| On the sandy coast,sandbar is an important part of the beach.Sandbars existing in near-shore zone make waves break far away from coastline,and protect beaches from wave attack;however,the mechanisms of the generation and the migration laws of sandbars are not obvious.The research on sandbar formation and migration is a significant subject for the coastal engineering,and important for the prevention of beaches from erosion and accretion. This paper studies sandbar motion by physical experiment.This paper presents different experiment results of sandbar motion under the actions of wave groups,regular and irregular waves.These experiment results show that under the action of irregular waves and wave group with amplitude modulationδ=1.0,sandbar stabilize at a place after moving offshore for enough time;under the action of wave group with amplitude modulationδ=0.5,0.25,sandbar mainly moves offshore and sometimes moves onshore;under the action of regular wave,sandbar always moves onshore and offshore alternately.For further studies on motion feature,sandbar's moving velocity is analyzed.The analysis presents under the action of regular waves and wave group with amplitude modulationδ=0.25,the direction of sandbar's moving velocity always changes between onshore and offshore and don't decay or grow;the action of irregular waves and wave groups with amplitude modulationδ=0.5,1.0,the direction of sandbar's moving velocity is offshore and exponential decrease.For helping understand the mechanisms of the generation and motion of sandbars, this paper presents experimental data set of suspended sediment concentration, cross-shore fluid particle velocity(including turbulent velocity) and water surface elevation,which were recorded simultaneously in surf zone under water wave.From these data,the suspended sediment flux in surf zone is obtained and the relationship between turbulent kinetic energy(TKE) and the sediment suspension events occurring under water waves was investigated...
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