Fluid Resonance Between Twin Floating Barges with Roll Motion Under Wave Action

The wave-induced fluid resonance between twin side-by-side rectangular barges coupled with the roll motion of the twin barges is investigated by both numerical simulation and physical model test. A 2D numerical wave flume, based on an open source computational fluid dynamics (CFD) package OpenFOAM, is applied for the numerical simulation. After numerical validations and convergent verifications, the characteristics of the fluid resonance in the gap between the twin rolling side-by-side barges are examined. The resonant frequency of the oscillating fluid in the gap between the twin rolling barges decreases compared with that between the twin fixed barges. Generally, the twin barges roll in the opposite directions, and their equilibrium positions lean oppositely with respect to the initial vertical direction. A physical model test is carried out for a further investigation, in which the twin barges are set oppositely leaning and fixed. From the present experimental results, a linear decrease of the resonant frequency with the increasing leaning angle is found. Combined with the numerical results, the deflection of the equilibrium positions of the twin barges is a relevant factor for the resonant frequency. Besides, the effects of the gap width and incident wave height on the fluid resonance coupled with roll motion are examined.

NUMERICAL STUDY ON MOVEMENT OF TSUNAMI BOULDER AND STORM BOULDER BY SPH METHOD

Smoothed Particle Hydrodynamics (SPH) is known as very useful method for large deformation problems, such as movement of wave absorbing blocks and sliding of caisson breakwater. Also, in the coastal area, boulders launched by tsunami and by high waves with typhoons (named tsunami boulders and storm boulders) are focused on because of risk assessment towards the tsunami or super typhoons. However, the difference of their movement mechanism have been rarely investigated in detail. This study aims to simulate the movement of the tsunami boulders and storm boulders, comparing with the hydraulic experiment, and evaluating the transport characteristics. Wave elevation and boulder displacement were reproduced in the numerical wave flume well compared to physical model. Also, there is difference between solitary and irregular waves when waves act on boulders.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/WOfXbU7m_8E

Performance Assessment of Three Turbulence Models Validated through an Experimental Wave Flume under Different Scenarios of Wave Generation

This study aimed to adjust the turbulence models to the real behavior of the numerical wave flume (NWF) and the future research that will be carried out on it, according to the turbulence model that best adjusts to each particular case study. The k-ε, k-ω and large-eddy simulation (LES) models, using the volume of fluid (VOF) method, were analyzed and compared respectively. The wavemaker theory was followed to faithfully reproduce the waves, which were measured in an experimental wave flume (EWF) and compared with the theory to validate each turbulence model. Besides, reflection was measured with the Mansard and Funke method, which has shown promising results when studying one of the most critical turbulent behaviors in the wave flume, called the breaking of the waves. The free surface displacement obtained with each turbulence model was compared with the recorded signals located at three points of the experimental wave flume, in the time domain of each run, respectively. Finally, the calculated reflection coefficients and the amplitudes of the reflected waves were compared, aiming to have a better understanding of the wave reflection process at the extinction zone. The research showed good agreement between all the experimental signals and the numerical outcomes for all the turbulence models analyzed.

Experimental and Numerical Investigations on Wave Dynamics of a Dual-Chamber OWC Wave Energy Device

Oscillating Water Column (OWC) wave energy device is one of the most studied and applied wave energy converters (WECs). The survivability of WECs is a major concern in the OWC design. In this study, the wave dynamics of a dual-chamber OWC device is numerically and experimentally investigated. The experimental tests were carried out in the wave-current flume at the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. A fully nonlinear numerical wave flume based on potential-flow theory and time-domain higher-order boundary element method (HOBEM) is developed and applied to simulate the interaction between air, wave and the dual-chamber OWC device. The numerical model is validated by comparing the simulated wave induced pressure on the barrier walls with the measurements. Then the wave forces and the moment on the device is numerically investigated. The model and experimental results indicate that the horizontal wave force on the front barrier wall is much larger than that on the internal barrier wall. The joint between the back wall and the ground withstands the largest bending moment, therefore, is most vulnerable to structure damage and fatigue.