to obtain a complete perspective of the energy balance of a violently accelerated flow confined inside a rectangular tank. The tank-fluid system was periodically excited with a predetermined law of motion and the force between the wall and the fluid and the global energy balance were computed. In this second part, the experimental validation of the previous formulation is presented. In order to make a comparison with a previous experimental campaign, where the tank moves along a single degree of freedom mechanical guide, two numerical problems have been studied: in the first, the decaying movement of the tank is prescribed according to the experimental measurements, and in the second the tank is coupled to a mass-spring-damper equation, and the sloshing force produced by the confined fluid acts as an external force. Both problems have been studied for two different fluids, water and oil, which implies a difference of two orders of magnitude in terms of Reynolds number. A complete description of the energy balance inside the fluid tank is performed and the complexity of the fluid dynamic behavior that takes place inside the tank is explained. The results are compared to the experimental measurements in terms of fluid-wall interaction and energy dissipation.