Abstract: The relevant calculation formulas of the steady force and the second-order force transfer function are derived from the second-order force calculation of the first-order potential. The second-order differential frequency forces of the incident and diffractive waves arethen approximately calculatedand the corresponding calculation program is compiled based on the method of AQWA. The calculated steady force and the second-order force quadratic transfer function of a floating production storage and offloading (FPSO) unit are compared with those results from the AQWA. It also analyzes the influence of the extended boundary integral equation method on the steady forces, and the contribution of the steady force components, such as thevariation of the wet surface and the square of the velocity potential gradient, to the resultants, as well as the variation of the quadratic transfer function of the second-order frequency difference force with water depth.At last, the problems that should be noticed are summarized.

Key words: hydrodynamic, steady drift force, second-order force transfer function, near field method

摘要： 基于一阶势的二阶力计算方法,给出了定常力、二阶力传递函数的相关计算公式推导;借鉴AQWA软件的方法,引入二阶入射和绕射差频力的近似计算方法,并编制相关计算程序;基于算例FPSO给出了与AQWA软件的定常力、二阶力平方传递函数计算结果对比;并且对扩展边界积分法对定常力结果的影响,湿表面变化、速度势梯度平方等定常力分量对合成结果的贡献,以及二阶差频力平方传递函数随水深的变化等进行了分析,并总结了研究中应注意的相关问题。

关键词: 水动力, 定常漂移力, 二阶力传递函数, 近场方法