Dynamic behaviours of damaged stability for floating energy storage unit after accidental collision

Abstract

The transient dynamic behaviour of floating energy storage unit (FESU) is a result of coupling between three non-linear effects, which are sloshing of floodwater, wave loading, and FESU dynamics. The coupling of these effects would result in the catastrophic failure of the FESU in extreme conditions. Computational Fluid Dynamics (CFD) has shown that it holds great potential in solving the problem in the time domain, which is suitable for the transient stage. In this study, CFD simulation of damaged stability was conducted by using OpenFOAM to determine the dynamic response of FESU under the effects of floodwater and wave in transient flooding. OpenFOAM CFD simulation was conducted for the flooding of barge shaped FESU with different water inlet and air outlet sizes in still water condition followed by damaged stability in Stokes’ fifth-order beam wave and head wave condition. Dynamic responses of FESU, such as roll, pitch, heave, and floodwater volume flow rates were determined using the dynamic meshing solver of OpenFOAM. Simulation results showed similarity to experimental results within the time frame of 16 seconds. Reduction in water inlet area and air outlet area decreased the flooding time and flow rate of flood water. The amplitude of vibration of roll and pitch motion increased as the flood water volume was increased due to the force of floodwater exerted on the wall. Sloshing effects also caused the model to roll and pitch in secondary vibrational motion. Due to the coupling effect of the three non-linear criteria, the inflow and outflow of floodwater changed with time, which concludes that transient effects should not be ignored in the damaged stability assessment of FESU.