# Simulating Slosh Induced Damping, with Application to Aircraft Wing-like Structures
## 5 Conclusions  
A preliminary investigation of the slosh-induced damping of an aircraft-wing-like structure was performed using a newly developed and open-source fluid-structure interaction framework. The first ten free-decay oscillation cycles were considered. We studied the impact of different excitation amplitudes and different numbers of compartments of the tank to slosh-induced damping. An idealised undamped cantilevered beam was employed to represent the aircraft-wing-like structure in order to make it possible to directly measure the slosh-induced damping from the time history of the tip displacement of the beam-tank system.  
Three initial excitation amplitudes and four compartment numbers were studied. When the compartment number of the sloshing tank equals one, we observed a difference of less than 2% for slosh-induced damping according to the non-dimensional initial excitation amplitude, \(D_{i}=1.0\) and \(D_{i}=0.5\). This is more than two times larger than that of \(D_{i}=0.25\). This is due to the strong impact on the ceiling and floor of the tank by the sloshing water during the free decay motion. The interaction between the sloshing wave crest and the tank wall is gentler under \(D_{i}=0.25\), leading to small slosh-induced damping. By increasing the number of compartments within the tank, the slosh-induced damping of the system with \(D_{i}=0.25\) reduced by 59% when using four tank compartments. This is due to a smaller impact between the tank ceiling and the wave crests due to the change in the sloshing wave frequency under this condition. When the compartment number of the beam-tank system with \(D_{i}=0.25\) is increased to eight, the slosh-induced damping of the system increased by 153% due to the generation of large periodic sloshing waves with water slamming to the front and rear baffled regions and also due to impact with the ceiling of the tank.  
For the beam-tank system with \(D_{i}=0.5\), increasing the compartment number from one to eight also increases the slosh-induced damping due to a significant change in the sloshing pattern. For the beam-tank system with \(D_{i}=1.0\), changing the number of compartments within the tank did not change the slosh-induced damping significantly within this study.  
The present study focuses on the behaviour and slosh damping profile over the first ten cycles of the free decay oscillation; future work will look to understand this over longer  
Figure 25: Normalised force–velocity diagram for the last five oscillation cycles with \(D_{i}=1.0\).  
oscillatory periods. The simplified structural model in the present beam-tank system will also be replaced by a more complex representation during the next phase of the study. In-depth analysis on sloshing frequencies with different compartments will be carried out, with the goal to obtain and analyse the forces in each individual compartment in order to allow for optimal design decisions in future wing design.  
Investigation, W.L.; Project administration, S.M.L. and D.R.E.; Writing--original draft, W.L.; Writing--review & editing, O.A.M., S.M.L., A.S. and D.R.E. All authors have read and agreed to the published version of the manuscript.  
The research leading to these results was undertaken as part of the SLOWD project which has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 815044.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.