ABSTRACT

Wave height distributions around a large cylinder due to wave-current interactions were investigated experimentally. Various experimental conditions were achieved through combinations of wave characteristics, current velocities, and different intersection angles between waves and current. Water depth was kept constant throughout the experiments. Time histories of the water surface elevation around the cylinder were measured and analyzed. Results were compared with numerical simulations, and qualitatively good agreements were found.

INTRODUCTION

Moving toward a large structure, waves are both reflected and diffracted. In shallow waters, the effect of refraction can play an important role in changing wave characteristics. The problem complicates itself even more in estuaries, where flows with different characteristics such as tidal and oceanic current must also be taken into consideration. With increasing engineering activities in coastal regions nowadays, accurate prediction of wave loads and the responses of large structures under the combined action of waves and currents have become progressively important. Since 1960, theoretical and experimental studies have advanced our knowledge in understanding the complexity of wave-current interaction. The first theoretically adequate description was proposed by Longuet-Higgins and Stewart (1960,1961), who introduced the concept of radiation stress. The effects of a following or opposing current on the propagation of linear waves were thoroughly reviewed in Peregrine (1976). Numerical and experimental studies reported by Thomas (1981) deal with linear waves interacting with currents. Peregrine and Jonsson (1983) presented a comprehensive review of the works on wave-current interaction up to the date of December 1981. Baddour and Song (1990) described the interaction of linear waves and uniform collinear currents. A comparison with the experimental results reported by Thomas (1981) was also given by them. Recently, Supharatid et al (1992) investigated interactions between waves and current based upon LDV and hot-film measurements.

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