Numerical analysis on the secondary load cycle on a vertical cylinder in steep regular waves
Numerical analysis on the secondary load cycle on a vertical cylinder in steep regular waves
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DOI：
10.1016/j.oceaneng.2018.08.064
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发表时间：
2018-11
影响因子：
5
通讯作者：
Xiang Fan;Jingxin Zhang;Hua Liu
中科院分区：
文献类型：
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作者：
Xiang Fan;Jingxin Zhang;Hua Liu
大振幅规则波引起的二次载荷循环对海洋结构物的振铃响应有重要影响。为了解直立圆柱周围自由表面局部剧烈水变形对波浪荷载影响的机理，对规则波陡波情况进行了数值模拟。数值波浪水槽通过求解两相不可压Navier-Stokes方程建立。采用VOF方法捕捉圆柱附近有自由表面的剧烈流动。实验测量和理论计算结果验证了数值模型的正确性。根据幅值、持续时间和相位定义了二次载荷循环的新特征参数。讨论了波陡、相对直径和相对深度对这些特征参数的影响。结果表明，特征参数主要取决于相对波高和相对圆柱直径，而对相对水深的依赖性较弱。利用拟合方法，提出了计算不同波陡和相对直径的二次加载循环特征参数的经验公式。
The secondary load cycle induced by regular waves of large amplitude has an important influence on the ringing response of offshore structures. To understand the mechanism of the effect of local violent water deformation of the free surface around a vertical cylinder on the wave loads, the numerical simulations are carried out for the cases of the steep regular waves. The numerical wave tank is established by solving the two-phase incompressible Navier–Stokes equations. The VOF method is applied to capture the violent flow with the free surface near the cylinder. The numerical model is validated by experimental measurement and theoretical result. New characteristic parameters of the secondary load cycle are defined in terms of the amplitude, duration and phase. The effects of wave steepness, relative diameter and relative depth on these characteristic parameters are presented and discussed. The results show that the characteristic parameters depend mainly on relative wave height and relative diameter of cylinder while the dependence on relative depth is weak. Using the fitting method, the empirical formulas are proposed to calculate the characteristic parameters of the secondary load cycle in terms of different wave steepness and relative diameter.