Coupling analysis for sway motion box with internal liquid sloshing under wave actions

Jiang, Sheng-Chao and Bai, Wei ORCID: https://orcid.org/0000-0002-3537-207X (2020) Coupling analysis for sway motion box with internal liquid sloshing under wave actions. Physics of Fluids, 32 (7). 072106. ISSN 1070-6631

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Abstract

This work investigates the coupling effects of internal sloshing flow on the sway motion response of rectangular box sections. The impulseresponse-function method is employed for external wave action, while the viscous two-phase flow model with the volume of fluid interface capturing technique based on the OpenFOAM® package is adopted for the internal sloshing flow. A new lower critical frequency is defined to understand the coupling effects of the internal sloshing flow, which is the corresponding frequency of the minimal sway motion amplitude. The external wave and internal sloshing forces are out-of-phase at the lower critical frequency. The numerical simulations show that the lower critical frequency is equivalent to the sloshing natural frequency when the internal sloshing flow is in the non-breaking pattern. The nonbreaking sloshing-induced force approaches the same magnitude as the external wave force, which leads to a zero-amplitude sway motion. When the internal sloshing exhibits the breaking phenomenon, a phase transition of the internal sloshing force can occur, which causes the lower critical frequency to be smaller than the sloshing natural frequency. The increased incident wave amplitude or decreased tank breadth can strengthen the nonlinear behavior of the sloshing coupling action. That is, the sway motion response deviates more from the linear sloshing flow results, including the smaller lower critical frequency and the larger minimal sway motion amplitude. However, with the increased breaking-sloshing-induced nonlinearity, the difference in the sway motion response between the coupling and uncoupling results reduces, which implies a lower coupling effect.