Fully nonlinear modeling of radiated waves generated by floating flared structures

• Published in: Acta mechanica Sinica Vol. 30; no. 5; pp. 667 - 680
• Main Authors: Zhou, Bin-Zhen, Ning, De-Zhi, Teng, Bin, Zhao, Ming
• Format: Journal Article
• Language: English
• Published: Heidelberg The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences 01.10.2014
• Subjects: Classical and Continuum Physics; Computational Intelligence; Computer simulation; Cylinders; Engineering; Engineering Fluid Dynamics; Heave; Higher harmonics; Mathematical analysis; Mathematical models; Nonlinearity; Potential theory; Research Paper; Theoretical and Applied Mechanics; 喇叭形; 数值模拟; 浮动; 结构; 自由表面; 辐射波; 非线性建模; 非线性数学模型; Bodynonlinear; HOBEM; Flared structure; Fully nonlinear; Wave radiation
• ISSN: 0567-7718; 1614-3116
• DOI: 10.1007/s10409-014-0045-6

The nonlinear radiated waves generated by a structure in forced motion, are simulated numerically based on the potential theory. A fully nonlinear numerical model is developed by using a higher-order boundary element method （HOBEM）. In this model, the instantaneous body position and the transient free surface are updated at each time step. A Lagrangian technique is employed as the time marching scheme on the free surface. The mesh regridding and interpolation methods are adopted to deal with the possible numerical instability. Several auxiliary functions are proposed to calculate the wave loads indirectly, instead of directly predicting the temporal derivative of the velocity potential. Numerical experiments are carried out to simulate the heave motions of a submerged sphere in infinite water depth, the heave and pitch motions of a truncated flared cylinder in finite depth. The results are verified against the published numerical results to ensure the effectiveness of the proposed model. Moreover, a series of higher harmonic waves and force components are obtained by the Fourier transformation to investigate the nonlinear effect of oscillation frequency. The difference among fully nonlinear, body-nonlinear and linear results is analyzed. It is found that the nonlinearity due to free surface and body surface has significant influences on the numerical results of the radiated waves and forces.