Range of applicability of the linear fluid slosh theory for predicting transient lateral slosh and roll stability of tank vehicles
An analytical model is developed to study the transient lateral sloshing in horizontal cylindrical containers assuming inviscid, incompressible and irrotational flows. The model is derived by implementing the linearized free-surface boundary condition and bipolar coordinate transformation, resulting in a truncated system of linear ordinary differential equations, which is numerically solved to determine the fluid velocity potentials followed by the hydrodynamic forces and moment. The model results are compared with those obtained from the multimodal solution. The free-surface elevation and hydrodynamic coefficients are also compared with the reported experimental and analytical data as well as numerical simulations to establish validity of the model. The capability of the model for predicting non-resonant slosh is also evaluated using the critical free-surface amplitude. The model validity is further illustrated by comparing the transient liquid slosh responses of a partially filled tank subject to steady lateral acceleration characterizing a vehicle turning maneuver with those obtained from fully nonlinear CFD simulations and pendulum models. It is shown that the linear slosh model yields more accurate prediction of dynamic slosh than the pendulum models and it is significantly more computationally efficient than the nonlinear CFD model. The slosh model is subsequently applied to roll plane model of a suspended tank vehicle to study the effect of dynamic liquid slosh on steady-turning roll stability limit of the vehicle under constant and variable axle load conditions. The results suggest that the roll moment arising from the dynamic fluid slosh yields considerably lower roll stability limit of the partly-filled tank vehicle compared to that predicted from the widely reported quasi-static fluid slosh model.