Wave flume

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

The turbulent flow fields and vortex structures inside surf zone

Abstract: In order to understand the characteristics of turbulence due to wave breaking, flow visualization techniques are used to observe the external and internal flow structures. Two typical spilling and plunging breakers are made in wave flume. 2W Argon-Ion laser, and 120W ultraviolet lamps are used to brighten the tracing particles respectively. In this situation, not only the external structures of wave breaking can be visualized but also the instantaneous velocity of particles in the internal flow field will be outlined. Moreover, it is valuable to point out that the three dimensional flow structures inside surf zone are also found in our elaborated experimental studies.

Experimental Study on Bottom Topography Change in Harbor due to Tsunami

Abstract: Bottom topography change due to tsunami was experimentally investigated using a rectangular harbor model in a 2-D wave flume. Water surface level and velocity field were obtained as well to discuss the external forces. Accumulation region was observed in the middle of the harbor inside. Formed was conical bed topography. Erosion was around the accumulated region and at the breakwater head as local scour. These topography changes were caused by the tsunami-induced vortices inside the harbor and at the breakwater head.

Experimental study on bottom boundary layer beneath solitary wave

Abstract: A tsunami as long wave and an oscillatory wave moves into shoaling water have behavior similar to solitary wave and therefore comprehension on its bottom boundary layer characteristics come to be essential key on near-shore sediment transport modeling. In the present study, the hydraulics phenomena of solitary wave are studied in deep through experiments utilizing a closed conduit generation system. This result was examined by analytical and numerical laminar solution. Moreover, wave friction factor is discussed based on the present laboratory experiment and previous studies of (Sumer et al., 2010); (Vittory & Blondeaux, 2011, 2012). As conclusions, in-consistent critical Reynolds number was found for solitary wave case. This observable fact is distinct difference with sinusoidal wave case which has consistency in critical Reynolds number.

Study on Flow Field Around Vertical Breakwater Under Different Overtopping Conditions Based on Numerical Simulation

Abstract: A numerical wave flume is constructed based on the Reynolds Averaged Navier-Stokes (RANS) equations with turbulence closure by a modified k-e model to study the viscous interactions of waves with vertical breakwaters for different overtopping cases. The governing equations,the turbulence model,boundary conditions,and solution method for the numerical wave flume are introduced briefly. The reliability of the numerical wave flume is examined by comparing the numerical results with the experimental measurements,and good agreements between them indicate the validity of the present model. The developments of mean velocity fields,the contours of vorticity,and the influences of wave nonlinearity on turbulence field as wave passing through vertical breakwaters are discussed in detail based on the numerical results. It is noted that the vortices at the rear of the lower submerged breakwater are close to the bottom and maybe induce the scouring to the leeside toe of marine structure in practice. Over all,a conclusion can be obtained from this study that the turbulence in wave field around structure is induced directly by the development of boundary layer on the solid boundary,the nonlinear interaction of free surface with obstacle,and the plunging of overtopping waves.

Innovative measures to mitigate overtopping of coastal structures

Abstract: Overtopping of coastal structures which can be attributed to sea level rise and increased storminess is a major design issue. It is likely that many existing structures are undersized based on future predicted climate changes and will not be able protect shores from future coastal forces. Current structures may also become damaged due to the undermining of the structure as a result of regular overtopping. This can have disastrous effects on coastal areas and communities such as damage to properties, infrastructure, agriculture and loss of life. Ongoing research at the Hydraulics and Maritime Research Centre of University College Cork seeks to explore innovative ways of redesigning or modifying coastal structures such that to future protect them without incurring excessive cost or increasing crest levels beyond acceptable levels. Physical model testing has been undertaken in a 25m long wave flume using coastal structure models with a scale of 1:30. These tests examine two separate wave overtopping protection measures: 1. Changes to the crest detail of rubble mound coastal defence structures by incorporating a reservoir system is being researched as it is expected that this would reduce crest elevation but provide the same level of safety. This may be necessary due to site limitations or for aesthetic reasons. The rate of overtopping q is measured through the use of weir boxes at the back of each reservoir with each weir being of compound composition with a v-notch weir for lower flow rates and a trapezoidal weir for higher discharge rates. Calculation of the inflow discharge rate is based on the outflow discharge rate over the weir into an overflow tank. This is achieved through accurately measuring the water level in the weir boxes using twin wire conductance probes. There are numerous factors being examined such as different reservoir designs, slope of the coastal defence structure, water level and use of a geotextile within the structure. This research of these various parameters will create an overtopping equation which is specific to the structure and can be used for future design purposes. It also incorporates the possibility of extracting energy from the power of waves which enter the reservoirs. Initial indications are that the reservoir system reduces the crest elevations as compared to a standard designed structure. 2. Reduction of overtopping of existing structures by floating a wave absorbent geotextile matting seaward of the structure. It is envisaged that this material would mitigate overtopping by reducing the power of the incoming waves. The matting system will float at water level and will adjust depending on water level. It is attached to the structure by an anchoring system. There are many varying parameters that will be examined such as the geotextile material, porosity and strength. These parameters can have significant effects on the amount of overtopping that occurs and it is through this research and testing that the optimum and most efficient system can be developed. This is a conceptual idea and together with the reservoir system forms part of a research programme which is due for completion in September 2010.