Computational scaling of SPH simulations for violent sloshing problems in aircraft fuel tanks

The wings of large civilian aircraft are designed to withstand a variety of loads whose causes range from atmospheric gusts to turbulence to landing impacts. Aircraft wings are essential structures that demand further research. One of the primary methods used for improving wing design is analysis of the damping effects that sloshing induces on the dynamics of flexible wing-like structures carrying liquids. This will be attained through the development of experimental set-ups that will help in building up numerical models that are used to reproduce the physics involved. Hence, the aim of this work is to analyze the effect of sloshing in reducing the design loads on aircraft structures using the numerical method smoothed particle hydrodynamics (SPH) as the main numerical tool. One of the key considerations in this research is the demand for scaled experiments, making it a necessary step in assessing whether computational tools are able to approximate the registered measurements for different scales accurately. To this end, a numerical model of a vertically oscillating tank built as a fully coupled fluid-structure interaction problem is developed. The structure is modelled through a mass-spring-damper system, and for the inner fluid the 6-SPH methodology is used. In particular, two open questions are studied: the first one is to what extent gravity has an influence on the damping and energy dissipation phenomena when the initial acceleration of the tank is ten times the standard gravity value. The second seeks to confirm that the SPH equations correctly reproduce the scaling laws when the problem parameters are scaled according to the dimensional analysis.