SEAKEEPING OF A RECTANGULAR BARGE WITH SKIRTS - FROM MODEL TESTS TO NUMERICAL WAVE TANK SIMULATIONS

For decades now, wave basin model tests have been the cornerstone of the verification of new concept global performance. Model tests are also the preferred approach to shed light on complex hydrodynamics phenomena that cannot be correctly handled by the conventional seakeeping engineer's toolbox. Two decades ago, model tests were performed on a seemingly simple geometry in the form of a rectangular barge with horizontal skirts fitted at its keel. The hull was held in place via a soft horizontal mooring system for simplicity and with a view to concentrating on the hydrodynamics. The objective was to investigate the likelihood of subharmonic resonance when the roll natural period is in the vicinity of twice the heave natural period (Ref. [1]). It is useful to revisit state of the art seakeeping toolbox and assess to what extent the beam regular and irregular wave tests can be reproduced numerically. Numerical Wave Tanks (NWT) are being considered as a possible substitute for model tests for well-defined scope of works. Such techniques based on Computational Fluid Dynamics (CFD) using Euler's equations have been applied to the rectangular barge with skirts as a test case for this new verification approach excluding viscosity. The paper briefly describes the scope of the model test campaign, documents performance of the ANSYS-AQWA suite of program in reproducing the key model tests (decay, monochromatic beam wave and irregular beam wave tests) and finally highlights the performance of the NWT for this specific geometry and abovementioned tests.