Assessment of Sloshing Loads for Tankers

Abstract

This chapter presents a new procedure to assess sloshing loads for tankers, which is then applied to a sample tanker. Starting with computed ship motions and fluid motions inside partially filled tanks, critical fill levels were identified. Simulation of fluid flow was performed with a finite volume method for each critical fill level. Two- and three-dimensional flow computations were employed to predict pressure loads for panel sized patches of tank walls. Time traces of pressure were analyzed, and resulting maximum loads were compared for all critical fill levels to determine overall maximum loads. Results generally agreed favorably with current rule based values. Sloshing simulations were performed for all the critical fill levels and selected results were presented to illustrate the new approach. Computed pressures were spatially averaged to characterize pressures over ship structural panels. Maximum pressures were extracted from time traces and displayed for all fill levels to identify an envelope of maximum pressure. For the forward tank, three-dimensional computations were necessary to account for the narrowing beam of the tank. For this case, three-dimensionally computed pressures were twice as large a two-dimensional computed pressures. Also, a systematic investigation of other three dimensional tank geometries is necessary to assess whether three-dimensional computations are required.