Development and applications of the free-surface random vortex method (FSRVM)

Free-surface flows with viscosity are of importance in the field of naval architecture and offshore engineering. Vortex shedding is closely tied to the investigation of the roll motion of floating bodies. Prediction of forces on a bluff body also depends on modeling separated flows around it with accuracy. The Free-Surface Random Vortex Method (FSRVM) was developed to study these flow phenomena.; The objective of this work is to apply the FSRVM to study the interactions of surface waves and bodies. A FSRVM-based “numerical wavetank” is used to calculate forces on submerged bodies. To study the response of a freely-floating body in waves, the dynamic coupling between a rigid body and the fluid is formulated. To further improve the efficiency of the FSRVM, merger and decay of blobs are introduced to alleviate computational efforts of vortex interactions.; The numerical model is validated against experimental data for both submerged and floating bodies. For submerged bodies, the numerical wavetank is applied to study flows around bodies in regular and extreme waves. Results of forces, hydrodynamic coefficients, and simulated flows are presented. The calculated hydrodynamic coefficients agree well with experimental data for regular-wave cases. A case of extreme waves past a submerged body is presented to investigate effects of viscosity on the forces.; For floating bodies, transient response and freely-floating body motion in waves are studied. The calculated response histories are very consistent with theoretical and experimental results for transient heave and roll response. Response of freely-floating bodies in waves are studied for cylinders being either partially restrained or completely freely floating. The inviscid solutions of the FSRVM are compared with its viscous solutions to examine effects of viscosity. The motion response amplitudes obtained from solutions with viscosity agree well with experimental data for both cases of two- and three-degree of freedoms.; For the merger and decay models, it is shown that the proposed formulations yield solutions that are convergent to the original FSRVM solutions. The problem of vortex induced vibration is also studied, which shows that the calculated vortex shedding patterns agree with experimental observations.