Session: 01-03-02 Hydrodynamics-2

Submission Number: 182200

Validation of a Heuristic Method for Potential Flow Wave-Current Effects Into QTFS of Wave Drift Loads 

Floating structures usually respond with horizontal resonant motions to wave drift loads. On one hand it is acknowledged that correct representation of the phasing and magnitude of wave drift loads require use a full quadratic transfer functions (QTFs). Wave-current interactions also influence the wave drift forces. Most often, there is an increase of wave drift forces for waves and current moving in the same direction, compared to conditions with waves only. However, there are presently no numerical tools available to the industry for solving the full second order problem accounting for wave-current interactions.

This paper presents and validates an heuristic method to correct zero-current potential flow QTFs for wave-current effects. Validation is provided by comparing numerical results with model test data for a FPSO. Comparisons include diagonals of the surge QTF and time series and spectra of the low frequency motions. The results show that the zero current numerical QTF compares reasonably well with the empirical QTFs for the zero current tests, while they significantly underestimate for the cases with current. The heuristic correction method provides good estimates of the QTF as compared to the empirical ones. Time domain simulations compared to measured low frequency motions lead to the same conclusions.

Presenting Author: Nuno Fonseca Sintef Norway

Presenting Author Biography: MSc in Naval Architecture from the University of Glasgow, 1994
PhD in ship hydrodynamics from the University of Lisbon, 2001
Assistant Professor at the University of Lisbon, 2001-2014
Presently Chief Scientist at SINTEF Ocean

Authors:

Nuno Fonseca Sintef Norway
Babak Ommani NTNU
Guillaume De Hauteclocque Bureau Veritas
Cédric Brun Bureau Veritas