SEA-WAVE-INDUCED SLOSHING OF LIQUID IN FLOATING STORAGE TANK WITH BAFFLES

Abstract

In the present study, a hybrid frequency-time domain simulation scheme is used to analyze the dynamic response of sea-wave-induced fully non-linear sloshing fluid in a floating tank with the present of baffles. The hydrodynamic coefficients and wave forces are firstly obtained by a potential-theory-based threedimensional (3D) radiation/diffraction panel program (DIFFRACT) in frequency domain. Then, a time domain model based on frequency domain data is built upon the Cummins equation to study the corresponding simulations of tank motions. State-space models are proposed as approximate representations of the convolutions in this equation. Navier-Stokes equations are applied to simulate the nonlinear fluid sloshing in time-domain and solved using the finite difference method (FDM) and the volume of fluid method (VOF). Rigid baffles are modelled by using internal-obstacle boundary conditions. The multi-cable mooring system is used as a sea-keeping approach. During simulation time, the sloshing model, the mooring model and the floating tank model are coupled so that the interaction between them can be considered. Several parameters of interesting, including type of baffles, dimension of baffles and location of baffles as well as effect of baffles under different wave frequencies are investigated. In order to show the effect of baffles, some results of the coupled dynamic system such as the dynamic response of the floating tank and sloshing elevation of liquid inside the storage tank will be presented and compared with corresponding results of the cases without baffles. The study is important for the floating storage system under sea conditions.