Wave flume

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

Experimental and Numerical Studies on Wave-Induced Instability in Suction Caisson Foundation Founded in the Seabed

Abstract: This extended abstract presents both experimental and numerical studies on the instability of suction caisson foundation founded in a dense non-cohesive seabed. A series of model scale wave flume tests were conducted to investigate the instabilities of both rectangular and circular suction caisson foundations subjected to various wave conditions. The pore water pressure responses around the caisson tip and across the caisson top cap were measured during the tests. A two-dimensional finite element tool, namely SWANDYNE II, was employed to verify the observed pore pressure responses around the rectangular caisson in the tests. The linear elastic finite element solutions successfully verified the hypotheses observed from the wave flume tests.

Interfacial wave motion in an impermeable rigid channel with stratified density fluid system,2,Waveform feature against stratification thickness ratio

Abstract: This paper presents the results of a series of laboratory experiments on internal solitary wave in a two-layer fluid system.The internal solitary waves(ISWs) of variable amplitudes and types were experimentally arranged from several physical variables,including the different layer thickness ratios H1/H2,the interface differences ηo, and the density ratios ρ1/ρ2.The wave flume used in this experiment is 12 meter long with a cross-section 0.5 m wide and 0.7m in height.Five ultrasonic probes placed at equidistance record the interface fluctuations.The data collection and processing were carried out through control software,Multi Nodes Data Acquisition System(MNDAS).This paper reports physical properties related to wave propagation.By comparing the relationship between nonlinear parameter and characteristic wave frequency,experimental results agreed well with the KdV and mKdV solutions.

Numerical Wave Flume with Immersed Boundary Method and its Applicability in Wave Field Simulation around a Horizontal Circular Cylinder

Abstract: In this paper, we present a new numerical wave flume model capable of handling interface problems with complex geometry on a standard regular Cartesian grid, using immersed boundary method. Force terms are incorporated to the momentum equations to represent the interface on a fixed Cartesian grid and they are calculated on a finite number of Lagrangian points distributed over structure-fluid interface. The wave field around a horizontal circular cylinder has been chosen in order to validate applicability of the proposed numerical wave tank model. The calculated wave forces acting on cylinder are compared with previous experimental and numerical results. Results show that the proposed model gives good agreement with experimental results.

Scour below the toe of breakwaters: Investigation of scour formation through a geometrically open filter configuration located at the toe of a rubble mound breakwater lying upon sand

Abstract: Scour formation at the toe of a rubble mound breakwater can lead to abrupt failure. Nowadays, counteraction of scour via geometrically closed filter rules, geotextiles or combinations is the common practice. Alternatively, in specific cases the use of geometrically open filters can save significant amount of time and decrease constructional costs. As a primary step towards this direction, the prediction of scour formation through a geometrically open filter can provide important information. Nevertheless, at this moment the knowledge upon this issue is insufficient and limited. A variety of recommendations occurs in literature, separately for toe design/scour protection and for the application of open filter criteria; however none of the studies treats these subjects combined. Therefore the objective of the present thesis is to get insight into scour formation and development through a breakwater toe lying upon sand and designed as a geometrically open filter. Thereby the research aims in drawing the link between scour characteristics with wave loading and filter configuration properties. In order to accomplish the research objective 2D physical model tests were conducted in the 25m long, 1m deep and 0.6m wide wave flume of DMC, installed in the company’s laboratory. In total, 23 tests were executed with irregular waves (Jonswap spectrum) and by varying wave loading and filter configuration properties. In particular, 5 different filter/base layer combinations were examined and 3 different wave conditions were used to investigate the effects of relative grain diameter, relative filter thickness, grading of filter layer, base layer stability Number and storm duration. Quantification of damage magnitude was accomplished via laser profile measurements of filter and base layer prior and after the execution of each test. Furthermore, wave particle velocity climate was determined via the use of an Electromagnetic Flow Meter (EMS) placed at the center of the toe. Finally, temporal evolution scour was captured through the side glass and was examined by digitizing and analyzing snap-shots from predefined time steps. Test results and observations have revealed the highly spatial character of scour formation. Nevertheless, tests with identical boundary conditions showed a surprising convergence in averaged maximum scour depth magnitude. In addition, in the majority of tests an S-curve erosion/deposition pattern was shaped while erosion started immediately at the downstream side of the box threatening breakwater stability. Equilibrium maximum scour depth was reached for less than half the data set; thus erosion process was still in progress. Based on this, two approaches were developed to investigate temporal evolution of scour. Furthermore, dimensional analysis and literature review have revealed the most important parameters that have significant effect in scour formation; their combination has led to the formation of a prediction tool. However, combination of the results from tests with different base materials would not be possible without the introduction of the base material stability Number (critical Shields’ Number). The derived tool is an empirical expression with limited physical background and range of validity. Additionally, it overestimates maximum scour depth due to a serious model effect; the different buoyancy between filter and base layer that was causing initial damage and damage exaggeration. Nevertheless, it is capable of delineating the relative contribution of each parameter in scour depth formation. For an overall view of scour formation, further research will be needed to provide a more accurate quantification of the interrelation between parameters that play a role in scour formation and development, and to implement the effect of missing parameters. Consequently the use of the derived expression as a scour prediction tool in real life is not yet recommended.

Research on Change Laws of Pore Water Pressure of Soft Clay in the Large-scale Wave Flume

Abstract: The study on the interaction between wave structure and soft clay foundation is carried out in the large scale wave flume trough of the Academy of communications and transportation under the construction of the research on the failure mechanism and design parameters of the port hydraulic structure under the harsh hydrology condition. The remolding technology of the soft clay foundation of the Yangtze River mouth is studied. The model test scale of is 1:5. In the test, the strength of the original soil can be reduced to the similarity of the test phenomenon. The soil strength is reduced by increasing the water content of the original soil, and a series of tests are made on the characteristics of the original soil. The strength of soil increases with the increase of static time. The early growth is fast and the later growth is slow. In the experiment, the soil pressure and pore water pressure sensor were arranged to observe the change rule of soil pressure and pore water pressure under the action of wave. By arranging water pressure sensor and laser displacement sensor, the force and settlement of the structure of the semicircle caisson were observed. In this paper, the variation rule of earth pressure and pore water pressure under different wave heights and longtime waves are studied. The pore pressure and soil pressure change with the wave action, the influence of pore pressure increases with the increase of wave height. Maximum pore pressure occurs at a certain depth of soil. The change in pore pressure is irregular. After a certain value is reached, the soil is softened and destroyed.