Prediction of energy dissipation in violent sloshing flows by Smoothed Particle Hydrodynamics

In the framework of the H2020 SLOWD project the damping effect of violent fuel sloshing on the dynamics of wings subjected to wind gusts is studied. In fact, if accurately evaluated fuel slosh can be taken into account to reduce the design loads on aircraft wing structures. To this aim Computational Fluid Dynamics (CFD) can be used along with physical models to assess the amount of mechanical energy dissipated by the liquid during its sloshing motion. This represents a quite challenging task for CFD tools, the flow being extremely complex due to violent impacts and intense fragmentation of the air-liquid interface. Among the different numerical methods, the Smoothed Particle Hydrodynamics (SPH) can be a good candidate for such a problem due to its meshless Lagrangian character, which allows to accurately resolve the evolution of liquid interfaces, and its intrinsic conservation properties. Notwithstanding that, the SPH approach to the problem suffers from some numerical issues which need to be carefully addressed before tackling the problem at hand. To this aim in the present work new models are described and applied to the SLOWD sloshing problem. The focus of the analysis is on the energy balance of the mechanical system, i.e. the oscillating tank and the sloshing liquid. In this first stage of the project the motion of the tank is imposed, the fully coupled system being addressed in a more advanced stage of the project. The study shows that single phase simulations confirm that the presence of liquid in the tanks attached to flexible structures introduces a damping effect that can be numerically measured in terms of energy dissipated by the fluid.