Browsing by Author "Thomas, Giles"

Now showing 1 - 5 of 5
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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 15° 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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    New tools to generate realistic ice floe fields for computational models
    (American Society of Mechanical Engineers, 2022-05-26) Huang, Luofeng; Igrec, Bojan; Thomas, Giles
    Global warming has extensively transformed Arctic sea ice from continuous level ice coverage to unconsolidated ice floe fields. Whilst the ice floes have a mixture of different sizes and their locations are randomly distributed, contemporary computational models lack effective methods to generate floe fields with such a natural pattern. This work introduces two original tools that can generate realistic ice floe fields for computational models. They are a sequential generator that sequentially handles ice floes one by one, and a genetic generator based upon a genetic algorithm. Demonstration of the tools is given, presenting samples of generating various shapes of floes and arbitrary mixtures of different shapes. Furthermore, an example is provided that combines the generated floe field with computational work modelling a ship transiting in ice floes. In addition, the source code of the tools is sharable with the public.
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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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    Optimal array arrangement of oscillating wave surge converters: an analysis based on three devices
    (Elsevier, 2024-01-02) Benites-Munoz, Daniela; Huang, Luofeng; Thomas, Giles
    Wave farms consist of arrays of wave energy converters. However, ocean waves perturbed by one device will interact with its neighbouring devices, which can lead to more or less power yielded than operating the devices in isolation. Therefore, it is of significant interest to study the optimal layout and spacing to deploy multiple devices. In this work, a validated high-fidelity computational approach is used to study the optimal arrays of three oscillating wave surge converters by systematically varying the array arrangement in different wave conditions. The simulations demonstrate the wave interaction with multiple dynamic bodies and how this affects the overall power output. Furthermore, novel empirical rules are derived to design the optimal constructive layout for three devices in a given wave condition, and this can be extended to cases of numerous devices.
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    Towards a full-scale CFD guideline for simulating a ship advancing in open water
    (Taylor and Francis, 2023-01-17) Huang, Luofeng; Pena, Blanca; Thomas, Giles
    Computational Fluid Dynamics (CFD) simulations of a ship’s operations are generally conducted at model scale, but the reduced scale changes the fluid behaviour around the ship. Whilst ideally ship simulations should be run directly at full scale, a guide has not been published to advise on the suitable setups that can provide accurate results while minimizing the computational cost. To address this, the present work explores an optimal approach for full-scale ship simulations. Extensive sensitivity studies were conducted on relevant computational setups to investigate their influences on the prediction of ship resistance, ship-generated waves as well as the boundary-layer flow of the hull. A set of CFD setups for full-scale ship simulations in open water was recommended. It was demonstrated that the ideal Y+ and Courant numbers in full scale are evidently different from those given in current model-scale CFD guidelines, indicating the necessity to establish full-scale CFD guidelines separately.