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CFD prediction of ship response to extreme winds and/or waves.

机译：CFD预测船舶对极端风和/或波浪的反应。

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摘要

The effects of winds and/or waves on ship motions, forces, moments, maneuverability and controllability are investigated with URANS computations.The air/water flow computations employ a semi-coupled approach in which water is not affected by air, but air is computed assuming the free surface as a moving immersed boundary. The exact potential solution of waves/wind problem is modified introducing a logarithmic blending in air, and imposed as boundary and initial conditions. The turbulent air flows over 2D water waves are studied to investigate the effects of waves on incoming wind flow. Ship airwake computations are performed with different wind speeds and directions for static drift and dynamic PMM in calm water, pitch and heave in regular waves, and 6DOF motions in irregular waves simulating hurricane CAMILLE. Ship airwake analyses show that the vortical structures evolve due to ship motions and affect the ship dynamics significantly. Strong hurricane head and following winds affect up to 28% the resistance and 7% the motions. Beam winds have most significant effects causing considerable roll motion and drift forces, affecting the controllability of the ship.A harmonic wave group single run seakeeping procedure is developed, validated and compared with regular wave and transient wave group procedures. The regular wave procedure requires multiple runs, whereas single run procedures obtain the RAOs for a range of frequencies at a fixed speed, assuming linear ship response. The transient wave group procedure provides continuous RAOs, while the harmonic wave group procedure obtains discrete transfer functions, but without focusing. Verification and validation studies are performed for transient wave group procedure. Validation is achieved at the average interval of 9.54 (%D). Comparisons of the procedures show that harmonic wave group is the most efficient, saving 75.8% on the computational cost compared to regular wave procedure. Error values from all procedures are similar at 4 (%D). Harmonic wave group procedure is validated for a wide range of Froude numbers, with satisfactory results.Deterministic wave groups are used for three sisters rogue waves modeling. A 6DOF ship simulation is demonstrated which shows total loss of controllability with extreme ship motions, accelerations and structural loads.
机译：通过URANS计算研究了风和/或波对船舶运动，力，力矩，可操纵性和可控性的影响。空气/水流量计算采用半耦合方法，其中水不受空气影响，但空气被计算假设自由表面为移动的浸入边界。修改了波浪/风问题的精确潜在解决方案，在空气中引入了对数混合，并将其作为边界条件和初始条件。研究了二维水波上的湍流气流，以研究波浪对入风的影响。船舶空中唤醒的计算采用不同的风速和风向，以模拟平静水面中的静态漂移和动态PMM，规则波中的俯仰和升沉，以及不规则波中的6DOF运动，以模拟卡米尔飓风。船舶空中唤醒分析表明，旋涡结构由于船舶运动而演化，并显着影响船舶动力学。强飓风头和随风影响高达28％的阻力和7％的运动。束风的最显着影响是会引起相当大的侧倾运动和漂移力，从而影响船舶的可控性。谐波群单程航海程序被开发，验证并与常规波和瞬态波群程序进行了比较。常规波浪程序需要多次运行，而单次运行程序则假设线性舰船响应，以固定速度获得一系列频率的RAO。瞬变波组过程提供了连续的RAO，而谐波波组过程获得了离散的传递函数，但是没有聚焦。对瞬变波群程序进行验证和确认研究。验证的平均间隔为9.54（％D）。程序比较表明，谐波组是最有效的，与常规波程序相比，节省了75.8％的计算成本。来自所有过程的错误值在4（％D）处相似。对大范围的Froude数验证了谐波波群程序，并获得了令人满意的结果。确定性波群用于三姐妹流浪波建模。演示了6DOF船舶仿真，该仿真显示了船舶极端运动，加速和结构载荷时，可控性完全丧失。

著录项

  • 作者

    Mousaviraad, Sayyed Maysam.;

  • 作者单位

    The University of Iowa.;

  • 授予单位 The University of Iowa.;
  • 学科 Engineering Marine and Ocean.Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 152 p.
  • 总页数 152
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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