Riassunto analitico
Numerical simulation of the airflow around sailboats presents a formidable challenge due to the exceptionally thin nature of the sail membrane. These slender aerofoil cross-sections introduce unique complexities into computational modeling and flow physics. These complexities manifest as phenomena like leading-edge separation and laminar separation bubbles, which are further compounded by the variability in input conditions arising from the turbulent and fluctuating wind velocities characteristic of sailboat environments.In the pursuit of this thesis, our primary objective revolves around the development of a meticulously validated Computational Fluid Dynamics (CFD) model. This model is constructed using a rich dataset of experimental data and sailboat geometry meticulously sourced from the esteemed Yacht Research Unit (YRU) at the University of Auckland. Leveraging the power of the K-$\omega$ SST model within the framework of a Reynolds-Averaged Navier Stokes (RANS) Solver implemented in OpenFOAM, an open-source CFD code, we achieve reasonable accuracy in resolving the steady-state coefficients of lift ($C_L$) and drag ($C_D$). These results consistently fall within a narrow margin of 5\% to 10\% when compared to the corresponding experimental data. Furthermore, the sectional pressure coefficient distribution extracted from our CFD simulations demonstrates a striking alignment with the experimental findings. This validation process not only affirms the reliability of our CFD approach but also establishes a set of best practices for conducting simulations of rigid sails in general.Following the successful validation, our research delves deeper into the intricate realm of wind fluctuations. Specifically, we direct our attention to the impact of Turbulence Intensity on the Laminar Separation Bubble and its consequences on the overall performance of sailboats. By subjecting our validated model to varying levels of Turbulence Intensity, we gain insights into how this crucial factor influences the behavior of the Laminar Separation Bubble and, by extension, the overall efficiency and performance of sailboats. This investigation contributes significantly to our understanding of the dynamic interplay between wind turbulence and sailboat aerodynamics, shedding light on an essential facet of sailing performance optimization.
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Abstract
Numerical simulation of the airflow around sailboats presents a formidable challenge due to the exceptionally thin nature of the sail membrane. These slender aerofoil cross-sections introduce unique complexities into computational modeling and flow physics. These complexities manifest as phenomena like leading-edge separation and laminar separation bubbles, which are further compounded by the variability in input conditions arising from the turbulent and fluctuating wind velocities characteristic of sailboat environments.In the pursuit of this thesis, our primary objective revolves around the development of a meticulously validated Computational Fluid Dynamics (CFD) model. This model is constructed using a rich dataset of experimental data and sailboat geometry meticulously sourced from the esteemed Yacht Research Unit (YRU) at the University of Auckland. Leveraging the power of the K-$\omega$ SST model within the framework of a Reynolds-Averaged Navier Stokes (RANS) Solver implemented in OpenFOAM, an open-source CFD code, we achieve reasonable accuracy in resolving the steady-state coefficients of lift ($C_L$) and drag ($C_D$). These results consistently fall within a narrow margin of 5\% to 10\% when compared to the corresponding experimental data. Furthermore, the sectional pressure coefficient distribution extracted from our CFD simulations demonstrates a striking alignment with the experimental findings. This validation process not only affirms the reliability of our CFD approach but also establishes a set of best practices for conducting simulations of rigid sails in general.Following the successful validation, our research delves deeper into the intricate realm of wind fluctuations. Specifically, we direct our attention to the impact of Turbulence Intensity on the Laminar Separation Bubble and its consequences on the overall performance of sailboats. By subjecting our validated model to varying levels of Turbulence Intensity, we gain insights into how this crucial factor influences the behavior of the Laminar Separation Bubble and, by extension, the overall efficiency and performance of sailboats. This investigation contributes significantly to our understanding of the dynamic interplay between wind turbulence and sailboat aerodynamics, shedding light on an essential facet of sailing performance optimization.
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