Numerical Investigation of Sloshing Characteristics in Long Moving Vessels with Embedded Concave Rigid-ring Baffle in Gravity Environment

Abstract

Flat Rigid–ring Baffle [1] (FRB) is a common slosh suppression device in Long Moving Vessel (LMV) to mitigate against oscillation-induced instability due to sloshing of its content but, its relative low performance is unacceptable for desirable safety standard thus, necessitating continuous efforts to investigate other baffle configurations. Investigation of Concave Baffles of varying geometries was carried out and analysed with the ANSYS/CFX [2] and the Computational Fluid Dynamics (CFD). Results were post-processed with the help of Mat lab [3-5] in a gravity milieu. This work was therefore designed to study the sloshing characteristics of Water-Carrying Cylindrical (WCC) tank equipped with three baffles. Model governing equations based on conservation of mass and momentum were developed and solved using Finite Element Analysis (FEA) technique. The model was used to evaluate Damping Ratio (DR) from Mile's equation [1] at 72, 66 and 59 percent standard positions, in a 75 percent filled WCC tank with slenderness ratio of 1.5 excited at a frequency of 2 Hz. The investigated baffles were Concave Rigid-ring Baffle-1 (CARB1) 0.02 m pitch, Concave Rigid-ring Baffle-2 (CARB2) 0.04 m pitch and Flat Rigid-ring Baffle, FRB (control). Data were presented in term of non dimensional DR and as the main performance index. Numerical results were obtained and compared with FRB results also obtained numerically. The results showed that, the concave baffles exhibited [better damping characteristics at 72 and 59 percent water-filled positions of the cylinder which mostly the critical states hence, Concave-Rigid-ring Baffle have better damping effectiveness than Flat-Rigid-ring Baffle.