Wave flume

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

Experimental study on wave forces to offshore support structures

Abstract: In this study, wave force tests were carried out for the four types of offshore support structures with scale factor 1:25 and wave forces to the support structure shapes were investigated. As the results of this study, it was found that, as the wave period increased at the normal wave condition, wave force decreased for the most cases. Extreme wave force was affected by the impact wave force. Impact wave force of this study significantly effect on Monopile and slightly on GBS and Hybrid type. Accordingly, Hybrid type indicated even lower wave force at the extreme and irregular wave conditions than the Monopile although Hybrid type indicated higher wave force at the normal wave condition of the regular wave because of the larger wave area of wave body. In respects of the structural design, since critical loading is extreme wave force, it should be contributed to improve structural safety of offshore support structure. However, since the impact wave force has nonlinearity and complication dependent on the support structure shape, wave height, wave period, and etc., more research is needed to access the impact wave force for other support structure shapes and wave conditions.

Numerical Modelling and Experimental Investigation on the Effect of Wave Attenuation Due to Coastal Vegetation

Abstract: Coastal areas are prone to natural disasters like tsunami and earthquake. The losses occuring due to these disasters are voluminous, since high population densities are generally located along the coastal region. The massive velocity and salinity of waves causes soil erosion and affect the structures present along the coastal belt. Coastal vegetation such as seagrass canopies acts as a natural barrier to soil erosion and to the wave impact. Seagrass is the most abundantly found marine species along the Indian coast. It is located at an ideal depth to dissipate the waves before reaching the shore. The use of seagrass as a buffer zone is gaining momentum in the field of coastal engineering as it also helps in conserving the ecosystem. This paper presents the wave attenuation due to seagrass by numerical modelling and experimental investigation. The Cymodocea Serrulata species (CSS) was selected for the study which is found in coastal regions of India like Palk Bay and Gulf of Mannar. Wave attenuation by the CSS vegetation for different wave heights and wave periods was studied. The numerical model for wave attenuation was created using Flow 3D software and artificial vegetation (silicon rubber tubes) was used for the experimental investigation carried out at wave flume in National Institute of Technology, Tiruchirappalli (NITT). Multiple waves were created from the numerical simulation by varying the wave heights, wave periods and transmitted wave heights at different meadow widths were recorded and analysed. The results of numerical modelling were compared with the experimental investigation. The submergence ratio increases from 0.47 to 0.53. The wave attenuation increases from 60 to 54% of that of original wave height. The model exhibits increased efficiency (the relative plant height (h/d)) in wave height reduction.

The interaction of small and finite amplitude long waves and currents

Abstract: The interaction of waves and currents is important for many engineering problems. For example, when considering forces on marine structures, the velocity and acceleration field must be defined, and thus the manner in which a current interacts with small and finite amplitude waves must be understood. When the current is large and oblique to the waves, the direction of the force on an offshore structure may change significantly with depth introducing a torsional moment. Wave refraction and the concomitant attenuation or amplification of waves are also affected by offshore currents. An example is the effect on incident waves of offshore currents induced by the discharge of cooling water from coastal-sited power plants. This current can modify the direction and magnitude of approaching waves, and by these changes the breaking waves at the shore and the nearshore sediment transport associated with these waves may be changed. A number of theoretical studies have been conducted on various aspects of wave-current interactions; see Peregrine (1976). One theoretical study, Thomas (1981), will be used in this investigation. Careful experiments in this area are limited; several are: Iwagaki and Asano (1980), Sarpkaya (1957), and Thomas (1981). Each of these has given attention to certain aspects of small amplitude wave-current interactions. The experiments are difficult to conduct because of the problems inherent in introducing waves into a flume with a steadyuniform current or conversely a current into a wave tank with permanent waves. Certain features of these experimental problems can be seen through the following two examples. If a plunger-wave machine were used and located at one end of a flume in which a steady current is flowing, although the waves would be developing as they interact with the current, the previously steady current would be changed to an unsteady one by the periodic blockage of the flow by the plunger. If the waves are generated at one end of the tank and allowed to develop, and a current is introduced from the bottom of the tank, this current must expand to the full depth of the flow; hence, the waves propagate on a developing current. Therefore, comparisons to theory are, to some extent, difficult to realize, because the theory generally assumes wavecurrent interactions when each is fully developed.

Laboratory Investigation on the Behavior of Reef Breakwaters

Abstract: An experimental investigation into the hydrodynamic behavior of reef breakwaters was carried out. The experiment aimed to provide full scale measurements of the main wave features at the front and rear of the breakwater, which have been analysed with variation of frequency and freeboard, for constant crest width and porosity. A series of tests was carried out at a 2-D wave flume. The analysis has shown that the reflection coefficient was a much more linear process than the transmission coefficient. The transmission coefficient was influenced mostly by the variation of the freeboard, in particularly, as the model became submerged.

Wave forces acting on model vegetation in water

Abstract: Laboratory experiments were performed to study the wave forces acting on model plants on the bed of two dimensional wave flume. The wave forces acting on the both directions of wave propagation (in line direction) and gravity were measured by using a two components load cell installed under the bed of wave flume. The influence of the ratio of plant height and water depth to the wave forces were evaluated. The drag and inertia coefficients of Morrison equation applied to the analysis of in line forces were obtained. The damping of waves due to the crowd of model plants are also evaluated.