Responses of an articulated tower in waves and currents
- Additional Document Info
- View All
The responses of an articulated loading platform (ALP) in random waves and currents are investigated both in frequency and time domain. The first- and second-order wave diffraction-radiation is solved by the ring source boundary integral equation method, and the viscous drag forces are computed from the modified Morison equation using relative velocity squared. In the frequency-domain analysis, the nonlinear drag is stochastically linearized and the resulting equation is solved iteratively. In the time-domain analysis, the nonlinear equation - including the quadratic drag term and a convolution integral - is directly integrated using a Newmark-beta method. From our numerical examples, it is shown that the slowly varying resonant responses in random waves are significant compared to wave-frequency responses when there is no current or when the current is normal to the wave direction, while they are greatly reduced when there exists strong in-line (coplanar or adverse) current. However, the presence of strong in-line current significantly increases the mean pitch angle.
International Journal of Offshore and Polar Engineering
author list (cited authors)
complete list of authors