Experimental study on solitary wave attenuation by emerged vegetation in currents

Abstract

An experimental study was conducted to investigate the effects of currents on solitary wave attenuation by rigid vegetation. In the experiments, the vegetation was simulated by cylinders, and the oscillation of cylinder was ignored. The experimental results showed that vegetation could effectively attenuate solitary wave. In positive currents, the wave attenuation rate in vegetation zone increases with increasing current velocity. However, in oppositive currents, the wave attenuation rate does not vary monotonously with increasing current velocity. The ratio of current velocity to the horizontal velocity of solitary wave has influence on wave attenuation effects in vegetation zones. For a small velocity ratio, positive currents would enhance wave attenuation due to vegetation, while oppositive currents weaken it. For a larger velocity ratio, wave attenuation due to vegetation is increased in both positive and oppositive currents. The solitary wave attenuation rate due to vegetation increases with increasing velocity ratio when velocity ratio is larger than the value at the transition point in both positive and oppositive currents. Moreover, positive currents increase the attenuation of solitary wave velocity in vegetation zone up to 46% while oppositive currents decrease it up to 23% compared to those in the absence of currents in the experiments.