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Title: The effect of free surface on classical ship hydrodynamics using RANSE : resistance, manoeuvring, propulsion, seakeeping and stability
Author: Gao, Qiuxin
ISNI:       0000 0004 2739 9445
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2012
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In this research, the Computational Fluid Dynamics (CFD) approach, based on the solution of the Reynolds Averaged Navier-Stokes (RANS) equations is used to study the classical ship hydrodynamic problems, all being affected markedly by the presence of free-surface, namely: ship resistance, propulsion, manoeuvring, seakeeping and stability, the latter focusing on flooding of a damaged ship. In this respect, this thesis represents a marked deviation from classical approaches and a unique contribution to ship dynamics and hydrodynamics. The RANS equations with SST K-w two-equation turbulence model and Volume Of Fluid (VOF) formulation were discretised by the finite volume (FV) method and the pressure-coupled governing equations were solved by the SIMPLE algorithm. The geometric reconstruction algorithm was adopted to locate transient free surfaces. The second order upwinding scheme was used for the discretisation of the convection flux and Multi-grid Acceleration was applied to improve convergence. In addressing ship resistance, grid sensitivity studies were carried out according to the “ITTC guideline of quality” manual. The computed results were verified and validated against available model test data. Additionally, the results of the effects of the turbulence models were investigated by comparing turbulence quantities predicted by SST K-w and RSM. In addressing ship propulsion, the propeller was modelled as an actuator disk of equivalent thrust and torque. Distributions of the body force were compared with results from a parametric study and the implementation of the body force approach was validated by model test data. In addressing ship manoeuvring, numerical PMM simulations of pure sway and yaw motions were performed. The numerical results were benchmarked against physical experiments. The computed hydrodynamic derivatives were compared with empirical formulae and subsequently implemented in manoeuvring simulations. In addressing seakeeping, incident waves were generated by a numerical wave maker and the computed results for wave diffraction were validated against physical measurements. Furthermore, RANS simulation for roll decay was undertaken and validated against results from model tests. Finally, a numerical roll tank was established to study the hydrodynamic coefficients of the roll motion in intact and damaged conditions and the corresponding results were compared with available model test data. In conclusion, systematic studies and ensuing results from numerical simulations of classical ship hydrodynamic problems using RANS demonstrated beyond doubt that CFD could and should play an important role in the design, analysis and evaluation of ship hydrodynamic performance. In addition, they provide unshakeable evidence of the level of capability to make the next important step: rendering CFD a routine "tool" in ship dynamics and hydrodynamics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available