Browsing by Author "Li, Minghao"

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    COVID-19 transmission inside a small passenger vessel: risks and mitigation
    (Elsevier, 2022-05-19) Huang, Luofeng; Riyadi, Soegeng; Utama, I.K.A.P.; Li, Minghao; Sun, Peiyign; Thomas, Giles
    The global shipping industry has been severely influenced by the COVID-19 pandemic; in particular, a significant amount of passenger transportation has been suspended due to the concern of COVID-19 outbreak, as such voyages confine a dense crowd in a compact space. In order to accelerate the recovery of the maritime business and minimise passengers' risk of being infected, this work has developed a computational model to study the airborne transmission of COVID-19 viruses in the superstructure of a full-scale passenger vessel. Considering the vessel advancing in open water, simulations were conducted to study the particulate flow due to an infected person coughing and speaking, with the forward door open and closed. The results suggest that keeping the forward door closed will help prevent the external wind flow spreading the virus. When the forward door is closed, virus particles' coverage is shown to be limited to a radius of half a metre, less than a seat's width. Thus, an alternate seat arrangement is suggested. Furthermore, investigations were conducted on the influence of wall-mounted Air Conditioner (AC) on the virus transmission, and it was found that controlling the AC outlet direction at less than 15Ā° downward can effectively limit the virus spread. Meanwhile, it was demonstrated that an AC's backflow tends to gather virus particles in a nearby area, thus sitting farther from an opening AC may reduce the risk of being infected. Overall, this work is expected to inform hygienic guidelines for operators to counter COVID-19 and potentially similar viruses in the future.
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    An investigation on the speed dependence of ice resistance using an advanced CFD+DEM approach based on pre-sawn ice tests
    (Elsevier, 2022-09-18) Huang, Luofeng; Li, Fang; Li, Minghao; Khojasteh, Danial; Luo, Zhenhua; Kujala, Pentti
    Over the past decades, the underlying mechanism of level ice resistance changing with ship speed has not been fully understood, particularly the resistance component due to ship interactions with broken ice pieces. Pre-sawn ice test can negate icebreaking component from the whole resistance of a ship in level ice, providing an effective approach to decompose ship-ice interactions and investigate the speed-dependent resistance from broken ice pieces. This work has built a computational model that can realistically simulate a ship advancing in a pre-sawn ice channel. The model applies Computational Fluid Dynamics (CFD) to solve the flow around an advancing ship, which is coupled with an enhanced Discrete Element Method (DEM) to model pre-sawn ice pieces. Model-scale experiments have also been conducted at the Aalto Ice Tank to validate the simulations, which shows the computational model can provide a reasonable estimation of the pre-sawn ice's resistance and movement around the ship. Upon validation, the dependence of ice resistance on ship speed was analysed. The simulations enable underwater monitoring of the ice motions, indicating that the speed dependence results from the mass of ice submerged underneath the ship and the displacement of broken ice induced by the ship. The identified relationships are more complex than the widely-used assumption that ice resistance linearly changes with ship speed in all cases, which provides a deeper understanding of ice resistance. As such, the findings from this study can potentially facilitate improvements in relevant empirical equations, useful for ship design, operational strategies and maritime management in polar regions.
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    Offshore COVID-19 risk assessment based on a fishing vessel
    (Elsevier, 2023-07-20) Huang, Luofeng; Hetharia, Wolter; Grech La Rosa, Andrea; Tavakoli, Sasan; Khojasteh, Danial; Li, Minghao; Riyadi, Soegeng; Setyawan, Dony; Utama, I. Ketut Aria Pria; Thomas, Giles
    Offshore crews often work near each other due to limited space, signifying a complex environment for the airborne transmission of the coronavirus (COVID-19). During offshore operations, a fishing vessel can be subjected to miscellaneous airflow conditions and will respond dynamically to ocean waves. To understand the risk of COVID-19 contagion, this research establishes a new computational model to analyse the airborne transmission of COVID-19 and develops effective mitigation strategies where possible. The concentration and coverage of coronavirus are scrutinised, considering typical airflows and wave-induced vessel motions. Furthermore, the COVID-19 infection risk is quantified using a probability index. The results show that the overall infection risk of a ship in tailwind is lower than in head or beam wind. Structural motions are for the first time coupled with the virus transmission, and it was found that the vessel's oscillating movement in waves can reinforce the virus concentration in close proximity to the infected person and may help diffuse the virus outside the proximal region. The presented findings can inform the airborne contagion risks and corresponding hygienic measures for maritime and offshore operations, facilitating long-term human health in seas.i
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    A review on the modelling of wave-structure interactions based on OpenFOAM
    (OpenCFD Ltd on behalf of the OpenFOAM Governance, 2022-08-28) Huang, Luofeng; Li, Yuzhu; Benites-Munoz, Daniela; Windt Windt, Christian; Feichtner, Anna; Tavakoli, Sasan; Davidson, Josh; Paredes, Ruben; Quintuna, Tadea; Ransley, Edward; Colombo, Marco; Li, Minghao; Cardiff, Philip; Tabor, Gavin
    The modelling of wave-structure interaction (WSI) has significant applications in understanding natural processes as well as securing the safety and efficiency of marine engineering. Based on the technique of Computational Fluid Dynamics (CFD) and the open-source simulation framework - OpenFOAM, this paper provides a state-of-the-art review of WSI modelling methods. The review categorises WSI scenarios and suggests their suitable computational approaches, concerning a rigid, deformable or porous structure in regular, irregular, non-breaking or breaking waves. Extensions of WSI modelling for wave-structure-seabed interactions and various wave energy converters are also introduced. As a result, the present review aims to help understand the CFD modelling of WSI and guide the use of OpenFOAM for target WSI problems.