School of Water, Energy and Environment (SWEE)

Permanent URI for this community

https://dspace.lib.cranfield.ac.uk/handle/1826/8737

Browse

Browsing School of Water, Energy and Environment (SWEE) by Publisher "AIP Publishing"

Now showing 1 - 5 of 5
  • Thumbnail Image
    ItemOpen Access
    An improved implicit direct-forcing immersed boundary method (DF-IBM) around arbitrarily moving rigid structures
    (AIP Publishing, 2024-10-01) Farah, Elias; Ouahsine, A.; Verdin, Patrick G.
    An improved implicit direct-forcing immersed boundary method (DF-IBM) is presented for simulating incompressible flows around complex rigid structures undergoing arbitrary motion. The current approach harnesses the pressure implicit with splitting of operators algorithm to handle the fluid–solid system's dual constraints in a segregated manner. As a result, the divergence-free condition is preserved throughout the Eulerian domain, and the no-slip velocity boundary condition is exactly enforced on the immersed boundary. A new pressure Poisson equation (PPE) is derived, incorporating the boundary force where the no-slip condition is already met, enabling the use of fast iterative PPE solvers without modifications. The improvement involves integrating Lagrangian weight methods having better reciprocity over the IBM-related linear operators with the implicit formulation. An additional force initialization scheme is introduced to further boost the algorithm's performance. The method's accuracy, efficiency, and capability are verified through various stationary and moving immersed boundary cases. The results are validated against experimental and numerical data from the literature. The proposed improvements seamlessly integrate into existing incompressible fluid solvers with minimal adjustments to the original system equations, highlighting their ease of implementation.
  • Thumbnail Image
    ItemOpen Access
    The design and modification of a parabolic trough system for the hydrothermal liquefaction of waste
    (AIP Publishing, 2019-07-26) Almond, Heather; Tonnellier, Xavier; Sansom, Christopher L.; Pearce, Matt; Sengar, Namrata
    We describe the design of a small-scale parabolic trough with a high-pressure absorber bundle to convert microalgae into bio-oil. The “proof-of-concept” system uses an existing Global CSP solar captor, with its reflectance enhanced by the addition of Skyfuel® ReflecTech Plus polymer film and has its original receiver tube replaced by a novel high-pressure multi-tube absorber and reactor. Initial results obtained at Kota University in Rajasthan, India demonstrated that temperatures up to 320°C are possible, and a bio-oil, similar to palm oil, was extracted from the reactor.
  • Thumbnail Image
    ItemOpen Access
    Effects of a breakwater on a floating solar farm in heading and oblique waves
    (AIP Publishing, 2024-11-01) Zou, Detai; Wei, Yujia; Ou, Binjian; Zhang, Chao; Chu, Shengnan; Huang, Luofeng
    Floating photovoltaic (FPV) solar farms have gained significant research and industrial interest in recent years. However, to support its deployment in abundant ocean space, FPV is required to be protected against wave loading. Thus, the usage of a breakwater in front of a floating solar farm is particularly promising. In this work, a time-domain simulation model for an array of FPV solar units in heading and oblique waves was established. Following validation against experiments, the model was used to predict the wave-induced motion and loading responses of each floating solar unit in an array, first without a breakwater, and subsequently with a breakwater. By comparison, it was found that a breakwater can reduce the wave-induced motions of a floating solar farm by up to 56%, alongside up to 55% reduction of loading on the joints between FPV units. However, the breakwater is less effective in relatively long waves and could induce some increase in loading on joints, signifying future work to optimize the design of the breakwater based on the intended environmental condition. Overall, the present results provide insights into a practical breakwater solution for FPV in offshore and coastal conditions, supporting the long-term development of this industry.
  • Thumbnail Image
    ItemOpen Access
    Nonlinear hydroelastic responses of a submerged horizontal plate under focused wave conditions: a cumulative fatigue perspective
    (AIP Publishing, 2025-01-31) Ding, Haoyu; Huang, Luofeng; Zang, Jun
    Most current analytical research on the hydroelastic interaction between water waves and submerged horizontal elastic plates remains within the scope of linear theory due to the underdevelopment of mathematical methods for solving nonlinear problems. To address this gap, this work employs an approach that combines computational fluid dynamics (CFD) with computational solid mechanics (CSM) to dynamically simulate the fully coupled nonlinear hydroelastic interactions between ocean waves and a submerged horizontal plate. This research highlights the significance of nonlinear point responses of a submerged horizontal plate under focused wave conditions. A phase-based harmonic separation method (i.e., phase-decomposition method) is used to isolate wave amplitude and force harmonic components in complex wave scenarios. This approach allows for the clean delineation of individual harmonics from the total wave force by controlling the phase of incident focused waves and is for the first time applied to the response analysis of elastic structures. This paper successfully used the phase-decomposition method to separate the individual harmonics of the point displacement of a horizontal elastic plate, directly demonstrating the significance of nonlinear responses. Additionally, the impact of plate rigidity, which relates to natural frequency, on nonlinear responses is investigated. The results indicate that plates with a certain dimensionless plate rigidity will exhibit more significant nonlinear responses. By cleanly separating each individual harmonic response, this study provides new insights into the nonlinear hydroelastic responses of a horizontal plate interacting with water waves and offers a new perspective on fatigue analysis, underscoring the importance of nonlinearity for future engineering designs.
  • Thumbnail Image
    ItemOpen Access
    Numerical investigation of wave induced thrust on a submerged hydrofoil
    (AIP Publishing, 2024-09-01) Xing, Jingru; Stagonas, Dimitris; Hart, Phil; Zhang, Chengchun; Yang, Jianhui; Yang, Liang
    Submerged flapping hydrofoils have the capability to directly convert wave energy into thrust, offering a sustainable approach to marine propulsion. This research employs computational fluid dynamics (CFD) to analyze the propulsion mechanism of wave-induced flapping hydrofoils. Initially validated through established benchmarks and experimental results with foil in uniform flow, the CFD model was then applied to examine the generation of thrust by flapping hydrofoils in heading regular wave. The study reveals a distinct transition from drag to thrust, characterized by the patterns of vortex flow. For the first time, the influence of pitch stiffness on this propulsion process is extensively explored, identifying optimal wave conditions and pitch stiffness for the application of future eco-friendly marine systems.