Motions and hydrodynamics of a high-speed search and rescue vessel based on a time-efficient computational fluid dynamics procedure

Abstract

This thesis proposes a time-effective procedure for numerical prediction of the hydrodynamic performance of a small high-speed craft (HSC) for Search and Rescue (SAR) operations. Following a naval architecture review of available SAR designs, engineering physics and numerical methods for the evaluation of resistance and seakeeping are explained. A method that utilises Reynolds-Averaged Navier Stokes equations-based Computational Fluid Dynamics theory is utilised to predict calm-water resistance and wave-induced motions of a sample SAR vessel operating in regular waves. Simulations are performed using the Orca3D Marine CFD environment, utilising the Simerics CFD package. The method is validated against experimental results found in literature. The comparative study of calm-water resistance allows for analysing the influence of the hull shape on the performance of the craft. Seakeeping analysis is performed in one wave length. Head, oblique and following seas conditions are simulated. In head and oblique seas, obtained results in the time domain present periodic motions. Non-linear pitch motions are displayed, followed by amplitudes of motions calculations. High non-linearity of roll motions in oblique seas is observed. The thesis concludes that for less demanding cases, the proposed procedure offers a time-efficient method to estimate the hydrodynamic performance of the vessel with satisfying accuracy. Further research is required to optimise the method for obtaining results in following seas in an acceptable time frame.