Transient wave diffraction around cylinders by a novel boundary element method based on Fourier-Laguerre expansions

ABSTRACT

A novel boundary element method based on series expansion is developed for wave diffraction by a vertical circular cylinder in the time domain. Unlike traditional potential flow boundary element methods in which velocity potentials are evaluated on each panel, both the velocity potential and its normal derivative are expanded by Laguerre functions in the vertical direction and Fourier series along the circumference of cylinder, respectively. A boundary integral equation is therefore established associated with expansion coefficients in the sense of Galerkin collocation. Free-surface Green function in the time domain is no longer explicitly computed but its integration involving Fourier-Laguerre basis functions on the whole cylindrical surface is evaluated. Incoming waves are transient with wavefronts, which are more general than steady-state plane progressive waves. Results obtained by using the present method are compared with those from existing time-domain analysing method.

KEYWORDS:

• Fourier-Laguerre expansions
• integrated Green function
• transient wave diffraction
• wavefronts

Acknowledgements

The first author gratefully acknowledges fruitful discussions with Dr H. Liang from Technology Centre for Offshore and Marine, Singapore (TCOMS) on Fourier-Laguerre series expansion.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Ruipeng Li is a PhD candidate at Harbin Engineering University.

Xiaobo Chen is Director of International R&D Cooperation of Bureau Veritas, Marine & Offshore (Paris, France) and Visiting Professor of Harbin Engineering University (Harbin, China).

Wenyang Duan is a Professor at Harbin Engineering University.

Additional information

Funding

This work has been partially supported by the National Natural Science Foundation of China [grant numbers 51779054 and 51490671].