Evaluation of a rapid method for the simulation of sloshing in rectangular and octagonal containers at intermediate filling levels

The Rapid Sloshing Model methodology developed by Godderidge et al. [13], is used for the simulation of sloshing in longitudinal and transverse cross sections of membrane liquefied natural gas tanks near the critical depth. Sloshing is induced by periodic translatory and rotational tank motions at and near the first resonant period. Subsequently irregular translatory motions obtained with a realistic wave spectrum and simultaneous translatory and rotational motions are applied to the tank cross sections. The validated Computational Fluid Dynamics (CFDs) methodology from Godderidge et al. (2009) is applied and it is found that the results from the Rapid Sloshing Model are typically within 5–10% of the corresponding CFD solution for linear, weakly nonlinear and strongly nonlinear sloshing with sloshing impacts. Simulation times are typically 0.1% of real time on a desktop PC. A similar level of agreement between Rapid Sloshing Model and CFD solution is observed when an irregular motion profile from a realistic seaway is applied to the tank for a duration corresponding to 35 min on a liquefied natural gas carrier. Compared to an existing phenomenological modelling approach the RSM methodology reduces the error by up to an order of magnitude in sloshing scenarios of practical interest.