Development of energy flow models to predict sound fields for sound absorbing structures in medium-to-high frequency ranges
Abstract Energy flow analysis (EFA) model for the treatment of sound absorbing structures is developed to predict sound fields of engineering systems in medium-to-high frequency ranges. Thus far, EFA for acoustic models has been developed only for low damping media, such as air and water. A new energy flow governing equation is derived in this […]
A Study on the Cavitation Model for the Cavitating Flow Analysis around the Marine Propeller
Abstract In this study, a cavitation model for propeller analysis was selected using computational fluid dynamics (CFD), and the model was applied to the cavitating flow around the Potsdam Propeller Test Case (PPTC) propeller. The cavitating flow around the NACA 66 hydrofoil was analyzed to select a cavitation model suitable for propeller analysis among various […]
Deep learning-based high-frequency source depth estimation using a single sensor
Abstract The sensitivity of underwater propagation models to acoustic and environmental variability increases with the signal frequency; therefore, realizing accurate acoustic propagation predictions is difficult. Owing to this mismatch between the model and actual scenarios, achieving high-frequency source localization using model-based methods is generally difficult. To address this issue, we propose a deep learning approach […]
Detection and Tracking for the Awareness of Surroundings of a Ship Based on Deep Learning
Abstract To prevent maritime accidents, it is crucial to be aware of the surrounding environment near ships. The images recorded by a camera mounted on a ship could be used for the awareness of other ships surrounding it. In this study, ship awareness was performed using three procedures: detection, localization, and tracking. Initially, ship detection […]
Exacerbation of Hydrate Agglomeration in the Presence of Kinetic Hydrate Inhibitor under High pH Conditions
Abstract The performance of Luvicap EG was investigated to verify the efficacy of mixing kinetic hydrate inhibitors (KHIs) and monoethylene glycol (MEG) while varying the pH conditions in an aqueous phase. The relative torque changes were relatively stable in an early stage of hydrate formation; however, they started to increase and showed fluctuation when the […]
Experimental investigation of model-based IMC control of severe slugging
Abstract Severe slugging formation has been investigated experimentally in a two-phase flow-loop composed of a downwardly inclined pipe and a vertical riser. In this study, a bifurcation diagram was made to more clearly identify which flow the current system has at each valve opening. A model was made by inputting the dimensions of the flow loop using […]
Design optimization of a marine current turbine having winglet on blade
Abstract Winglets on a turbine blade can modify flow features and improve a marine current turbine (MCT). In this work, to maximize the power coefficient (CP) and torque (T), cant angle (α), and height (h) of a winglet of an MCT were modified. The problem was solved using a high-fidelity solver code Fluent 2019R2 containing Reynolds-Averaged Navier–Stokes (RANS) equations. The […]
Undrained bearing capacity of spudcan in soft-over-stiff clay after penetration
Abstract As the boundary condition of jack-up systems, the foundation model of offshore structures affects the vibration mode and structural behavior of leg structure. Typical simple foundation models such as pinned and linear spring do not reflect either plastic failure or the resulting plastic behavior of the soil. Alternatives, for example Model B for clay, derived for consideration of […]
Yield interaction model of jack-up considering nonlinear load-displacement relationship before yield
Abstract Offshore structures with jack-up systems can be operated at depths up to 150 m and are used not only as drilling rigs and production rigs but also as support and accommodation units. Jack-up operation is carried out under environmental loads such as wind and wave, for which it is essential to understand jack-up behavior and structural response. As […]
Application of analytical model in the prediction of dynamic responses and fatigue damage of flexible risers: Part II – Dynamic analysis of flexible risers in large-scale domain using a direct moment correction method
Abstract In recent years, the dynamic responses of flexible risers have been the focus of many researchers. Most flexible risers undergo a substantial level of irregular motion from environmental loadings, which involves a continuous slip of helical wires. The slip of helical wires especially leads to a hysteretic effect by reducing the bending stiffness, making it hard to […]
