Absorption of outgoing waves in a numerical wave tank using a self-adaptive boundary condition

Citation
G. Duclos et al., Absorption of outgoing waves in a numerical wave tank using a self-adaptive boundary condition, INT J OFFSH, 11(3), 2001, pp. 168-175
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Civil Engineering
Journal title
INTERNATIONAL JOURNAL OF OFFSHORE AND POLAR ENGINEERING
ISSN journal
1053-5381 → ACNP
Volume
11
Issue
3
Year of publication
2001
Pages
168 - 175
Database
ISI
SICI code
1053-5381(200109)11:3<168:AOOWIA>2.0.ZU;2-O
Abstract
An absorbing boundary condition for time-domain Numerical Wave Tanks (NWT) is developed from a previous study related to active physical absorbers for a wave basin. The starting point is the same: The optimal (ideal) time dom ain absorption condition for a moving piston is expressed as convolution pr oducts of the velocity by the hydrodynamic force on the moving piston. The present extension to fixed boundaries of the numerical fluid domain is base d on the approximation of the convolution kernels by exponential series exp ansions. This is achieved by using Prony's method, which is detailed in the Appendix. The time-domain absorption condition is then expressed as a set of ordinary differential equations which can be easily and naturally append ed to the initial ODEs set of the NWT algorithm. The coefficients of the ne w ODE for a piston-like condition are given. In order to improve absorption efficiency, some of these coefficients are continuously varied during the simulation, according to the output of a Kalman filter scanning the instant aneous frequency of the force signal. For this reason the method is said to be self-adaptive. This results in very high absorption coefficients in a b road range of wave frequency.