Fluid-structure interaction mapping method for sloshing loads in liquid cargo tanks based on Flow-3D

The accurate transfer and mapping of sloshing loads in liquid cargo tanks are critical to fluid−structure interaction (FSI) simulations for liquid cargo vessels. At present, the engineering field lacks standardized, general-purpose load mapping methods and dedicated standalone tools, which hinders efficient data exchange and integrated analysis between mainstream sloshing load prediction software and structural finite element analysis software in the shipbuilding industry. This technical bottleneck not only reduces the efficiency of liquid tank FSI simulations but also constrains the accuracy and reliability of structural strength assessment and optimization design for liquid cargo vessels. To address this key technical problem, this study aims to overcome the technical barriers in data transfer between sloshing load simulations and structural analysis, and to develop a generalized and efficient load mapping solution.

Based on an in-depth comparative analysis of the data interface characteristics, mesh formats, and load output schemes of Flow-3D (a professional software for sloshing load prediction) and Patran (a structural analysis software), this study establishes a standardized data exchange framework between fluid simulation results and structural model inputs. On this framework, three sloshing load FSI mapping methods are proposed: the nearest single-point mapping algorithm, the multi-point averaging mapping algorithm, and the shape function-based mapping algorithm, which balance computational efficiency and numerical accuracy. An independent load mapping software tool is developed using C++. The tool integrates five core functional modules: load mapping parameter input, structural model import, sloshing load data import, mapping algorithm execution, and mapping result output, enabling a complete automated workflow from fluid load prediction to structural load application.

A 45 m twin-hull liquid cargo tank is adopted as a validation case for a real-ship example test. The results show that the developed mapping tool can accurately transfer sloshing loads from the fluid model to the structural model, faithfully reproducing the time-dependent evolution and spatial distribution characteristics of sloshing loads acting on tank walls and internal structures. Quantitative error analysis indicates that the relative data transfer errors of all three mapping algorithms are controlled within 5%, meeting the engineering accuracy requirements for structural strength assessment. In terms of computational efficiency, the nearest single-point mapping takes 5 s, multi-point averaging mapping takes 6 s, and shape function-based mapping takes 14 s, which satisfy the application requirements for various operating conditions and model scales.

The generalized FSI mapping tool and methodological framework developed in this study fill a critical gap in dedicated tools for sloshing load mapping in liquid cargo tanks. The proposed approach can be widely applied to multi-physics coupling simulations, structural strength optimization, and safety performance evaluation of liquid cargo vessels. The tool features standalone operability, strong compatibility, and user-friendly implementation, effectively reducing manual data processing and significantly improving the efficiency of liquid tank FSI simulations. It provides robust technical support and an efficient solution for the design and research of liquid cargo vessels.