近水面水平圆柱在波浪作用下的水动力系数

Hydrodynamic Coefficients of a Horizontal Circular Cylinder near Free Surface under Wave Action

【目的】研究大幅非线性波浪作用下近水面水平圆柱上波浪力和水动力系数的特征。【方法】基于黏性流理论和有限体积方法开发数值波浪水槽模型,分析入射波波幅和波频率对波浪力特征的影响,提出可以考虑圆柱完全暴露于空气情况的改进Morison方程,通过大量的数据拟合得到水动力系数,并讨论改进的Morison方程对波浪力预测的适用性。【结果】圆柱上波浪力随波幅和频率增大逐渐增大,而由于浮力占重要比例,正垂向力受波频率的影响并不显著;所得近水面水平圆柱惯性力系数和速度力系数最大值比淹没圆柱在线性波浪作用下的水动力系数大。【结论】所提出改进的Morison方程对波浪力的预测有较好的适用性。

【Objective】This study investigates wave forces and hydrodynamic coefficients on a horizontal circular cylinder near the free surface under large-amplitude wave actions.【Method】A numerical wave tank model is developed based on the viscous fluid theory and finite volume method.By analyzing the characteristics of the wave forces on the circular cylinder,the influences of wave amplitude and wave frequency on the wave forces are investigated.A modified Morison’s equation for predicting the wave forces is derived,consider the condition of the circular cylinder is completely exposed to the air phase under the action of large-amplitude wave.The inertia and drag coefficients are obtained by solving the modified Morison’s equation.The applicability of the modified Morison’s equation for predicting the wave forces on the circular cylinder is discussed.【Result】The wave forces on the circular cylinder increase gradually with the increase of wave amplitude and wave frequency.The effects of wave frequency on the positive vertical waves are not significant because the buoyancy forces take up an important proportion.The maximums of the hydrodynamic coefficients obtained are larger than those for a submerged circular cylinder under linear wave action.【Conclusion】The modified Morison’s equation works well for the prediction of the wave forces.