Showing papers on "Wave flume published in 1987"
TL;DR: A review of previous work precedes a description of laboratory tests in a 103m-long wave flume at Canada's National Water Research Institute as discussed by the authors, where pressure transducers and surface-piercing capacitance wave probes were used to collect data in water depths of 0.9 and 1.2 m with monochromatic and irregular waves.
166 citations
TL;DR: In this article, a simple and inexpensive method is proposed to measure time-averaged concentrations under waves, which is defined by sucking samples in a direction normal to the ambient water motion at an intake velocity which exceeds the ambient flow velocity more than three times.
77 citations
01 Oct 1987
TL;DR: In this article, a laboratory study was carried out to extend the knowledge of the basic phenomena of sediment transport, and sediment concentrations have been measured in case of irregular non-breaking waves alone, and in combination with following or opposing currents.
Abstract: In many coastal, engineering problems the sediment transport plays a part. A transport gradient causes accretion or erosion. Various models, such as that of Bijker, Engelund and Hansen (van de Graaff and van Overeem, 1979) and Nielsen (1985) are available to estimate the sediment transport rate if the hydraulic and environmental conditions (wave height, current velocity and direction, sediment size) are known. Since reliable data under field conditions are extremely scarce, the reliability of these models is not known, while also no understanding of the basic relations between the sediment transport, current velocity and wave height can be obtained. To extend the knowledge of the basic phenomena, a laboratory study was carried out. Fluid velocities and sediment concentrations have been measured in case of irregular non-breaking waves alone, and in combination with following or opposing currents.
22 citations
01 Jan 1987
TL;DR: In this paper, the appropriate variables necessary for computation of sediment transport are grouped into a few dimensionless force ratios using the techniques of dimensional analysis, forming a sediment transport model, and the results suggest that the appropriate power of fluid velocity necessary for computing and transport may itself be a function of the flow intensity.
Abstract: : Sand transport as bedload on nearly flat beds in shallow water outside the breakers is the subject of this study. The appropriate variables necessary for computation of sediment transport are grouped into a few dimensionless force ratios using the techniques of dimensional analysis, forming a sediment transport model. Field experiments measuring fluid velocity and sand transport were performed seaward of the breaker region. Fluorescent sand tracer was used to measure both sediment-transport velocity and thickness. Thirty tracer experiments were performed under differing wave and sediment conditions. Transport thickness is well correlated with orbital diameter but not wave height or fluid velocity. Different powers of the fluid velocity are compared with sediment transport. The lower velocity moments perform much better than the higher moments. Use of a threshold criterion is essential in predicting whether the sand transport is onshore or offshore. Results suggest that the appropriate power of fluid velocity necessary for computing and transport may itself be a function of the flow intensity.
14 citations
TL;DR: In this article, a practical method has been formulated to predict the second order wave loads on large offshore structures, including cylinders and square caissons, and the theoretical predictions have been compared with the experimental measurements and the comparison shows good agreement.
7 citations
01 Apr 1987
TL;DR: In this article, a brief outline of the way in which waves and currents have traditionally been treated in the offshore design process is given, focusing on three unsatisfactory features: i) the arbitrary selection of one of a range of inequivalent wave kinematic theories; ii) the lack of a sound theoretical basis for extension of the current velocity profile above the mean sea level up to the wave crest, and iii) the neglect of any interaction between the wave and current flows, both in the measurement of currents in the wave zone and in calculations of the total fluid flow.
Abstract: A brief outline is given of the way in which waves and currents have traditionally been treated in the offshore design process. Emphasis is put on three unsatisfactory features: i) the arbitrary selection of one of a range of inequivalent wave kinematic theories; ii) the lack of a sound theoretical basis for extension of the current velocity profile above the mean sea level up to the wave crest, and iii) the neglect of any interaction between the wave and current flows, both in the measurement of currents in the wave zone and in calculations of the total fluid flow. This paper reports some developments in non-linear wave-current interaction theory which promises to help resolve these problems.
5 citations
TL;DR: WAVE as discussed by the authors is a FORTRAN-77 program for two-dimensional simulation of onshore-offshore transport of sand caused by oscillatory wave motions, which is limited to the nearshore area, seaward of the breaker zone, where onshore offshore transport dominates.
4 citations