Numerical simulation of Faraday waves in a rectangular tank and damping mechanism of internal baffles

Abstract

Parametric sloshing and damping mechanism of internal baffles were systematically investigated through an in-house numerical model NEWTANK (developed by Xue and Lin, 2011). The internal baffles were modelled by the Virtual Boundary Force method. A good agreement of validation was achieved, then the numerical model was applied to investigate the mode 2 to mode 5 Faraday waves in tanks with various baffles, and the damping mechanism has been uncovered. Four kinds of baffles, including vertical, horizontal, ring and T-shape baffles, have been considered. The wave was divided into two categories: symmetric and asymmetric modes. The effectiveness of those baffles was identified by estimating the waveform, velocity and vortex fields; and the effective baffle configurations for various waveforms were proposed. The key issue was to suppress the vertical motion at the tank sidewalls for the symmetric mode; as for the asymmetric mode, the constraint of the horizontal movement at the wave nodes was proved to be more vital. The ring baffle was effective to suppress the mode 2 Faraday wave but lost efficacy for the mode 3 Faraday wave; the horizontal baffle was applicable for both mode 2 and mode 3 Faraday waves; and the vertical baffle was superior to the T-shape baffle in mitigation of the mode 2 Faraday wave, but was inferior to the latter as for the mode 3 Faraday wave. The effectiveness of the T-shape baffle in/close to the wave nodes was further identified through simulations of higher modal Faraday waves. Finally, the mitigation of the sloshing under coupled resonant surge and unstable heave excitations was presented and discussed.