Hamid Sadat-Hosseini

Computational ship hydrodynamics: Nowadays and way forward

Computational fluid dynamics for ship hydrodynamics has made monumental progress over the last ten years, which is reaching the milestone of providing first-generation simulation-based design tools with vast capabilities for model- and full-scale simulations and optimization. This is due to the enabling technologies such as free surface tracking/capturing, turbulence modeling, 6 degree of freedom (DoF) motion prediction, dynamic overset grids, local/adaptive grid refinement, high performance computing, environmental modeling and optimization methods. Herein, various modeling, numerical methods, and high performance computing approaches for computational ship hydrodynamics are evaluated thereby providing a vision for the development of the next-generation high-fidelity simulation tools. Verification and validation procedures and their applications, including resistance and propulsion, seakeeping, maneuvering, and stability and capsizing, are reviewed. Issues, opportunities, and challenges for advancements in higher-fidelity two-phase flow are addressed. Fundamental studies for two-phase flows are also discussed. Conclusions and future directions are also provided.

Recent progress in CFD for naval architecture and ocean engineering

An overview is provided of CFDShip-Iowa modeling, numerical methods and high performance computing (HPC), including both current V4.5 and V5.5 and next generation V6. Examples for naval architecture highlight capability and needs. High fidelity V6 simulations for ocean engineering and fundamental physics describe increased resolution for analysis of physics of fluids. Uncertainty quantification research is overviewed as the first step towards development stochastic optimization.

Evaluation of Seakeeping Predictions

Test cases related to seakeeping are studied in this chapter including heave and pitch with or without surge motion in regular head waves for KVLCC2 and KCS and wave diffraction and roll-decay with forward speed for DTMB 5415. For seakeeping, the total average error is E = 23 %D, comparable to the average error for previous seakeeping predictions. For resistance, the largest error values are for the 1st harmonic amplitude and phase (34 %D), followed by 0th harmonic amplitude (18 %D) and steady (7 %D). For motions, the largest error values are for the 0th harmonic amplitudes (54 %D), followed by 1st harmonic amplitude and phase (13 %D) and steady (9 %D). The errors for the CFD predictions are similar for the different geometries and wavelengths, the small and large amplitude waves, and for the cases with and without surge motion. The errors are larger for the cases with zero forward speed. Compared with potential flow, CFD showed larger errors for motions for the medium and long wavelengths. For wave diffraction submissions, the large grid size DES simulation has achieved an average error value of less than 10 %D, while for the small grid size URANS simulations the average error is 28 %D. For roll decay submissions, the average error values are 10 %D for resistance and less than 1 %D for roll motions.