Wave flume

About: Wave flume is a research topic. Over the lifetime, 1627 publications have been published within this topic receiving 23335 citations.

Numerical simulation of water wave impacts using a navier-stokes solver

Abstract: The calculated results for the violent impact of water waves onto rigid stationary coastal structures are presented in this paper. The simulation is performed in a numerical wave flume using our recently developed in-house Navier-Stokes solver([4]) named LVOF. It is a VOF finite volume approach that incorporates the surface tension effects, coupled with a dynamic subgrid-scale (SGS) turbulence model. Test cases concern a combination of wave propagation, shoaling, reflection, diffraction, breaking and overtopping after impact. Additionally, the effects of a current on wave-structure interactions are investigated, including the study of the influence of viscosity on the wave boundary layer under breakwater and the 3D effects. Our results demonstrate that our solver can describe most of the significant features of motions induced by regular and irregular waves. In particular, the shape of the free surface agrees well with measurements under grid refinementscaptured and even during lengthy computations.

Investigations of Wave-Induced Turbulent Structures in Vegetated Flows

Abstract: The role of coastal vegetation in mitigating shoreline erosion by damping of incoming waves and the resultant effect on sediment transport is a critical area of coastal management research. However our understanding of the underlying hydrodynamic processes is limited. Laboratory flume experiments were conducted where a naturally grown emergent vegetation channel and a vegetation-less sand channel were exposed to regular waves. Wave height data was collected using wave gauges located at various points along the channel in the direction of oncoming waves. Acoustic Doppler Velocimeters (ADVs) placed at various depths in the water column measured wave orbital velocity signatures. This thesis investigates the wave-damping phenomenon of the vegetation and attempts to quantify it using the wave attenuation factor. Variation of plant drag coefficient with distance in the vegetation field as well as dependence with Reynolds number, Keulegan Carpenter number and the Viscous Frequency Parameter â are investigated. Horizontal and vertical orbital velocity signals from ADV measurements were analyzed and variation of turbulent kinetic energy with depth has been presented. Comparisons with Linear and Stokes Wave Theory predicted values, calculated using wave height data from wave gauges, were made to understand the turbulence generated by the vegetation bed under wave action. Frequency analysis of the power spectra of wave orbital velocities was used to separate the wave and turbulent portions from the total component of the velocity and has been separately studied to understand the depth variation of the turbulent structures. Wave attenuation factor decreased with increasing distance in the vegetation field while the drag coefficient remained almost constant after a couple of meters. The drag coefficient decreased with both Reynolds number and Keulegan Carpenter number. The observed orbital velocities were less than the wave theory predicted values with the horizontal component showing a zone of decreased attenuation in the mid-depth region, while the vertical velocities showed greater attenuation near the free surface. This work advances the existing knowledge base of vegetative wave attenuation and turbulence studies involving emergent vegetation canopies under regular wave action by employing natural vegetation effects in the laboratory environment as an unique feature of the experiment.

Experimental Investigation of the Wave Force on the Caisson According to Different Coverage of Armor Units

Abstract: This study experimentally investigated the change of wave force on front wall of the caisson according to different coverage of Tetrapods. Physical experiments were conducted in a two-dimensional wave flume by generating regular waves of different heights and periods by changing the coverage rate of Tetrapods that are placed in front of the caisson model. The front wall of the caisson model was composed of a number of segments to measure the local wave force at different elevations independently. The measurement was carried out by using uni-axial load cells and pressure transducers as well. The measured wave forces were compared with the estimates of Goda’s formula. It was clarified that the wave force on partially-covered caisson is significantly greater than Goda’s formula, especially around top sections of the caisson, probably due to occurrence of impulsive wave loading on the structure.

Extended elliptic mild slope equation incorporating the nonlinear shoaling effect

Abstract: The transformation during wave propagation is significantly important for the calculations of hydraulic and coastal engineering, as well as the sediment transport. The exact wave height deformation calculation on the coasts is essential to near-shore hydrodynamics research and the structure design of coastal engineering. According to the wave shoaling results gained from the elliptical cosine wave theory, the nonlinear wave dispersion relation is adopted to develop the expression of the corresponding nonlinear wave shoaling coefficient. Based on the extended elliptic mild slope equation, an efficient wave numerical model is presented in this paper for predicting wave deformation across the complex topography and the surf zone, incorporating the nonlinear wave dispersion relation, the nonlinear wave shoaling coefficient and other energy dissipation factors. Especially, the phenomenon of wave recovery and second breaking could be shown by the present model. The classical Berkhoff single elliptic topography wave tests, the sinusoidal varying topography experiment, and complex composite slopes wave flume experiments are applied to verify the accuracy of the calculation of wave heights. Compared with experimental data, good agreements are found upon single elliptical topography and one-dimensional beach profiles, including uniform slope and step-type profiles. The results indicate that the newly-developed nonlinear wave shoaling coefficient improves the calculated accuracy of wave transformation in the surf zone efficiently, and the wave breaking is the key factor affecting the wave characteristics and need to be considered in the nearshore wave simulations.