High-fidelity CFD investigation on parametric roll resonance of the KCS hull under various wave headings

Parametric roll is a severe dynamic instability that critically threatens the safety of modern large-scale vessels. To systematically resolve the profound directional asymmetry in wave-hull interactions—where vulnerability drastically shifts depending on the wave heading—this study establishes a high-fidelity numerical benchmark using Unsteady Reynolds-Averaged Navier-Stokes (URANS) CFD. Overcoming the inherent challenges of multi-directional wave simulations, a specialized grid topology was developed, featuring both high-resolution horizontal wave discretization and vertically extended free-surface refinement. This was coupled with VOF wave forcing boundaries to guarantee stable, long-duration wave propagation without reflection. Furthermore, a tightly controlled 4-DOF (surge, heave, roll, pitch) bare-hull configuration was uniquely employed to rigorously isolate the hull's inherent hydrodynamic vulnerability from the confounding noise of active steering and transverse drift. By evaluating the dynamic responses of the KRISO Container Ship (KCS), the multi-directional instability zones were mapped. The fully coupled simulations successfully quantify this extreme directional asymmetry: at a low forward speed of 8 knots, waves approaching from the stern—specifically following and quartering seas—pose the most critical threat, inducing severe roll amplitudes close to or exceeding 25.0° due to parametric resonance near the principal 2:1 encounter frequency ratio. Conversely, head seas constrain the resonance to an exceptionally narrow range of long waves, attenuating the maximum amplitude to 16.0°, while bow seas exhibit complete dynamic stability. Ultimately, this rigorously validated methodology and the resulting multi-directional dataset provide profound physical insights, serving as an essential reference to calibrate and refine simplified operational guidance models.