Towards a Computational Fluid Dynamics implementation of the critical wave groups method

Abstract

The prediction of extreme ship responses continues to be an important and longstanding topic in ship hydrodynamics with a significant focus on developing probabilistic methods based on simple descriptions of the hydrodynamics that mainly provide qualitative observations. While simple nonlinear hydrodynamic formulations provide insight into extreme events, their underlying assumptions can prevent accurate quantitative representations of the mechanisms that are ultimately responsible for the extreme responses.Thus, research must strive to utilize increasingly more accurate hydrodynamic formulations to provide quantitative evaluations of extreme events. The present work aims to integrate extreme event probabilistic research based on the critical wave groups (CWG) method and fully nonlinear Computational Fluid Dynamics (CFD) to achieve a high fidelity representation of extreme events. This aim is achieved by embedding deterministic wave groups into irregular wave trains with known responses to produce different states at the moment of wave group encounter. The new framework is demonstrated by predicting the probability of exceedence of roll with a 2-D midship section of the Office of Naval Research Tumblehome hull in Sea State 7. The framework showcases how CFD and CWG can together reduce the computational burden of predicting extreme ship responses.