The Numerical Investigation of Structural Strength Assessment of LNG CCS by Sloshing Impacts Based on Multiphase Fluid Model

Sloshing flows of liquid natural gas (LNG) with multi-phase flow characteristics consisting of liquids and gases can affect the load conditions and structural response of cargo containment systems (CCS). The compressible properties of the sloshing flow can limit the maximum pressure, so a multi-phase fluid model is required to represent the sloshing physics. In this study, we identified a suitable numerical model to simulate the sloshing flow and structural strength evaluation based on the inhomogeneous fluid model. The computational fluid dynamics (CFD) is based on a Eulerian domain model, which is in turn based on the constant volume based finite element method (CVFEM) in a commercial Reynolds-averaged Navier–Stokes CFD code (ANSYS CFX). It includes the interphase momentum transfer between the liquids and gasses. The physics for the sloshing assessment were considered to identify the main aspects of the inhomogeneous multiphase model. For numerical analysis of the sloshing, we conducted a sloshing simulation on the experimental data of the model scale to examine the validity of the results. The velocity of the sloshing flow was extended to the real scale and applied to a local two-way fluid structure interaction (FSI) analysis model. Structural strength evaluation of the LNG CCS by sloshing flow was performed by FSI analysis. Through the example of structural response analysis of Mark III type CCS, the results were discussed and effectiveness of the proposed structural response assessment model by sloshing was reviewed.